I'm Christine Lindenboom, Senior Vice President of Investor Relations and Corporate Communications. We're pleased that you've tuned in to hear about our progress across our portfolio. Turning to our agenda, you can see that we have a very exciting lineup of presentations scheduled during our time together, with some strategic perspective on how we are building our business and executing towards our R&D strategy to deliver our goals. We will then turn to deep dives on different elements of our pipeline, spanning from our early- and mid-stage pipeline to progress with zilebesiran as a potential treatment for hypertension, before closing with some R&D and commercial perspectives on our leading TTR franchise. A few quick reminders before we dive in. This event is scheduled to run until 12:45 P.M., and we've incorporated a break into the agenda. We'll be hosting two live moderated Q&A sessions during the meeting.
To ask a question, please type your question in the Q&A box on your screen. A replay of today's session will be available on the investors page of our website later today. During the course of our meeting, we will be making forward-looking statements. For additional information, I encourage you to review the most recent SEC filings posted in the investor section of our website. Finally, I'd like to thank our external speakers, Dr. Werring and Dr. Touyz, for joining us, and I'd like to share some additional information about their disclosures here. With that, I'd like to turn it over to Akshay. Akshay?
Good morning, everybody, and welcome to Alnylam's 2023 R&D Day. I'm Akshay Vaishnaw. In my role as Chief Innovation Officer, over the course of the morning, my colleagues and I will take you through a very exciting set of presentations outlining our R&D strategy and overall progress. We'll be sharing data conveying Alnylam's clear leadership of the RNAi space and how that has led to one of the most exciting pipelines in biopharma. You'll also learn why we think we're still at the earliest stages of writing the Alnylam story. Today, we'll share the next chapter. In this chapter, we hope to extend our leadership by reaching more tissues beyond the liver and CNS, and dramatically increase our pipeline, with the goal of filing a significant double-digit number of INDs or CTAs in the next 12-24 months.
With that, let me turn to a landmark accomplishment that continues to inspire me and also serves as an excellent backdrop to the Alnylam story. We all remember publication of the first draft of the human genome in 2000. The Mirror, a British tabloid known for its headlines, quipped, "It's one small piece of man, one giant leap for mankind." In that pun, there is, however, an important grain of truth, namely, that the first draft in that 2000 Nature paper equated to another momentous leap for mankind in 1969, when Neil Armstrong stepped off the Lunar Module onto the Moon. The reason for thinking about the two in the same breath is that deciphering the human genome has given us a potential, a powerful potential roadmap to understanding the full Genetic basis of human disease.
Indeed, work over the last 20+ years, spurred on by the human genome advances, has led to a much deeper understanding of the molecular basis of disease. Although you can't easily see in this figure, it nevertheless serves to remind us that now we have knowledge of hundreds of Genetically validated targets for rare and common disease, targets which were simply unknown prior to 2000. But despite the availability of those targets, the ability to drug them using existing modalities such as small molecules and antibodies, remained limited, and so the need for new modalities to address the burgeoning list of targets was clear. Fortunately, in 2001, just after the Nature publication, a powerful new endogenous cellular pathway to an RNA interference or RNAi was described. This pathway could silence any Gene in the genome, and with siRNAs acting at the mRNA level, enabling upstream intervention of today's medicines.
In fact, to the scientific founders of Alnylam, a new door appeared to open with RNAi, namely, a way to address Genetic targets using Genetic medicines. With that, Alnylam was founded in 2002 to discover, develop and commercialize RNAi therapeutics. Since then, we've significantly fulfilled the promise of our founder's vision via focused R&D strategy, developing RNAi therapeutics against Genetically validated targets in the liver, utilizing proprietary delivery solutions such as LNPs and GalNAc conjugates. To date, and as shown on the right here, five transformative drugs have resulted for diseases ranging from the rare to the prevalent. We're gratified by the fact that these advances in creating a whole new class of medicines have been recognized both by regulators, with this snapshot showing FDA's acknowledgment upon the original ONPATTRO approval, and in the literature by academics.
But with those accomplishments behind us, the question that remains is: What is the path to realizing the full potential of RNAi to treat human disease? The answer to that question lies here in the three panels, which represent a powerful scaling of our original liver-focused R&D strategy. So we now aim to, A, via extrahepatic advances delivered to many new tissues. Indeed, we have the ambition to reach all major tissues by the end of the decade. B, via platform advances, work on the fundamental designs of siRNAs in an attempt to make them yet more safe, efficacious, and convenient. And C, via access to large databases, harness the power of human Genetics to continue to identify Genetically validated targets.
In the short term, over the next 12-24 months, we're now guiding that we'll file Alnylam proprietary INDs for nine or more programs, including five to the liver, two CNS, and two more targeting novel tissues, namely adipose and muscle. If we include partnered programs, the total number of INDs anticipated is 15 or more by the end of 2025. I hope you agree that is a very significant resizing of the Alnylam pipeline. Let's now turn to the specifics of how we're going to do that, which gives me the opportunity to walk through today's agenda. We'll begin with my colleagues, Vasant Jadhav and Karyn Schmidt, reporting progress we've made with innovative delivery solutions for the CNS, including preliminary preclinical evidence for our drugs crossing the blood-brain barrier, and novel conjugates for muscle and adipose tissues.
In addition, Vasant will highlight how continuing work on sRNA fundamentals aims to further enhance the pharmacological and clinical profile of our drugs. Then, Paul Nioi and Anna Borodovsky will outline how we're using platform and delivery advances to further build a Genetically validated pipeline across rare specialty and prevalent disease areas. You'll see why we think we're on track to deliver five new liver INDs, where some of the indications include cholestatic disorders, for example, primary biliary cirrhosis, a range of bleeding disorders, as well as obesity and type 2 diabetes. They'll also discuss details of work towards two muscle and adipose-targeted INDs to address, once again, Genetically validated targets, which complement our work in the metabolic space. Finally, we'll turn to expansion in our CNS pipeline with Regeneron.
To that end, Kirk Brown will discuss how we went from a powerful preclinical POC to our first CNS-directed program, ALN-APP, and its initial human phase I POC described earlier this year. Kirk will go on to discuss next steps with ALN-APP, most importantly, the initiation of a phase II study in cerebral amyloid angiopathy or CAA. We're delighted to be joined today by Professor David Werring, an expert neurologist with a deep understanding of this disease, who'll describe the unmet need and clinical picture in CAA. Kirk will then close by sharing work on four new CNS targets, which leverage the encouraging clinical translation of ALN-APP, and how we aim to file two or more CNS INDs in the next 12-24 months. Turning then to clinical progress, which has continued at pace since our last R&D Day. We'll begin with zilebesiran, which we are developing for hypertension.
We're fortunate to have with us today, Dr. Rhian Touyz, one of the world's leading experts on that disease. Dr. Touyz will discuss the continuing nature of high unmet need in hypertension, how poor control leads to it being the number one factor in cardiovascular morbidity and mortality, and the urgent need for new therapies. My colleague, Simon Fox, will then walk you through the latest developments in the zilebesiran program, including completion of the phase I study and its publication in the New England Journal of Medicine, our 12th such publication in that prestigious journal. He'll also cover the very exciting recent data from the first of the phase II studies, CARDIA-1. The phase II data confirm what we learned in phase I and suggest the very exciting possibility of a Q6-monthly subcutaneous zilebesiran injection, delivering a transformative approach to the management of blood pressure.
The phase II data are also propelling us into late development, and Simon will cover further zilebesiran plans for phase II and beyond. Finally, our TTR franchise, which has been so crucial in helping patients with hATTRPN, and where we await with great anticipation the readout of our ATTR-CM study, HELIOS-B. John Vest will cover the evolution of the TTR cardiomyopathy space from the unmet need as we currently perceive it, to the positive learnings from the Apollo B study, the phase three study of patisiran in ATTR-CM, and how those data inform expectations of vutrisiran in the HELIOS-B ATTR-CM study. Importantly, the discussion will highlight why we continue to be very confident about HELIOS-B, which reads out in early 2024. We always endeavor to incorporate platform advances into our drugs in an attempt to develop the optimal product profiles for patients.
In that regard, ALN-TTRsc04 utilizes our IKARIA technology for optimized potency and durability. My colleague, Ali Murad, will report striking TTRsc04 phase I data, showing highly durable TTR knockdown, with up to 97% target suppression, and also further development plans and timelines, given the strength of those data. We're happy to have with us today, Tolga Tanguler, our CCO or Chief Commercial Officer, who will close out this TTR section by reviewing our progress with the TTR franchise to date and how pending positive data from HELIOS-B will further extend our leadership in this space. Finally, Yvonne will bring R&D Day to a close by reviewing the highlights of the day and also sharing with you our exciting goals for 2024. In closing, I want to say two things.
First, this pipeline chart you see today of five approved RNAi therapeutics and 16 proprietary and partnered programs across four therapeutic areas stands to be dramatically scaled over the next 12-24 months as we aim to file another 9 or more programs to the clinic, with targets across four tissues. That number, of course, increases to 15 or more if we count our partnered programs. That is exciting indeed, and constitutes the next chapter for RNAi Alnylam. The second and last thought I want to leave you with is nicely summarized on this slide. We believe we have that rarest of things in biopharma, an organic, sustainable model for innovation. With continued access to novel, Genetically validated targets and the tissues we can deliver to, we look forward to adding many more transformative agents to the five already contributed by Alnylam.
With that, let me now invite Vasant Jadhav to kick us off. Vasant?
Thanks, Akshay. Hello, everyone. My name is Vasant Jadhav. I am Alnylam's Chief Technology Officer. My colleague, Dr. Karyn Schmidt, and I will describe how exciting advances in platform technology innovation extend Alnylam's RNAi leadership and will enable us to sustainably expand our pipeline. We have previously outlined our sources of innovation. These three pillars include extrahepatic delivery, enabling rapid knockdown in tissues like CNS, muscle, and adipose. Platform designs like IKARIA with annual dosing potential, and human Genetics expertise to identify therapeutic targets of interest. All of these sources of innovation directly contribute to the advancement of a robust pipeline in a sustainable fashion, where by the end of 2025, we plan to advance nine new INDs. That number becomes 15 new INDs when we include partner-led programs. Let's begin with the update on extrahepatic delivery. Our goal for extrahepatic delivery solutions is to be best in class.
So how are we accomplishing that? First, extensive know-how from our previous delivery efforts. Second, investment in our core capabilities to discover and advance targeted delivery solutions. Third, exploring wide range of ligands for delivery, from small molecules, lipids, and peptides to large proteins, including antibodies. Similar to our GalNAc platform, we are discovering delivery solutions that allow for subcutaneous dosing, rapid knockdown with an ED90 of 3 mg/kg or less, and efficient manufacturing, allowing for lower cost of goods. We believe that these will provide highly competitive, best-in-class delivery solutions for tissues of interest. The wonderful thing about the naturally occurring RNAi mechanism is that it allows for rapid knockdown of any target in all tissues and cell types. We have shown utility of RNAi for liver and CNS targets. Now, we have prioritized muscle and adipose and several additional tissues: kidney, heart, lung, and eye.
Long term, we'll be able to rapidly knock down targets in every organ. For today, we will share additional progress in CNS delivery and DC-enabling advances in adipose and muscle delivery. Let's begin with CNS delivery. We were thrilled to see the human translation of our C16 platform in the CNS. It was just last year when we published the preclinical work in Nature Biotechnology. In reality, it was an effort 20 years in the making, building upon the lessons learned from liver delivery about ligand and linker optimization, and siRNA modification designs optimized for in vivo activity and importantly, specificity. Earlier this year, we shared this exciting data from our ALN-APP program. The beauty of modular and reproducible platform is that the technology is Generalizable across targets.
As demonstrated here in data from NHP experiments, the C16 platform is both modular and capable of rapidly knocking down any desired CNS target, even targets expressed deep in the brain striatum. In humans, we have seen impressive rapid knockdown via intrathecal dosing with ALN-APP at doses as low as 15 milligrams. This unprecedented potency bodes well for exploring systemic delivery across the blood-brain barrier, as very little drug goes a long way in the CNS. In fact, we have initial data shown here in mice with systemic dosing of antibody siRNA conjugate. We see rapid and durable knockdown of more than 50% in different brain regions. This is also reflected in improved CNS exposure by about 10- to 15-fold versus control conjugate. We are excited to see this data and are continuing to optimize this approach further.
Another important tissue for diseases such as obesity, diabetes, metabolic syndrome, and others is adipose. Data shown here represent our novel adipose-targeting conjugate platform. We see uniform distribution in adipose depots that result in dose-dependent rapid knockdown with IV dosing. Very importantly, we see comparable activity with subcutaneous dosing at doses as low as 0.5 mg/kg. As expected, we continue to see long duration of activity with these conjugates. In NHPs, we also achieve robust and durable knockdown by this novel conjugate using subcutaneous dosing. Another key feature of these conjugates is minimal activity in other tissues, such as liver. We believe this profile is ideally suited for advancing programs for adipose targets and are actively working towards several development candidates in 2024, and our first IND in adipose by the end of 2025.
Now, having provided this brief update on CNS and adipose, we'll share advances in muscle delivery. We have taken a systematic approach to find the best-in-class delivery solutions with a differentiated profile. To walk you through this systematic approach, I will now turn it over to my colleague, Karyn Schmidt. Karyn?
Thank you, Vasant, and it is a pleasure joining you all today. My name is Karyn Schmidt, a Principal Scientist on the research team here at Alnylam. In the next few slides, we will cover our recent advancements to achieve targeted delivery to skeletal muscle. As Vasant highlighted, our goal is to develop GalNAc-like solutions, meaning high potency with subcu dosing, to enable a 2024 development candidate. Like others in the field, our first example, shown here, uses a novel receptor-targeting antibody optimized for affinity, directly conjugated to the siRNA. To date, antibody delivery of siRNA to muscle has required IV administration of very high doses of antibody, around 40 mg per kg, similar to the high 5 mg per kg siRNA normalized dose shown here. So it is prudent that we also explore other conjugate-based approaches to achieve muscle delivery. In parallel, we are also developing peptide conjugates.
In rodents, we demonstrate robust dose-dependent and rapid knockdown of two various peptide conjugates, depicted in blue, compared to no knockdown with the non-binding peptide conjugate controls, in gray, across skeletal muscles. Shown here is gastrocnemius. We also observe activity in the heart. Similar to our liver and CNS platforms, this activity is durable, with no loss of activity 28 days post-dose. Excitingly, our novel peptide approach translates very nicely to non-human primates. The light blue depicts our first-generation peptide conjugate, while the dark blue represents enhanced conjugate design developed through additional systematic optimization. The additional benefit of this further optimization is clearly observed in the 50%-80% transcript knockdown across multiple skeletal muscle types, as well as cardiac muscle, as shown here. Note the lack of liver targeting.
Finally, and most excitingly, we have also developed a novel small molecule or GalNAc-like conjugates for delivery to skeletal muscle. Here, the small molecule is targeting a unique receptor in muscle. A single subcutaneous dose enables dose-responsive and robust knockdown across a broad range of rodent skeletal muscle. Three such tissues shown here, with knockdown in the trapezius, likely maxed at even a single 1 mg per kg subcu dose. On the right, we demonstrate rapid and durable knockdown across two different targets, depicted by the circles versus squares, in two different representative muscles: quadricep in green and gastrocnemius in maroon. Regardless of the target, we see about 75% knockdown maintained 56 days after a single 1 mg per kg subcu dose. Finally, we are pleased to share that our small molecule conjugate platform also translates very robustly into non-human primates.
Again, we show 50%-80% target mRNA knockdown across multiple skeletal muscles, as well as cardiac muscle. The small molecule delivery platform is also highly specific, with no knockdown in other tissues and is amenable to Efficient CMC scaling. The long history of human translation of our platforms, like GalNAc, LNP, and C16, gives us great confidence that we have in hand a best-in-class delivery solution to skeletal muscle to enable INDs in 2025. I will now turn it back to Vasant to take us through a few additional platform advancements.
Thanks, Karyn. Now, I'm pleased to share an exciting update on a new advancement in what we call reLNPs, or rapidly eliminating lipid nanoparticles. Alnylam launched the first approved nucleic acid therapy delivered via LNPs with patisiran, demonstrating the ability to deliver RNAi therapeutics to the liver. Continuous investment from Alnylam and collaborators led to LNP platform refinement and advances over the last 16+ years. Now, why develop new reLNPs? With earlier LNP containing stable ionizable lipids, they were found to be persistent in vivo, that is, they exhibit long elimination half-lives in plasma and tissues. To overcome that, we have identified a new class of ionizable lipids with an improved in vivo elimination profile and a wide safety margin. Let's take a look at the data with these rapidly eliminating LNPs.
With a novel reLNP, we now report further improvements in potency for siRNA delivery, with robust knockdown at doses as low as 0.1 mg/kg in NHP. Really exciting to see this further boost in activity. Continuing our theme of extrahepatic expansion, as an example demonstrated on the right, here is a potent and durable knockdown in mouse macrophages. As you know, macrophages have been challenging for delivery, as endosomal escape is more difficult in that cell type, and there are many diseases where rapid knockdown of macrophage targets would be highly desired. So while conjugates remain our priority, reLNPs remain a potent part of our delivery arsenal. In fact, I'm happy to announce we have filed an IND utilizing reLNPs for an oncology indication in HCC, targeting the beta-catenin pathway.
We focused on HCC because, as you know, the LNPs deliver a great deal of material to the liver. Our preclinical work shown here clearly demonstrates that our ALN-BCAT had remarkable activity in models of HCC at doses as low as 0.3 mg/kg. We show shrinkage of the tumors in liver, shown by liver weight going down, and see strong reductions in tumor burden. We have recently completed the preclinical development of ALN-BCAT, submitted the IND, and received the safe to proceed with an estimated start of the clinical trial in HCC patients early next year. The phase I will be an open-label, dose-escalation, safety, and PK/PD trial conducted in advanced HCC patients as a monotherapy, as well as in combination with immunotherapy. Finally, while we have focused most of the update today on extrahepatic expansion, we will also continue to advance the siRNA designs.
Our latest design, that is IKARIA, with a once-a-year dosing potential for therapeutic benefit, is the culmination of lessons learned from almost two decades of conjugate development. We are pleased to see the initial data in humans with TTRsc04 that is consistent with predicted long duration of activity, and my colleague, Alim Rana, will share those phase I data later this morning. We also have REVERSIR for control of RNAi pharmacology and have identified a development candidate for the zilebesiran program. As we have described previously, this technology can rapidly reverse silencing. With our Gemini platform, we have shown simultaneous knockdown of two targets. While we are pleased, and with the advances with RNAi technology and focus very much on RNAi therapeutics, we continue to innovate other ways in which RNAi may be utilized to make medicines.
In fact, we recently reported RNAi-based rheostat for the control of AAV transgene expression. This is an exciting example where we are using RNAi to transform Gene therapy into an inducible and titratable technology. In summary, through our continued platform innovation, we are marching towards a large multi-organ pipeline of clinical stage programs by 2025. In addition to the multiple INDs in liver and CNS, we expect the first IND for adipose target and another for muscle target by 2025. We also have preclinical data for additional tissues, and the IND timelines for them are to be determined. Exciting possibilities with RNAi delivery and human genetics expertise that have the potential to lead to a broad range of programs spanning rare, specialty, and broad indications. To talk more about these pipeline opportunities, handing it over to my colleague, Paul Nioi. Paul, over to you.
Thank you, Vasant, and good morning, everyone. I'm Paul Nioi, Senior Vice President of Research at Alnylam, and I want to turn your attention to our exciting Alnylam proprietary preclinical pipeline and highlight some of the programs that we see moving into clinical development in the next two years. As mentioned previously, we have a bold vision with plans to file nine new INDs between now and the end of 2025, including five INDs for new liver opportunities with our GalNAc platform, two INDs for new opportunities in the CNS, and two new tissues for which we plan to file INDs. All of the targets for these new potential therapies are bolstered by our investment in human Genetics, allowing us to have a high level of confidence that we will be successful in the clinic.
We have a proven track record in using human genotype/phenotype data to identify new targets and advance RNAi medicines. We've made investments in U.K. Biobank in the past and now are part of even larger efforts, such as Our Future Health, with an aim of recruiting 5 million people in the U.K. and obtaining genotype/phenotype data for those individuals. We are unique amongst our technology peers in this regard, and this has played a central part in our higher than industry average probability of success in the clinic. With numerous exciting opportunities across rare, specialty, and prevalent indication spaces, highlighted in light blue is our wholly owned pipeline of preclinical and clinical opportunities, along with our approved medicines. Partner programs are indicated in the darker font. Note that I'm not including our CNS portfolio here, and my colleague, Kirk Brown, will take you through that later in the presentation.
We are incredibly excited to be filling our pipeline with the substrate you see on this slide. I'm now going to hand you over to my colleague, Anna Borodovsky, who will give you an insight into two of the programs in specialty and rare indications that we believe have the potential to have a big impact for patients.
Thank you, Paul. Hi, everyone. My name is Anna Borodovsky, and I am Vice President of Research here at Alnylam. In the next few slides, I'm going to share some of the exciting preclinical progress in our efforts toward advancing novel RNAi therapeutics in bleeding disorders and cholestatic liver disease. I'll start with bleeding disorders, where we believe we have a differentiated opportunity with a target we're calling Gene A. Hemostasis can falter at multiple steps involved in the control of blood vessel injury. Diseases associated with the various steps in hemostasis have different challenges, whether it is the availability of effective treatment, lack of treatment options in the case of vessel wall defects, or an increased risk of thrombosis for treatments addressing factor deficiencies.
An approach that can improve hemostasis without increasing the risk of thrombosis would have the potential to be a universal hemostatic agent and treat bleeding disorders of multiple etiologies. We believe that Gene A has the potential to be such an agent based on analysis from the U.K. Biobank. Analysis of protein levels in U.K. Biobank participants has shown that higher levels of the protein encoded by Gene A are associated with heavy menstrual bleeding and GI bleeding. Conversely, loss of function variants in Gene A show a reduction in both GI and heavy menstrual bleeding, but importantly, do not show an increase in thrombotic risk.
A further analysis of the relationship between the levels of the protein encoded by Gene A and thrombotic risk demonstrates a lack of association between protein levels and thrombosis as compared to known thrombophilic Genes, lower levels of which are associated with a higher odds ratio of a thrombotic event. We utilized a well-established model of laser vessel injury to address both the efficacy of Gene A silencing in restoring hemostasis, as well as its potential to induce thrombosis by using two different mouse strains. In this model, clot formation is monitored by tracking the accumulation of labeled fibrin and platelets at the injury site in real time. Hemophilia A mice exhibit continued bleeding and were used to assess efficacy 14 days after siRNA treatment. As shown in the graphs on the right, hemophilia A mice in gray show minimal clot formation.
By contrast, wild-type animals in black show robust accumulation of platelets and fibrin at the injury site. When hemophilia A mice are treated with a comparator hemostatic siRNA in green, the response is improved. Treatment with an siRNA targeting Gene A in blue provides a more robust correction of hemostasis in this very stringent model. Now, turning to the question of thrombosis. We utilize the same model, but this time in wild-type animals, to evaluate whether excessive thrombosis is observed following Gene A silencing. In this experiment, untreated mice in black show the expected platelet and fibrin accumulation. Treatment with a comparator hemostatic siRNA in green shows exaggerated clot formation, consistent with the known risk of thrombosis associated with this target. By contrast, an siRNA targeting Gene A, shown in blue, shows a response comparable to untreated animals.
These studies highlight the potential of Gene A to improve hemostasis without the risk of thrombosis and serve as a universal hemostatic agent. We are excited about the potential for ALN-Gene to function as a universal hemostatic agent for multiple bleeding disorders. We recently selected a GalNAc conjugate targeting Gene A as a development candidate that demonstrates robust and durable silencing in non-human primates and plan to file an IND for this program in 2024. Another exciting opportunity we're pursuing is in the treatment of cholestatic liver diseases. There are multiple diseases in the cholestatic liver disease category, including PBC, PSC, and PFIC. While the initial insult is distinct in these conditions, in all of them, elevated bile acids are a major disease driver and mediate damage to the biliary tree.
It is our hypothesis that targeting a Gene that can improve bile flow would have a therapeutic benefit in these conditions. We are targeting Gene B, a Gene which is involved in the biosynthesis of bile acids. We hypothesize that silencing Gene B will improve bile flow and cholestasis, resulting in reduced inflammation and bile duct damage. To validate this hypothesis preclinically, we evaluated the efficacy of silencing Gene B in a mouse model of chemical bile duct injury with DDC treatment. Treatment with either of the two siRNAs targeting Gene B in blue and green on these graphs, led to a robust lowering of mRNA and was associated with a dramatic reduction in the markers of inflammation, ductular reaction, and fibrosis. Importantly, consistent with our therapeutic hypothesis, bile flow was increased in the siRNA-treated animals.
Moreover, the bile acid profile of mice with silenced Gene B is similar to that of humans with a homozygous loss of function in Gene B, further supporting the potential for Gene B silencing to treat cholestasis. We expect to select a development candidate for Gene B in 2024. I will now hand it back over to Paul.
Thanks, Anna. Now, turning our attention to some of the major opportunities we have in the prevalent indication space, I'm going to focus on our portfolio of programs for obesity and diabetes. We see some exciting new opportunities for Alnylam, using Genetically validated targets to address unmet needs in cardiometabolic disease. The success of GLP-1 receptor agonists has redefined the unmet need in obesity. Despite their success, three major areas of need still exist. One, there is the issue of loss of lean mass. These data come from the recent New England Journal publication on the clinical trial of tirzepatide, and you can see a roughly 8% loss of lean mass, which is roughly 30% of the total weight lost in these patients. A similar picture was seen with semaglutide.
Second, tolerability is a big issue, with up to 50% of patients no longer taking their medication after one year due to nausea and GI side effects. The issue is illustrated here in this table showing the side effect profile of semaglutide. Finally, and related to tolerability, when patients stop taking their GLP-1 RA, they rapidly regain weight, with two-thirds of their starting weight regained after one year, as shown here for semaglutide. At Alnylam, we have an exciting portfolio of three potential medicines that we believe can be used as standalone agents or in combination with GLP-1 receptor agonists to address these unmet needs. The first program I will talk about is Inhibin E or INHBE. Inhibin E is induced by the liver when it senses higher levels of free fatty acids and released into the blood to tell adipose tissue to store fat.
We discovered this biology from our Genetics efforts. Consistent with this, we see that Inhibin E levels are elevated approximately threefold in obese humans versus people in the normal weight range. Furthermore, we can demonstrate robust and durable silencing of Inhibin E at clinically relevant doses of a GalNAc conjugated siRNA in non-human primates, as shown here. Finally, we also have human evidence that's consistent with the role of Inhibin E in promoting lipogenesis. Here, we're showing data from our own internal analyses from the U.K. Biobank, where we found that carriers of loss-of-function variants in Inhibin E have elevated levels of ketone bodies in their blood: 3-hydroxybutyrate, acetone, and acetate, which is consistent with a lipolytic state.
Obviously, a fantastic profile would be if you could have this state of lipolysis but maintain muscle mass, and that's exactly what we see in these carriers with handgrip strength, creatinine, and whole body fat-free mass, all being identical in carriers and non-carriers. We're on track to declare a development candidate for Inhibin E next year. The next program I'm going to tell you about is our first adipose tissue program, Gene C, using a novel subcutaneously administered siRNA conjugate to achieve delivery, as my colleague Vasant showed earlier. We identified Gene C from our efforts with the U.K. Biobank cohort, and found that a combination of loss of function and predicted damaging missense variants in the Gene Associate with a beneficial distribution of fat in carriers, as shown by lower waist-to-hip ratio, lower visceral adipose volume, and lower liver fat.
We also find a reduced level of HbA1c and a markedly lower risk of type 2 diabetes in these carriers. We also find that lean mass is preserved or even increases slightly in the carriers, as seen in measures of grip strength, creatinine, and whole body fat-free mass, which is actually increased slightly and nominally significant. Together, these data indicate that an RNA therapeutic, which knocks down Gene C and adipose, would be beneficial in obesity and metabolic syndrome. We're on track to declare a development candidate in 2024. The final program on obesity that I want to introduce is ALN Gene D. This is our first muscle program using a novel conjugate that targets muscle, as described earlier by my colleague, Karyn Schmidt. Gene D is Genetically validated, and loss of function carriers have increased muscle mass.
We see deep dose-dependent silencing of this target with our novel small molecule conjugate across different muscle groups, as shown on the left. Furthermore, as seen in the right-hand panel, we see sustained knockdown through 60 days following a single dose of our conjugate. We are on track to declare a development candidate for Gene D next year. I've just taken you through three important programs for patients with obesity. Importantly, we can think about these as not just three separate drugs, but potentially one drug silencing three targets with an extremely competitive profile in obesity. For example, we can imagine combining ALN Inhibin E with Gene C to drive profound fat loss, and then add in Gene D to block the loss of lean mass. Our Gemini platform allows us to silence two or more targets simultaneously and with a single subcutaneous injection.
These potential combinations are very much top of mind as we move further towards development, as are combos of our agents with GLP-1 RAs. I now want to highlight two pipeline programs that we think could be transformative for type two diabetes patients. ALN-KHK, and a new target, ALN Gene Y, for which we will be filing an IND next year. There remains considerable unmet need in type two diabetes, including an inability of patients to sustain glycemic control, lack of management of associated comorbidities such as NASH, and a lack of adherence of patients to their medications. The first program I want to highlight is ALN-KHK, which is in phase I development for the treatment of T2D. We believe ALN-KHK has a potential to provide benefit across the spectrum of unmet need in type two diabetes.
I'm pleased to be able to share with you some interim phase I data today. KHK is responsible for the first committed step in fructose metabolism, catalyzing the formation of fructose 1 phosphate, or F1P. F1P drives numerous pathological processes that include gluconeogenesis and de novo lipoGenesis, which contribute to insulin resistance and related comorbidities such as NASH. ALN-KHK is a GalNAc siRNA targeting the KHK transcript, the silencing of which should inhibit formation of F1P. We expect ALN-KHK to increase serum fructose and block the F1P-mediated upregulation of FGF 21. Both of these are endpoints in our phase I study. This is an overview of the two parts of our phase I. Part A, which I will show some data from today, focused on safety, along with measuring markers of target engagement.
Part B, which will kick off in 2024, is focused on proof of concept to show an effect of ... on HbA1c and evidence of a reduction in liver fat. For Part A, we enrolled 40 overweight, obese, non-diabetic healthy volunteers. They were randomized 3 to 1, active to placebo, and administered 5 increasing doses of ALN-KHK. As mentioned, the primary endpoint was safety. Our secondary endpoints included serum fructose and FGF 21 levels following a fructose tolerance test at various time points. I'm excited to be able to share the fructose data that we have to date, where we see clear evidence of target engagement. Here you can see the fructose AUC data for the fructose tolerance test performed at various time points following ALN-KHK treatment. At day -1, all groups show comparable results.
However, from day 29 onwards, we see a dose-dependent increase in serum fructose AUC, indicating that we are effectively silencing KHK in the livers of these subjects, providing evidence for target engagement. We also saw the expected decrease in circulating FGF 21, and we will share those data at an upcoming congress. Finally, touching on safety, AEs were all mild, non-serious, and recovered. There were also no safety signals identified, including hepatic safety signals. We look forward to sharing additional data from this program with you in the future. But to summarize, Part A has confirmed adequate safety and supports continued development with a profile with a potential for quarterly or even biannual dosing. In terms of next steps, we are initiating the multi-dose Part B of the phase I study in Type 2 diabetes patients next year, with a primary endpoint of reduction in HbA1c.
The final diabetes program I will highlight is ALN-Gene Y. ALN-Gene Y is a novel insulin sensitizer. It is Genetically validated and was discovered by our in-house Genetics team, and we highlighted this finding at last year's R&D Day. We believe ALN-Gene Y will provide sustained glycemic control and drastically improve patient adherence. We've also seen evidence of liver fat reduction in preclinical models, meaning that ALN-Gene Y may help tackle the comorbidities of Type II diabetes. We also see opportunities in Type II diabetes prevention and lengthening the time that newly diagnosed T1D patients have before commencing insulin treatment. There are opportunities for ALN-Gene Y to synergize with existing therapies, given its novel mechanism of action. Gene Y functions as a negative regulator of insulin receptor signaling in the liver, acting to decrease glycogen storage and increase glucose output.
Therefore, knockdown of Gene Y is expected to enhance hepatic insulin receptor signaling, increase glycogen storage, and decrease glucose output by the liver. Previous attempts to develop a liver-specific insulin failed because of liver toxicity that was seen preclinically and clinically, although a very robust antidiabetic effect was also observed. In contrast, silencing of Gene Y has not been associated with any liver tox in our preclinical studies, and as I'll show you in a moment, actually seems to be beneficial in liver disease. So this mechanism may offer the possibility of glycemic control without the liver liability. Ob/ob mice are a gold standard, Genetically defined preclinical model to assess the efficacy of antidiabetic agents.
The panel on the left shows the impact of EMPA, an approved SGLT2 inhibitor, on HbA1c in this model, where a greater than 2% reduction in HbA1c was seen, and which translated into a clinically meaningful benefit. Importantly, three separate Gene Y siRNAs, as shown here, caused a very similar, if not greater, reduction in HbA1c compared to EMPA in the same model. To further emphasize the mechanistic points, we performed an insulin sensitivity screen in mice with diet-induced obesity treated with PBS or Gene Y siRNA. As shown here, silencing Gene Y improves hepatic insulin sensitivity, as measured by the ratio of phosphorylated to unphosphorylated AKT. We also saw that peripheral insulin sensitivity, for example, in adipose tissue, is also improved.
Furthermore, we found that consistent with human Genetics, hepatic triglyceride levels are actually reduced after silencing Gene Y, and importantly, we also found that knocking down Gene Y did not cause weight gain in these animals. Finally, we've identified a development candidate that causes deep and sustained knockdown of Gene Y, as shown here in these non-human primate data. We're advancing this molecule, and we're on track to file an IND next year. We're really pleased with the progress we're making in liver and extrahepatic targets and indications, and look forward to sharing more data soon. I'll now pass you over to my colleague, Kirk Brown, who will talk about the marked advancements we've made in our CNS work. Kirk?
Thanks, Paul. Today, I'm very excited to showcase our CNS platform and our burgeoning CNS pipeline. The data we've seen so far with our CNS conjugates suggests we have the potential to unlock significant opportunities for RNA therapeutics in the CNS. Amyloid precursor protein is a Genetically validated target for both Alzheimer's disease and cerebral amyloid angiopathy. By knocking down APP at the messenger RNA level, ALN-APP reduces APP protein production, which is anticipated to slow the formation of new deposits and potentially enable natural clearance mechanisms to remove the deposits over time. In addition, by acting at the mRNA level, ALN-APP also knocks down intracellular levels of APP cleavage products, such as amyloid beta and the beta C terminal fragment, which are believed to contribute to neuronal dysfunction in AD. This intracellular effect distinguishes this approach from other approaches that only act on amyloid outside of the cell.
Preclinically, after a single intrathecal lumbar puncture administration of an siRNA targeting APP in non-human primates, we've observed potent and sustained knockdown of both soluble APP alpha as well as soluble APP beta in the CSF, which both serve as target engagement biomarkers. The pharmacodynamic response has lasted six months. We next looked at the relationship between the CSF biomarker lowering and that of tissue mRNA silencing. A strong correlation is observed between the level of APP messenger RNA lowering in the frontal cortex and the level of CSF biomarker knockdown. These data, combined with the human Genetics, gave us confidence to go into a phase I clinical study in early-onset Alzheimer's disease. The phase I study of ALN-APP is a two-part study in patients with ROAD.
Part A is a randomized, double-blind, single ascending dose study, and Part B is a multi-dose study where patients who previously participated in Part A all receive active treatment. The primary endpoint of the study is safety and tolerability, and the secondary endpoints are focused on characterizing the pharmacology of ALN-APP. Exploratory biomarkers of disease activity are also measured and include fluid biomarkers, neuroimaging, as well as cognitive measures. So far, we've reported data from the first three cohorts of Part A at doses of 25 milligrams, 50 milligrams, and 75 milligrams. Dosing in additional cohorts in Part A is ongoing, and Part B has also recently begun, with first patients who have completed Part A now entering the study in United Kingdom, the Netherlands, as well as Canada. Part B in the U.S. remains on partial clinical hold.
Since the study is ongoing, blinded safety data is presented by cohort. As you can see, there have been no serious adverse events and no deaths, and all adverse events recorded in the first three cohorts are mild or moderate in severity. In addition to the encouraging safety profile, the pharmacology profile of ALN-APP is also very exciting. This slide shows the trajectory of target engagement biomarker, CSF soluble APP alpha. You can see here that ALN-APP treatment with either 50 mg or 75 mg results in rapid, robust, and sustained lowering of soluble APP alpha, with significant knockdown sustained up to 10 months with the 75 mg cohort. Similar dynamics can be seen for soluble APP beta. Here we see mean knockdown in CSF soluble APP beta of 82% for the 75 mg dose occurring at month two, with a maximum individual knockdown achieved of 90%.
The knockdown in soluble APP was also sustained, with 48% mean knockdown at month six after a 50 mg dose, and either 65% or around 40% mean knockdown at months six and 10, respectively, after the single 75 mg dose. We believe these robust levels of knockdown show the potential of our RNAi platform to set a new standard of achieving deep target engagement and a long duration of action, and suggest that we are getting therapeutically relevant levels of ALN-APP into the brain with a very broad distribution. These robust levels of knockdown in our target engagement biomarkers are also translating to knockdown in CSF amyloid beta peptides.
Although we only have limited data to date, we can already see significant knockdown of between 50% and 75% are seen in CSF amyloid beta 40, as well as CSF amyloid beta 42 levels, the soluble forms of the primary components of amyloid deposits in Alzheimer's disease, as well as CAA. This gives us confidence that ALN-APP is doing what it is designed to do. We are very excited about the human translation data, and while it is only our first example, we anticipate that similar to our liver experiences, we are able to predict the likely activity of our molecules in human from our NHP data. We believe the profile we are seeing is highly attractive and demonstrates the potential of RNAi therapeutics as a new modality for drug development in CNS diseases, with APP and Alzheimer's disease and CAA, and with many other targets to come.
The interim results of ALN-APP have increased our confidence in ALN-APP. With this in mind, we are expanding our development of ALN-APP to CAA. We're announcing today that we expect to initiate a phase II trial in CAA in 2024, so that we can explore these two significant opportunities in parallel and unlock the potential to help more patients with serious neurological conditions. To provide a detailed overview of CAA and critical unmet need for treatments in this area, it is my pleasure to introduce Dr. David Werring, a stroke neurologist and researcher for whom CAA has been an important area of focus.
Thank you very much, Dr. Brown, and it's my great pleasure to be here to talk to you about cerebral amyloid angiopathy, which is a great unmet need in stroke and dementia research. My name is David Werring. I'm a professor of clinical neurology at the UCL Institute of Neurology at Queen Square in London, U.K. These are my declarations. None of these are directly relevant to this talk. This is the structure of what I'm going to talk about to you today. I'm going to remind you, or tell you what CAA is, and then we'll talk a little bit about the epidemiology of CAA, so the burden of the disease, why it's an important condition for us all to be familiar with, and therefore an important unmet healthcare need for research and treatment.
I'm gonna tell you how we approach clinically the diagnosis of cerebral amyloid angiopathy, which I will henceforth refer to as CAA, and then I will talk about the clinical syndromes associated with this condition. So the way in which it may present to stroke physicians or neurologists or, or other physicians. I'll say a little bit about the current approach to managing this disorder, and then if we're thinking about trials of treatment in this condition, we need to know about potential biomarkers of disease progression. So I'll just mention one or two potential neuroimaging biomarkers of this condition that could be relevant, and then we'll sum up at the end. So firstly, what is CAA, cerebral amyloid angiopathy? Well, as you'd imagine from the name, it's the deposition of beta amyloid in very superficial, very small vessels in the brain, predominantly cortical and leptomeningeal arterioles.
You can see here the brown staining is amyloid beta; it's immunostained. What you can see is the stages of deposition of this peptide within the wall of small vessels. Just to say by small, we mean less than about one millimeter, usually in the hundreds of microns. You can see the deposition begins partially affecting the abdominal side of the wall, and then it begins to become circumferential in panel two, and then you can see there's a distortion and cracking of the wall in panel three, and in panel four, there's a complete occlusion of this particular vessel. But the amyloid beta deposition makes the vessel fragile and brittle and potentially prone to bleeding, which is one of the key manifestations of this condition, which we'll talk about.
So just to put it into context, in terms of diseases of the small blood vessels of the brain, we can think of two networks. There's a deep network affected by a condition generally called arteriolosclerosis or hypertensive arteriopathy, but I just want to emphasize that today we're talking about the superficial network, which is affected by amyloid beta peptide deposition, as I mentioned. This is a slide from quite an old paper, but it sums up quite nicely the way in which amyloid beta deposition within the vessel wall can cause architectural alterations in the structure of the vessel, which then leads to functional problems. This can lead to either leakage from the vessel in the form of erythrocyte extravasation to form cerebral microbleeds that you can see here at the bottom.
But also, there's a disturbance of autoregulation, which can lead to difficulties with maintaining perfusion in the underlying cortex and white matter, leading to so-called microinfarcts, and it's also associated with blood-brain barrier leakage and endothelial dysfunction. So, and potentially an inflammatory component as well, which may turn out to be quite important. So it's the deposition of the peptide makes the brain susceptible to both ischemia and hemorrhage. So next, let's just move on to the epidemiology of CAA. How common is this disease? So this is quite a nice study which looks at studies of neuropathological examination of the brain, and it was a systematic review and meta-analysis, and the definition of CAA in this study was moderate to severe. So this means there's a lot of peptide in the walls of the arterioles.
This is not an incidental finding, it's quite severe disease. And what we see on neuropathological studies with this definition is about a 20% prevalence in the general population, about 6% of cognitively normal elderly, about one in four people with intracerebral hemorrhage. That's an important cause of lobar intracerebral hemorrhage. But also, I just draw your attention to the high prevalence in Alzheimer's disease. So around 50% of people with Alzheimer's disease have evidence of moderate to severe CAA, and if we look at less severe degrees of CAA, almost everyone with Alzheimer's disease has some degree of vascular amyloid deposition, certainly over around 90%, but moderate to severe CAA is 50%. So you can see this is clearly a highly prevalent disorder that's likely to be very relevant to stroke and dementia.
So now I'm just gonna mention a little bit about how clinicians approach the diagnosis of CAA in practice. And this is a slide showing a particular biomarker in the brain. These are little black dots here, seen on blood-sensitive sequences, or sequences sensitive to magnetic susceptibility, I should say. So the so-called susceptibility-weighted imaging or T2 star-weighted gradient echo, the names of some of these sequences, but they're sensitive to paramagnetic products. And of course, when bleeding occurs in the brain, the blood gets broken down and ultimately forms a compound called hemosiderin, which is highly paramagnetic, and that's why you can see bleeding in the brain on these sequences. And these little black dots are termed microbleeds, and you will see that the...
There's a distinct topography of these bleeds on the slide here, from a deep distribution on the left-hand side to a kind of mixed, deep, and lobar pattern in the middle. And then on the right-hand side, we see a strictly lobar pattern with this cluster of microbleeds, particularly in the parieto-occipital region. And these, these microbleeds are a useful biomarker of the distribution of bleeding-prone small vessel arteriopathies, and this is highly relevant for diagnosing cerebral amyloid angiopathy. So what we know is if we have a strictly lobar pattern of cerebral microbleeds, so that's in the cortex or the underlying cortico-subcortical junction without having any microbleeds in deep structures of the brain, this has good diagnostic accuracy for cerebral amyloid angiopathy.
Whereas other patterns of microbleeds, such as on the right-hand, of the slide here, where you can see both deep and lobar microbleeds, that's more likely to be associated with the arteriolosclerosis or possibly a mixture of arteriolosclerosis and CAA. So some of you may be familiar with the Boston criteria, which were developed, by Steve Greenberg and colleagues, some years ago now in the 2000s, but have been modified and developed since then. And these so-called modified version 1.5 criteria basically rely on the demonstration of areas of bleeding near the brain surface, so where those cortical and leptomeningeal arterioles are located. And that bleeding can take the form of either small bleeds in the brain, which is microbleeds-...
Or it could be larger bleeds in the brain, sometimes called macrobleeds, but it can also be bleeding on the very surface of the brain, which, ultimately leads to this pattern of, what's called cortical superficial siderosis, which you can see up on the top right of the slide. And this means there's been some bleeding into the subarachnoid space over the cerebral convexity, and the blood has become broken down and deposited as hemosiderin, either side of a sulcus, giving this rather characteristic serpiginous kind of stripe appearance. So probable CAA radiologically is defined as, at least two areas of bleeding near the surface, and as I said, they could be microbleeds, macrobleeds, or siderosis. So this was the, state of play as of the modified Boston criteria.
You can see a part of those, criteria also are that the patient is over 55 years of age, and there is no other apparent cause of intracerebral hemorrhage or intracranial hemorrhage. So this will depend on the degree of workup, of course. So these were the criteria that we had up until fairly recently. So these came out in around 2010. But the difficulty with these criteria is that they, although they have good diagnostic accuracy in people with intracerebral hemorrhage, they've come to the stroke unit usually, so you can see sensitivity of 70s, 73%, 77%, and specificities of 100%, 95%, and 88%. So pretty good, in hospital-based studies of people with intracerebral hemorrhage on the stroke unit, but they've got limited sensitivity in other populations.
So these could be people perhaps attending a memory clinic who have not got any evidence of intracerebral hemorrhage, or they could be population-based older cohorts. So these criteria were. This was felt to be quite an important limitation of the criteria that we couldn't diagnose the disorder in populations other than intracerebral hemorrhage. So an international group led by Steve Greenberg in Boston and Andreas Charidimou, but also us, we contributed in developing this at UCL in London. The aim of this study was to develop new Boston criteria, which would have improved sensitivity for the disorder, and also to apply this in non-intracerebral hemorrhage populations, such as those that may be seen in a cognitive clinic. So what did we do?
Well, we looked at some of the newer markers that have appeared over recent years, relevant to cerebral amyloid angiopathy, and these are non-hemorrhagic markers. If you look to the right-hand side of the panel here, you can see on the far right, we have the so-called white matter multi-spot pattern on this axial FLAIR image, and this has turned out to be somewhat related to cerebral amyloid angiopathy. The next one along, these little dots in the centrum semiovale, the high white matter of the brain, these are enlarged perivascular spaces. Both of these biomarkers are associated with CAA pathology in neuropathologic studies. We found that these, using these as a diagnostic biomarker, so you'd have one, at least one hemorrhagic marker, plus at least one other hemorrhagic marker or one of the non-hemorrhagic markers.
This does indeed increase the sensitivity of the Boston criteria without compromising their specificity. So time's limited, so I'm not gonna go through the results in detail, but you can read the paper in Lancet Neurology from last year. This refers to the International Journal of Stroke, refers to the protocol paper. So I'm now gonna talk about the clinical syndromes associated with CAA. On the next slide, you can see this is an illustration of those clinical subtypes, and we can look at intracerebral hemorrhage, which I've already briefly mentioned. We can also look at cognitive decline, which may be seen in those cognitive clinics or memory clinics. Then we have transient focal neurological episodes, which are distinct, stereotyped, usually somatosensory attacks associated with siderosis and convexity bleeding.
I'm not gonna have time to discuss iatrogenic CAA or CAA-related inflammation during this brief overview, but they're also known to stroke physicians and neurologists. Okay, first, let's just take a brief look at intracerebral hemorrhage, which is arguably a key manifestation of CAA and is often devastating. Intracerebral hemorrhage still has a three-month mortality of around 40% despite modern stroke care, so it's a really important challenge. Let's look at that in the context of CAA. Well, the studies that we have suggest that around one in four to one in five people with spontaneous lobar intracerebral hemorrhage have evidence of CAA. The characteristics of this type of intracerebral hemorrhage are that there's often an early recurrence risk, which can be really within weeks and months of the initial intracerebral hemorrhage.
We don't, we don't yet fully, understand the tendency for spatial and temporal clustering, but it does seem to be a phenomenon associated with this pathology. Sometimes there's a history of minor trauma. Sometimes there can be a mismatch with, a large hemorrhage, but a minor clinical deficit, but a lot of this depends on where the hemorrhage is located within the brain. And as I mentioned, we can now diagnose this condition with some reasonable diagnostic accuracy using, using various iterations of the Boston criteria. I just want to say at this point that although microbleeds are used as, one of the key diagnostic biomarkers, it turns out that superficial siderosis, this, serpiginous, stripe-like, dark signal on the paramagnetic sequences that I showed you either side of a sulcus, turns out to be the strongest bleeding predictor.
This is a study that we did quite some years ago, where we looked at those with and without siderosis, and you can see there's a very strong prognostic marker of the risk of recurrent intracerebral hemorrhage, and that's been replicated now by many other studies. If we take cohorts of people with intracerebral hemorrhage who've been investigated with MRI biomarkers, and we classify them into those with CAA and without CAA, we can see that those with CAA have a larger risk of intracerebral hemorrhage, around 7% per year, compared to around 1% per year for those without evidence of CAA.
This is another study that we published much more recently, just this year, which shows essentially the same phenomenon, that those with cerebral amyloid angiopathy have a much higher risk of recurrence compared to other forms of arteriopathy underlying intracerebral hemorrhage. I'm gonna now briefly mention these transient focal neurological episodes. So these are typically areas of usually somatosensory disturbance with tingling, numbness, weakness, or a combination of all of those things, typically migrating from one body part smoothly to another over a matter of minutes. And Steve Greenberg described these a long time ago in 1993, but their prognostic significance wasn't realized until a bit more recently. And these are the key features, characteristic spread of symptoms into contiguous body areas.
And I just wanna highlight this study that suggests that they occur in around 15% of people with CAA, and they're associated with convexity subarachnoid bleeding, cortical superficial siderosis, or both. And the physiology is really interesting. I don't have time to go into it here, but it's to do with those blood products probably setting up waves of spreading depolarization. And these are also significant, like intracerebral hemorrhage, because they herald a high risk of future symptomatic intracerebral hemorrhage. This is neuroimaging of showing an acute convexity subarachnoid hemorrhage in a sulcus here at the top, someone presenting with these characteristic recurrent stereotyped somatosensory attacks. And then if we scan the patient a bit down the line, we can see three months later, there is evidence of cortical superficial siderosis in those areas that previously had subarachnoid bleeding.
This is just some more data showing that the prognosis of convexity subarachnoid hemorrhage with these transient focal neurologic episodes, or TFNE, is also associated with a high risk of intracranial bleeding. So just very briefly, I'm gonna mention CAA-related cognitive decline. So some lovely data from Julie Schneider's Rush Memory and Aging Study, showing that this was a pathology study looking at cognition in life and then autopsy-defined pathology. We can see the progression of global cognitive function is accelerated in the presence of severe CAA, and there's a nice graded relationship between the severity of CAA and the cognitive decline. This is even when adjusted for all the other pathologies that occur in the aging brain. So I think this is an unrecognized cause of cognitive impairment, and likely important in the context of Alzheimer disease as well.
So what about the management of cerebral amyloid angiopathy? It's gonna be very brief here because we manage it the same as any other acute intracerebral hemorrhage. We treat the blood pressure, we reverse anticoagulation, we take people to the stroke unit or the intensive care unit, and there can be a role for neurosurgery, as well as hemostatic therapy, which is under investigation. We control the blood pressure to a target of around 130 over 80 is the current guideline for this. And, we don't have randomized data, but the observational data suggests that this could reduce the risk of recurrence. Anticoagulation can be a concern in people with CAA and atrial fibrillation, and I think the ENRICH trial is providing us with new evidence on this.
It's not yet fully published, but I would just note that we've been encouraged not to randomize people with lobar hemorrhage into this study of people with AF who restarted anticoagulant with edoxaban, edoxaban, and I think we have to be cautious about anticoagulation in people with CAA. This shows that left atrial appendage occlusion is an alternative to anticoagulation. So just briefly looking to markers of disease progression that we might be able to use in clinical trials. Well, I've already mentioned many of these. We could also potentially look at white matter hyperintensity volume. We could also look at structural metrics of the white matter integrity over time, such as on diffusion tensor imaging, as well as these hemorrhagic biomarkers of this disorder and subclinical DWI ischemic lesions....
Functionally, we can look at reactivity to visual stimulation using the fMRI BOLD response, and this is a nice study that shows that we can demonstrate a change in both the gradient of the BOLD response and its magnitude over a 1-year period in people with CAA. So this is looking at the vascular health and reactivity. Just to show that these biomarkers probably occur at different points.
So it may be that with the deposition of amyloid beta, loss of vasoreactivity is an early finding of the disease, which could be potentially reversible, and then we maybe get the non-hemorrhagic markers of injury at an intermediate point, and then hemorrhagic lesions may well be a later feature of the disease, which is when the disease tends to present to physicians as either hemorrhage or intracerebral hemorrhage or transient focal neurological episodes. So let me sum up then by saying that CAA is really common. It's a key cause of intracerebral hemorrhage, a devastating stroke type, as well as transient neurological episodes and cognitive decline. I think it's really underrecognized in the latter context.
There is a high risk of recurrent intracerebral hemorrhage, and we've got now a range of neuroimaging markers, which are transforming diagnosis and understanding, as well as the ability to monitor the disorder. We don't have proven interventions to treat either acute CAA-ICH or to prevent recurrence or progression. So this... I think I would hopefully have made the strong case here that CAA is an important and unmet healthcare need. So I'm grateful to you for your attention, and I will stop there. Thank you. I'm now gonna hand over back to Dr. Brown for the rest of the seminar. Thank you.
Thank you, Dr. Werring, for that wonderful presentation. As you can tell from the presentation, this is a very significant unmet need. There are tens of thousands of strokes caused by CAA every year, and there is no treatment that can address the underlying disease and prevent further progression and stroke recurrence. With this in mind, we are expanding our development program for ALN-APP into CAA. Our hypothesis here is similar to that in AD. By knocking down APP at the messenger RNA level with ALN-APP, we lower APP production and knock down the substrate for the amyloid deposition in the vessels in the brain. By doing so, we aim to slow the progression of CAA and potentially enable natural clearance of the amyloid.
We know from our early work in the rTg-DI rat, an established rodent model of CAA, that APP siRNA demonstrates human mRNA silencing as soon as four weeks after treatment, and this decreased human APP protein in both the hippocampus and the cortex in these animals. You can see in the control-treated animals in the panel on the left, substantial amyloid deposits are present in the vasculature as well as the brain parenchyma, consistent with published work. Whereas animals treated with APP siRNA show pronounced clearance of amyloid deposits along the vessels, as well as throughout the brain. Importantly, treated animals with amyloid clearance also showed a decrease in microhemorrhages at the same time point in the panel on the right.
This suggests that targeting amyloid upstream at the mRNA level has the potential to inhibit new deposits from forming and naturally clear existing deposits, such that the vascular health is maintained, and importantly, bleeding events are reduced. As we think about our key goals for 2024, we will continue to progress our phase I study in ROAD and expand the number of patients enrolled in part B. In addition, we'll be starting up our phase II study in CAA. Our ambitious goals for this program reflect our enthusiasm for the target, the significant unmet need for patients in these disease areas, and the importance of our continuing our journey of discovery for our platform. We look forward to sharing further updates about this exciting program through the coming years.
Now, given the translation of our CNS platform in humans with our Sentinel ALN-APP program, we, along with our Regeneron partners, have significantly expanded our CNS platform into many new targets, each of which shows a consistent and reproducible pattern of silencing. In addition to APP, SOD1 and HTT are in IND-enabling development. Other emerging targets, including MAPT for tauopathies and SNCA for Parkinson's, are in preclinical work, with other targets work ongoing. Working with scientists at our collaboration partner, Regeneron, we tested MAPT-targeting sRNA in a mouse tauopathy model, the P301S transgenic mouse. Symptom onset in these mice occurs at six months. Here, we treated animals at eight months after symptom onset and followed them for an additional three months. We observed knockdown in tau mRNA and protein up to 70%, which resulted in a dramatically lower tau aggregates.
This also resulted in improvement of multiple disease-related measures, such as CSF neurofilament light chain, which is elevated in these animals, as well as locomotor function. Importantly, robust MAPT transcript and protein lowering is also observed after a single intrathecal administration in non-human primates, with protein lowering between 75%-95% across key brain regions. CSF tau also achieved roughly 65% lowering by day 85 after a single intrathecal administration. Consistent with other programs, we have identified a lead molecule with robust activity across the brain. Switching gears to another next wave of CNS target, SNCA or alpha-synuclein, here in collaboration with our Regeneron scientist partners, we evaluated SNCA-targeting sRNAs in a synucleinopathy mouse model. We observed close to 80% silencing in the substantia nigra....
With this level of knockdown, alpha-synuclein aggregates were cleared from the midbrain, as well as the substantia nigra, three months post-treatment, with improved both movement and behavioral endpoints. Looking at one example, using a pull test, treatment with SNCA siRNA improved the slowness of movement three months after treatment, suggesting the clearance of these aggregates is having a functional benefit on movement in these animals. Consistent with our CNS platform, alpha-synuclein transcript and protein lowering is observed after a single intrathecal administration in non-human primates, with protein lowering between 50%-90% across key brain regions. CSF alpha-synuclein achieved roughly 80% lowering by day 85 post a single dose. With robust non-human primate data, we've declared a development candidate, and this program is moving toward an IND. We are currently also advancing ALN-HTT02 program toward clinical development.
Three months after a single intrathecal administration of ALN-HTT02, we observe a dose-dependent lowering of HTT protein or huntingtin protein in the dorsolateral prefrontal cortex up to 80%, as well as a dose-dependent huntingtin protein lowering in the caudate between 50% and 75%. Importantly, no treatment-associated adverse findings were observed during the in-life or through histological evaluations in these animals. Altogether, our C16 siRNA conjugates, similar to our liver platform, demonstrate reproducible, potent, and durable silencing in the CNS, with ALN-APP demonstrating robust translation in humans. Together with our partners at Regeneron, we continue to rapidly expand our pipeline, anticipating many additional CNS INDs and development candidates across 2024 and 2025. I will now hand it off to Kevin to moderate our first Q&A session.
Thank you, Kirk. Hi, everyone, I'm Kevin Fitzgerald. I'm Alnylam's Chief Scientific Officer. We got a lot of great questions about what I, you know, hope you believe is a great amount of material that's come in. I'd like to quickly note that Dr. Werring will be joining our second Q&A session. Due to his scheduling, he was unable to join us, so save your questions for Dr. Werring until the second session. I'm gonna try and group the questions that have come in around platform, NextWave, and CNS, and we'll start with a couple of the questions around platform. First question coming in is: What will make your platform.
You've mentioned best-in-class a couple of times, so, you know, what makes you think, you know, the portions of your platform are best-in-class? I'm gonna kick that over to Vasant for a quick, quick answer.
Thanks, Kevin. No, that's a great question. So as we have shown, right, we have an experience of many years of taking the RNAi drugs through the approval, and have built a world-class RNAi engine that is capable of systematic exploration of the ligands, multiple types of ligands and the receptors. That helps us identify a solution that is best-in-class, not just a solution, and best-in-class solution. But what do we mean by the best-in-class solution? For that, we're taking the inspiration from what we have done with our GalNAc siRNA conjugates. So the three features that we really focus on this one are high level of knockdown, so that is the ED90 in the range of 3 mg per kg or less, subcutaneous dosing, very important, and a streamlined path for the development that is also cost-effective.
We believe achieving all of these should certainly give us a best-in-class delivery solution.
Thanks, Vasant. So, a related question, I think I'll kick it over to Karyn. How does your work with muscle delivery compare to some of the other solutions that are, you know, emerging out there, like, from companies like Avidity and Dyne?
Great question. Thanks, Kevin. So the data reported so far has been somewhat underwhelming in terms of both the extent of knockdown, as well as the lack of a clear dose response. Both Avidity and Dyne are also developing antibody-based conjugate platforms, and these antibodies are very large compared to the size of the siRNA, about 10 times larger. So this means if you're targeting a dose of 4 mg per kg of siRNA, you're actually dosing about 40 mg per kg of antibody. We also believe that antibody-based platforms are also more difficult to develop and are restricted to IV dosing. This, however, is not the case for peptide or small molecule-based platforms, which is why we are developing a GalNAc-like solution.
Ultimately, our goal will be to develop a best-in-class and subq solution, as Vasant highlighted, amenable to an easy, convenient administration, as well as ease of CMC scalability.
Thanks, Karyn. So along the lines, you know, thinking about ligands, one of the questions was, why not use sugar ligands like we've used for GalNAc for extrahepatic delivery? I guess I'll take that one quickly, which is to say that, you know, we consider small molecules, GalNAc a small molecule. So when we talk about small molecules, they could be actually sugar ligands, or they could be other small molecules that bind, you know, ligand receptor pairs. So I think, you know, what we do... We think about sugars as part of that small molecule development. Shifting over to sort of the CNS on the delivery side-
Before you, before you do that, Kevin, yeah, just reflecting on those questions, I think the big picture here that's emerging for me is, and it took us about 10 years to get to the first set of solutions for the liver, and those POCs we had in 2012 and 2013. The CNS, we went, I think, about four years from the initial rodent work to the human POC. And now we see the acceleration coming. And so the learnings from each of these delivery systems feeds onto the next, and so I'm very excited about, as you put it, Vasant rightly, you know, best in class for muscle and adipose. And I'm very confident we'll have potent, durable subacute therapeutics for those tissues.
And indeed, you know, by the end of the decade, we've all agreed that our ambition is to get to every tissue in the body, and I think we can really do that. I'm very excited that Alnylam has taken that challenge on, and confident that we can, we can meet that. So looking forward to a very exciting few years on the delivery front.
Yeah, and like I say, we also have a pretty good track record of converting from preclinical to, to clinical proof of concept, you know, as evidenced by our recent, you know, APP success with C16. So going back to sort of... A question came in around blood-brain barrier, and when might we expect, you know, something to move along on blood-brain barrier? So maybe, Kirk, you could talk to us, talk a little bit about our progress on blood-brain barrier and, and where we're headed with that.
Yeah, great question. I mean, we're extremely encouraged by what we're seeing right now in the clinic with our first generation C16 siRNA RNAi therapeutics in the CNS space. We see rapid, robust knockdown of APP target engagement biomarkers, and we're pretty excited by the molecule that we have designed here. The sequence, the chemical modifications, the specificity and potency we have with this molecule is quite robust. Now, where we see BBB, that's also extremely exciting. We'd love to see that we're able to get across the BBB with systemic administration. Where we see that fitting in is more in the lifecycle management of the APP program down the road, but it's particularly exciting.
I think the ability to deliver a systemic injection and get to the brain and see what is likely to be a very comparable degree of knockdown across all reaches of the brain is extremely exciting.
So a follow-up question there, Kirk. You know, it, it looks like you're, you have quite an emerging pipeline in the central nervous system. Do you imagine that as you go across the BBB, you'd be able to apply that, that technology to all of those different targets, or would it be select targets?
Yeah, I think it's highly likely we'd be able to apply it to at least a large number of our emerging CNS pipeline. We've got quite a bit of work ongoing with a whole list of exciting targets in the CNS space that we're currently looking at in transgenic models and iPSC lines to explore our activity across a variety of different targets and a variety of different indications. But certainly, I do believe down the road, applying a BBB approach is likely going to be amenable to many of those targets.
I'm gonna move on a little bit to Next Wave, if we have time. There's a couple more platform questions. I'll come back to them, but I wanna make sure we have enough time across all of the topics. So, in the Next Wave, so a question came in, "Glad to see you're moving so many new liver targets into clinic." And I think you said five or more. Do you think the liver will continue to be a source of targets in the future, you know, or will it, you know, at some point, just peter out? I guess I'll ask Paul that question.
Well, first of all, it's great to hear the enthusiasm. You know, we're also really excited by the number of new liver targets that we're able to move forward. And I want to make one point on that. These are high-quality liver targets insofar as they're Genetically validated. And as you know, we were some of the very early investors in human Genetics databases like the U.K. Biobank, and now we're part of a much larger effort called Our Future Health, where we're recruiting 5 million people in the U.K. And in fact, I've been the chair of the founders board for that effort for the past year. So we think there's still a large number of yet-to-be-discovered liver targets, actually.
If you look at the number of Genes that we, you know, we can say definitively what the role of that Gene is in a given disease, it's actually a pretty small number. So there's still a lot to be discovered, and a lot of those things will indeed be liver targets. So we think we still have plenty of opportunity in the liver going forward. And one final point, as we move into new tissues, keep in mind that we have this expertise in Genetics, so we're able to bring that to bear in new tissues, and again, prioritize targets where there is a strong foundation of human Genetics.
That's all right. I would also... I mean, I'm so excited about our investment in Genetics and what we get out of that investment, both from U.K. Biobank to Our Future Health. I think, you know, that investment has and will continue to pay off in this space. So I think, you know, I agree with your answer. I think there's still more to come. So-
There's an important aspect we shouldn't forget, and Paul, I know you've emphasized it internally, which is, you know, if U.K. Biobank at 500,000 has given us about one high-quality liver target per annum, having 5 million people with this new effort-
Yeah
S hould teach us a lot more about null alleles and the role of those null alleles in human physiology. So that in and of itself should allow us to significantly scale not just the liver effort, but also targets in the other tissues. So, you got some work ahead of you, Paul. I'm looking forward to it.
So, a question coming in around, you know, the program in hemostasis. So, the question was, "I think I heard you say that you could treat bleeding disorders without a thrombotic risk, and how is this possible?" And a follow-up question there around, "How predictive are the vessel model injuries, injury models that you've used to assess this and that?" So I think I'll go over to Anna on that question.
Yeah, no, thank you. That's a great question. Yes, no, we are very excited about this target there, that we have for the treatment of bleeding disorders, and you're correct that we do think that we have a target that can treat bleeding disorders without increased thrombotic risk. In fact, our preclinical data shows that it works across bleeding models, and then the human Genetics does not appear to carry thrombotic risk, and we also see this in the preclinical models of thrombosis. So we're very excited about this prospect, and we believe that it could be a successful treatment in many bleeding disorders that is administered very infrequently.
With regards to the models that we're using for addressing this preclinically, the vessel laser injury model is a tool that's been used to look at different pharmacological treatments of platelets and coagulation function, and it is sensitive to all classes, actually, of the agents that are used, antiplatelet and anticoagulation therapeutics. And so this it's been utilized with a number of different hemostatic agents, and that show an effect in this model, especially with hemophilia mice. These types of agents are often not always tested in wild-type mice because of their expected exaggerated thrombotic response, so this is maybe a less commonly used application.
We have also actually used a different model of thrombosis, a ferric chloride model, to show that GalNAc siRNA does not exaggerate the thrombotic response in these wild-type animals. So this is why we are particularly so excited about our potential new agent in its ability to improve hemostasis and not increase thrombosis.
So I mean, Anna, I, I think this is a really fascinating target because as we know, from human Genetics and what happens in clinical medicine, loss of function for protein like protein C and protein S, that can attenuate bleeding phenotype, also predisposes to thrombosis in humans if you're deficient in those proteins. But this protein looks rather unique, both in terms of the human Genetics profile, where there's protection from bleeding without an evident risk of thrombosis, and now your wonderful mouse work, which seems to, parallel those observations very nicely. So I'm very keen to get this to the clinic soon, and I think it's gonna have a very unique profile. Should be very exciting to explore.
Completely agree, Akshay. So onto the next couple of questions that are grouped around our emerging obesity and diabetes portfolio. So the first question is, how do you plan to develop your obesity medicines with the GLP so entrenched in the market? I think for that, I'll go over to Paul for first, then maybe Akshay can follow up.
Yeah, thanks for the question. You know, well, I showed in the presentation that certainly GLPs have redefined unmet need in obesity. And I think we can all agree that data on the long-term compliance and the long-term safety of these agents is still really an open question, and we'll learn more with time. But the data that we have in hand to date shows that a couple of things are really obvious. One is that much of the weight loss that patients benefit from is, in fact, coming from loss of muscle. We know that compliance with these agents is a big deal. And we also know that when patients stop taking their GLP-1, they rapidly regain the weight. So clearly, there is still a large amount of unmet need.
If you look at what we're trying to do with our medicines, they're actually designed to fill those gaps. So preserving lean mass, dealing with the issue of tolerability, addressing the issue of weight maintenance, post GLP-1 treatment. So you can imagine there are opportunities for us with our medicines, maybe in certain patient populations, where at least could be standalone agents, but there's a huge potential for us to synergize with GLP-1s. So allowing patients to lose weight, maintain muscle, and, be able to stay on their medicine. So we're excited about the opportunities that we have there.
Yeah, I mean, I think you characterized it well, Paul, and, and the pharmacologic profile of our drugs, potent, durable, infrequent administration, to date, you know, well-tolerated and safe, is very encouraging because, again, it's, it's could be a once every six, once every 12-month injection, to prevent, you know, regain of weight, preserve muscle mass, and, and give a much better quality of weight loss to patients than the quantitative loss we're seeing currently, but with some distinct qualitative issues emerging, as you described. So I think it's gonna be a very exciting time for the space in general, and I certainly believe the portfolio you and my colleagues have put together will, will add significantly to that.
So in a follow-up question there, Akshay, will, you know, the target that we talked about in Inhibin E and a couple of the others, will this method result in decreased hunger, or do we think it's more of an impact on metabolism?
Yeah, we don't know exactly, but some of the data that Paul shared, you know, may shed important light on the situation. So, for Inhibin E , for example, he shared data that those individuals who have loss of function in Inhibin E are an intrinsic lipolytic state with elevated ketone bodies, and some of you might recall that slide. That's a very interesting observation, which means if you have loss of function of Inhibin E , you're relying on fat for your calories, so you're burning fat for calories and maintaining a lipolytic state. And, that's obviously very advantageous to us as humans when we're in a caloric-filled environment, and so we'll reduce the need for external sources of calories.
I think that's my speculation, and we'll tilt the metabolism in favor of lipolysis to derive energy and have ATP for everything we need ATP for. So, I think that these Genetic observations and their implications, both for Inhibin E and ALK seven, are profound, and again, let's just follow what the Genetics is teaching us and let nature do its course and have the profound impacts that I think these drugs can have.
Thanks, Akshay. So some related questions, sticking to obesity for a minute. So we mentioned adipose tissue as a target going forward. Should we assume that one of those would be obesity? Would it be in general or subsets of obesity? And a follow-on question to that was, do we imagine that we would be able to do, you know, multi-organ, not just multi-Gene targeting, but multi-organ targeting? So for instance, could you target one Gene in the liver, one Gene in the adipose tissue with the Gemini technology? So I'll start with actually maybe Vasant on the Gemini technology and whether you think...
You know, whether the possibility of going to multiple tissues with different targets is possible, and then turn it back over to Paul to talk a little bit about, you know, thinking about, you know, what those targets could look like and what we're thinking about in adipose.
Yeah. No, that's a great question. I mean, with Gemini, we have obviously shown that we can take two different targets, or antibodies against two different targets and show activity in liver with, with the GalNAc delivery. With the solutions that we are developing, and this is where it also becomes important to focus on, you know, small molecule-like ligands, that we can in fact put these together in a way to reach multiple tissues with these single agents. So, we believe it is feasible, it is within, within the realms of achieving the activity for different targets in different tissues with the single agent. And maybe, Paul, over to you then.
Yeah. So to the question of whether we're planning on treating obesity with our adipose-targeting platform, I think I highlighted, in the presentation, we're working on ALN-GNC. GNC is a Genetically validated adipose target, and, it's something we're very interested in moving forward with for the treatment of obesity. Beyond that, there are numerous other targets that we're considering, but I think it's important to make the point that just like with liver, we can consider any indication where we know adipose tissue plays a central role. Obesity is one of those, but there's other indications that we're exploring as well.
Thanks, Paul. So, another question coming in around this one around your bile acid program. So I'll turn this one over to Anna, and can you just describe a little bit about the types of different diseases that you think that that program could apply to?
Yes, certainly. So there's a few different types of cholestatic liver disease and some, you know, both of more kind of autoimmune and inflammatory origin, as well as Genetic diseases such as PFIC. And we believe that this particular target, Gene B, can actually be potentially utilized to treat any of those conditions because the cholestatic mechanism of injury is there, is a common mechanism across all of them, and so in that sense, we believe that we could treat you know, several of the cholestatic liver diseases by targeting this particular enzyme in the synthesis of bile acids.
Thanks, Anna. So, you know, in summary, I think it seems like there are a number of, you know, orphan diseases that where bile acids are involved. You know, and we think that this will apply to, you know, a large number of those different diseases.
I think, you know, they're all high unmet need areas. Increasingly, PFIC and PBC have been explored extensively recently, and there are a number of interesting agents either approved or in development. But, you know, the quality of life in those patients still hasn't improved. The itch that they get from their jaundice hasn't improved, so there's still much more to do. There are segments of those patients that don't respond to the current drugs. And then PSC, primary sclerosing cholangitis, is kind of an open landscape where patients desperately need help because none of the drugs so far seem to particularly cater to the unmet needs.
So I think the idea of improving the cholestatic picture with this drug is an enticing one, where we can help both with bile flow and hopefully with other aspects like quality of life and itch as well.
Thanks, Akshay. So I'm gonna turn to CNS, but before I do that, there was one question that came in around our beta-catenin program. Can you discuss the WNT pathway and why RNAi is optimal in that pathway? And I'll start, you know, maybe Akshay can chime in as well. You know, it's been very difficult. People have known that the WNT pathway is involved in all sorts of tumors, in particular hepatocellular carcinoma, for years. It's been very hard to make specific small molecules or other approaches that are safe to that target. And so we got very intrigued with that target.
Obviously, we get a lot of drug into the liver, into tumors in the liver, and so we have really pretty amazing preclinical data showing that, you know, targeting this pathway, especially in WNT-driven tumors, but also there are other tumors that are driven within that pathway or related pathways, where targeting, you know, beta-catenin itself has a profound effect on the tumor burden in the liver. In addition, you know, a little bit different than previously, there are now, you know, immune therapies, you know, the PDLs and of the world, where you can think of a combination. And as we've combined the ability to knock down in a tumor with RNAi, now with this immune component, we really see profound changes, you know, and in these models.
This gives us great confidence that we'll see, you know, activity as a monotherapy, but, you know, more importantly, we think we'll see a huge benefit as a combination therapy. Anything to add to that, Akshay?
Yeah, I mean, you know, so you've said most of the important points. Just to reiterate that WNT and beta-catenin mutations are prominent in hepatocellular carcinoma. A significant proportion have them as a driver mutation. It's been difficult to drug, and focusing the drug in a potent manner with an RNAi-based approach, with an RLNP, should save any extra hepatic toxicities and really gives a chance to try and have an impact on what remains a very high unmet need area still, and that is HCC.
Thanks, Akshay. So now I'm gonna transition over to central nervous system, some questions around APP. So I'll start with one to Kirk. So, you know, excited about the pivot to CAA, you know, in terms of, you know, next stage clinical trial. So what level of APP knockdown do you need- do you think you need in, in CAA? Is that the same or different as in, you know, Alzheimer's disease?
You know, that's a really great question, and honestly, there's somewhat limited data there to address it, but we have seen in our animal models that an siRNA targeting APP that reduced the messenger RNA 50%-75% was associated with clearance of amyloid beta plaques in the parenchyma, and also along the vasculature, which in turn ended up producing the bleeding events that were observed in those animals, and this was a rat model of CAA. We can see that even after a single month of knockdown, which was observed in the 75% range, microbleed clearance was observed or reduction was observed at six months following a single dose. We also know from other experiences in amyloidosis, like TTR amyloidosis, that the higher level of knockdown that you see tends to show greater clinical benefit.
So with that in mind, we are also aiming for that 50%-75% knockdown in patients with CAA, and so far, this level of knockdown would be similar to what we've seen in APP phase I study in ROAD.
I think it's, it's interesting, isn't it, Kirk, that in a vast range of systemic amyloidotic disorders now, and I would regard the vascular amyloid in CAA as one such disorder. We certainly see it in TTR, it's been seen before with disorders like AL amyloidosis, Aβ, AA, alpha-fibrinogen alpha chain. In all of them, that 50%-80% range seems to be associated with therapeutic impact. So I, I totally agree with your answer, and coincidentally, your rodent work very nicely supports that. So, I hope this drug, ALN-APP, can have a huge impact in this disease, and pharmacodynamically, I think we're in the range to, to try and translate that to significant clinical benefit.
So, a follow-up question on APP. So I'll direct this one over to Akshay. So any update on when the FDA might lift the partial clinical hold on Part B? And can you complete Part B ex U.S.? And for the, a follow-up to that was in for the phase II CAA, assume that the hold would apply there.
Yeah, you know, we continue to work with the agency on lift of that partial clinical hold. We again continue to be confident that we can get that lifted. In the meantime, Part B is ongoing ex US, and we can complete it ex US if needs be. That's not a problem. And as for CAA, I'm sincerely hoping that with the ongoing work, the FDA will lift the clinical hold, and we can have a global CAA study. However, as Dr. Werring said, this is a big disease, and even if we weren't, you know, enrolling in the U.S. for the CAA phase II study, we can comfortably, I think, enroll ex US. But the goal is to have it as a global study and involve the U.S., and I'm confident we can do that.
So there was a question, a follow-up to that. When can we expect to see data from Part B? I think we've guided late 2024.
Yeah, that's right. I mean, I think the single dose data, as Kirk illustrated, a number of you will have seen at international meetings this year, look incredibly promising, a once every six or once every 12 month intrathecal administration for profound knockdown. The safety looks very encouraging. I think what lays ahead is multi-dose impact on other biomarkers, other imaging, and those are the kinds of data we look forward to sharing, obviously, along with continued safety later in 2024 at a suitable meeting.
Good. We only have a few minutes left, so I'm gonna come back to a question around Next Wave. So there was a question that came in around Gene Y. The question is, you know, really interesting with what appears to be sort of a novel, you know, insulin-like sensitizer in the liver. So can you talk a little bit about that program and why you're excited about it? And, you know, how you think it's differentiated from the number of agents that are out there, you know, in diabetes today that are relatively, you know, cheap. I'm gonna talk to Paul first and maybe a follow-up from Akshay.
Yeah. Well, you know, as I pointed out in my remarks earlier, this is a target that we discovered from our Genetics effort by the U.K. Biobank. So we're really excited about the fact that it has that foundation in human Genetics. The other really important point here is that the mechanism through which it acts is completely novel. It's not a me-too drug. It's not something that's acting on a pathway that's been drugged before. This is a new approach to treating diabetes, and so with that comes the potential for synergy or additivity with existing agents. So we're not gonna be impacting insulin sensitivity in the same way a-...
As you know, some of the drugs that are on the market already, for example, SGLT2 inhibitors, which have a very different mechanism. So we're excited about combinations there. The other thing to point out is, back to the Gemini platform, we have the opportunity to combine ALN-Gene Y with some of the other exciting medicines that I ran through in my presentation. ALN-KHK, for example, but also things that we're doing in obesity with Inhibin E and some of those other targets. So there's lots of combinations that we can think about. And again, because this mechanism is dis-
Amazing that you're expanding your pipeline. You know, you have very rapidly, a little bit about the funding needs for the broadening pipeline. Should we expect further collaboration or business develop-
The clinic and get to POC, and we're funded to do that.
Thanks, Akshay. You know, we've been working very hard to get optionality right. And I think that's always a good thing to have the option to pick the best programs, not only to take forward, but, you know, also, you know, the right time, place to partner or not partner. You know, in addition, you know, I think, you know, we're just overall excited to be now, you know, pushing into new tissues and new frontiers, you know, using our expertise in Genetics to pick the right target, you know, to get the right dose as we've always done. And so never been more excited about the future. And with that, I set out and thank you, and we'll now proceed to a 15-minute intermission.
Welcome back to the second half of Alnylam's 2023 R&D Day. I am Simon Fox, Vice President and Program Lead for zilebesiran. I'd like to introduce Dr. Rhian Touyz, who is an expert clinician scientist with an interest in hypertension. Dr. Touyz is an Executive Director and Chief Scientific Officer of the Research Institute of McGill University Health Center, Montreal, Canada. Dr. Touyz is now going to present her expert opinion of the unmet needs that currently exist in the treatment of hypertension. Dr. Touyz, over to you.
Good day, and I really need to thank Dr. Fox, who's invited me here today to this very interesting Alnylam R&D Day, and I'm delighted to be able to share with you some thoughts related to hypertension treatment, the needs, and the gaps. Now, it's really important for me to put into context the importance of hypertension with respect to the clinical diseases and the burden of health that we have to deal with as medical doctors on a day-to-day basis. And what I want to highlight to you is these are data that have been published since many years ago, right up until very recently, to really highlight the fact that the major modifiable risk factor for global attributable deaths is high blood pressure in both women and in men.
The reason why high blood pressure is such an important component in terms of the burden of health, both at the population, societal, and individual point of view, is that high blood pressure, as we know, is the major risk factor for heart disease, kidney disease, stroke, and even vascular dementia. Understanding the importance of hypertension in the context of our clinical realm is really important. I also want to highlight to you that systolic blood pressure and diastolic blood pressure indicate that the higher the pressures, the greater the percentage of individuals who will have an event related to cardiovascular disease. We can see that regardless of the definition of hypertension, whether this is 130 over 80 or 140 over 90, this continuum in terms of the association between increases in blood pressure and cardiovascular events is really quite consistent.
So I'm really highlighting to you the importance of blood pressure levels and the associated cardiovascular risk. Here is another study, actually, a very old study, that showed us that even at pressures as low as 115 millimeters of mercury, which today we would consider as a normal blood pressure, already is associated with an increase in the prevalence or the incidence of ischemic stroke, as well as the association with heart disease. And we can see this especially with systolic blood pressure and almost in a linear association with ischemic heart disease, and as I said, with stroke. So even at levels as low as 150 millimeters of mercury, there's already an increased predisposition to a cardiovascular event. So the question really is then: What is the optimal blood pressure to prevent cardiovascular events?
Actually, this has been a huge amount of discussion and debate for many years, but it was really in 2015 when this paper was published, the results of the systolic blood pressure intervention trial or the SPRINT trial, which was really a landmark trial, where these investigators asked a very simple question: What is the optimal blood pressure that we should be targeting when we treat our patients to prevent cardiovascular events? What the study did is that it looked at about 9,000 patients divided into two groups. Half the group were treated on standard therapy, and half the group were treated by intensive therapy. They received the same blood pressure-lowering medications. The only intervention is that the doctor was very, very careful in terms of treating to a blood pressure systolic of 120 millimeters of mercury.
And indeed, over the course of this study, which actually was supposed to take place over the course of five years, showed us that with intensive blood pressure treatment, again, using treatment similar to the standard arm of this group, they did achieve a blood pressure maintained at about 121 millimeters of mercury. So what were the outcomes of these patient groups who were treated with their normal standard therapy and those who were treated with blood pressures that were maintained at a level of that of about 120 millimeters of mercury? Well, the results were extremely interesting.
What the results showed us is that those patients who were treated in the intensive arm, in other words, where their blood pressure was targeted to 120 mm Hg systolic, there was a 27% reduction in death, indicating that by simply reducing your blood pressure to levels of 120, the incidence of death could be reduced by almost 30%. So from these studies, we have now redefined targets for treating blood pressure to that of less than 130/80 and ideally, 120/70. Now, I've shared with you the importance of high blood pressure, and the reason why it's so important, as I said, is because it is a major risk factor for cardiovascular events.
Over the years, there's been a huge amount of effort to ensure that blood pressure is well controlled at the level of the individual and patients. We can see from the 1990s that if we consider control of blood pressure, and at these times it was treated to 140 over 90, we can see that from the 1990s, control of blood pressure in this very large cohort of patients, the NHANES cohort, we can see that control was actually improving over the past 20-odd years. However, very disappointingly, since about 2011, both in the United States, as indicated through these national NHANES data, as well as in Canada and in Europe, the control of hypertension has actually been declining, as we can see here. Associated, as we know, with declining control of blood pressure, there will be an increase in cardiovascular events.
Moreover, something which, of course, we didn't anticipate three or four years ago, is that we now have to consider the impact of COVID-19 in many of the chronic conditions that we deal with on a day-to-day basis in our clinics. What is very interesting to note, and this has been shown now in a number of studies, is that during COVID and in those patients who developed COVID, there has been an increase in the prevalence of hypertension. We are certainly seeing this more and more in our clinics, in that those patients who had COVID, and who were not hypertensive before, are now presenting in our clinics with hypertension. The blood pressure levels have been increasing, and hypertension control rates have actually declined over the course of the COVID years. This is due to many complex factors.
But the bottom line is that those patients who had COVID are now presenting with hypertension, and this, too, is adding to the challenges that we have in managing patients with hypertension. In terms of our global blood pressure control rates, this is a very complex slide, but it's a very important slide because the data are very comprehensive. These are data that show us blood pressure control rates across the world in many different countries, in both women and in men. And the red dots, as we can see here, are the control rates that were evident in 1990, and the black dots are the control rates that are evidenced in 2019. And what we can see is that in some countries, especially in the higher income countries, control rates have been better in 2019 than in 1990.
In the majority of countries in the world, both in women and especially here we can see in men, the control rates have been pretty bad. Despite the fact that there have been huge efforts, both in the development of guidelines and in the promotion of antihypertensive therapies, control rates across the world are very bad, and as I've just shown you, are actually worsening over the course of time… Moreover, what we know is that most people with hypertension do not have it under control, even though they are treated for their hypertension. In this study, we can see of the 1.4 billion people who have high blood pressure, 734 million may be aware.
Of these, 489 are treated, but only 14% of those who are actually treated are treated to targets that have been defined by guidelines. This, again, is contributing to the increased cardiovascular event rate that we are seeing today. So again, although we have lots of medications, we continue to do a pretty bad job in terms of treating patients, especially globally. So let's look at hypertension as it was in 2009, and this is based on a very famous paper and presentation given by Avram Chobanian called the Shattuck Lecture. It was published in the New England Journal in 2009. He said that the treatment of hypertension is one of medicine's major successes because the advances in therapy in 2009 provided the capacity to lower blood pressure in almost every patient.
However, uncontrolled disease occurs despite improved therapy, and he termed this the hypertension paradox. We know that uncontrolled hypertension causes those terrible, devastating diseases, as I mentioned to you, heart disease, dementia, stroke, et cetera. What I want to say to you is that he published this in 2009, but in 2023, not that much has changed. If anything, as I've shown you the statistics, some of the parameters have actually worsened. So what may be responsible for the reasons for this hypertension paradox? Well, hypertension is a multifactorial disease. There are many complex environmental factors that contribute to high blood pressure. We know that it's a lifelong condition, by and large, and that this means that patients need to be on treatment lifelong, and associated with this, there will be challenges related to adherence and to compliance.
Perhaps we still don't have the best therapies, and at the end of the day, the phatogenesis underlying essential hypertension, that is in 95% of patients, still remains unclear. As I said, the phatogenesis of hypertension is very complex, and in the 1960s, Irvine Page put together a fairly simplified mosaic theory of hypertension. Today, we've had to redefine this mosaic of hypertension to include a number of important factors that we do know contribute to the development of hypertension, especially new components of the renin-angiotensin-aldosterone system. The renin-angiotensin-aldosterone system does play a critical role in the development of hypertension, and it interacts with many of the other systems that do contribute to the pathophysiology of hypertension. What is the renin-angiotensin system?
Well, many years ago, when this system was actually defined, it was a fairly simple system whereby angiotensinogen, the precursor of angiotensin one, which under the control of various enzymes, particularly angiotensin-converting enzyme, Generates angiotensin two, and angiotensin two binds to its AT1 receptor and its AT2 receptor. However, over the past few years, we know that this system is much more complex, and there are now a number of new peptides that have actually been identified as derivatives of either angiotensin one or angiotensin two. And there are also a whole host of new enzymes, such as ACE2 and other enzymes, which play an important role in the renin-angiotensin system.
At the end of the day, it's really angiotensin two signaling through the AT1 receptor that is responsible for vasoconstriction, vascular hypertrophy, cardiac hypertrophy, fibrosis, inflammation, that underpin the characteristic changes that underlie the development of hypertension and its target organ damage. Therefore, there have been huge advances in targeting various components of the renin-angiotensin system to decrease the activity of some of the enzymes responsible for the production of angiotensin two, and also blocking the effects of angiotensin two at its receptor to decrease its downstream effects, including not only cardiovascular fibrosis, constriction, inflammation, but also the production of aldosterone. Today, we have very effective inhibitors of the renin-angiotensin system, including ACE inhibitors, very well known to us, angiotensin receptor blockers, and also blockers of the aldosterone system through mineralocorticoid receptor blockers, and also more recently, aldosterone synthase inhibitors.
What we do know, again, going back to the data from the SPRINT trial, is that despite the fact that many of the patients who were treated with many of these inhibitors of the renin-angiotensin system, as well as other antihypertensive drugs, here again, we see those who were treated, usually the normal control group, and here we see the intensive group.
While there was very good control over the first five years in terms of blood pressure lowering in the intensively treated group, we can see that with time, blood pressure tracks up to those patients who are on the standard drug therapy regimen, indicating that indeed, due to various factors in, probably related to the adherence and compliance of intensive therapy, this results in the tracking up, such that blood pressure control is not as good as it was at the beginning of the study. Again, many factors probably underlie the fact that long-term SPRINT trial shows loss of medication effect over time, including adherence and compliance. We know that poor antihypertensive drug adherence is associated with increased mortality risk, as evidenced in this study, both for all-cause mortality and for stroke.
In those patients who are compliant, as we can see here, defining them as good comp, adherence or good compliance, the hazard ratio with respect to all-cause mortality is lower than that compared to patients who are poor in terms of their adherence and compliance. So indeed, it is very important that patients do take their therapy as indicated by their physicians. So what are some of the barriers that continue to be present with respect to blood pressure control? Well, again, it's multifactorial. There are those factors that involve the patients, you know, such as perhaps limited access to treatment. As I've said, hypertension is a chronic condition and needs long-term treatment, and therefore, compliance and adherence really do remain as barriers. We know in chronic conditions, there might be some therapeutic inertia, either by the physician or by the patient.
Some patients, some doctors are reluctant to actually treat patients with hypertension, and also we know that there's poor adherence to current guidelines in terms of treating hypertension. There are also many complex systems at the level of health provision that may also contribute to the barriers of blood pressure control. Importantly, to appreciate that many of our patients, especially those with resistant hypertension, do need to be on lifelong treatment therapy, which usually comprises more than three antihypertensive drugs on a daily basis. It's not unusual to have patients coming into the clinic who say they're tired of taking six or seven drugs every day for the rest of their life.
However, these are exciting times because these therapeutic gaps are now being addressed in what I would call a new era in hypertension trials, where perhaps some of these new treatments may provide better blood pressure control, especially if we are in a position to be able to stratify those patients who may be responders and non-responders. These are some of the newer drugs that are now available through some of the evidence-based clinical trials, those that inhibit aldosterone synthase, those that are targeting the endothelin receptors, the importance perhaps of SGLT2 inhibitors, non-steroidal mineralocorticoid receptor antagonists, devices such as renal denervation, and then, of course, the very exciting area in terms of silencing through targeting RNAi angiotensinogen, the very exciting work associated with zilebesiran.
I have shared with you our current treatments in terms of targeting the renin-angiotensin system through classical ACE inhibitors and angiotensin II receptor blockers. Now, we probably could be adding to our therapeutic regimen the potential of actually targeting angiotensinogen, which is the forerunner or precursor of angiotensin II. This has been indeed a hugely exciting time for this drug, zilebesiran, which is, as we know, an agent that targets RNA at the level of hepatocytes to result in the reduction of angiotensinogen Gene expression, which will ultimately result in a decrease in the generation of the protein of angiotensinogen, and thereby clamping down the whole of the renin-angiotensin system. We know by doing this, the control of blood pressure can be improved.
We also know from here, we see in preclinical studies, that by inhibiting angiotensinogen through the siRNA approach, indeed, if angiotensinogen levels are measured in the plasma, as we can see here in experimental models, compared to some of the other classical inhibitors of the renin-angiotensin system, angiotensinogen is targeted to siRNA, is associated with an almost complete downregulation or generation of angiotensinogen, at least as measured in the circulation. We also know that this decrease in angiotensinogen is associated with compensatory effect on the renin system, and this is associated with what we would call an escape mechanism by renin. Because in the body, there is a consistent pursuit of homeostasis, and as angiotensinogen is downregulated, so too is this associated, interestingly, with an increase in plasma renin. And you don't see that much with some of the other more classical renin-angiotensin system inhibitors.
Also, if we look at angiotensin II levels, as we can see here, there is a difference in terms of angiotensin II, as indicated by the angiotensinogen siRNA approach by the light orange bar, relative to the classical ACE inhibitors, as we can see are in the blue, the angiotensin levels are indeed reduced. Again, going back to the control on blood pressure, the most recent very beautiful studies that were published in the New England Journal by Desai and colleagues, we can see that when zilebesiran, the angiotensinogen inhibitor, is given, there's a consistent reduction in both systolic and diastolic blood pressure from week six right up until week 24. As we can see here, this effect on a reduction in blood pressure with one injection of the siRNA targeting angiotensinogen is indeed sustained for up to 24 weeks.
And interestingly, the adverse effects associated with this approach were really non-significant. The other very important component in terms of blood pressure control is that blood pressure over the circadian rhythm, it's important that the circadian rhythm is maintained because of normal homeostasis. And what we can see again, in terms of the effects of the siRNA angiotensinogen therapeutic strategy, is that the normal circadian rhythm of normal dipping during nighttime is indeed preserved for all of the doses of zilebesiran that have actually been studied, at least to date. So with that, I would like to conclude then, to really emphasize to you that it is not cancer, it is not infectious diseases or trauma that is the number one killer in the world. It is indeed hypertension.
The reason for that, as I've said, is that hypertension causes heart disease, it causes stroke and vascular dementia, and it causes, very importantly, kidney disease as well. Importantly, the prevalence of hypertension is increasing worldwide and especially in women. The cardiovascular disease events increase as high normal blood pressure levels start to increase, and I've shown you that from a blood pressure systolic of 115, already there are associated cardiovascular events, especially ischemic heart disease and stroke. We know that targeting 120 over 80 reduces mortality by almost 30%. Despite the fact that we know this, the control rates are declining globally, and the emphasis on increased adherence and more user-friendly approaches for lifetime therapy really remain a major challenge and a need that we absolutely do need to address if we want to improve these statistics.
So it continues that there should be a need to define new mechanisms and new therapeutic targets and strategies. And as I have just shared with you, there are some very exciting and promising new therapeutic approaches that hopefully will address the needs, the challenges, and the gaps. With that, I thank you for your attention, and, at this point, I would like to now hand over to Dr. Fox, who will give you the next presentation in this session. Thank you.
Thank you, Dr. Touyz. It is great to get your expert perspective on the unmet need that persists in the management of hypertension. I am Simon Fox, Vice President and zilebesiran Program Lead at Alnylam. Zilebesiran is an investigational and innovative RNAi therapeutic for the treatment of hypertension that is currently in phase II development. It is my pleasure to speak to you about how we are reimagining the treatment of hypertension with zilebesiran. Today, I will discuss our view of the unmet need that still exists today and provide an update of our clinical development plan, as well as an overview of the results from our first phase II study, CARDIA-1. There are over 200 million adults with primary hypertension across the 7 major geographies.
But despite widespread availability of numerous oral daily antihypertensive therapies across several different drug classes, uncontrolled hypertension is still the leading cause of morbidity and mortality globally, and up to 80% of adults with hypertension have uncontrolled disease. In addition, marked variability in blood pressure over the 24-hour period, as well as over the long term, lack of nighttime blood pressure control, and of course, poor medication adherence, further exacerbates the risk associated with uncontrolled hypertension. Indeed, improving the management of hypertension includes more than just lowering blood pressure. It is done with the hope of further reducing cardiovascular risk and end organ damage. T o do this, you need to achieve a magnitude of blood pressure reduction to reach your target blood pressure goal, which is the quantity of blood pressure control.
But you also need to reduce blood pressure consistently, avoiding exaggerated blood pressure variability throughout the 24-hour period and over the long term, as well as maintaining nighttime dipping of blood pressure, which contributes to the quality of blood pressure control. A treatment option that could achieve tonic blood pressure control, targeting not only the quantity of blood pressure lowering but also the quality of blood pressure lowering, with the ability to achieve consistent 24-hour blood pressure control, which is sustained over the long term, could address the key unmet needs in hypertension management. Zilebesiran is an investigational GalNAc-conjugated small interfering RNA, targeting the hepatic production of angiotensinogen or AGT, the most upstream precursor of renin-angiotensin system.
The data Generated in our phase I study highlighted zilebesiran's transformative potential, where we demonstrated early evidence of a greater than 90% dose-dependent reduction in AGT, which was sustained for at least six months after a single subcutaneous dose. This translated into a robust reduction in both systolic and diastolic blood pressure, with excellent durability that resulted in over 20 millimeters of mercury reduction in systolic blood pressure at six months after a single injection. We believe these attributes create a highly differentiated profile from all other existing antihypertensive therapies. It is well known that even if patients take their medication, they may still experience inconsistent blood pressure control throughout the 24-hour period. The left-hand chart is the mean 24-hour ambulatory systolic blood pressure profile of losartan, a commonly used once-daily angiotensin receptor blocker. At the beginning of the daily dosing interval, patients achieve good blood pressure-lowering effect.
However, the magnitude of blood pressure lowering and the consistency of blood pressure lowering decreases throughout the evening into the early hours of the morning and towards the end of the dosing interval. On the right-hand chart, we have the mean 24-hour ambulatory systolic blood pressure of a single dose of zilebesiran 800 milligrams compared to placebo at week six from our phase I study. You will see that just one dose of zilebesiran achieved tonic blood pressure control at week six, with consistent and durable blood pressure reductions throughout the daytime and nighttime for the entire 24-hour period. This consistent blood pressure-lowering effect was also sustained up to month 6 with a single dose of zilebesiran. For this reason, we believe zilebesiran has best-in-disease potential, with the ability to achieve consistent and durable tonic blood pressure control with infrequent dosing.
Given zilebesiran's compelling phase I data, we've entered into a partnership with Roche to realize the full potential of zilebesiran to address unmet medical needs in patients with hypertension by combining Alnylam's leadership in developing RNAi therapeutics with Roche's global commercial footprint, regulatory expertise, and a proven track record of successfully launching innovative medicines. Through this arrangement, we intend to progress a robust development plan for zilebesiran, Generating cardiovascular outcomes data prior to launch and thereby optimizing the commercial opportunity globally. In partnership with our colleagues at Roche, we have agreed on a clinical development plan focused on exploring the benefits of tonic blood pressure control to potentially reduce cardiovascular risk in patients with uncontrolled hypertension.
As a reminder, our phase I study, which explored the safety, tolerability, and pharmacokinetic/pharmacodynamic profile of zilebesiran in patients with mild to moderate hypertension, was published in the New England Journal of Medicine in July of this year. In 2021, we initiated our phase II program with two studies, CARDIA-1 and CARDIA-2, and we were thrilled to have CARDIA-1 results presented as a late breaker at the American Heart Association Scientific Sessions in November. In just a moment, I will provide an overview of these study results. In addition, I will also provide more details on the progress of our ongoing phase II clinical development plan, including the first details of CARDIA-3, our next phase II study. As already mentioned, we believe zilebesiran's best-in-disease potential, as well as its potential to reduce cardiovascular morbidity and mortality in patients with hypertension and high cardiovascular risk.
These are patients for whom the urgency to treat is the greatest, and we believe that this innovative therapy has a significant role to play in reducing cardiovascular risk by helping more patients achieve their blood pressure targets, maintain tonic blood pressure control, and mitigate the adherence challenges that are well known with the current standards of care. To realize the full potential of an innovative therapy like zilebesiran, we believe it is critical to launch the product with a robust and comprehensive data set that will help ensure a rapid and smooth adoption of zilebesiran into the treatment paradigm. To that end, we plan to conduct a large cardiovascular outcomes trial as a pivotal trial to deliver compelling data package for regulatory review, and if approved, we expect the outcome of this study will significantly differentiate zilebesiran and provide the most compelling value proposition at launch.
I will now present a brief overview of the findings of CARDIA-1, which is a randomized, double-blind, dose-ranging study of zilebesiran in patients with mild to moderate hypertension. For additional details, please see the presentation from the American Heart Association meeting on Capella section of our website. The study enrolled adult patients with hypertension who are either untreated or on stable therapy with up to 2 antihypertensives. Following antihypertensive therapy washout of at least two-four weeks, patients were then required to have a daytime mean ambulatory systolic blood pressure of 130-160 mm Hg. Patients were then randomized equally to receive subcutaneous placebo once every three months, or one of four subcutaneous zilebesiran regimens: 150 mg, 300 mg, 600 mg every six months, or 300 mg every three months.
The primary endpoint of the study was the change from baseline at month three in 24-hour mean systolic blood pressure, assessed by ambulatory blood pressure monitoring, and this is reported as the placebo-adjusted result. That is the difference between the zilebesiran arm and the placebo arm. Key secondary endpoints were changes from baseline in ambulatory systolic blood pressure at month six and office systolic blood pressure at month three and month six. Here are the baseline demographics for CARDIA-1. In total, 394 patients were randomized. 16 patients were enrolled in Ukraine, but excluded due to difficulties with data collection during the conflict, and on patient in the placebo group was not dosed, resulting in 377 patients in the analysis set. Baseline demographics were generally balanced across groups.
78% of patients were from the United States, and the mean age was 57 years, and just over half the patients were male. We are very proud to have enrolled a diverse and representative patient population into CARDIA-1. It is worth noting the average baseline systolic blood pressure was relatively low at approximately 142 mm Hg, which is indicative of a mild to moderate hypertension population. Starting out with the pharmacodynamic data, in line with our phase I results, zilebesiran-treated patients had rapid and sustained reductions in serum angiotensinogen levels. Serum AGT reductions were dose-dependent and near optimal at month three and sustained greater than 90% at month six, with the higher doses of 300 milligrams and 600 milligrams of zilebesiran.
Consistent with our therapeutic hypothesis, these profound and sustained reductions in serum AGT translated to effective reductions in systolic blood pressure. For the primary endpoint of the study, treatment with a single dose of zilebesiran was associated with clinically meaningful and significant reductions in twenty-four-hour mean ambulatory systolic blood pressure across all doses of up to 16.7 mm Hg at month three. Across all doses, twenty-four-hour mean ambulatory systolic blood pressure reductions persisted out to month six, with zilebesiran achieving placebo-adjusted reductions of up to 14.5 mm Hg. In three out of four of the zilebesiran arms, this result was achieved after a single dose at the beginning of the six-month study period. We believe these findings strongly support the potential for biannual dosing of zilebesiran.
Two key secondary assessments of clinical efficacy were changes in office systolic blood pressure at month three and month six. Here you can see the changes in office systolic blood pressure from baseline month three, were consistent with observed changes in ambulatory systolic blood pressure reductions, with zilebesiran achieving placebo-adjusted reductions in office systolic blood pressure of up to 12 millimeters of mercury. Again, consistency of blood pressure-lowering effect on office systolic blood pressure persisted out to month six, particularly with zilebesiran 300 and 600 milligram doses, with placebo-adjusted reductions in office systolic blood pressure of up to 12.1 millimeters of mercury. Earlier in the presentation, I spoke to the fact that even when patients take their antihypertensive medication, they can experience inconsistent blood pressure control over the 24-hour period.
Again, the left-hand chart shows losartan's mean 24-hour ambulatory systolic blood pressure profile, which illustrates that the magnitude and consistency of blood pressure control decreases over the daily dosing interval. On the right-hand chart, similar to what we saw in phase I, a single zilebesiran dose achieves tonic blood pressure control over the full 24-hour period, consistent blood pressure control during the daytime and nighttime, shown here at month three. In addition, it was extremely encouraging to see that this effect was maintained out to month six, particularly at the higher doses of 300 and 600 milligrams, which gives us further confidence in the ability to achieve durable blood pressure control with biannual dosing. These results are very exciting. We've now shown the ability to provide clinically meaningful blood pressure reductions that persist for at least six months after a single dose of zilebesiran.
But to truly understand the importance of these data, it is necessary to reiterate the need for tonic blood pressure control. Poor medication adherence remains a significant issue, which further increases a patient's exposure to cardiovascular risk. Studies have shown that up to 35% of patients stop taking their antihypertensive medication within 6 months, and up to 50% have stopped by month 12. Moreover, it is well known that nighttime blood pressure is a strong predictor of cardiovascular mortality, and the risk of cardiovascular mortality significantly increases with a higher nighttime systolic blood pressure.
Given the CARDIA-1 results demonstrating zilebesiran's ability to achieve 24-hour-to-tonic blood pressure control, with consistent 24-hour mean systolic blood pressure reductions of up to 16.7 mm Hg, including preserved nighttime blood pressure dipping, sustained out to six months with just a single dose, we truly believe in zilebesiran's potential to affect the key clinical challenges, such as controlling nighttime blood pressure and poor adherence, with the goal of further reducing cardiovascular risk. In CARDIA-1, zilebesiran demonstrated an encouraging safety profile during the 6-month treatment period. Rates of serious and severe adverse events were low in zilebesiran overall and were comparable to placebo. No serious and severe adverse events were considered related to zilebesiran. Drug-related adverse events leading to the discontinuation of zilebesiran occurred in four patients and were orthostatic hypotension, blood pressure elevation, and injection site reaction...
Most injection site reactions and hyperkalemia adverse events were mild, transient, and did not require therapeutic intervention. I'd now like to briefly review the progress of our phase II studies. The ongoing phase II study, CARDIA-2, enrolled a total of 672 patients. The primary objective is to evaluate the efficacy and safety of zilebesiran as a combination therapy with one of three standardized background treatments, that being the maximum dose of the angiotensin receptor blocker, olmesartan, a calcium channel blocker, amlodipine, or indapamide, a diuretic. Enrollment completed in June 2023, and top-line results are expected in early 2024. And now, for the first time, I would like to provide some additional details of the CARDIA-3 study. CARDIA-3 will be a randomized, double-blind study in patients with high CV risk.
The study will enroll adult patients with uncontrolled hypertension who have a history of atherosclerotic cardiovascular disease or chronic kidney disease. They will have an office systolic blood pressure between 140-170 mm Hg, and patients coming into the study must be on stable doses of at least two background antihypertensives. Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers will be allowed at appropriate therapeutic doses. The study will have two cohorts of patients. Cohort A will enroll approximately 270 patients who have an eGFR greater than 45. In cohort A, patients will be randomized to biannual doses of zilebesiran, 300 mg, 600 mg, or placebo, with a double-blind period lasting for 6 months. Cohort B will enroll up to 120 patients with an eGFR between 30-44.
In cohort B, patients will be randomized to biannual doses of zilebesiran at 150 milligrams, 300 milligrams, 600 milligrams, or placebo, with the double-blind also lasting for six months. The primary objective of the study is to evaluate the add-on effect of zilebesiran on systolic blood pressure at month three, as measured by change from baseline in seated office systolic blood pressure. Additional assessments of blood pressure control will be evaluated as secondary endpoints. CARDIA-3 is expected to initiate in early 2024. To summarize this presentation, with so many patients suffering from uncontrolled hypertension around the world, despite the multiple classes of antihypertensives available, there is a clear unmet need for a novel and innovative therapeutic option. Achieving consistent and durable tonic blood pressure control could help overcome the current challenges we face in the management of hypertension.
Our development plan has been designed to explore the benefits of tonic blood pressure control. We have made substantial progress over 2023, with more to come in 2024 and beyond. We believe zilebesiran has best-in-disease potential, and this has been further validated by the results of CARDIA-1. Thank you. I would now like to hand over to my colleague, John Vest, who will start the discussion of our TTR franchise.
Thanks, Dr. Fox, and good morning. I'm John Vest, Senior Vice President and Head of Clinical Research for Alnylam's TTR franchise. I'm here today, along with Ali Murad, Senior Director of Clinical Research, to provide an updated overview of the franchise, including context on the upcoming HELIOS-B readout, as well as exciting new data presented for the first time today on our clinical progress with the third program in our franchise, ALN-TTRsc04. To begin, I'll briefly review the disease of ATTR amyloidosis and our therapeutic hypothesis. ATTR amyloidosis is a rare, progressively debilitating disease caused by misfolded transthyretin protein, typically resulting in polyneuropathy and cardiomyopathy manifestations of disease. As with most rare diseases, the true prevalence is difficult to know, but we believe there are approximately 50,000 patients worldwide with the hereditary form of the disease, where the patient carries a TTR gene variant.
Patients without a TTR variant can also accumulate misfolded transthyretin protein in tissues, often associated with advanced aging, and this leads to wild-type ATTR amyloidosis. Prevalence estimates for this patient segment are significantly larger, perhaps 300,000 patients worldwide, though some estimates are much higher. Both the hereditary and wild-type forms of disease may present with multisystem involvement and a high burden of disease that is often fatal. To look in more detail at the pathophysiology of ATTR amyloidosis, in patients with this disease, the TTR protein, either variant or wild type, which is produced in the liver, can misfold and form amyloid fibrils. These amyloid fibrils deposit in the peripheral nerves and the heart to cause polyneuropathy and cardiomyopathy manifestations, respectively, which are the hallmarks of this disease.
Our therapeutic hypothesis follows on from this well-understood pathophysiology and has remained consistent since we began working in this space over 10 years ago. Patisiran and vutrisiran are small interfering RNAs that target a highly conserved region of the TTR Gene found in both variant and wild-type patients. By inhibiting hepatic synthesis of both variant and wild-type TTR protein via the process of RNA interference, these agents drive rapid knockdown of TTR production at the source, which results in lower circulating levels of the pathogenic protein, which in turn, reduces further amyloid deposition in the nerves and the heart, thereby halting or even improving the manifestations of disease. To summarize and put our data in context, there is a singular common pathophysiology in ATTR amyloidosis across hereditary and wild-type forms of the disease, resulting in both cardiomyopathy and polyneuropathy, and transthyretin is the common pathogenic protein.
With the rapid knockdown of transthyretin seen with patisiran and vutrisiran, there is consistent and growing evidence that the Alnylam TTR franchise has strong potential to meaningfully address the full spectrum of disease manifestations across the broad patient population. To date, both our patisiran and vutrisiran programs have established definitive evidence for the treatment of polyneuropathy in hereditary patients, and data in these patients also provide strong corroborative evidence in cardiomyopathy. The treatment effect on cardiomyopathy was most recently demonstrated in the APOLLO-B study, where patisiran demonstrated a favorable impact on important clinical measures of patient function, health status, and quality of life.
Although data from the APOLLO-B study was submitted to the FDA in the supplemental new drug application and a complete response letter citing lack of clinically meaningful benefit was issued, the data are exceedingly important in contextualizing the potential for RNAi therapeutics to benefit outcomes measures in the treatment of this disease. Collectively, these data provide an extraordinarily solid foundation that gives us confidence as we await the results of the next major chapter in this story with the readout of HELIOS-B in early 2024, potentially providing evidence of an outcome benefit with vutrisiran in ATTR amyloidosis with cardiomyopathy. As we look towards the readout of HELIOS-B, we feel the study is poised to address the substantial unmet need that remains in ATTR amyloidosis. Let's begin with the context of the stabilizer landscape and several important observations across the available data.
First is the evidence of disease progression observed with stabilizers across multiple endpoints. Second is the delayed impact of stabilizers on mortality. And third is the greater benefit observed in patients with less advanced disease, New York Heart Association Class I and Class II. These trends have now been consistently reflected across two phase III stabilizer studies: the ATTRACT study of tafamidis and the ATTRibute-CM study of acaramidis, and highlight the unmet need in this disease. We also believe that these data support the potential for RNAi therapeutics to help address this unmet need. We'll now look at these important observations in the stabilizer data in more detail. Let's start with the important measure of functional capacity assessed by the six-minute walk test, and patient health status and quality of life assessed with the Kansas City Cardiomyopathy Questionnaire.
The results from the ATTRACT study of tafamidis are shown on the left, and the results from the ATTRibute-CM study of acaramidis are shown on the right. While in both studies, stabilizers showed a benefit compared to placebo, you can see, on average, patients receiving stabilizer therapy still experienced a steady decline from baseline. This is an important observation, given that we know maintaining function and quality of life is of, of extraordinary importance to patients, and what patients lose, they do not gain back. This decline in these elements reflects irreversible accumulation of disability. Turning to assessment of mortality, we see our second important observation. While both the, the ATTRACT study on the left and ATTRibute-CM on the right demonstrate improved mortality compared to placebo, the benefit does not emerge until at least 18 months, a consistent observation across both stabilizer studies.
In this progressive disease, this again highlights an important unmet need. We believe that these data support the potential for RNAi therapeutics to help address this unmet need. The associated hazard ratios for mortality are outlined in the table and range from 0.77 with-- on the ATTRIBUTE study, to 0.7 on the ATTRACT study. Of note, the Attract-- in the ATTRACT study, the treatment effect was greater in patients with less advanced disease, New York Heart Association Class I and Class II, a concept we'll discuss further on the next slide.
Here, we are looking at the subgroup data with ATTRACT on the left and ATTRibute-CM on the right, where we see a consistent observation that the treatment effect appears to be substantially greater in patients with less severe disease, New York Heart Association Class I or II, compared to patients with more advanced disease, New York Heart Association Class III. Indeed, for the ATTRACT study, the treatment effect on CV hospitalizations in New York Heart Association Class III favored placebo. It is now generally accepted that patients diagnosed with ATTR amyloidosis in the current era are less advanced in their disease course, and their heart failure symptoms are better managed than when the patients were originally enrolled in the ATTRACT study.
Nonetheless, the data from these two studies consistently support that patients on stabilizers, on average, continue to progress and that earlier in their disease course, and that patients earlier in their disease course have potential to benefit from early therapeutic intervention. This is important as it further heightens our confidence in seeing a positive outcome on HELIOS-B when we consider the design and enrollment window, as well as the patient population on that study. We'll discuss this later in the presentation. With this context of the consistent observations seen across the stabilizer data in mind, we will now turn to the data from RNAi therapeutics that we believe highlight our potential for a differentiated and market-leading profile, including rapid knockdown of the disease-causing protein, driving the potential for early clinical benefit.
Consistent data across multiple phase III studies in multiple disease manifestations, demonstrating the ability to halt or reverse disease progression. The market-leading profile of vutrisiran in hereditary polyneuropathy, including efficacy, safety, and infrequent dosing. And finally, the beneficial effects of RNAi therapeutics seen across multiple important predictors of outcomes, which collectively give us confidence in the upcoming readout of HELIOS-B. First, as we think about the potential for RNAi therapeutics to address unmet need for ATTR amyloidosis patients, we would like to highlight our conviction in this mechanism of action, in the ability of these therapeutics to halt disease progression, which has now been demonstrated across multiple manifestations of the disease. First, let's start with RNAi therapeutics' powerful mechanism of action, where with both patisiran and vutrisiran, we see rapid knockdown of the disease-causing protein within a matter of weeks.
This rapid knockdown is unique to RNAi therapeutics, and we believe underlies our observed ability to halt or potentially reverse a broad range of disease manifestations, and ultimately, the potential for earlier impact and outcomes. To this end, I want to first remind you of the profound impact that RNAi therapeutics have demonstrated on polyneuropathy manifestations of hereditary ATTR amyloidosis is illustrated by results with patisiran on the APOLLO study in the left-hand panels, and vutrisiran on the HELIOS-A study in the right-hand panels. We see a consistent pattern for both neuropathy impairment, assessed by mNIS+7 in the top panels, and quality of life, assessed by Norfolk Quality of Life in the bottom panels. Where for both endpoints, in contrast to the rapid decline that's observed in placebo-treated patients, denoted in red, patients treated with RNAi therapeutics demonstrate halting or reversal of polyneuropathy progression.
Now, when we look at the cardiac manifestations of the disease in ATTR amyloidosis patients with cardiomyopathy on APOLLO-B, we see a remarkably similar pattern. For both functional status, assessed by six-minute walk test on the left, and health status and quality of life, assessed by KCCQ on the right. When we look at the data, including the double-blind period and 12 months on the open label extension, what we can see is that the treatment effect of patisiran observed during the double-blind period is maintained out to 2 full years, with patients showing preservation of functional status and health status and quality of life. We can also see that for both endpoints, patients randomized to placebo, who showed steady decline during the double-blind period, appeared to stabilize after crossing over to patisiran in the open label period.
This is clearly illustrated by comparing the observed data for the placebo group with the extrapolated dotted trend line, which represents the projected change from baseline for patients in the placebo group if they had not received patisiran in the open label period, which was modeled using data from the double-blind period. Here, we're looking at the same endpoints, six-minute walk test on the left and KCCQ on the right, in the monotherapy subgroup on APOLLO-B, which consisted of those patients not receiving tafamidis at baseline. I'd like to point out several observations. First, the magnitude of the treatment effect is larger than that observed in the overall population. Second, we see the exact same pattern of essentially no change in walking distance compared to baseline, up to two full years in patients randomized to patisiran.
Finally, we see the same pattern for patients randomized to placebo in the double blind period, where they show clear evidence of maintaining their walking ability after crossing over to patisiran in the open label period. This pattern of clinical stability is further supported by multiple assessments on APOLLO-B that reflect well-recognized tools used clinically to inform disease progression, including NYHA class and ATTR amyloidosis disease stage. You can see here that the odds of progression based on NYHA class and ATTR disease stage are substantially lower in patisiran-treated patients compared to placebo, and the effect is maintained at two years. I'd like to further highlight additional data suggesting the potential for RNAi therapeutics to have a broadly beneficial impact on the heart and underscoring the potential for early impact and compelling treatment benefit.
Here, we're showing the exploratory results from APOLLO-B for the cardiac biomarkers NT-proBNP and troponin I, which reflect cardiac stress and heart failure severity, and myocardial damage, respectively. These are clinically important biomarkers that are routinely monitored in clinical practice.... and are incorporated in recognized ATTR amyloidosis disease staging systems and expert consensus criteria for defining disease progression. Furthermore, NT-proBNP levels and increases in levels are prognostic of outcomes in ATTR amyloidosis. Over the double-blind period, the placebo group showed a steady increase or worsening in the levels of both biomarkers. While in marked contrast, the patisiran group demonstrated relative stability, resulting in a nominally significant beneficial treatment effect for both biomarkers at month 12. Of note, evidence of beneficial treatment effect is seen as early as 6 months.
The biomarker results are complemented by exploratory echocardiographic assessments of cardiac structure and function on APOLLO-B, shown here in the top panels, where patisiran again demonstrates a favorable treatment effect. In contrast to the expected increase in LV mass seen on the placebo arm, reflecting ongoing amyloid deposition, patisiran-treated patients demonstrated essentially no change in LV mass, consistent with the suppression of amyloid deposition, which in turn was accompanied by a substantially smaller increase in global longitudinal strain compared to placebo, which is an important measure of cardiac function in this disease. They also maintained or slightly improved in LV stroke volume. These results were all nominally significant and consistently suggest a beneficial effect on disease pathophysiology, linking the mechanism of action of patisiran, reducing the amyloidogenic protein, to the observed clinical improvements on APOLLO-B.
Additionally, the exploratory results for technetium scintigraphy imaging, shown on the bottom panels, further supports this link. This has become a standard in the field for diagnosing ATTR amyloidosis. These results reflect a pre-specified analysis from a planned sub-study at select sites and were analyzed by blinded readers at a central lab. In the placebo arm on the right, at baseline, as expected, the patients were all Perugini grade two or three, and the vast majority of placebo patients remain unchanged at the end of the 12-month double-blind period, with no patient demonstrating improvement. In contrast, on the patisiran arm in the left-hand panel, by month 12, 38% of patients had improved by at least one Perugini grade. Of specific note, five patisiran-treated patients improved to Peregini grade zero or one, which is below the standard threshold grade for diagnosis of ATTR amyloidosis.
Finally, we would like to specifically focus on how the data from RNAi therapeutics reinforces our confidence in the upcoming readout of HELIOS-B. As I've underscored throughout the presentation, RNAi therapeutics have consistently demonstrated halting of disease measures of both neuropathy and cardiomyopathy in clinical trials. This was most recently highlighted with the impact of patisiran on multiple clinically important cardiac parameters on APOLLO-B. But why does this all matter? Because collectively, these data continue to bolster our confidence in the potential to demonstrate a benefit on outcomes in HELIOS-B. Here we see published data for six-minute walk test, KCCQ, NT-proBNP, and amyloidosis disease stage. In all cases, these published data suggest that these assessments are predictive of survival outcomes. This is important, given that, as we've shown in the previous slides, these are all assessments where an RNAi therapeutic, patisiran, has demonstrated benefit.
Thus, when taken together with the data amassed from multiple phase III studies across our TTR programs, we believe the results of the APOLLO-B study of an RNAi therapeutic showing consistent results across a broad range of predictive endpoints, support the potential for demonstrating an outcome benefit on HELIOS-B. With this in mind, we will now look at the outcomes data on all-cause mortality from APOLLO-B. First, on the left, we are showing data from the double-blind period, where you can see a beneficial trend in mortality emerging as early as 9 months. Given the short duration of the 12-month double-blind period, an analysis of all-cause mortality that includes data from the open label extension after all patients had completed month 24, was performed to provide a more robust assessment of outcomes, which is shown on the right.
The data reflects overall experience in the study, including the randomized treatment in the double-blind period, plus patisiran treatment effect in the open label extension. The apparent separation of the all-cause mortality curves between the randomized treatment groups in the open label extension continues to suggest a beneficial trend, which again emerges as early as nine months. It's important to note that there were no statistically significant differences in outcomes observed on APOLLO-B at any time point, and the study was not designed to demonstrate this. Beyond the potential early separation of mortality curves at month nine on APOLLO-B, in terms of the overall effect on mortality, here we are summarizing the hazard ratios for mortality from APOLLO and APOLLO-B.
While no statistically significant differences on mortality have been demonstrated with RNAi therapeutics, and the studies were not designed to assess outcomes, I would like to highlight the consistency of the trends on mortality observed across those two studies of patisiran... and while it's important to note the limitations of cross-trial comparisons, and stabilizers and RNAi therapeutics have not been studied head-to-head, when taken together with the results from the two stabilizer studies shown earlier in the presentation, the results bolster our confidence in the potential to demonstrate an outcomes benefit on HELIOS-B, which is twice as large and three times as long as APOLLO-B. With that, I would like to transition to discussion of HELIOS-B specifically, and our belief that it is well-positioned for success.
Many of you are familiar with this, but by way of brief reminder of the study design, HELIOS-B is a randomized, placebo-controlled phase III trial in patients with hereditary or wild-type ATTR amyloidosis with cardiomyopathy and symptomatic heart failure. The study was designed to enroll approximately 600 patients. Patients are randomized 1:1 to receive patisiran 25 mg quarterly or placebo. The primary endpoint is a composite of mortality and CV events to be analyzed after the final patient completes month 30, with follow-up up to 36 months in most patients. Importantly, I would like to highlight that when we designed HELIOS-B, we had the foresight to exclude the sickest patients, many of whom may be unable to respond to any therapy.
As we have previously said, the inclusion/exclusion criteria for HELIOS-B, and thus the patient population, is very similar to APOLLO-B, where over 90% of patients were NYHA class I or II, with the vast majority being class II. Thus, HELIOS-B is enriched for patients with less severe disease who are most likely to benefit from TTR-directed therapy. An observation which has now been confirmed across multiple stabilizer trials in this disease, as highlighted earlier in the presentation. Following on from this, we feel that collectively, there are numerous factors that make HELIOS-B well-positioned for success. The study was designed for outcomes and is twice as large and three times as long as APOLLO-B. As just mentioned, the study is enriched for patients most likely to show strong benefit. We anticipate a robust data package with follow-up for up to 36 months in most patients.
The study was conservatively powered, and despite that, we see several additional tailwinds. The study over-enrolled by 10%, bolstering our confidence in the sample size, and we came in below our 50% target for patients on baseline tafamidis, and we have seen a low rate of tafamidis drop-in, with rates well within expectations. When we take these factors, along with our powerful mechanism of action and the supportive data with patisiran from APOLLO-B, it collectively gives us great confidence in our ability to demonstrate an outcome benefit on HELIOS-B. To briefly review upcoming milestones, top line data readout for HELIOS-B is anticipated in early 2024. If positive, we anticipate an sNDA submission for vutrisiran label expansion in ATTR amyloidosis with cardiomyopathy in mid 2024, and pending successful regulatory review, AMVUTTRA commercialization in ATTR amyloidosis with cardiomyopathy is expected in 2025.
Looking forward beyond HELIOS-B, I would now like to turn the discussion to our continued commitment to innovation in ATTR amyloidosis with ALN-TTRsc04. I will turn the presentation over to my colleague, Dr. Ali Murad, for further discussion of this program, including promising initial results from our ongoing phase I study.
Thank you, Dr. Vest. I am Dr. Ali Murad and, as mentioned, delighted to share for the first time top-line results from the ongoing ALN-TTRsc04 phase I study. I will begin by presenting modeling analysis derived from the patisiran phase III APOLLO study. As depicted on this graph, this analysis shows that achieving higher levels of serum TTR reduction greatly improves the probability of successful clinical outcomes in patients with ATTR amyloidosis. Therapies that have the potential to offer even higher levels of TTR knockdown could, therefore, improve ATTR amyloidosis clinical outcomes. Alnylam is committed to continuing to innovate in the development of ATTR amyloidosis therapies, and we are excited by the potential for ALN-TTRsc04 to offer very high levels of TTR reduction, which could be expected to translate into improved clinical outcomes. ALN-TTRsc04 has been developed using IKARIA technology to offer potent and durable TTR knockdown.
This means that it has the potential to achieve high levels of TTR knockdown with a convenient subcutaneous dosing regimen, potentially as infrequently as once annually. ALN-TTRsc04 is currently being studied in an ongoing double-blinded, placebo-controlled, single-dose healthy volunteer study. The study is progressing well, and dose levels up to 600 milligrams have been administered, with pharmacodynamic data from doses up to 300 milligrams available to share currently. Data from the study outlined on this slide show that ALN-TTRsc04 results in rapid dose-dependent TTR knockdown. We also see that even with relatively low doses of ALN-TTRsc04, for example, the 25 milligram dose shown on this slide, TTR reduction is sustained through at least day 180.
Data from the 300 milligram cohort, which is the highest dose for which we currently have data to share, confirms that ALN-TTRsc04 has the potential to achieve rapid, deep, and sustained TTR knockdown. As highlighted on this slide, we see rapid TTR knockdown of greater than 90% by day 15, with a mean TTR knockdown of 97% at day 29. Importantly, these high levels of TTR reduction are sustained, and 180 days after administration of a single dose of 300 milligrams of ALN-TTRsc04, we continue to see a mean of 93% TTR reduction. Moving on to safety, ALN-TTRsc04 has been well tolerated across all doses studied. There have been no adverse events considered related to study drug by investigators, and no safety signals have emerged, including no liver-related safety signals and no injection site reactions.
To summarize, a promising profile is emerging for ALN-TTRsc04, which has the potential to offer greater than 90% serum TTR reduction with dosing as infrequently as once annually. In the ongoing phase I study, ALN-TTRsc04 has been well tolerated, and Alnylam is actively exploring ways to rapidly advance it as a treatment for patients with ATTR amyloidosis. It is now my pleasure to hand over to Tolga Tanguler, Alnylam's Chief Commercial Officer.
Thank you very much, Dr. Murad, and hi, everyone. I'm Tolga Tanguler, Alnylam's Chief Commercial Officer. Beginning in 2018, with our introduction of ONPATTRO for adults with polyneuropathy of hATTR amyloidosis, and later with the launch of AMVUTTRA in 2022, we've Generated robust 57% CAGR growth with our TTR franchise between 2019 and 2022. Due to its impressive rapid knockdown profile, demand for AMVUTTRA in existing and newly launched markets has been strong. And together with continued demand for ONPATTRO in markets where AMVUTTRA is not yet available, we anticipate our polyneuropathy business will continue to grow and be a key contributor to our company's 40% compound annual growth rate P to the fifth by 2025 goal.
Today, Alnylam's TTR franchise is the clear market leader in the treatment of hATTR polyneuropathy category, including markets like Japan and Europe, where Alnylam holds an average of over 80% market share versus other treatment options, including in regions where the stabilizer class is indicated for polyneuropathy. With that in mind, I'd like to highlight a few particularly important metrics that demonstrate AMVUTTRA demand in the US, our most important market since its launch in July 2022, including doubling the number of naive AMVUTTRA start forms since launch compared to previous ONPATTRO trends as of Q3 2023. 60% growth in prescriber physician base since the launch.
In alignment with our patient access philosophy, a commitment we made before even becoming a commercial company, we're also proud that nearly 100% of patients have confirmed AMVUTTRA access, 70% of AMVUTTRA patients have no out-of-pocket costs, and over 90% of patients on AMVUTTRA comply with the dosing regimen and remain on therapy. At Alnylam, we pride ourselves on being pioneers, not just in our scientific discovery, but also in paving the way as a growing biopharmaceutical company on a mission to become a top-tier biotech company by the end of 2025. Since the commercialization of ONPATTRO, we've been focusing on the foundational capabilities that have delivered impressive growth and metrics, some of which you saw on the previous slide.
We've also been focusing on scaling our commercial capabilities, not only by knowing our science best, but by fully understanding the patient and provider communities who can benefit from it. Examples seen here are: our global customer-centric field strategy, award-winning patient support services team that has been enabling us to help patient access their Alnylam treatments quickly with one of the fastest timelines in transition from start form to therapy in the industry, and also supports our over 90% patient adherence metrics. Advanced physician targeting for lead generation system with the help of artificial intelligence and advanced analytics capabilities that we've been building for the last five years that allows our customer-facing teams to be incredibly effective and agile.
It's also worth noting our track record for strong payer and health system partnerships that, again, enables exceptional patient access, not only in the US, but also across all major global markets, including Europe and Japan. As we look ahead to the potential of AMVUTTRA for adults with the cardiomyopathy of ATTR amyloidosis, assuming positive HELIOS-B results and regulatory approval, we expect to leverage the capabilities built in hATTR amyloidosis with polyneuropathy to prepare for rapid expansion of our TTR franchise. Importantly, we believe we are well-positioned to win along each step of the patient journey. AMVUTTRA would launch into a fast-growing ATTR-CM market. Our unique mechanism of action would offer rapid knockdown, durability of effect, with a well-characterized safety profile, and physician and patient-preferred four times a year dosing.
In AMVUTTRA and hATTR-PN, as a healthcare professional administered Part B reimbursed product, has received optimal coverage across a variety of payers, and we believe this would likely carry forward for our ATTR amyloidosis with cardiomyopathy in the U.S. Lastly, adherence. We believe the AMVUTTRA's four times a year dosing would align well with the cadence of ATTR-CM patient healthcare professional visits and would allow help ensure high adherence and compliance. As I mentioned before, the dynamics of ATTR-CM market are rapidly evolving. Assuming successful data and approvals, we're poised to deliver the potential of RNAi therapeutics to what we believe remains a significant unmet patient need and to maximize additional growth for the franchise.
Since the introduction of the first approved therapy of ATTR amyloidosis with cardiomyopathy in 2019, and the availability of non-invasive diagnostic tools like scintigraphy, there has been a steady increase in diagnosis rates. Similar to other undiagnosed and undertreated disease categories, we anticipate the diagnosis rates will continue to increase, driven by the introduction of new products over the next 1-3 years. The diagnosed patient curve present even higher growth opportunities than outlined here, given the multiple players helping drive greater patient diagnosis, and we remain confident in our ability to be a potentially leading option in this growing disease category.
Assuming successful data and regulatory approvals, we believe that AMVUTTRA would be very well positioned to serve patients in ATTR-CM with a highly competitive and market-leading profile, including rapid knockdown of TTR, the disease-causing protein, a unique MOA that works upstream of protein development and prevents disease-causing toxic proteins, and an attractive four times a year dosing schedule that aligns well with doctor visits and supports strong patient adherence. AMVUTTRA's compelling clinical profile, assuming positive data, could support first-line positioning that could drive significant growth in our TTR franchise over the long term. We expect the market to be primarily monotherapy, driven before tafamidis loss of exclusivity, anticipated in late 2028, given the cost of combination therapy. Once loss of exclusivity occurs for tafamidis, it may open the additional opportunity for combination therapy.
Assuming positive data and regulatory approval in 2025, we anticipate that AMVUTTRA, with its rapid knockdown profile, has the potential to become the first-line treatment for new cardiomyopathy patients and those patients who continue their disease progression with stabilizers due to its rapid knockdown of disease-causing TTR in this category. All of which gives us confidence that AMVUTTRA has the potential to be a great driver, great growth driver for our business. We are committed to being the leader in this category of high unmet medical need, and we will continue to Generate robust data for the TTR franchise in cardiomyopathy post-HELIOS-B. Currently, we're on track to deliver top-line results for HELIOS-B in the first half of 2024, which has the potential to support AMVUTTRA as the rapid knockdown agent for adults with the cardiomyopathy of ATTR amyloidosis, assuming regulatory approval.
With the potential of becoming the first and only agent with the established efficacy in both hATTR polyneuropathy and ATTR cardiomyopathy. As we've committed to for some time, we are continually innovating for the TTR franchise to solidify the potential for first-line use of AMVUTTRA in ATTR cardiomyopathy, including the CONTRIBUTE registry and real-world evidence generation, imaging studies to evaluate how RNAi therapeutics impacts the disease trajectory, and SWITCH data to support patients progressing on existing therapies. Importantly, continuing to build on our TTR leadership, as you've seen today, we're also progressing our third-generation rapid knockdown therapy for TTR with our ALN-TTRsc04 program, with potentially greater than 90% serum TTR reduction, with rapid knockdown and longer durability that could serve TTR patients in the years to come. As a reminder, the TTRsc04 program is wholly owned Alnylam program with no royalty obligations to any third parties.
As you can see today, both clinically and commercially, we're excited about the potential of expanding our TTR franchise as we remain confident in our ability to become the market leader, not only in polyneuropathy, but also across ATTR amyloidosis indications, assuming positive studies. Given our compelling product profile with robust data generation plan, our deep experience and understanding of the TTR patient and medical community, and the capabilities that effectively address this large and growing opportunity with a global footprint across 60 markets. I'd like to thank you, and I would now like to proceed to the next Q&A section.
She's gone? She's back on my screen. Well, hello, everybody, and welcome to the second question and answer session of Alnylam's R&D Day. I'm Pushkal Garg, and I'm the Chief Medical Officer at Alnylam. So it's great to see you all, and I'm really delighted to be here with all of my colleagues from the second session. And we're also joined by Dr. Werring, who is gonna be participating in this second question and answer. We have some questions around CAA and his wonderful presentation that we'll direct to him in this session. We've already gotten a lot of questions coming in covering zilebesiran and hypertension, TTR, and CAA. So I'll try and select from all of those and make sure that we get a good smattering on all those different topics.
So let me start. First of all, I think there were some questions coming in around zilebesiran, which is a really exciting opportunity that we're pursuing at Alnylam. And one of the questions, maybe Simon, for you, was if you can just put a little... and maybe Dr. Touyz would like to speak to this as well, a little bit of context around the magnitude of blood pressure lowering that we're seeing, where we're seeing this up to about 15, 16 millimeters of blood pressure lowering. How do we put that in context in terms of how it addresses the clinical needs that are out there and what that might translate to?
Right. So I'll go first. So to put this into context, obviously, a 5 mm Hg reduction in systolic blood pressure is seen as clinically relevant, and it can result in up to a 10% relative risk reduction in cardiovascular events. So it's very exciting to see that with 1, just 1 dose of zilebesiran, we can see up to a 16.7 mm Hg systolic blood pressure reduction at month three. And this is sustained out to month 6. We're seeing that consistency of effect during the 24-hour period, both daytime and nighttime, out to month 6 with infrequent dosing. So we're very pleased to see that.
Dr. Touyz, might you comment? I mean, how do you think about, you know, you highlighted some of the unmet needs in hypertension. How do you, maybe you could sort of reiterate a little bit of where you see those unmet needs and how what you're seeing in terms of the profile of zilebesiran may be able to address some of that, including the magnitude of effect that we're seeing.
Yes, thank you so much. I think one of the greatest unmet needs that we have in the management of hypertension is that we are doing a pretty bad job in controlling hypertension, and this is due to many complex factors. We know, whether this is adherence and compliance, or it's due to the fact that we are just not targeting the right pathophysiological mechanism in terms of what is causing high blood pressure. You know, we treat hypertension the same in every patient. Whether they're tall or short or old or young, they get the same drugs. And we know that a whole lot of patients are non-responders. Some will respond better to drugs than others.
Actually, the treatment of hypertension is very complex, and that is one of the reasons why, if we look globally, the number of patients that are treated—what we call to target—based on guideline targets, we're doing such a bad job. Universally, we are treating effectively about 15% of our patients who are receiving antihypertensive therapy are treated to target, which means that there's a whole community of people with hypertension at risk of cardiovascular events that are not being properly treated and are certainly not being treated to target. So there's a huge unmet need, a huge gap in terms of treatment.
So the data that Simon has shared with you, an agent that reduces blood pressure to as much as 10-15 or more millimeters of mercury, that's sustained and has a pretty consistent profile in terms of 24-hour circadian rhythm, you know, with the nighttime dipping, is hugely impressive in terms of the magnitude of blood pressure drop, but also the fact that the effect is sustained. And I guess building into that is the whole concept of addressing adherence and compliance. Because we know patients who are on lifelong therapy for a disease that doesn't have any symptoms, it's a problem. Patients are not compliant. They don't adhere to what they have to do in terms of taking their drugs.
And so having an agent that has, you know, long-term effect with just one intervention, could have huge benefits in improving blood pressure control, addressing that unmet need.
... That's very helpful. And maybe one more question while we have your attention, Dr. Touyz, is could you comment a little bit on what you're seeing as the emerging safety profile of zilebesiran? I think in Simon's presentation, there was a mention of some hyperkalemia that was seen. It was transient in the CARDIA-1 study, but maybe you could elaborate on how you're perceiving that.
Yes, of course, that's obviously at the top of everybody's mind when one is discussing new agents, new therapies. And what we have seen in the trials that have been done, the safety profile, as I'm sure Simon has highlighted, has been good. It's not that different to placebo. But the one, of course, factor that clinicians don't like to see is, of course, hyperkalemia. And we know that, at the end of the day, aldosterone, which is right downstream from the renin-angiotensin system, that is controlling aldosterone, which is responsible for sodium and potassium at the level of the kidneys. If you're blocking all of that, of course, you'll get accumulation of potassium, which, of course, could be an unwanted effect of some of these agents.
But we do know from the studies that have been presented, the studies that have been published, and of course, what Simon has said, interestingly, the hyperkalemia. And there were some patients who did have hyperkalemia in the trials that have been publicized. Interestingly, the magnitude of the hyperkalemia was not that it demanded a therapeutic intervention. So the fact that there is hyperkalemia means that the drug is obviously working well. But the fact that there wasn't significant hyperkalemia to the point that needed therapy, I think is hugely encouraging. That being said, we'll have to see as to what happens with more long-term studies, different types of patients in terms of their profiles.
What we do know to date, it seems that from the safety profile, the potassium retaining profile, I don't think there was anything out of the ordinary, in terms of the effect of the zilebesiran
Thank you, Dr. Touyzrix. Maybe we can turn to Dr. Werring. There's been a number of questions and comments on-- I think people didn't really appreciate the magnitude of CAA and the burden of that disease and appreciating what you commented on. But maybe you could talk a little bit about... I think there's questions coming in about: Why haven't antibodies that have been developed for Alzheimer's disease been directed against CAA? Or have they been studied there and, you know, if they, if beta amyloid is involved in that phatogenesis of CAA, why aren't the antibodies effective there? And/or do you see potentially differential approach with using an SI that may offer benefits?
Thank you, Pushkal. Thank you for the question, and thank you for the invitation to join. Yeah, I mean, it's a great question because there is a, there's a rationale for clearing amyloid beta from blood vessels, just as there would be for, from clearing it from the parenchyma via an antibody approach. I'm only aware of one antibody trial in cerebral amyloid angiopathy, which was using a drug called aducanumab, which was a drug that had been used in Alzheimer's disease previously, but had been noted not to aggravate micro bleeding within the brain. So we did a small, randomized controlled trial that was led by Steve Greenberg and others of aducanumab, and the primary outcome from that trial was using a, a visual fMRI functional, BOLD response.
So looking at how healthy are the blood vessels in the occipital cortex at responding to a visual stimulus. So a measure of kind of vascular reactivity and health. And those results were disappointing. In fact, they showed slightly worse cerebrovascular reactivity in the antibody treated group. And, you know, why might that be? Why might antibodies be less effective in vascular amyloid? And we know from the Alzheimer's trials that you get a mobilization of soluble amyloid beta from the brain parenchyma, and then it goes toward the blood vessels and can get stuck in the perivascular spaces, which is where cerebral amyloid angiopathy deposits can cause problems.
And we all know about the ARIA phenomenon in those Alzheimer trials, where you get edema and swelling, which is thought to be to do with overload of the amyloid drainage pathways because of this mobilization of soluble amyloid beta. So to cut a long story short, immunotherapy is very likely in people with CAA to cause a very high incidence of ARIA. And we know that this can be associated with bleeding, sometimes very serious bleeding. Although most often, of course, ARIA is not. It doesn't cause very serious symptoms, but nonetheless, it's been a major barrier to the implementation of amyloid immunotherapy in Alzheimer disease.
So I think the first answer to the question is mobilizing amyloid beta from the parenchyma, which is what may happen with these antibodies, is likely to make CAA worse. So we shouldn't be using things like aducanumab or lecanemab in CAA at the moment. And the second answer to the question is that the data we do have suggests that these antibodies may not improve vascular health. They might make things worse.
Very helpful. And do you see a contrast with the siRNA, the siRNA approach there?
... Yeah, well, that's a different approach, isn't it? So that's gonna reduce amyloid production, which may not then be subject to the same difficulties with overloading the amyloid elimination pathways. And in fact, one can imagine if there's reduced amyloid going into the system, that that might in fact improve the overall kinetics of the various elimination pathways, and should not lead to this difficulty with amyloid becoming more deposited in the vessels, leading to ARIA and all those complications. So theoretically, it's a really attractive option, but it, you know, remains to be tested, of course.
Yeah. I think the results of this upcoming study will be very, very exciting, and this suggests there's a real possibility for a differentiated and effective approach, so we're looking forward to that. Maybe, we're getting a lot of questions about TTR, and so maybe we should turn our attention over to that a little bit, and maybe a question, John, and then Tolga, you both may wanna address, which is, you know, building, John, on your presentation in terms of design of the HELIOS-B study, people are very much anticipating those results in early 2024. Can you comment a little bit about, are we designed to really see an effect on top of tafamidis, and is that a requirement?
How that sort of dovetails, maybe Tolga, with what you're seeing and we're seeing in terms of the evolution of the market in this rapidly growing field. So maybe you could comment on those two things, John first, and then Tolga.
Yeah. Thanks for the question. So I think it's to start, it's important to note that HELIOS-B was designed to observe a treatment effect in the overall population, and it wasn't powered to detect a difference in any subgroup, including with tafamidis. However, you know, we believe that we will be entering into a monotherapy market, at least until the loss of the exclusivity of tafamidis and potentially beyond. So with that in mind, you know, we believe what we're seeing emerge here is a differentiated profile that starts with the rapid knockdown of transthyretin.
A number of the things that were highlighted during this presentation, most notably from the APOLLO-B study, where we've now seen up to two full years, a stabilization of important manifestations of cardiomyopathy with six-minute walk test, and health status and quality of life with the KCCQ. Which again, acknowledging that there have not been any head-to-head studies, and the limitations of cross-trial comparisons, we believe is a different picture than what has been seen with stabilizers. We'd also note the effects on mortality, the beneficial trends that we see emerging early, as early as nine months. And, you know, collectively, this gives us great confidence.
We'd also point, again, when we think about moving into HELIOS-B, that that study is, as was pointed out, has been enriched for patients with New York Heart Association Class I and Class II heart failure. Patients earlier in their disease, where we believe, based on all of the available data, we're most likely to see the strongest benefit. So I'll perhaps, Tolga, maybe you can talk a little bit further about the commercial perspective.
Yeah. No, thanks, John. Thanks, Pushkal. Obviously, this is an important topic, and, you know, since it's a rapidly evolving category and we have about 5 years' experience, specifically in, polyneuropathy, let me provide you with some color about what we're seeing and how we're actually, foreseeing the future. First and foremost, we believe, HELIOS-B trial will potentially demonstrate that AMVUTTRA should be used as both, first-line therapy for newly diagnosed cardiomyopathy patients and also as a switch therapy for those patients who progress with their existing stabilizer therapy. So let me expand on that. First, given that this is a rare disease and the cost of tafamidis remains what it is, pressure, will result in a monotherapy environment until tafamidis loses exclusivity in late 2028 or possibly early 2029.
Second, we also know that TAF patients progress based on the data that we see from the ATTRACT trial, and patients and physicians are looking to switch. In fact, our market research shows that according to cardiologists, the vast majority, about 70% of their patients either progress or not respond to the stabilizer treatment. Lastly, at the same time, and based on Pfizer's early reporting, a big portion of the patients that are prescribed tafamidis are not getting access to their medicines and not filling their prescriptions. So look, I mean, if approved, we believe AMVUTTRA has a great and really compelling profile based on what John described here and has the potential to be a first-line agent in this category where there is definitely significant unmet medical needs.
It will be the first and only product in this category that rapidly knocks down disease-causing protein and upstream in its source, safely and directly. Potentially with a 4 times a year healthcare professional administered dosing fits very nicely into how cardiologists monitor and treat this severe disease. Obviously, there are adherence benefits that of infrequent subcutaneous dosing as well. Also, our track record already with our hereditary polyneuropathy shows that half the patients are eligible for home care, and about a third of those polyneuropathy patients are taking advantage of that service. We have, you know, 90% access, where 70% of our patients pay zero copay.
... So I believe this kind of provides the right level of color and why we are thinking that if HELIOS-B is positive and approved, we are in really good place to be considered as a first-line or the first-line switch agent.
That's super helpful, John and Tolga. Thank you for those responses. I mean, maybe building on a little bit of that, there's a question around in the trial itself, John, maybe this is for you. You know, it's noted from the presentation that stabilizer patients continue to progress, in the real world based on some of the existing data that you shared. Is that the case in the HELIOS-B study, where patients required to have progressed? And, do we know anything more about the baseline characteristics that you can speak of? You talked about the enrichment for NYHA class I or II. Is there more that you can, more color around that?
Yeah. So thanks again for the question. So, starting with the first part around progression, we did not have this as a requirement for HELIOS-B, as we did with the APOLLO-B. However, given the nature of this disease, you know, we certainly imagine that patients were progressing as they came into the trial.
As we've talked about with regard to baseline characteristics, probably not going into too much detail, but certainly, if we look at APOLLO-B, which had very similar inclusion, exclusion criteria, I think that gives us a sense and we are going to be looking at a population that is earlier in their disease course, certainly than the patients that were enrolled in ATTRACT in a different era for this disease. And as we pointed out on APOLLO-B, for example, you know, 90% of the patients were New York Heart Association Class I and Class II. A vast majority were New York Heart Association Class II.
So we'll be, we're anticipating looking at this earlier patient population, which as we've highlighted, we believe is enriched for those who will of a beneficial treatment effect.
Very helpful. And maybe there's a follow-up that came up around that point, John. Is there... Are you concerned that we may get a label that restricts us to NYHA Class I and II based on the enrichment that you talked about?
No. I mean, again, we believe we'll be in an earlier population, but this we still absolutely think will be a broadly representative patient population with a wide spectrum of disease severity that will include patients with New York Heart Association Class III. By the way, on average, patients will be earlier in the disease. But no, certainly we're hopeful and would anticipate being able to show a consistent treatment effect across the spectrum of disease.
Makes tons of sense. Makes tons of sense. All right, and then, maybe Ali, turning to you, a number of notes saying how exciting the SCO4 data are, and the knockdown. Can you... But really wanting to understand, what is that gonna mean relative to what we're seeing with AMVUTTRA, in terms of the profile? What does that added knockdown mean, and how do we think this is gonna compare, to AMVUTTRA?
Thank you for the question, Brisco. As John outlined, we are very confident the HELIOS-B study will be successful, and that AMVUTTRA has the potential to be an effective and convenient treatment for patients with ATTR amyloidosis and cardiomyopathy. That said, Alnylam believes in innovation, and we believe it's important to continue to innovate and bring new therapies to patients, and that's why we're developing ALN-TTRsc04. Because we believe it has the potential to have a leading profile by dint of causing a rapid and deep TTR knockdown, which could have the potential to deliver greater efficacy and once-annual dosing. And once-annual dosing would, of course, further ease the treatment burden on patients, but even deeper knockdown of TTR could result in better outcomes. And the modeling data from APOLLO that I shared earlier supports that theory.
So-
That was super helpful. And then you showed data out to six months. What gives you confidence that this could be an annually dosed drug?
Yeah, thank you for the follow-up. We think the results so far have been very strong, and with the 300 milligram dose, as I showed earlier, we see a knockdown of 93%, six months after dosing. Those results clearly demonstrate the potential for biannual dosing. We feel very confident that we'll see extended durability through to 12 months. And that's for a few reasons. Firstly, if you look at the degree of recovery between dosing and day 180, the degree of recovery is very shallow. Secondly, we are dosing higher doses, so we have very recently dosed a cohort with 600 milligrams of ALN-TTRsc04, and we plan, should the results from that go well, to dose a cohort with 900 milligrams of ALN-TTRsc04.
Of course, we would expect these higher doses to have even more durability than the 300 milligram dose.
That sounds great. Thanks, Ali. And maybe the other question is, the data you showed are in healthy volunteers, right? So the question came in, "How does TTR knockdown compare between healthies and patients?
Thank you for the question. Yes, the phase I study is a healthy volunteer study.
... we would expect that the high degree of TTR knockdown we've seen in healthy volunteers to translate to equally high levels of TTR knockdown in ATTR amyloidosis patients. That would be consistent with what we've seen in our patisiran and revusiran programs, which also had phase I studies in healthy volunteers.
Pretty much a one-to-one relationship there, right? So that's as we expect the same. That's great. All right, well, maybe we'll turn back a little bit to zilebesiran, and some of the questions that are coming in there. Simon, you talked about the CARDIA-2 study. Can you just remind people when we should be expecting those results, and what are we gonna be sharing when we get those data?
Yes. So we're very much looking forward to reading out the CARDIA-2 results early in 2024. And just to remind everyone, CARDIA-2 is looking at the experience we have with zilebesiran in combination with commonly used antihypertensive agents. It's gonna be on a background of a high-dose ARB, which is olmesartan, in combination with amlodipine, and also in combination with a diuretic, indapamide as well. And we'll be looking at both the efficacy, but more importantly, to build on what Dr. Touyz said, we'll be looking at the safety of zilebesiran in combination with these agents. And we believe we will see clinically meaningful and significant reductions in systolic blood pressure. The primary endpoint will give us a view of that, and we'll also be looking at the safety, as mentioned.
Fantastic. Very helpful there. And then I think a question that, that came in also around zilebesiran, I mean, both you, Simon, and, and Dr. Touyz have talked about the long-acting nature and the benefits of that. But maybe, Dr. Touyz, are there drawbacks to the long-acting nature? And how do you think about that clinically, when you have a long-acting antihypertensive agent?
Yeah. So that's a really important question because imagine if we're giving these injections once every 6 months or so, and blood pressure's reduced, and that's fantastic, but you've downregulated completely the renin-angiotensin system. Of course, the question always arises: What happens in the case of an emergency? What happens in the case of severe shock or, you know, a severe bleed, for example, where you actually need the renin-angiotensin system to come into quick action? So that is probably one of the clinical scenarios where one would think about having some concern in terms of the very sustained long-term effect, not so much of the low blood pressure, but of course, of the downregulation of the renin-angiotensin system. But I think there are...
Obviously, this has been very importantly addressed in the context of the development of zilebesiran, and we do know that Alnylam is developing a compound, or an agent, or an approach that will actually antagonize the effects of the siRNA on angiotensinogen very rapidly. And so there is that safety factor that certainly could come into being. And of course, there are other approaches. For example, salt loading, for example, would be another condition that would result in activation of the renin-angiotensin system. But that being said, you know, there's obviously that caveat that one needs to be cognizant of. And certainly, measures are being considered as to how one would be able to correct that, should that emergency situation arise.
Great. Thank you, Dr. Touyz. And maybe, you know, I think you're right to comment that I think salt and fluid loading have been helpful in managing can be used, and luckily, the safety profile we've seen so far hasn't really shown really any significant cases of hypotension. But maybe, Simon, that leads to you to just talk about the REVERSIR program that Dr. Touyz mentioned, and maybe you can give an update on that, and what's the status, and how are we thinking of moving that forward?
Sure. So as Dr. Touyz alluded to, we have selected a drug candidate known as the REVERSIR, and what we've seen in non-human primate data is that the REVERSIR actually reverses the effect of zilebesiran. So, we're in the early stages of developing our clinical development plan. We're gonna be engaging with the regulatory agencies, and we are looking to try and get the clinical development plan going by the end of next year. So we're looking to file a CTA sometime in the second half of 2024, with the hope of starting the development plan thereafter.
Perfect. That's gonna be very exciting to see. And I think we just have time for maybe one or two more questions at most. But, John, maybe this one goes to you. You presented a number of reasons to be optimistic about the HELIOS-B trial based on the profile and spoke to a number of different measures that are prognostic to survival. Can you talk about which of those factors is most important when you look at it as a clinician and as a trialist? What are the most important predictors of survival, and what are you seeing in the RNAi profile that gives you that confidence, which people look at?
Yeah. So I really think the takeaway here is that we don't need to pick or point to just one important predictor. It's – from my perspective, this really has to do with the totality of the data.
... and the consistent nature of the data, that we've Generated, across, we have multiple now, multiple phase III studies in ATTR amyloidosis. Starting with studies of polyneuropathy in hereditary patients and now cardiomyopathy, in patients with hereditary and wild-type disease. Even we believe we're seeing again this, a differentiated profile where RNAi therapeutics, starting with this rapid knockdown of transthyretin, which now, again, across multiple studies, has resulted in stabilization, across a variety of different disease manifestations. And most recently, again, on APOLLO-B, where we've seen this with 6-minute walk test, and KCCQ, both very important parameters. And out to, with, you know, relative stability out to 2 full years.
And, as well as what we've seen with, again, the trends on mortality, that have been consistent, and suggest the possibility for, you know, early separation of those curves. Again, acknowledging that there were no statistically significant outcome benefits demonstrated, and the studies weren't designed to look at that. We were really encouraged by these trends. So it's really, we think all these things speak to a differentiated profile or the potential for a differentiated profile. And it's the totality of the data that gives us confidence in eventually demonstrating outcomes on HELIOS-B.
That's, that's very helpful, John. Thank you. I think at that point, we're gonna have to wrap it up. I wanna thank all of my colleagues and our clinical experts for joining us today, Dr. Touyz and Dr. Werring. I'm gonna return it over now to Dr. Yvonne Greenstreet, our CEO, who's gonna make some closing remarks. Thank you all for your attention.
Well, I hope you all enjoyed the presentations today. I'm personally very pleased with the progress that we continue to make across all facets of our portfolio. Alnylam continues to drive the wave of RNAi innovation that's changing medicine with a multi-product commercial portfolio, a robust pipeline, and a sustainable innovation engine setting the stage for the future. We expect our track record of strong commercial and pipeline execution to continue through the end of 2025 and beyond. We remain deeply committed to the notion that our modular and reproducible approach to designing new medicines, and with 100% of the human genome, in theory, available for targeting via RNAi, this technology represents a potential opportunity to significantly expand our ability to fight human disease. Leveraging this, we believe Alnylam is poised to become a top-tier biotech.
Throughout the course of our day together, we've had the chance to touch on several of our pipeline programs. You'll see here a full list of our company goals for 2024, which show that we do have a very exciting year ahead. I'm not gonna walk through all of these, but at a high level, we look forward to ongoing commercial execution for the four Alnylam owned products: the readout of the highly anticipated HELIOS-B study of vutrisiran, and if positive, filing as an sNDA; sharing data from phase II CARDIA-2 of zilebesiran; initiating potentially five new studies in phase II or phase III; and potentially filing three new INDs from our organic R&D engine to bring new programs into the clinic and position Alnylam for sustainable future growth.
In addition to pursuing programs under our control, we also look forward to the growth opportunities and value creation from programs driven by our partners. One is fitusiran, partnered with Sanofi, a first-in-class RNAi therapeutic discovered by Alnylam, targeting antithrombin. Sanofi is conducting multiple phase III studies designed for patients with hemophilia A or B, with or without inhibitors, and expects an NDA submission by the end of 2024. Another is ALN-HBV02, led by Vir Biotechnology, who are evaluating combination regimens as a potential functional cure for chronic HBV infection. We look forward to additional phase II readouts and plan to make an opt-in decision ahead of phase III. Before we conclude, I'd like to take a moment to briefly recap the exciting progress discussed during our R&D Day today.
As we look ahead to the next frontier of RNAi therapeutic innovation, we're excited to be presenting promising results from our efforts in adipose, muscle, and tumor delivery. The promising phase I data with ALN-TTRsc04 and ALN-KHK we announced today further demonstrate the strength of Alnylam's R&D engine as we continue to innovate and advance assets for rare and more common diseases, including ATTR amyloidosis and type 2 diabetes, with a sustained knockdown of key targets supporting infrequent dosing regimens for investigational therapies with transformative potential. We made significant progress with our clinical portfolio in 2023, with a proof of concept for our CNS platform with ALN-APP, and demonstration of potent tonic blood pressure control with zilebesiran. Finally, we believe we have the right strategy, the right products, and the right opportunities in front of us to lead in the ATTR amyloidosis marketplace with our TTR franchise.
We look forward to bringing vutrisiran forward as the rapid knockdown therapy for TTR. In conclusion, and as we've talked about previously, we believe we are well on our way toward achieving our latest five-year vision, Alnylam P5x5 by 2025, which is aimed at establishing Alnylam as a top-tier biotech company with transformative medicines in both rare and common diseases for patients around the world, and a robust and high-yielding pipeline of first- and/or best-in-class product candidates from our organic product engine, while delivering exceptional financial performance. We believe that 2024 will have many milestones that will move us even further along in our quest to realize this exciting vision. Thank you, and we look forward to keeping you updated on our progress.