Welcome to SELLAS Life Sciences corporate update call. At this time, all participants are in listen-only mode. If anyone should require operator assistance during the conference, please press star zero from your telephone keypad. Please note, this conference is being recorded. I'll now turn the conference over to Bruce Mackle from LifeSci Advisors. Bruce, you may now begin.
Thank you, Rob. Good morning, and welcome to SELLAS' corporate update call. Before we begin, I would like to remind you that SELLAS will be making statements on today's call relating to future expectations regarding the further development of regulatory plans for and milestones regarding its clinical candidates, Galinpepimut-S, or GPS, and SLS-009. These statements constitute forward-looking statements for purposes of the safe harbor provisions under the Private Securities Litigation Reform Act of 1995, and by their nature, involve estimates, projections, goals, forecasts, and assumptions, and are subject to risks and uncertainties, which include, without limitation, risks and uncertainties associated with oncology, product development and clinical success thereof, the uncertainty of regulatory approval, and other risks and uncertainties affecting SELLAS and its development programs that could cause actual results or outcomes to differ materially from those expressed in the forward-looking statements.
These forward-looking statements speak only as of the date of this conference call and should not be relied upon as predictions of future events. While SELLAS may elect to update these forward-looking statements at some point in the future, the company disclaims any obligation to do so, even if the company's views change. Additional information about the material factors and assumptions forming the basis of the forward-looking statements and risk factors can be found under the caption Risk Factors in SELLAS' Annual Report on Form 10-K, filed on March 16, 2023, and in its other SEC filings. With that, I would like to turn the call over to Dr. Angelos Stergiou, President and Chief Executive Officer of SELLAS. Please go ahead, Angelos.
Thank you, Bruce, and good morning, everyone. Welcome to SELLAS' corporate update call as we kick off what we believe to be an exciting year for our company. On that note, I wish you, all of you and your families a happy, healthy, and successful new year, and thank you for joining us this morning. 2024 should be a transformational year for our two promising assets, Galinpepimut-S, or GPS, and our highly selective CDK9 inhibitor, SLS-009, as they are progressing through clinical development with several near-term and potentially value-creating clinical milestones. I'm grateful for the SELLAS team's extraordinary efforts getting us to this pivotal time for the company, and I can assure you that this group is dedicated and committed to seeing GPS and SLS-009 make a difference in patients' lives.
As we continue SELLAS's strong growth trajectory, we closely monitor and assess potential risks, including financing, clinical development, and regulatory risks, which every small biotech company faces, and we think carefully how to overcome those and deliver on our core mission: to prolong patients' lives. Before I dive into more detail of our corporate update and key initiatives for 2024, I would like to briefly introduce our two participating KOLs on our call. We are indeed privileged to be joined this morning by two renowned hematologists who have enrolled a significant number of patients, either into our phase III GPS AML REGAL study and/or the phase IIa relapse/refractory AML SLS-009 study. Mainly, Dr. Tsirigotis, Professor of Hematology at the National and Kapodistrian University School of Medicine of Athens, our highest enrolling REGAL site, who will share his perspectives around GPS and the REGAL trial. And Dr.
Tapan Kadia, Professor in the Department of Leukemia at The University of Texas MD Anderson Cancer Center, will provide an overview around SLS-009 in the currently ongoing phase IIa study. Let me start with a corporate update first. Today, I hope to convey a theme of an exciting evolution at SELLAS. While the success of our clinical programs is undoubtedly a cause for celebration, I recognize that the biotech capital market has been volatile for the last 18+ months. We strongly believe that the decline in stock value is not indicative of the intrinsic value of our company or the potential of our products. Our team is committed to implementing strategic initiatives to maximize shareholder value in 2024 and beyond, to not only remain well-capitalized as we expect key data readouts in REGAL and SLS-009 this year, but we will also further adjust and refine our internal resources.
This will be key. I expect that for this year in particular, as we have done over the past years as well, but with 2024 being the most crucial year for us, we have asked our dedicated small team to wear even more hats, so to say, and take on roles and responsibilities beyond what was expected. Rest assured, I've led and will continue to lead by example, and we will all work tirelessly to make sure GPS and SLS-009 hopefully have a profound impact on patients' lives. Again, although we are a small team, we will make tough decisions and adjustments when needed. I also want to discuss with you our partnership with 3D Medicines, our development and commercialization partner for the Greater China territory, which includes mainland China, Taiwan, Hong Kong, and Macau.
We had to make a difficult but necessary decision to pursue the arbitration route with 3D Medicines as per the dispute resolution provisions of our license agreement. As of September 30, 2023, we have received an aggregate of $10.5 million in upfront and milestone payments under the license agreement, with a total of $191.5 million in potential future development, regulatory and sales milestones, not including future royalties remaining under the license agreement, which milestones are variable in nature and not under our control. Although I cannot comment on pending legal matters around 3D Medicines, I do want to provide some brief thoughts as to how we got to the point of going down the arbitration path.
In November of 2022, we announced that 3D Medicines had agreed to participate in the REGAL trial through the inclusion of approximately 20 patients from mainland China. Since mainland China is a significant market, this was an important outcome for us on many levels, with both short and potentially long-term milestone payments and royalties to sell us. A win-win for both companies, since 3D Medicines would potentially have an additional product on the market years sooner than anticipated for them, i.e., rather than if they were to conduct their own registrational Phase 3 study, and the registration study would be run much more cost-effectively via the REGAL trial. In April of 2023, we met with a senior executive team of 3D Medicines in Shanghai and discussed the progress of the REGAL study and received 3D Medicines' assurance that they would promptly open the study in mainland China.
Additionally, we explored potentially expanding our strategic partnership with them. Around that time, we projected that at the latest in Q3, the REGAL study would be open in mainland China. In the late summer, early fall time frame, we alerted 3D Medicines to the many unexpected delays in starting enrollment in REGAL in mainland China. We had chosen to work with 3D Medicines because of their experience and expertise in clinical development in China, and were therefore surprised by and growing concerned about the delays. In good faith, we continued to work diligently through operational matters with 3D Medicines in order to avoid further delays and to include mainland China into the REGAL study ASAP. Two points I would like to state here. First, patients were enrolled in the REGAL study in Taiwan, which is part of the Greater China licensed territory, prior to the second half of 2023.
And second, we strongly believe that 3D Medicines has failed to use commercially reasonable best efforts to develop GPS in the licensed territory, and particularly in mainland China. Thus, we are currently engaged in a dispute regarding, among other things, the trigger and payment of the relevant milestone payments to SELLAS. Accordingly, as we announced at the end of last month, we have commenced a binding arbitration proceeding administered by the Hong Kong International Arbitration Centre and governed importantly by New York state law as per the license agreement. The Hong Kong International Arbitration Centre is one of the top three most preferred arbitration centers in the world. In 2022, approximately 90% of its administered arbitrations were international, and disputes were subject to 16 different governing laws. Many of the arbitrators on the HKIAC panel are licensed attorneys from around the world, including New York.
I cannot comment in more detail on the pending arbitration as the proceedings are confidential, but to be very clear, we are confident in the claims that we have made. We do not expect the overall timing for the interim and final data in our REGAL study to be affected by the dispute arbitration proceeding. The only timing which might be affected is when GPS, assuming positive data from REGAL, will be approved for patients in mainland China. Importantly, we remain steadfast in our belief that the true value of our company lies in the groundbreaking science and the positive impact it can have on patients' lives. Over the past years, we have only had positive clinical and regulatory news. I, we encourage you to focus on the long-term potential and the exciting milestones that lie ahead, and we need your support.
On that front, we'll be focusing this year next to driving hopefully successful clinical programs and regulatory outcomes on four very important items. First, enhancing investor relations. We value your trust and belief in transparent communication. I'm committed to providing regular updates on our progress, financial performance, and other relevant information, not only through the ordinary quarterly reports, investor presentations, and investor relation events, which we have done, but also we will hold periodic state of the union calls to address pertinent corporate and clinical updates as they arise. Second, strategic partnerships and licensing opportunities. We understand the value and collaboration and are actively seeking strategic partnerships and licensing opportunities with other biotech and pharma companies and healthcare organizations that could accelerate our growth trajectory.
These partnerships would not only provide additional resources, but also validate the potential of our technology in the eyes of the market, and importantly, could lead to significant strategic outcomes, including co-development and co-commercialization or beyond. We're deploying internal resources as well as working closely with Torreya Partners, part of Stifel Financial Corp, on that front. Third, share purchase. I want to make you aware that all SELLAS executives purchase SELLAS shares through the SELLAS Employee Stock Purchase Plan, the ESPP. Other than the ESPP, given SEC-mandated blackout periods and the continual knowledge of material non-public information, other stock purchases on the open market by management on a consistent basis are difficult. However, we have recently implemented stock ownership guidelines for senior management and directors regarding ownership of SELLAS stock, which are to be met over a five-year period, and we'll be updating you accordingly. Four, internal resource allocation.
As I mentioned at the beginning, we will further adjust and refine internal resources this year. As we have done in the past, we will continue to carefully manage our expenditures, and we will ask members of our team to take on more responsibility as we weather through the current market conditions. There will be tough decisions to be made, and I already started this process last quarter, even if it means becoming a leaner organization while not compromising the integrity of our ongoing studies. We believe that these strategic initiatives, combined with our strong clinical data and commitment to maximizing shareholder value, will position us for long-term success, and I'm committed, the entire SELLAS team is committed to delivering positive outcomes for our shareholders. Before hearing from Dr. Tsirigotis on the REGAL study and Dr.
Kadia on SLS-009, I would like to make a few personal remarks related to our clinical programs and expected milestones. I'm very excited that we have already surpassed our enrollment target, ex-China, in the REGAL study. The interim analysis will occur at 60 deaths, after 60 deaths, and the final analysis, if warranted, will happen after 80 deaths have been reported in the REGAL study. The Independent Data Monitoring Committee, or IDMC, is expected to meet again this quarter to review the data and provide guidance. The phase 3 REGAL trial is designed to provide reliable evidence about the effects of GPS maintenance monotherapy for its key primary endpoint of overall survival. In our REGAL study, patients are randomized to receive either GPS treatment or best available treatment, or BAT, B-A-T.
In our previous AML phase 2 study, in this exact CR2 patient population as our phase 3 trial, we observed a clinically and statistically significant survival benefit in patients who received GPS, an almost 16-month differential survival benefit, 21 months versus 5.4 months, with a p-value of 0.02, and a substantial difference in leukemia-free survival. Although REGAL has an open label design to protect the integrity of randomization, as well as to enable the potential for refinements in study design during its conduct based on emerging aggregate study data, SELLAS, as the study sponsor, remains blinded to any data by treatment arm, i.e., by GPS versus BAT.
We have provided guidance to the best of our ability based on statistical and clinical expert input and assumptions when we designed the study and statistical analysis plan, which has also been cleared with the U.S. FDA, as to when we expect the interim analysis to occur. But because these analyses are event-driven, as I mentioned, number of deaths, they may occur at a different time than expected. At this point, we believe this may happen this quarter. The IDMC must not disclose event rates and clinical data to us, so we will not know in advance when the 60 deaths have been reached. However, we'll be providing you with updates as they become available by the IDMC. Furthermore, and importantly, we have concluded a Type C meeting with the FDA regarding our CMC sections in a potential biologic license application or BLA for GPS in AML.
The FDA reviewed the submission package of data and company questions we provided to the agency and responded favorable guidance. For those of you who don't know, when I founded SELLAS about 12 years ago or so, my goal was to identify potential breakthrough immunotherapy and oncology drugs, highly differentiated, that can make a difference in patients' lives. We've accumulated exciting data with GPS, not only in AML, and expect the REGAL data readouts this year, but we've also had positive data readouts in WT1-positive platinum-resistant advanced ovarian cancer in combination with Keytruda, as well as in relapse refractory advanced mesothelioma of GPS in combination with Opdivo. Overall, we continue to observe robust and intriguing data for our lead asset, GPS, in various types of cancer.
We believe that it is crucial for us to bring the investment community along as we prepare for the upcoming milestones for GPS, and we also expect very important data around our CDK9 inhibitor, SLS-009. Now, as for SLS-009, our highly selective CDK9 inhibitor, we have made significant progress in our clinical development and regulatory outcomes. The phase 1 clinical trial for patients with AML and lymphomas was completed last year, and importantly, we met the key primary and secondary endpoints. Antitumor activity and clinical responses across dose levels were observed, indicating a broad therapeutic index and meaningful cell-killing activity, defined as greater or equal to 50% reduction in blasts in the bone marrow, which was observed at several dose levels.
A durable, complete remission, or CR, with no minimal residual disease, was observed in a patient with AML who had failed prior venetoclax plus azacitidine or Aza-Ven therapy. The patient continued to be alive 11 months following commencement of treatment per last follow-up. The recommended phase two dose for patients in AML was established at 60 milligrams. For the patients with lymphomas, no off-target safety issues were observed at any dose level, and responses were observed across dose levels. In focusing on PTCL, we observed a 36.4% clinical response rate. The recommended phase two dose for patients with lymphomas was established at 100 milligrams, administered as once-weekly infusion. We quickly started the phase IIa study in relapsed refractory AML, SLS-009 in combination with Aza-Ven.
The enrollment in the 45 milligram cohort was completed this past quarter, and we have already enrolled patients in the final 60 milligram cohort. Patients in the 60 milligram dose cohort will be dosed with 60 milligram once per week or 30 milligram twice per week. Early top-line data from the phase IIa study in patients with AML dosed at the 45 milligram level include a patient with a CR and significant anti-leukemic effects, greater or equal to 50% decrease in bone marrow blasts, as I mentioned, have been observed in the majority of patients, and importantly, we seem to observe a survival benefit. Patients with relapsed refractory AML live approximately 2.5 months, and as an indicative data point, the first patient enrolled is still alive seven months out, and the second patient is alive for six months thus far.
I need to state again that we have observed a favorable safety profile of SLS-009, and the current efficacy combination data of SLS-009 with Azaen may allow us to proceed towards a registration study for approval expeditiously. We expect to report data from the fully enrolled 45-milligram cohort and initial data from the 60-milligram cohort in the first quarter of 2024, and expect the 60-milligram cohort to be analyzed and reported by the second quarter of this year. As for PTCL, we have a phase 1b/2 study that is currently ongoing. It is fully funded by our partner for SLS-009, GenFleet Therapeutics. We expect top-line data from this study in the first half of this year.
I'm also proud of our regulatory team, in addition to the successful Type C Meeting with the FDA on GPS, to have received orphan drug designations for the treatment of AML and PTCL with SLS-009, and Fast Track Designation for the treatment of relapsed refractory PTCL with SLS-009. Rest assured, they continue working diligently to further optimize the success of GPS and SLS-009. Before I make final remarks, it is time to turn it over to our leukemia specialist now to discuss the REGAL and SLS-009 trials. We will first start with Dr. Tsirigotis, Professor of Hematology at the National and Kapodistrian University School of Medicine of Athens, who will share his perspectives around GPS and the REGAL trial. As I mentioned before, he's the highest enrolling site in our REGAL study. Professor Tsirigotis?
Well, good morning to everyone. I would like to thank SELLAS, especially Angelos here, for this kind invitation to participate into this exciting trial. For the last 25 years, I'm working in the field of acute myeloid leukemia and allogeneic stem cell transplantation, as well as in, I'm involved in cellular therapies like CAR-T cells and in other forms of immunotherapy. As you know, well, currently, the most effective anti-leukemic treatment for patients with acute myeloid leukemia still remains the allogeneic stem cell transplantation. Allogeneic stem cell transplantation actually is a form of immunotherapy. Usually, before transplantation, we give to the patient really high doses of chemo, radio, and radiotherapy, also in the form of total body irradiation, with the aim to eliminate the very last leukemic cells, but also normal hematopoietic stem cells.
However, despite this intensive chemotherapy, we don't manage to destroy even the very last leukemic cells, and the residual leukemic stem cells that survive this strong conditioning, they finally give rise to relapse. Here it comes, the immunotherapeutic effect of allo stem cell transplant, because, as you know, the therapeutic potential of allogeneic stem cell transplantation mainly relies on the so-called immunologic graft-versus-leukemia effect. In other words, the new donor system, the new immune system, which is of donor origin, recognize the leukemic stem cells and destroy them. This is the way that the patients can achieve cure of their leukemia through allogeneic stem cell transplantation.
But of course, this is not that simple, because allogeneic stem cell transplantation has significant side effects. It's a toxic treatment. It is associated with significant morbidity and mortality, and this is a great limitation. Therefore, the application of transplantation is restricted only to young patients or to those who are fit enough and without significant comorbidities. So if we take into account now that the median age of AML diagnosis is approximately 68 years of age, then you can really appreciate that the vast majority of those who are in need for this curative treatment are not eligible for this simply due to age. So we need to develop a new and more effective and less toxic forms of immunotherapy.
A few years ago, I was first become aware of the, of the WT1 vaccine in a most, in a more primitive, form of this, kind of vaccine. WT1 is an important protein that is necessary for normal, development of, progenitor, cells. However, it is not expressed on normal, on normal myeloid cells, or it is expressed only in tiny amounts. However, for leukemic cell, leukemic cells, the vast majority of leukemic cells, almost 90% of them, overexpress WT1, and this overexpression gives to these cells a significant proliferative advantage on the one hand, but also, these cells are marked because they express WT1. This expression, this antigenic, this target, can be a target for the immune system.
So people in the past, they tried to develop vaccines and to mount an immune response against WT1, and this primitive vaccine consisted of just a couple of peptides derived from WT1. Researchers at those times injected this simply intradermally to patients, to a dozen of patients with active acute myeloid leukemia and high-risk myelodysplastic syndromes, which is a similar disease. I was really surprised when I saw that there were a few patients that they achieved complete remission of the disease simply by injecting this couple of peptides. And imagine this, that the cells that are resistant to radiotherapy, they can be destroyed by the immune system. So I was really surprised, surprised about this early trial.
And then, when I was approached by SELLAS, and we had this discussion to participate in this trial, I was really excited. And, I really was highly motivated to participate into this really nice trial. Then, when I saw this is the new vaccine, the GPS vaccine, is not a primitive, like the primitive one. It's a product of modern technology for many reasons. First, it consists of a mixture of peptides for WT1, and this is very important because these peptides have been selected by in, by the use of artificial intelligence, so we select the most immunogenic peptides.
Most importantly, these peptides can be applied to every patient with acute myeloid leukemia without any HLA restriction, because the previous formulation, it was, these peptides were only for certain patients, that they had certain HLA alleles. So this is a great achievement. The second one is that, this is a product also of a heteroclitic technology, and by using a heteroclitic technology, again, we can create a, a, a very small changes in the, in the amino acid sequencing of these peptides. And then, then we create peptides that, look really similar to the old ones, but they are much more immunogenic. So we can have, these peptides can mount a robust immune response against the WT1.
And finally, another really important thing is that by using these peptides, we can activate not only CD8 cells, but also CD4 cells. And this is really, really important because, as you know, all CD4 cells are the so-called T helper cells, and they give help to cytolytic CD8 cells, but also they are responsible for the generation of immunological memory, which is an integral part of an effective immune response. So, GPS is. I think it's a great product. There is no doubt about this. And also, the guys at SELLAS, they decided to do something that for me is very clever.
They decided to test this drug not to offer to patients with overt leukemia, but to patients with a residual disease, and that's why they chose to test it in patients with complete remission. And we all know that the less the bulk of the disease, the higher the efficacy of any form of immunotherapy. For all of these reasons, I was really excited, and I wanted to participate into this trial. Now, please allow me to give you a brief overview of the new treatment landscape of AML nowadays. First, as you all know, for the last 40 years, there was no new drug in AML.
And now, during the last 5 or 7 years, many more new drugs have entered into the clinical armamentarium. There are many approvals from FDA and from EMA, so now we have many drugs, and this changed the treatment landscape of AML for many, many reasons. First of all, I will focus on those patients who are older. And in the past, we used, in many countries, we didn't give treatment to patients over 70 or even 75, simply because they were unable to tolerate the intensive chemotherapy. But right now, with these new drugs, we treat almost every patient. This is the first. The second is that we can achieve remission in a significant proportion of these patients. But again, the situation is more complicated because these remissions are not long. They are short remissions.
Moreover, in order to maintain this remission, we have to treat our patients indefinitely. We treat them until disease progression, and this is a really big problem because these drugs are myelosuppressive, and we have many, there is the requirement of close monitoring of these patients with many admissions to hospitals. Transfusion, growth factors administration, and sometimes these patients develop infection, and so they need admission to hospital. And this has a significant negative impact in the quality of life on the one hand, but also it goes a significant burden, a financial burden on the health system. So I strongly believe that drugs like GPS come to fill this gap, because now we need to find safe and less toxic treatment to maintain this remission.
So let me now say just a few things about the REGAL study, which is very important. In REGAL study, we decided to treat patients in second or even later remission. And just to remind you that these patients have an extremely poor, poor outcome, because the median survival is in the order of 5-7 months. So patients were randomized to receive either the GPS or the best available treatment, which was at the discretion of the treating physician. I can say to you that most of us, and as I know from Greece, because in Greece, you know, we are among the top recruiters in this study. All of us, we prefer to use the combination of Ven, of Ven, Azacitidine, which is a toxic combination.
It is associated, this administration, with all the negative consequences that I briefly mentioned before. On the other hand, GPS is very; the administration is really easy. I'm not allowed to give you much more details about the efficacy because of the confidentiality agreement, but I can say to you, and I would like to thank the SELLAS, because I have great experience, because I have personally enrolled more than 10 patients into this trial, so I have gained experience from this trial. I can say to you that GPS is an extremely safe drug. I didn't see, and neither I nor my colleagues in Greece, we didn't have any systemic toxicity.
The only side effect that we observe is that the simple irritation at the site of injection, like you see with the COVID vaccine. So, our patients, they do not need close monitoring. They have an excellent quality of life. I strongly believe that GPS will reach the primary endpoint of this study. Please allow me not to give any more other details about this. And, finally, I just want to say to you that, if, which is something that I strongly believe, and I eagerly really wait for the results.
But if, and I believe so, if GPS shows the expected survival advantage, then you can imagine that it, it will be, it will revolutionize the field of AML treatment, because then, we have to anticipate that this drug will be, introduced to as maintenance treatment, not only to patients with second or third, complete remission, but also to patients with the first complete remission, or even to patient after, after allogeneic stem cell transplantation. And for all these reasons, again, I want to say that I'm excited to participate in this trial, and I want to again thank SELLAS for this opportunity, to be here with you today. And thank you very much for your attention.
Thank you very much, Professor Tsirigotis, for your insight here. I think at this point, I would like to turn it to Dr. Tapan Kadia, Professor in the Department of Leukemia at The University of Texas MD Anderson Cancer Center, will provide an overview around SLS-009 and the currently ongoing phase IIa study. Dr. Kadia?
Yes. Thank you, Angelos. Good morning, everyone, and thank you for having me on the call. As you just heard from my colleague, Dr. Tsirigotis, we are sort of working and living in a very exciting time right now for the development of therapies in AML. There are many new drugs, just in the last five years, that have been developed, drugs that target various specific subsets that are defined by mutational profile. Drugs that have low toxicity, high specificity, and maintain high response rate. Now, all these new drugs play important roles in patient treatment, but I think one that strikes out, one that stands out is venetoclax, which represents the backbone of many, both approved and investigational AML treatments. And so when I say...
What I mean by backbone, I mean that most of the new treatments that are currently being built, going forward in the current AML landscape, are being built as combinations of other new and existing agents in combination with a venetoclax-based backbone or venetoclax-based therapy. Some of these combinations are approved only as frontline therapies, but both of these combinations in the frontline, as well as investigational combinations, are broadly used in the second line and beyond. That is for patients who have failed other therapies. So we see venetoclax routinely used in the frontline as standard of care, but also, being used in the relapsed and refractory setting in combination with other therapies.
Because of this fact, it is fair to say that effectively, virtually all of the patients with AML in the USA today, at some point in their treatment, receive a venetoclax-based combination therapy. And so undeniably, venetoclax has provided significant advancement in AML treatment by improving the number of remissions and providing a plethora of treatment modalities that can be tailored to individual patients' condition and extending survival. But one of the issues that we all run into with any of these treatments is that venetoclax indeed is not a curative agent. In the absence of a bone marrow transplant, as Dr. Tsirigotis has nicely summarized, most patients, including those venetoclax patients, will eventually relapse. And about a third of the patients who are initially treated with venetoclax don't respond to venetoclax-based combinations. So there's a refractory population that also needs to be highlighted.
One of the critical matters, that we need to address, in our field is to treat those patients, or how do we treat the patients who do not respond initially to venetoclax, or who stop responding to venetoclax? When I say this is an urgent matter, I'm referring to the fact that, that once these patients lose response to venetoclax, they have a very dismal outcome. There has been nothing currently available that has been shown to work in that setting. There aren't any monoclonal antibodies, no targeted drugs, no combinations, that work in patients who have either failed the venetoclax frontline or who have relapsed after being initially treated with venetoclax. Now, many studies have been done to figure out why or what the resistance mechanisms are, but those are still in progress.
The chances of putting such a patient who is resistant to venetoclax into remission with other therapies is less than 20%, except for some very narrow targeted mutations. For example, there's a subset of KMT2 rearranged AML, where there are many inhibitors which may work in this setting, but these are still in the investigational phase and not in commercial use as of yet. Overall, in treating the broader patient population that's resistant to venetoclax remains a very daunting challenge. Unfortunately, once patients are confirmed to be refractory venetoclax or they relapse after initial response to venetoclax, their survival is very poor in the range of 2-3 months only.
So when I got the opportunity to work with SELLAS, I was very heartened that we would be able to address this very specific patient population, patients whose leukemia is so-called venetoclax resistance or Ven failures. So SLS-009, as you heard, is a novel CDK9 inhibitor that has anti-leukemic activity, as we showed in the early phase trial, including the ability to induce complete remission as a single agent, which is, you know, which is a big deal in AML, which many agents don't, you know, are not able to achieve that threshold. But I think its real potential may be realized when it's added to standard venetoclax-based regimens, using the inhibition of BCL-2 as well as CDK9, to provide synergy and overcome some of the resistance.
So this is based on cancer biology, which my colleagues and I have discussed in some detail in a prior webinar with SELLAS several months back, when we were enthusiastically preparing for the current trial that I'm updating now. Based on the SLS-009 preclinical and phase I data, we have been looking for a so-called add-on strategy. In patients who have HMA ven, who are starting to fail or losing response, to add on a drug that makes sense biologically, as well as effectively, clinically, and safe. Then the strategy of a tolerable and effective CDK9 inhibitor, combined with venetoclax-based therapies, became an important strategy to pursue.
So we have actually, as you can imagine, or as you can see, collectively enrolled a substantial number of patients just in the last six months, and we're continuing to go strong with a lot of enthusiasm and excitement, from leukemia specialists, both at my center and around the country. So the trial, just to briefly summarize, accepts only patients, that I described, those who are resistant to venetoclax-based combination therapies. And so they're treated with the most common venetoclax-based combination regimen, which is HMA venetoclax. So these patients are, who have received or are receiving HMA venetoclax, then will receive HMA venetoclax plus SLS-009. There are two dose levels in the trial.
I think, Angelos mentioned earlier, 45 mg once per week, and then 60 mg, given either once per week or divided into two doses of 30 mg twice per week. We have just completed enrollment at the first dose level and are starting to enroll at the second dose level. The early results actually are quite exciting, even the first patient dose level. The safety profile, fortunately, is, appears to be very benign in terms of, drug-related toxicity, even in combination with the HMA and venetoclax. There are no, non-hematologic toxicities that are related to the drug, and the hematologic toxicities are actually in line with what we expect with Ven/Aza alone.
It's important to have this confirmation that SLS-009 can be safely combined with venetoclax at the 45-milligram dose level, and there were no indications that toxicity is likely to increase with the 60-milligram dose level. Secondly, the combination undoubtedly has significant anti-leukemic effects, with all but one of the patients who are evaluable having a decrease in the blast count in the bone marrow of at least 50% or higher. So bone marrow blasts are how we determine the burden of leukemia in these refractory and relapsed patients. And then, most of these patients had a 50% or higher decrease in bone marrow blasts during treatment, which is a significant signal of anti-leukemic activity, which is a good, an interesting bar to overcome.
So let me describe just a couple of patient outcomes thus far on the 45 milligram cohort to sort of illustrate what I mean by anti-leukemic activity. Since this is not a registrational blind study, I can discuss a few of these cases sort of as anecdotes. I think the most interesting case so far is that of the first enrolled patient. This patient specifically had received 6 full cycles of HMA plus venetoclax, but failed to respond. So normally just in clinical practice, after a patient receives 2, 3, 4 cycles of therapy with HMA venetoclax, if the patient does not respond, we usually would stop that treatment. You know, this patient was continuing on therapy because that's likely what happens in the real world, is that-...
There aren't many other therapies available in these patients, so you often have to continue whatever you have just because that's the best you have at that moment. So the patient was continued for 2 tumor cycles for a total of 6, because no further options were available. Then finally, the patient was enrolled on this SLS-009 trial. The patient actually went into complete remission with no visible leukemia cells after enrolling on the clinical trial. So just to be clear, first, he was receiving a venetoclax-based combination, went into the trial with the venetoclax-based combination with SLS-009, went into complete remission. Because venetoclax is also known to affect normal blood cells, which are mostly neutrophils causing suppression, the treatment is paused with all the drugs, including SLS-009, once the patient achieves complete remission.
When you get complete remission, you hold the drug, allow count recovery. Fortunately, the patient's remission actually continued even in the absence of the treatment, and all the blood counts actually recovered to normal, suggesting that they had recovery of hematopoiesis, which is the gold standard of achieving what we want, is a complete remission and full count recovery. Fortunately, the patient's counts were then able to protect the patient from infections and bleeding, and the patient is now, you know, leukemia-free, undergoing a very robust recovery of the blood counts. The remission is now in the third month and counting, and the patient has been alive now for seven months, which is a remarkable feat in and of itself, given the expected survival of two to three months.
As I said before, this is something that can hardly be expected in AML patients resistant to venetoclax. Emphasizing again, the patient is still alive, not hospitalized and transfusion independent seven months after previously being determined to be resistant to six cycles of venetoclax. Other patients are still being treated ongoing in clinic, on the clinical trial, with a very good quality of life, and we are eagerly all waiting for the results. In parallel, we'll be seeing soon the early results from the two higher cohorts, as I mentioned, that are currently enrolling, which is the 60 milligram cohort, either once a week or in two divided doses, which is 30 milligrams twice a week.
And then furthermore, we'll be performing thorough analyses of patient-specific cancer characteristics, so we can target specific mutations and specific leukemia characteristics to kind of really individualize this therapy, then maximizing and potentially predicting the number of responders that we would have in these subsets. To all that, I, I look forward to completing this important trial, working with my colleagues. So thank you very much.
Thank you very much, Dr. Kadia. I appreciate your thoughts as it relates to SLS-009 and its prospect in relapsed refractory AML. I think in conclusion, I want to say that we have placed great emphasis to bring about the next stages of value creation on behalf of SELLAS's shareholders. On behalf of the entire management team and our dedicated employees, we want to express our gratitude for your continued support and confidence in our company, a matter that I do not take lightly, and believe me, we live and breathe SELLAS here. We're confident that by staying true to our mission, working diligently, and executing our strategic initiatives, we will unlock significant value for our shareholders. I also want to thank our employees, who are most integral in our mission, and for whom our clinical programs would not be possible without their diligent and tireless work.
We look forward to sharing more positive updates with you throughout the year, and thank you once again for your unwavering support and belief in our vision. Wishing you and your family again, a wonderful new year, and thank you.
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