Good morning, and welcome to the Kyverna Therapeutics AAN conference call. At this time, all participants are in a listen-only mode. A Q&A session will follow the prepared remarks. Please note that this call is being recorded. I would now like to introduce Jessica Serra, Head of Investor Relations. Please go ahead.
Thank you. Good morning, and thank you for joining us today. We will be discussing the primary analysis from our KYSA-8 registrational trial of mivocabtagene autoleucel, or miv-cel, formerly referred to as KYV-101 in Stiff Person Syndrome, as well as longer-term follow-up data from our KYSA-6 phase II trial in generalized myasthenia gravis. I'd like to remind everyone that we will be making forward-looking statements during today's call. These statements reflect our current expectations and beliefs and are subject to risks and uncertainties that can cause actual results to differ materially. Please review the risk factors discussed in our press releases, our presentation materials, and in our filings with the SEC for additional information.
On the call today are Warner Biddle, our Chief Executive Officer, Naji Gehchan, our Chief Medical and Development Officer, Dr. Amanda Piquet, Professor of Neurology at the University of Colorado Anschutz, Celine Dion Foundation Endowed Chair, and lead investigator in our KYSA-8 clinical trial, and Dr. Sri Muppidi, Clinical Professor, Adult Neurology of Stanford Medicine, and investigator in our KYSA-6 phase II trial. Warner will first provide brief remarks for today's call. Naji, Dr. Piquet, and Dr. Muppidi will cover our data for stiff person syndrome and generalized myasthenia gravis. After, Warner will close on our commercial opportunity in stiff person syndrome. Following prepared remarks, we will have a Q&A session with all speakers, including Mark Rassa, our Chief Financial Officer. With that, I'll turn the call over to Warner. Warner?
Thank you, Jessica. Here at Kyverna, we're excited to share unprecedented data from our neuroimmunology franchise, including the first registrational primary analysis for an autoimmune CAR T, marking a significant milestone for Kyverna and for the field. In Stiff Person Syndrome and generalized myasthenia gravis, our transformative data continue to strengthen our conviction in miv-cel's differentiated profile and potential to change the treatment paradigm. Importantly, we continue to demonstrate our leadership in this space by advancing miv-cel towards a potential first approval in autoimmunity. Our SPS BLA submission is our top priority as we work towards unlocking a valuable commercial opportunity that not only establishes our first-in-class leadership, but also lays the foundation for expansion into additional indications, including gMG and progressive MS over time.
Our phase III trial in gMG is also advancing and paves the way to a large and growing market opportunity, and one where miv-cel's differentiated clinical profile may offer meaningful advantages relative to standard of care and other therapies currently in development. Now let's turn to the next slide for highlights of our SPS and gMG data. From a high level, the new data presented here this week continue to reinforce miv-cel's differentiated profile and our conviction in our neuroimmunology franchise. Results from a registrational phase II primary analysis in SPS demonstrate miv-cel's potential to transform patient care, which we believe further supports our path to approval and confidence in our launch. Importantly, we are showing new data on our secondary endpoints, including unprecedented SPS-specific outcomes, as well as translational data that demonstrate the full spectrum of clinical benefit achieved by miv-cel.
We also saw transformative results from our longer-term follow-up data in GMG. Recall, we shared the interim results from our phase II trial back in October of last year. We are very pleased to see even deeper responses as the data mature, with durability of treatment effects sustained out to one year. Notably, 100% of patients achieved clinically meaningful, rapid, and robust responses, and the majority of patients continue to have few or no symptoms as of their last follow-up. These data continue to set a new standard in gMG clinical outcomes, further increasing our confidence in our ongoing phase III trial. Importantly, across both data sets, we're continuing to see miv-cel significantly reduce treatment burden from chronic immunotherapies. In addition, miv-cel demonstrated a consistent, well-tolerated safety profile, which we believe will support the potential for outpatient administration. Turning to slide six.
Today's results are underpinned by our potential first-in-class, best-in-class CAR T construct. miv-cel is designed for enhanced potency with the only fully human CD19 targeting autologous CAR T with a CD28 costimulatory domain that mediates rapid and robust signaling. More than 100 patients have been treated with miv-cel to date across multiple indications. Based on the data thus far, miv-cel has demonstrated deep B-cell depletion in the periphery and in targeted tissues, supporting a broad immune reset and durable remissions. In addition, miv-cel has been shown to have a positive impact on a broad set of immune cell types, and in particular, regulatory T cells, which are key for keeping the immune system in check. Finally, miv-cel is a fully human CAR, which is designed to enhance patient tolerability.
Across the patients treated to date, miv-cel has demonstrated a consistent and manageable safety profile with no high-grade CRS or ICANS. Importantly, the first SPS and GMG patients treated with a single dose of miv-cel have achieved durable efficacy beyond 24 months without the need for chronic immunotherapies. This is truly a remarkable outcome. Now I'd like to share with you a patient from our trial, which brings to light how miv-cel is transforming the care for SPS. Let's play the video. This is a 39-year-old male patient from our trial performing the timed 25-Foot Walk test, which is our primary endpoint for the trial. Prior to receiving miv-cel, the patient requires a walker to ambulate, and despite the walking aid, you can see his walk is still slow and unstable. He has a slouched posture and is focused on maintaining his balance with each step.
Here is a video of him walking at just 16 weeks after a single dose of miv-cel. As you can see, this is a remarkable transformation. His time to complete the walk went from 17.3 seconds to 5.4 seconds, comparable to a healthy adult. Importantly, he no longer needs a walker. Now, I'll turn the call over to Naji and Dr. Piquet to cover our registrational primary analysis for SPS. Naji?
Thank you, Warner. Slide nine. As you saw from the video, SPS is a highly debilitating and progressive autoimmune disease, and unfortunately, there are currently no FDA-approved therapies for patients. SPS impacts the inhibitory signaling pathways that control the brakes on muscle contractions and help muscles relax. Symptoms include severe muscle stiffness and painful spasms due to uncontrolled muscle contractions that impact mobility and gait. Patients often resort to the use of symptomatic therapies such as multiple daily doses of benzodiazepines, in addition to chronic off-label immunotherapies. Despite these treatments, most patients have an inadequate or no response. Further, chronic immunotherapies also carry long-term safety risks. SPS has a devastating impact on patients' lives, with the disease often occurring in adults during their prime years in life.
Up to 80% of patients lose mobility over time, and only about 19% of patients remain able to work after four years with this disease. In addition, patients experience disease progression, which can lead to permanent disability and place them at risk of increased mortality. Turning to slide 10. The high disease burden of SPS and the urgent need for an effective therapy is highlighted in a natural history study conducted by the University of Colorado and Johns Hopkins University. For background, this was a large, multicenter, retrospective natural history study examining the impact of SPS on walking speed. The study included 153 patients treated with off-label immunotherapies and with available longitudinal Timed 25-Foot Walk test data collected over the course of 10 years. Data demonstrated that despite being on therapies, the majority of patients showed no or minimal improvement in the Timed 25-Foot Walk test.
In addition, over time, disability did not improve and patients' reliance on walking aids increased. Overall, the natural history study provides important evidence of the underserved SPS patient population and provides greater context to the transformative data that we've generated with miv-cel. Turning to slide 11. We are very excited to present full results from our primary analysis, building on the top-line data that we shared last December with data cut off November 26th, 2025. Our FDA-aligned KYSA-8 clinical trial is a single arm, multicenter, open label, registrational phase II trial. We have received both the RMAT and Orphan Drug designations for miv-cel in SPS. The trial included 26 patients. All patients discontinued their immunotherapies prior to a single dose of miv-cel. Let's turn to slide 12. Before Dr. Piquet shares the details of the data, it is important to understand how mobility is assessed for Stiff Person Syndrome.
The Timed 25-Foot Walk test is our primary endpoint and a validated tool to assess walking ability, as well as to evaluate stiffness and loss of mobility. To put this into perspective, the time that it takes a healthy individual to walk 25 feet is about four to five seconds. For patients with SPS, that time can be twice as long or even longer, depending on the severity of their disease. For this endpoint, a 20% improvement in the Timed 25-Foot Walk is considered clinically meaningful. Slide 13.
Now let's turn to our secondary endpoints, which include the Modified Rankin Scale, or mRS, that measures the degree of disability, the Hauser Ambulation Index, or HAI, which measures the time and degree of assistance to complete the Timed 25-Foot Walk Test, the Distribution-of-Stiffness Index, or DSI, that measures muscle stiffness in various parts of the body, and lastly, the Heightened Sensitivity Scale, or HSS, that measures the number of triggers of muscle spasms. All of these measures are included in our trial to ensure a robust evaluation of miv-cel's efficacy. Now I'll turn the call over to Dr. Amanda Piquet to present our impressive data.
Dr. Piquet.
All right. Thank you. I'm excited to present this unprecedented data. The results showed miv-cel delivered rapid, statistically significant, and clinically meaningful improvements across all primary and secondary endpoints at week 16, with the majority of patients regaining function. Importantly, all patients discontinued chronic immune therapies and remained off as of last follow-up. From a clinical perspective, the magnitude and consistency of functional improvement observed is unprecedented. To take you through this slide here, the primary efficacy endpoint was met. Miv-cel resulted in significant improvement in the Timed 25-Foot Walk at week 16, representing a 46% median improvement from baseline. 20% improvement is considered clinically meaningful. You can see here the results were statistically significant. 81% of patients achieved or exceeded this bar, with nearly a third walking at the speed of a healthy adult by week 16.
Of the 12 patients requiring a walking aid at baseline, two-thirds no longer needed assistance at week 16. This reflects a meaningful functional independence of these patients. The Timed 25-Foot Walk improvement was also sustained through 24 weeks for 16 patients who reached the time point. These findings are compelling and potentially paradigm-changing for the SPS community. Next slide. miv-cel achieved significant improvements in disability, mobility, stiffness, and hypersensitivity. We saw significant improvements in other measures. As you can see here, the shift plots show a significant reduction in disability using the Modified Rankin Scale. Additionally, there was significant improvement in mobility using the Hauser Ambulation Index. Now, this incorporates the time and degree of assistance needed to walk 25 feet. There were significant improvements observed in SPS-specific measures.
This included the Distribution-of-Stiffness Index, which demonstrates that reduction in muscle stiffness across body regions, and the Heightened Sensitivity Scale, demonstrating that reduced sensitivity to stimuli triggering spasms. To put this in a clinical perspective, even in prior trials looking at SPS, we generally don't see, with off-label therapies, any reduction in that hypersensitivity. This is incredible to see this in this population. Importantly, 96% of patients had improvement in at least one primary or secondary efficacy endpoint. Next slide. There were substantial improvements observed in other secondary endpoints, including the six-minute walk test and the SF-36 at 16 weeks. This really reflects the improvements that we saw in physical and mental functioning in our SPS patients. In the six-minute walk, the patients experienced a median improvement of 89 m. That's essentially walking almost the length of a football field.
That is greater than fourfold from the clinical meaningful change of 20 m. In the SF-36, patient scores at week 16 were comparable to healthy adults. In this disease, we can see significant impairments in social functioning, emotional status, and mental health. To have these patients exceed what we see in a healthy adult is just incredible. Next slide. Here we see robust miv-cel expansion leading to complete peripheral B-cell depletion and significant reduction in autoantibody titers. The first panel shows this robust T-cell expansion, where you can see the CAR T-cells peaking at day 14, and then 54% of patients had B-cell reconstitution at week 16. Efficacy, importantly, was maintained with B-cell reconstitution. Again, reiterating that no patients were resumed on immune therapies as of this follow-up. Then on the other panel here, we see this 56% reduction in GAD65 autoantibody levels.
Moving on to the next slide. This slide here further demonstrates that broad immune reset after miv-cel treatment. Of those patients that I commented on had B-cell reconstitution. They are listed here as recoveries. Looking at baseline to recovery, we see these newly emerging B-cell populations showing a significant increase in the naive phenotype and a decrease in the memory phenotype. What this means is we're seeing new, healthier B-cells reemerging. Again, markers of this broad immune reset that we can see after miv-cel. Additionally, on the right side of the screen, you have significant increase in regulatory T-cells at week 16. Again, further evidence demonstrating this broad immune reset extending just beyond the B-cell effects. Next slide. Miv-cel demonstrated a well-tolerated safety profile. Importantly, miv-cel was tolerated, everything was manageable, and no high-grade cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome was observed.
There was Grade 3/4 neutropenia, a known adverse event that is associated with lymphodepletion and CAR T treatment that was observed in four patients, and it was manageable. The serious treatment-related AEs occurred in three patients, all of which fully resolved, and again, emphasizing that this was fully manageable. Next slide. I just want to reemphasize, in this registrational trial, we saw a single dose of miv-cel significantly reverse disability, reduce stiffness, and hypersensitivity. It improved mobility in these patients, and they remained free of chronic immune therapy treatments. These are outcomes we have not seen before in this disease. These findings represent a potentially transformative advancement for the patient population that historically have had a lack of treatments in the past and offers great promise for CAR T.
Thank you, Dr. Piquet. Next slide, please, 20. In summary, we're pleased to see a single dose of miv-cel demonstrating the potential to transform patient care in SPS. First, an ability to deliver significant clinical improvement while reversing disability. Second, the potential to eliminate chronic immunotherapies. Third, a well-tolerated safety profile. Fourth, and importantly, durable clinical benefit achieved through B- cell depletion and a broad immune reset. Collectively, these outcomes represent a treatment breakthrough for patients and physicians. Now let's turn to generalized myasthenia gravis on slide 21. Before we begin, I'd like to share a video of a patient with refractory gMG who received miv-cel through an IH in Germany. The video illustrates the significant disease burden and impact on quality of life prior to treatment, as well as the transformative improvement observed following a single dose of miv-cel. Let's play the video.
[Presentation]
Mr. Ackermann's improvement after miv-cel is remarkable, now two and a half years in remission and off all MG therapies. His story, along with many others, inspires the work we do here at Kyverna. Turning to slide 23. As you saw from the video, gMG is a serious B-cell and antibody-mediated neuromuscular autoimmune disease. Symptoms are highly disruptive to quality of life and can include muscle weakness and fatigue, difficulty chewing and swallowing, trouble with speech, and in severe cases, respiratory failure, which can be life-threatening. Despite the many treatment options available on the market today, including immunosuppressants and biologics, patients still struggle with symptom control, with few reaching minimal symptom expression or MSE. As a result, the majority of patients require frequent and chronic treatment options in addition to background therapies that carry a significant treatment burden.
For these reasons, novel therapies are needed to address the underlying drivers of the disease, with the goal of minimizing or eliminating symptoms while reducing the reliance of chronic immunotherapy. Slide 24. This is the study design for our KYSA Study, a phase II trial which included seven patients who had failed prior immunotherapies. It is important to note that all patients discontinued their MG immunotherapies prior to receiving a single dose of miv-cel. The primary endpoints in phase II of this trial were the reduction from baseline in MG-ADL score at 24 weeks and tolerability. We continue to follow these and other secondary measures on the slide, including QMG and MGC, throughout the 18-month follow-up period, which is ongoing. The data cut-off was February 25, with the longest follow-up up to 52 weeks.
Now I'll turn the call over to Dr. Muppidi to cover the data in greater detail.
Good morning. These results are unprecedented and exciting for the field. We've seen even deeper reduction in MG-ADL, QMG compared to previously approved therapies. The MG-ADL, QMG reduction seems sustained and further reduces as you go on to week 52. MG-ADL demonstrated a quick reduction at week two of 6.4 points and further reduction of 8.5 by week 24. QMG demonstrated rapid and robust reduction as early as week two of 8.6, with further deepening up to 11.3 at week 24. While there are a number of therapies that have been approved in Myasthenia, this degree of deep and sustained reduction has not been previously noticed. Next slide, please. After a single dose of miv-cel, patients achieved sustained and clinically meaningful reductions in all the outcome measures that we use in Myasthenia Gravis. 100% of the patients had clinically meaningful response in MG-ADL.
100% of the patients were responders from baseline in MG-ADL as well as QMG. 57% of the patients had achieved MSE at the follow-up. 100% of the patients had clinically meaningful response of MG composite and a dramatic reduction of 16 points. More importantly, all of these patients were able to come off their prior immunosuppressive therapy, including non-steroid drugs, high-dose steroids, FcRn, and complement inhibitors up to week 24. This part needs to be emphasized again. We do not usually take off their prior immunosuppressive therapy in other MG trials and MG agents. The fact that we're able to take these medications off and still retain the clinical benefit is not seen previously. Next slide. miv-cel demonstrated a well-tolerated safety profile. There were no high-grade CRS or ICANS. There was only low-grade CRS that were mostly fevers and were manageable quite easily.
Three patients had grade three out of four treatment-related adverse event of neutropenia, lymphopenia, and low lymphocyte count. These are expected adverse events of lymphodepletion and CAR T-cell therapies. Neutropenia was again fully manageable and fully resolved. There were no serious adverse event, and the previously reported treatment serious adverse event was reclassified by the investigator as not serious. Results continue to support a very favorable risk-benefit profile of miv-cel. Next slide, please. Robust CAR T-cell expansion led to a very deep B-cell depletion. As you can see on the slide on the left side, there was a robust increase in CAR T-cell expansion. This reflects on the slide on the right, these deep B-cell depletion. B-cell recovery was detected in two patients at week 12 and week 16. Next slide, please.
In those patients where we had prior antibodies available, you're able to see there are two patients with AChR and one patient with MuSK. There's a robust reduction in antibody levels, and the reduction in antibody levels is sustained. At the same time, patients still have continued preservation of humoral immunity, as you can see on the right side, to common vaccinations. This is a critical point, of miv-cel, is that it's able to reduce the pathological antibodies and yet preserve other humoral immunity. With that, I'll pass it on to Naji.
Thank you, Dr. Muppidi. Let's go to slide 30. As Warner mentioned earlier, we are truly setting a new standard across clinical outcome measures in gMG that has not been seen to date with any approved or investigational therapies. As you saw from today's results, a single dose of miv-cel resulted in robust, rapid, and durable improvements across all endpoints, regardless of prior biologic exposure, and with the majority of patients at MSE as of last follow-up. Opportunity to remove immunotherapies, a well-tolerated safety profile, and finally, evidence of immune reset and preserved humoral immunity. Combined, these transformative outcomes underscore miv-cel's potential to change treatment paradigm in gMG. Importantly, we believe the significant effect size observed in MG-ADL and QMG, the core primary endpoints of our phase II trial, meaningfully increases the probability of success for the phase III trial. Turning to slide 31 next.
As we outlined during our Q4 earnings, enrollment for our FDA-aligned phase II trial continues to advance with 14 sites activated globally. As we've already shared the trial design, I won't go over this slide in detail, but it's important to note that this is the first CAR T superiority trial in gMG evaluating miv-cel versus standard of care. Standard of care includes traditional agents or complement inhibitors. FcRn inhibitors are excluded due to their fluctuating efficacy over dosing intervals. However, patients who have had an inadequate response to FcRns can be included in our trial. Turning to slide 32. Before I turn the call over to Warner, I'd like to conclude on an important slide that highlights miv-cel's differentiated profile.
While cross-trial comparisons are not based on head-to-head studies, you can see that across all primary endpoint measurements for approved and investigational therapies, miv-cel is the only product candidate that has demonstrated this deep magnitude of response while freeing patients from chronic background immunotherapies with a single dose. With that, I will turn the call over to Warner.
Thank you, Naji. I'd now like to focus on our valuable market opportunity in SPS. Moving to slide 34. With the results from our primary analysis, which are further reinforced by natural history data, we believe we have a strong clinical evidence to support our BLA pathway and a pathway to approval. As the only company with a late-stage asset in this rare disease, we are uniquely positioned for a compelling commercial opportunity in SPS. As we have previously mentioned, there are approximately 6,000 diagnosed patients in the United States. Our initial priority will focus on patients with the highest unmet need who are ready now for a better treatment option. This accounts for 2,000-2,500 patients, or roughly 30%-40% of diagnosed patients who have had an inadequate response to off-label immunotherapies.
In this patient population, we believe miv-cel can be immediately established as the new treatment standard. In addition, given the inadequate responses associated with symptomatic treatments, we believe that we can also target the rest of the 5,500 patients over time based on real-world clinical evidence and increased patient education. Turning to slide 35. Initial feedback from physicians reflects both excitement in our data as well as the potential for a strong early adoption of miv-cel. We surveyed 20 high-volume SPS treaters in the U.S. using a product profile informed by miv-cel's top-line data. 80% pointed specifically to the efficacy data and the one-time treatment paradigm as the most compelling attributes of miv-cel's product profile. We believe this reinforces what we see as one of the most important aspects of miv-cel's value proposition supporting commercial success. 90% of patients viewed the profile as compelling versus current treatment options.
Most importantly, 85% said they would use miv-cel in moderate to severe patients at launch, which represents a meaningful proportion of patients that could immediately benefit from miv-cel. Next slide 36. We have a focused go-to-market strategy, initially targeting approximately 10 centers with immediately addressable patient population and attractive launch dynamics. Importantly, these centers were selected because they all have in common what we believe are critical attributes supporting early adoption and launch execution. First, these are centers with recognized SPS leadership, institutions that include thought leaders and high-volume treaters, along with strong institutional support. Second, there are already a significant number of SPS patients being treated at these centers, with additional patient flow supported by established referral networks. Third, all of these sites already have commercial CAR T experience and accreditation.
Finally, these centers have the potential to realize strong economics through robust inpatient and outpatient treatment models, as well as favorable reimbursement dynamics. Taken together, our launch strategy allows for an effective and efficient market entry, focusing on a relatively small number of high-priority launch centers that are well-positioned to treat a meaningful proportion of immediately addressable patients. Moving to slide 37. Before we move to the Q&A, I would like to summarize our excitement about the data we presented today and our promising pathway forward. At Kyverna, we're executing on our mission to deliver the curative potential of CAR T in autoimmunity. We believe miv-cel positions us to deliver the first approved CAR T therapy in autoimmune diseases, supported by a potential best-in-class clinical profile and growing evidence of a durable drug-free remission.
Our focused neuroimmunology strategy enables a first-to-market opportunity in Stiff Person Syndrome, representing a high-value, commercially attractive launch and establishing a strong foundation for expansion into generalized myasthenia gravis and additional indications, including progressive MS. Finally, we remain well-capitalized to support our SPS BLA submission, the anticipated commercial launch, and our phase III GMG trial. With that, I'll turn the call over to our operator for the Q&A.
Thank you, Warner. I will now open the call up to a question-and-answer session. To ask a question, please press star one one on your telephone and wait for your name to be announced. To withdraw your question, please press star one one again. We ask that you please limit to one question, and any additional questions, return to the queue. The first question comes from Thomas Smith with Leerink Partners. Your line is open.
Hey, guys. Good morning. Thanks for taking our questions, and congrats on these really strong data updates. Great to see the consistency of these data sets as they continue to mature. Just for Dr. Piquet, if I could, we heard quite a lot of buzz around Stiff Person Syndrome at the meeting. There was a really well-attended symposium on Saturday and then a seminar on Sunday. Can you just comment on the level of interest you're seeing in miv-cel from other academic and community center colleagues who weren't involved in the KYSA-8 study but have SPS patients that are looking for new therapeutic options? Thanks so much.
Yeah. Dr. Piquet, do you want to handle this question?
Yeah. A ton of excitement, and I think this is just a reflection of the lack of therapies that we've had for this rare disease over decades. Obviously, there's a lot of public interest in this disease over the last couple of years, and it's just been incredible to see the amount of research going into helping these patients. As you said, there's a lot of excitement at this meeting. It just continues to grow, and I think a lot of excitement over miv-cel, seeing a treatment for these patients.
Thank you. The next question is going to come from Derek Archila with Wells Fargo. Your line is open.
Hey, good morning, and congrats on the updates here. All the data turning very excellent. Just quick question on how efficacy kind of tracks the GAD65 antibody reductions that we see. Then just a follow-up on that, and then this is for Dr. Piquet. As we think about this impressive data that we're seeing in SPS, are there considerations for which you would not prescribe miv-cel for an SPS patient? Thanks.
Thanks, Derek, appreciate that. Naji, why don't you start with the correlation of efficacy data versus the antibody titers, and then, Amanda, you can touch on the other subject.
The efficacy, as we've seen in this trial and Dr. Piquet shared here, is really remarkable on all our primary, secondary endpoints. We've seen exploratory endpoints also being, well, really very significant. When you look at the totality of the titers, actually, it's correlated, right? You have this decrease in the antibody titers that is significant. We know that these titers, and Dr. Piquet can comment a little bit more, are not extremely correlated exactly to the disease. What's really key here is this consistency of results clinically and this decrease of titers that has been seen is really important to look at. Amanda, I'll pass it over to you also on the other question.
Yeah. You had asked who would not be a candidate potentially for miv-cel. I just want to say that SPS is a very heterogeneous disease. However, we know from natural history data that 80% of patients progress. I'd say the vast majority are actually going to benefit from miv-cel because in those patients that are progressing, we see increased disability, the need for ambulatory aids. I think actually that's going to be a fair minority of patients that are our unicorns that tend to do okay. We know this to be a progressive disease.
Yeah, I think that's.
Thank you so much.
Yeah, Derek.
Go ahead, Warner, sorry.
No, no. Thanks for the question. I think it's supported as well from the market research we were doing across a number of SPS treaters where we know that 85% said they would use miv-cel in the moderate to severe patient population. As you pointed out, Amanda, the prognosis of these patients gets worse over time. The fact that we now have something that can be transformative for these patients and give them some hope, I think is truly remarkable progress. Thanks, Derek.
Warner, just a follow-up on that real quick. Just on the 10 high volume centers that you guys talked about being the target at launch, how many patients does that represent?
Well, of the immediately addressable patient population, we know there's between 2,000-2,500 patients that we've identified that are already refractory to existing immunotherapies or existing off-label treatments. Of the 10 high-value centers that we're targeting at launch, that'll cover roughly half of those patients. I think it's really, really important to keep in mind that those 10 centers are just the starting point for us. We're targeting that as a launch target for ourselves, but we're going to continue to add authorized treatment centers as we continue to move through the launch sequence. The additional centers that we add will not only provide additional patient potential for SPS, but as you know, we're looking ahead to generalized myasthenia gravis.
Because of the synergy between these two indications, the additional centers that we're adding will also allow us to treat more patients with gMG over time as well.
Excellent. Thanks again, guys.
Thank you. Our next question is going to come from Brian Chung with JP Morgan. Your line is open.
Hi, guys. Good morning and congrats on the data again. This is Ron on for Brian. Looking ahead into the approval for miv-cel and SPS, how should we think about the label language? Do you see potential for this therapy to be approved for the broad SPS population, or do you anticipate approval will be dedicated only to GAD65 or LADA positive patients?
Yeah, thank you for the question. Yeah, the BLA preparations are a top priority for us, and we're moving with a strong sense of urgency. Based on this really robust clinical data, we feel really confident in our clinical package, and we've had some really productive dialogue with the FDA up to this point. Naji, maybe you want to provide a little bit of perspective on how we see the label, because this data is truly unprecedented.
Yeah. We're not disclosing specific label, obviously, at this point, and it's certainly our top priority as we are going through the BLA process. As you can see, and as Dr. Piquet shared here, there's no current approved therapy for this disease. The impact we're seeing is truly remarkable, and majority of patients could benefit from. This is something how we're thinking about it as we are going through our BLA filing.
Thank you, guys.
Thank you. The next question will come from Michael Ulz with Morgan Stanley. Your line is open.
Great. Good morning. Thanks for taking my question, and congratulations on all the updates as well. Maybe another question for Dr. Piquet on SPS. You shared a number of benefits across endpoints that were consistent. Just curious if there's particularly one endpoint that really stood out to you, or do you think that might be most meaningful for patients? Thanks.
Thanks, Michael. I think when you take a step back and think about the totality of this data set, I think it's worth reinforcing that we're not only seeing statistically significant and clinically meaningful impact on just one of these endpoints, but just across the entire spectrum. Amanda, maybe you want to comment on some of the secondary and exploratory endpoints and what piques your interest from a clinician's perspective.
Yeah. Again, reiterating, all endpoints are amazing. You're asking me to pick basically my favorite child, which you're trying not to do. I would say what is really amazing is the six-minute walk test, because to walk an additional football field, that's just incredible. I would say, I think I was most impressed with that endpoint.
Great. Thank you.
Thanks, Michael.
Thank you. Thank you. Our next question comes from Matt Phipps with William Blair. Your line is open.
Good morning. Thanks for taking my question, and congrats on all the updates. Dr. Piquet, I was wondering if you could talk a little bit about how your center will manage patient demand or how you see that going on approval. Is this something where it might be one patient a week, given there's obviously lots of other CAR-T trials and heme indications, or maybe any idea on how many patients you could process? Just wanted to confirm that only two patients received tocilizumab in the SPS study. Would you ever think about using prophylactic toci? Thank you.
Yeah, I think one of the key learnings we're seeing, Matt, as we set up these centers, both from a clinical trial perspective as well as looking ahead to commercial, is this partnership between the autoimmune treater, in this case, the neuroimmunology specialists, and the CAR-T specialists. I think that's been one of the keys of success to us as we have enrolled in clinical trials, and it's what we're working on right now as we gear up for launch. Amanda, if you want to provide a little perspective on how you guys are thinking about it from the University of Colorado, that would be helpful.
Yeah. We have a cellular therapy program that's been established, and we are partnered with our hematology group in the autoimmune space. We have representative neurologists like myself, as well as rheumatologists, nephrologists, and GI docs, all coming together and having this multidisciplinary cellular therapy program. Basically what that group does is help support our current clinical trials, as well as planning for future commercial implementation. We're investing in basically increasing the capacity for these patients. I'm just very excited to be able to bring this CAR-T therapy, potentially, if approved, into the commercial setting. Like I said, our university is investing improvements for the treatments of patients with autoimmune diseases, including SPS.
Yeah. This is very similar to what's happening at Stanford as well, this partnership between the neuromuscular physicians and with the CAR-T specialists as well. Sri, I don't know if you want to just provide a little bit of color on the situation at Stanford, which is progressing very nicely too.
Yeah. Thank you. We have a similar protocol where we have a dyad model, so disease expert like myself in different diseases, and then we have a bone marrow transplant. Our CAR T expert from hematology, we work together closely, and our teams work together. It really improves the efficiency from point of patient selection all the way down to the time that we're able to offer CAR T to the patient.
That's great. I know there's a second part of the question about using prophylactic therapies in order to manage and advance the A profile. Naji, do you want to start on that? Because I think there's been a tremendous amount of progress on how these protocols have been put in place over the past few years.
Yeah. As we've said, with miv-cel dosing more than 100 patients, we have no high-grade CRS ICANS, and certainly, in the past 15 years in CAR-T, the management of CRS and ICANS have dramatically improved. For miv-cel, we do have dex doses, so the regimen of how to treat CRS and ICANS. We are looking into prophylaxis, to your point, prophylaxis dex. It has shown to be efficacious to avoid CRS and also not impacting the expansion. This is well-known. Certainly, the way those are managed and then this consistency of the safety profile that we have with miv-cel is certainly prone for it to be an outpatient when it gets into commercial.
Thank you. As a reminder to ask a question, please press star one one on your telephone. Our next question comes from Mitchell Kapoor with H.C. Wainwright. Your line is open.
Hi. Can you hear me?
You bet, Mitch. Hello.
Hi. This is Jan Zies sitting in for Mitchell Kapoor. Thanks for taking my question and for the exciting data. This is great. I have a question on the sustained 52-week response. The mean curves look rapid and then durable. But beneath those averages, are you seeing distinct response patterns, such as patients who plateau early versus patients who, say, benefit and that continues to deepen over time?
Jan, are you speaking about the Stiff Person Syndrome or Myasthenia Gravis?
The MG-ADL.
Right. Sure. Naji, you want to take that because this deepening impact is I think one of the most important aspects that we're seeing coming out of the data.
What we're really excited about with this update, we're seeing here six patients at 24 weeks with this profound response on MG-ADL and QMG. As you can see, we have five patients at nine months and three patients at a year with this continued sustained impact on their disease, whether it's MG-ADL or QMG. Importantly, as Dr. Muppidi shared here, and I'll turn it over to him, those strong impact on the disease itself is also achieved with freedom of drug and burden of background therapies. This is really one of the key points in this disease and how we're changing the paradigm, is this ability to free patients from their disease and their background immunosuppressants, and it's sustained in the patients that have reached this one-year time point. I don't know, Sri, if you want to add something to that.
Sure. Yeah, I think other important thing to add, and sometimes we tend to forget when we look at this data, is we have to always think of where the patient started. These seven patients were refractory, had tried multiple other therapies, including currently FDA-approved therapies, and they were still symptomatic on those therapies. We are able to offer something that they hadn't experienced before. For me, both the depth of the response and the sustained response is quite remarkable and hadn't been appreciated before.
Thank you so much.
Thank you. At this time, there are no further questions in the queue. Now I would like to turn the call back over to Warner.
Thank you, operator, and thank you all for joining us today at AAN. On behalf of my entire leadership team, I want to express our gratitude to the patients and families who participated in the KYSA-6 and KYSA-8 trials, and to our investigators and the clinical site teams, including Dr. Piquet and Dr. Muppidi, who graciously shared their time with us today. I also want to acknowledge the entire Kyverna organization for their hard work and dedication on behalf of these patients. We look forward to updating you on our progress ahead. Thank you.