Good morning and welcome to the Kyverna Therapeutics Investor Conference call. At this time, all participants are on 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 at Kyverna Therapeutics.
Thank you. Good morning and thank you for joining today's conference call to discuss the positive interim data we announced this morning from the phase II portion of the KYSA-6 Phase 2/3 trial of KYV-101 in patients with Generalized Myasthenia Gravis, or gMG. Before we begin, I encourage everyone to visit the Investor Relations section of our website, where you can find today's press release and presentation materials accompanying this call. 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 may cause actual results to differ materially. Please review the Risk Factors discussed in today's press release, our presentation materials, and in our filings with the SEC for additional information.
On the call today with prepared remarks are Warner Biddle, our Chief Executive Officer, and Naji Gehchan, our Chief Medical and Development Officer. Marc Grasso, our Chief Financial Officer, and Dr. Sri Muppidi , Clinical Professor, Adult Neurology of Stanford Medicine, who is also an investigator in our phase II trial, will join the Q&A portion of the call. As a reminder, our interim phase II results will be presented later today in an oral presentation by Dr. Muppidi at the AANEM Annual Meeting. With that, I'll turn the call over to Warner. Warner.
Thank you, Jessica. Good morning, everyone, and thank you for joining us. We're excited to share very promising interim data from our phase II study in generalized myasthenia gravis, marking a significant milestone for Kyverna and KYV-101. I'll start with some brief remarks on MG and our interim data before turning the call over to Naji to review the results in greater detail. I'll close with some final thoughts on our neuroimmunology CAR T franchise before going into the Q&A. Let's turn to slide five. Core to our mission is helping patients living with debilitating autoimmune diseases achieve durable, disease-free, drug-free remissions. This goal is especially important for patients living with myasthenia gravis. Despite treatment options, patients with this progressive B-cell and antibody-mediated neuromuscular autoimmune disease face significant unmet needs.
Symptoms are highly disruptive to their 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 many treatment options available on the market today, including immunosuppressants and biologics, patients still struggle with symptom control, few reaching minimal symptom expression or MSE. As a result, the majority of patients require frequent and chronic treatment options on top of their background therapies that not only carry a significant treatment burden but are also costly. Novel therapies are needed to minimize or eliminate symptoms of disease while reducing risks associated with ongoing immunosuppression. For all of these reasons, we believe that KYV-101, our CD19 CAR T construct, has the potential to deliver a profound patient impact. Let's turn to slide six.
While there are many approved therapies and new therapies under development, none address the underlying disease on a mechanistic level. Unlike other modalities, KYV-101 aims for upstream targeting at the disease source by deeply depleting autoreactive B cells in tissues. In addition, KYV-101 is shown to have a positive impact on a broader set of immune cell types and, in particular, regulatory T cells, which are essential for keeping the immune system in check. These unique components of KYV-101's mechanism of action could enable a holistic immune reset in patients for which durability of treatment effect and remissions are possible. This signifies a fundamentally different approach for treating MG that only KYV-101 can deliver. Looking at slide seven, in addition to KYV-101, it has a unique construct that's designed for potency. The construct includes a CD28 co-stimulatory domain, which mediates rapid and robust signaling.
Further, KYV-101 is also designed to promote safety with a fully human CAR and other design features. The differentiated clinical outcomes associated with this unique CAR is supported by over 100 patients treated with KYV-101 through the compassionate use pathway, our own KYSA clinical trials, as well as IITs. In these patients, KYV-101 demonstrated deep and broad B cell depletion, along with an expected and manageable safety profile, with no high-grade CRS or ICANS observed across multiple autoimmune indications. For MG specifically, in the first three patients treated under the compassionate use pathway with KYV-101, we've all achieved durable, drug-free, and disease-free remissions, and these results remain ongoing for 15 to 24 months. These are profound outcomes compared to what current treatment options can offer. Importantly, we are confirming these results in a controlled clinical study with our phase II study. Moving to slide eight.
With the data we're sharing today, we're setting a new standard across clinical outcome measures that have not been seen to date with any approved or investigational therapies in MG. KYV-101 achieved all primary and secondary endpoints, delivering unprecedented reductions in MG-ADL and QMG, in addition to a consistent, well-tolerated, and manageable safety profile. Further, after a single dose of KYV-101, the majority of patients with longer-term follow-up reached minimal symptom expression or MSE and remained off immunosuppressants. To summarize and put our results into perspective, unprecedented disease control plus a manageable safety profile, more patients staying symptom-free, the opportunity to remove background therapies, and a simplified single-dose treatment. Any one of these outcomes alone would represent a significant treatment advance for these patients. With KYV-101, we are demonstrating the potential to deliver all four, changing the treatment paradigm for MG.
What this could mean for patients is the opportunity to regain their quality of life and be drug-free and disease-free. From a physician and payer perspective, this could represent a novel therapy with significant pharmacoeconomic benefits. Today's results further increase our confidence in the phase III portion of our clinical trial, as well as our path forward in bringing this potential therapy to the market. I'll turn the call over to Naji to cover our results in more detail.
Thank you, Warner, and good morning, everyone. I'm excited to be with you all today to detail our interim data. Let's turn to slide 10. As a reminder, KYSA-6 is a single-arm, multicenter, open-label phase 2/3 trial designed to evaluate the safety and efficacy of KYV-101 in patients with generalized myasthenia gravis. Today's update is from the single-arm phase II portion of the trial, in which we enrolled six patients diagnosed with gMG class IIB - IV per MGFA criteria and expressing positive AChR or MuSK antibodies. These patients must have had an MG-ADL score of at least 6 and have failed at least two immunosuppressive therapies or have failed at least one immunosuppressive therapy and required chronic plasmapheresis or IVIG to control symptoms. The primary endpoints in the portion of the trial are the reduction from baseline in MG-ADL score at 24 weeks and tolerability.
We are following these and other secondary measures on the slide, including QMG and MGC, throughout the 18-month follow-up period, which is ongoing. The data cutoff for the interim analysis is October 3rd, 2025. At data cutoff, the duration of follow-up was up to 36 weeks. Let's turn to our baseline patient characteristics. The trial enrolled patients with moderate to severe gMG, with average disease burden of 5.3 years and a mean MG-ADL score of 11.2, QMG score of 17.3, and MGC score of 21.8. All patients had failed prior immunosuppressant therapies that can include steroids, nonsteroidal immunosuppressants, FcRNs, and/or complement inhibitors. After a single dose of 100 million KYV-101 CAR T cells, all patients had robust CAR T cell expansion and deep B cell depletion. Now let's turn to the next slide for our efficacy results.
On the left side is the mean MG-ADL score for the number of patients who have reached that time point assessment. What you can see here is a rapid and robust reduction of the MG-ADL score of 7.8 points at just two weeks from baseline. This robust reduction is then sustained through last follow-ups, with a mean reduction of 8 points at week 24, our primary endpoint. This is a four-fold improvement over what is considered a clinically meaningful response, or the green straight line on the graph, defined as a greater than or equal to 2-point reduction in MG-ADL. Further, it's important to note the high mean baseline MG-ADL score of 11.2 points, underscoring KYV-101's strong efficacy in patients with high disease activity despite having been on current standard of care therapy. Similar results were seen in QMG.
The mean baseline QMG score was 17.3 points, and a rapid mean reduction of 7.8 points was observed at week two. Response was sustained at 24 weeks, with a mean reduction of 7.7 points. Again, these results exceed clinically meaningful improvement of a greater than or equal to three points reduction in QMG. Turning to slide 13. In addition to the depth and durability of response, we are seeing for the first time in a clinical trial setting 100% of patients achieving clinically meaningful responses in MG-ADL and QMG, and a 100% responder rate, which is defined as the proportion of patients achieving a greater than or equal to a three-point reduction in MG-ADL. Further, of the three patients with at least 24 weeks follow-up, two reached minimal symptom expression, defined as MG-ADL score of zero or one.
Finally, we also saw all patients achieve clinically meaningful response by MGC score, with a robust mean reduction of 12 points at 24 weeks. As a reminder, a three-point reduction is considered clinically meaningful. On top of these remarkable results, KYV-101 significantly reduced treatment burden up to 24 weeks, with 100% of patients discontinuing nonsteroidal immunosuppressants, high-dose steroids, FcRns, and complement inhibitors. Of the six patients, five remained off immunosuppressants at their last follow-up. Collectively, the efficacy results are in line with what we have observed from compassionate use pathway, further demonstrating the potential for KYV-101 to address the significant unmet needs of MG patients today. Let's turn to safety on the next slide. Consistent with the safety profile seen across more than 100 patients treated to date, KYV-101 was well tolerated, with no high-grade CRS and no instances of ICANS observed. Low-grade CRS events consisted of mostly fevers.
There were three patients that had expected AEs associated with CAR T cell therapy and lymphodepletion. Two patients had transient Grade 3/4 neutropenia, which were resolved within 10 days of infusion. We saw one Grade 4 neutropenia that was manageable with GCSF. This AE was not associated with infections and had improved to Grade 1 by the time of the data cutoff. Overall, we are very well encouraged with a consistent, well-tolerated, and manageable safety profile of KYV-101. Turning to slide 15. In summary, KYV-101 continues to demonstrate differentiated clinical outcomes. Based on data from the six patients treated, we saw robust, rapid, and sustained improvement regardless of prior biologic exposure. The majority of patients are at or trending to MSE as interim readouts, the opportunity to remove background therapies, and lastly, a manageable safety profile.
Importantly, with these results, we believe we are well-positioned and even further de-risked to advance into our registration of phase III trial. Turning to slide 16. I'll spend a few minutes to highlight how we believe our phase II data increased the probability of success for our upcoming phase III trial. First, the substantial effect size, as observed in the mean reduction in MG-ADL and QMG, well exceeded the magnitude of treatment effect assumed for our phase III co-primary endpoints. As we have noted previously, our phase III trial is well-powered at over 90% to meet both of our co-primary endpoints of MG-ADL and QMG. Today's results further increase our confidence in our powering assumptions for our superiority trial. In addition, the magnitude of treatment effect that had been observed with KYV-101 supports our efficient trial size of 60 patients.
Second, the deep and sustained treatment effect from our phase II was observed at week 24, which is the time point of assessment for our phase III co-primary endpoints. We believe this further reinforces our phase III trial design. Now let's turn to the next slide for a brief review of the phase III trial design. As we outlined at our KOL event earlier this year, we had aligned with the FDA to expand KYSA clinical trial programs into a registrational phase II three trial. This is an innovative trial with an efficient and robust design, which supports a clear and rapid path to BLA. The phase III portion of the trial is a global open-label randomized control trial. We are enrolling approximately 60 patients who will be randomized one-to-one to receive either KYV-101 or standard of care that will enable us to establish superiority.
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 failed FcRns can be included in our trial. Patients in the control R will have the option to cross over to KYV-101 after the primary evaluation period. Our co-primary endpoint is the change from baseline in MG-ADL and QMG at 24 weeks. A key secondary endpoint is the change from baseline in the MGC score at 24 weeks compared to the standard of care. Other endpoints will further seek to measure the magnitude of the anticipated clinical impact, including the responder rate, patients achieving MSE, and remaining off immunosuppressant therapy following treatment. We will follow these patients for 18 months from baseline measurements.
I'll also remind everyone that our inclusion and exclusion criteria are generally in line with our phase II trials and representative of a real-world clinical setting. Further, our criteria will allow us to stratify for biologic naive patients, which is unique to our phase III trial. Overall, we are very confident in the design of our superiority trial and believe it will establish KYV-101 as the new treatment standard in gMG if approved. Now let's turn to slide 18. Before I turn the call over to Warner, I'd like to conclude on an important slide that highlights our unprecedented data. 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, KYV-101 exceeds all.
No other therapy has demonstrated the ability to achieve the effect size, percentage of responders, and the percentage of patients reaching MSE, as KYV-101 has demonstrated so far. Importantly, these results were achieved with a single dose of therapy. This table also highlights the suboptimal outcomes associated with various modalities in treating MG, including FcRn and complement inhibitors, monoclonal antibodies, and BCMA mRNA CAR T cell therapy. As Warner mentioned earlier, patients still rely on background immunosuppressants while being on these chronic therapies. In this current treatment landscape, patients and physicians are simply looking for better treatment options with better outcomes. This is what motivates us every day at Kyverna Therapeutics, and we are one step closer to our mission to help patients achieve durable, drug-free, disease-free remission with a single dose with KYV-101.
In summary, we are energized by our path forward in gMG and are committed to making our mission a reality for people living with neuroimmunology diseases. We look forward to initiating our phase III trial, which we believe will generate the data needed to support an approval. The team here is working hard and partnering with sites to be activated, and we are on track to initiate enrollment by the end of this year. With that, I will turn the call over to Warner.
Thank you, Naji. Turning to slide 20. As Naji noted, we have a compelling opportunity ahead in MG and remain focused on bringing KYV-101 to market. As many of you know, MG is a large and growing market with approximately 80,000 patients diagnosed with generalized myasthenia gravis in the U.S. Of these patients, roughly half, or 40,000, are treated with immunosuppressants and have inadequate responses. Today, these patients are considered for a biologic. As I mentioned earlier, while novel therapies such as FcRns and complement inhibitors have entered the market, these therapies require chronic dosing that is costly and yet often leaves patients with residual disease burden. Given the differentiated profile that we're seeing across our own data and from the compassionate use pathway, we believe, if approved, we can compete directly with biologics.
Further, we believe our results continue to support a potential outpatient administration for KYV-101 at launch, particularly as treatment centers continue to optimize capacity and improve the patient journey for CAR T therapies. Our initial focus would be with patients with the highest unmet need or patients who have failed at least one biologic, which we estimate to be about 12,000 patients in the U.S. As we generate longer-term follow-up data from our KYSA clinical trial, we believe we can grow our total addressable market to 40,000 patients over time. Moving to slide 21, our robust market opportunity is supported by our efficient and scalable commercial strategy. As a reminder, our neuroimmunology CAR T franchise includes our late-stage indication in stiff person syndrome, or SPS, which has a first-in-class potential.
Our ability to achieve rapid market entry and uptake in MG will be supported by our first-mover advantage in SPS, as well as by our franchise synergies, which allow us to leverage many of the same treatment centers, same care teams, and shared infrastructures. Given these synergies, we plan to commercialize with a lean and focused team, which can be scaled over time as we move into other indications. In short, with our planned launch of SPS, we believe we have a running start to commercialize KYV-101 to an immediate pool of patients. Looking at the next slide, with today's positive interim results, along with the many other clinical and regulatory milestones we've achieved across our pipeline, I'm very proud of how far we've come in a growing organization. Our strong execution today positions us to accelerate our neuroimmunology franchise while advancing our broader pipeline opportunities.
We are ending 2025 with strong momentum. In MG, we have a clear path to a BLA with our FDA-aligned phase III trial that is further de-risked with these phase II results. In SPS, we're advancing to top-line data and a BLA filing to unlock a valuable commercial opportunity in this rare disease with no approved therapies. Beyond neuroimmunology franchise, we continue to evaluate our indication expansion strategy. Through IITs, we've seen promising early results in multiple sclerosis and rheumatoid arthritis that reinforce KYV-101's differentiated clinical outcomes and potential across multiple autoimmune indications. We're also excited about KYV-102. This is our next-generation CAR T built on the whole blood rapid manufacturing process. It's a second pillar in our strategy where we will seek to simplify and broaden patient access by removing the step-free apheresis, as well as speeding up manufacturing and lowering the overall cost of goods.
Finally, and importantly, we have a strong balance sheet with cash into 2027 supporting our near-term milestones, including our SPS BLA filing, our phase III MG trial, and our pre-launch activities. Next slide, please. Looking ahead, we have several expected key milestones coming up in the near term. Phase three MG trial enrollment and KYV-102 IND filing by the end of this year. SPS top-line data and BLA filing in the first half of 2026. Lupus Nephritis data from our KYSA- 1 and KYSA- 3 studies also expected in 2026. We believe we're well-positioned to continue to show the promise of KYV-101 across multiple autoimmune indications while also advancing our new innovations to expand CAR T access.
I want to take this time to thank the patients and families who participated in the KYSA-6 study, our investigators and clinical site teams, and our entire Kyverna Therapeutics organization for their hard work and dedication on behalf of these patients. Finally, I'd also like to express gratitude to Dr. Sri Muppidi for being an investigator on our phase II clinical trial, as well as presenting our data later today at AANEM. With that, I'll turn the call over to the operator for our Q&A.
Thank you. I will now open the call up to a question and answer session. Ladies and gentlemen, to ask a question at this time, you will need to press star one one on your telephone and wait for your name to be announced. To withdraw your question, simply press star one one again. Please stand by while we compile the Q&A roster. Our first question coming from the line of Derek Archila with Wells Fargo. Your line is now open.
Hey, good morning and congrats on the data here. Great progress. Just two questions from us. I guess first, you know, of the two out of three patients achieving MSE at week 24, obviously very impressive. Is there anything that we can learn from these initial patients? What's your expectations for the other four for them achieving MSE by week 24? I have a follow-up.
Sure. Thanks, Derek. Thanks for dialing in with us this morning. I mean, I think we have to remind ourselves these are interim data, and we're going to be looking to see the final data as more patients reach that important 24-week milestone. The fact that we're actually seeing two out of three patients now reaching MSE and the others trending towards MSE, I think it's a really powerful indicator and reinforces the data that we saw in our compassionate use patients earlier that we've discussed with you in prior conversations. We feel really, really confident with the data, the way they're progressing, even at this interim stage. The fact that we saw these really significant drops in MG-ADL and QMG as early as two weeks and seeing those actually sustained over the treatment period is another reinforcement here that we've got something really powerful for these patients.
Got it. The second question is just on, you know, were there any patients here that were completely biologic naive? If so, how did they perform relative to the experienced patients? This is just curious because you have the ability to enroll those biologic naive patients into the phase III. I just want to understand the impact of the trial potentially.
Sure. Naji, maybe you want to comment a little bit about the patient profile we have, and all patients were exposed to multiple therapies, including biologics.
Correct. All patients were treated by biologics. Five out of six had complement inhibitors and FcRns. As you shared, in the phase III portion of the trial, we will be stratifying to biologic naive for us to be able to see this.
Got it. Thank you very much, and congrats again.
Thank you.
I think one other point to just emphasize there, Derek, is the fact that we're treating some of these patients with really difficult disease, but with also multiple prior therapies, including these biologics, and seeing these tremendous results, I think bodes really well for our phase III trial where we'll be enrolling a similar patient population.
Totally makes sense. Thanks, guys.
Thanks, Derek.
Thank you. Our next question coming from the line of Brian Cheng with JP Morgan. Your line is now open.
Hey, guys. Thanks for taking out a question and congrats on the update. Warner, can you remind me if the phase II design here has the same washout requirement for standard of care as the phase III? Can you provide a bit more color on that patient, on that one patient that appeared to be in need of other agents? Are you seeing a rebound of their MG-ADL score? What was the driver there? We have a quick follow-up. Thank you.
Sure. Naji, maybe you want to take a little bit on the washout period, and then we'll come back to the one patient.
Yeah. The phase II design, the short answer is yes. It's similar to the phase III one. Do you want me to speak about the patients?
Yeah, sure. We can talk about the patient as well.
Yeah. The important piece here is 100% of patients were drug-free up to 24 weeks, and five out of six patients were drug-free after that last follow-up. To answer specifically your question, there was no flare of MG for this one patient. This was a unique case and a patient-initiated decision where the patient had failed three prior agents and achieved MSE after KYV-101 and went back at week 33 on a patient decision, even though the physician did not think it was needed, went back off one of their immunosuppressants and kept being at MSE at their last follow-up at 36 weeks. What's really important is really looking here at the data in its totality, where we're overall seeing a significant reduction in those background therapies for the majority of patients and a significant and deep response in MG-ADL and QMG, as you've seen so far across all patients.
Got it. Maybe just one quick one on the SPS front. As we head into the pivotal readout and also the BLA filing over the next couple of months, can you also give us some detail on the pre-launch work that you mentioned in your prepared remarks? What can be done today between now and BLA filing? Thank you.
Yeah. Thanks, Brian. There's a lot of work going on behind the scenes in order to prepare for launch. Of course, we are working to ensure that our manufacturing readiness is in place. That's been happening now for a number of months, and we feel really confident about our manufacturing success rate, as well as the scalability of our manufacturing to meet the commercial demand. In addition, we're spending a lot of time with patients, Brian, and the SPS patient groups that are supporting this disease. They are very interested in the progress that we're making as a company. Because there's no approved therapies, they are very anxious to see these results and are very excited about the results that are coming.
In addition, we're also doing a lot of work behind the scenes in order to prepare our commercial infrastructure here, and specifically the logistical requirements for managing and navigating the cells and what we're calling the Kyver system. We're making investments in that to get that ready in advance as well, as well as doing some pre-work around assessment of the payer market and the payer and market access landscape. As we've talked about in previous calls, we believe that KYV-101 offers a really significant and compelling differentiation in SPS as well as MG that can be really cost-effective and provide a really, really strong alternative for payers in this marketplace. We're preparing the documentation and the support in order to support that from a launch perspective as well. A number of things are happening right now that we're really, really excited about in terms of preparing.
Great. Thank you. Thanks, Warner.
Thank you. Our next question coming from the line of Mitchell Kapoor with H.C. Wainwright. Your line is now open.
Hey, team. Congrats on the data. First question is that, you know, the patients in the trial got to an MG-ADL of around 3 by the three-month mark. Just bringing that up because we saw the compassionate use patients reach zero by three months and the three compassionate use patients. Can you just talk about the differences that might be contributing whenever we're looking at the compassionate use patients versus the in-trial patients? Separately, obviously, impressive mean MG-ADL reduction over time. Can you talk about the uniformity or the variability between different patients of the MG-ADL reductions at each time point?
Yeah. Thanks, Mitchell. I think it's really important to note that these are interim results. The significant reductions we saw as early as two weeks by having the drops of 7.8 in MG-ADL as quickly as two weeks is actually indicative of how well KYV-101 is working. In addition, 100% of patients responded. I think that's actually really important to keep in mind that there were no patients that didn't respond to therapy. We believe this is an interim data set, so we need to continue to watch as those patients continue to mature. All of them were trending towards MSE. I think that's actually important for us to document as we see the data set continue to mature. Naji, maybe you want to comment a little bit further around the uniformity of patients and the results that we're seeing.
Yeah. As Warner shared, you know, as we were moving into a clinical trial, sponsored clinical trial setting, we do anticipate some variability in responses. Nonetheless, these results really are validating our IH experience. As Warner shared, this is interim data, and we're really raising high the bar on MSE here with 67% reaching minimal symptom expressions. What's key is the substantial effect size we're observing here across both our co-primary endpoints, MG-ADL and QMG, and our secondary endpoint MGC that is far exceeding clinical significant effect. When you look at what we're delivering here on phase II, the data delivered is supporting and increasing our confidence and probability success of our phase III trial.
That's great. Thank you. Last one for me, I think you touched upon it, but just want to confirm, how many patients continue to either deepen in MG-ADL or remain flat at the last follow-up versus trending upward?
Yeah. As we look at our data and specifically in our clinical trials, we're going to be looking at these from a cohort perspective. What's key here is those mean drops you're seeing are based on time point reached by patients. It's, again, a rapid, robust, and sustained mean reduction that's maintained over time. Really, the key aspect, as Warner also shared, 100% of patients did reach clinical significance reduction as soon as two weeks and was sustained up to their last follow-up, which is for two patients, as you can see on the slide, 36 weeks.
Yeah. As Naji mentioned previously as well, no patients in this data set had had a disease flare or MG flare as well. I think that's important to keep in mind. There were no major uptakes in terms of MG-ADL or QMG in this patient data set.
Correct.
Wonderful. Thank you. Thank you both very much. Really appreciate it.
Thanks, Mitchell.
Thank you. Our next question coming from the line of Mike Ulz with Morgan Stanley. Your line is now open.
Hi. This is Rohan on for Mike. Thanks for taking our question. Can you just talk about the baseline MG-ADL scores and QMG scores at baseline and how they compare to the real-world setting? Secondly, just provide some additional context on the three patients that had neutropenia and how they were treated. Thank you.
Sure. Yeah. The baseline scores for MG-ADL were 11.2. This puts us into a moderate to severe range in terms of disease severity for these patients. Very similar, if not even maybe slightly more severe, but very similar to the patients that we were treating in our compassionate use program. We feel these are actually really indicative of support of KYV-101's efficacy and gives us confidence that, you know, given that we're targeting the same patient profile going into our phase III, we can replicate these results when we move into our phase III program. Maybe you want to take the second part of that as well?
The neutropenia question, sorry.
Yeah. Sure. On the neutropenia, we had three patients with neutropenia, as we shared here. Two of them were Grade 3/4 transient neutropenia that resolved within 10 days of infusion, and it's related to lymphodepletion and potentially CAR T. We had one Grade 4 neutropenia that resolved to a Grade 1 at their last follow-up. I would say what's really where we're encouraged is this totality of safety profile that we have that is consistent, manageable, and expected with KYV-101.
Thank you. Our next question coming from the line of Thomas Smith with Leerink Partners. Your line is now open.
Hey, guys. Good morning. Congrats on the data, and thanks for taking our questions. Looks like really impressive depth of response here in a really heavily pretreated patient population. Can you just clarify the split between AChR positive patients and the MuSK patients in this data set? Can you comment at all on what you're seeing with respect to the autoantibody levels for these patients? I have a follow-up.
Yeah. I mean, just in terms of the split, Tom, five were AChR positive, one was MuSK positive. Maybe, Naji, you want to talk a little bit about the antibody titers?
Yeah. Sure. Yes, five AChR, one anti-MuSK, and you've seen, and certainly agree with you, Tom, on how you're seeing the depth of response across those six patients, regardless of their autoantibodies. That's a key piece. For the biomarker, this is, again, an interim data cut that we've done, and we will be sharing more data on our secondary endpoints and our primary endpoints next year as the data mature and all patients reach 24 weeks.
Got it. That makes sense. Okay. Maybe one for Dr. Muppidi. If I could, can I just ask you to comment on these interim results and how you think about the positioning here for KYV-101 in the treatment paradigm? Maybe just help us understand within your center, like how many patients do you think are candidates for KYV-101? How are you thinking about enrolling patients into a potential phase III study here relative to other mid and late-stage MG studies? Thanks so much.
Great. Thank you.
Dr. Sri, are you on the line there?
Yeah.
Go ahead.
Yeah. Thank you. I certainly think the data is quite promising. I think one of the things that was highlighted but worth re-emphasizing is that these were refractory patients with a very high disease burden, with the ADL of 11, which is quite high. This is higher than some of the phase III studies that have been published to date. For example, most of them have a mean MG-ADL of 9 to 10 when they're enrolled into the phase III study. I think even for those patients with a high disease burden, the level of improvement that we are seeing, even with the interim analysis, is quite impressive. The question regarding how many patients we will have, I think part of the challenge is going to be much more on the deployment side of things.
I certainly expect the data to be as promising as it is in this trial to sort of carry forward to phase III data. That's much more of a health organization and how we organize different centers. Some centers might be ready to go in terms of using CAR T therapy in autoimmune diseases from their prior experience in oncology. That is going to be something that we'll have to figure out. We've had quite a few patients who are quite eager and ready to participate in these trials because of the excitement behind the field and the promising early data. We probably will use some patients who have a disease burden.
I hope as we do these studies, and I know there's a lot of correlative analysis that is going to come out, including from this study, where we'll be able to identify patients who are going to be best responders for these therapies. That way, we can capture them early, potentially offer them these life-changing therapies.
Very helpful. Thanks for the comments.
Yeah. Thanks, Tom. Thanks, Sri. Maybe I'll just add a little bit more context too about your question around the centers, Tom, and how we're thinking about it from a Kyverna perspective. First, we, you know, our first indication and we believe our first launch will be in SPS, which is a highly concentrated patient population. These patients are largely centered or circulate through the key academic centers because of the fact that there's no unmet needs and because these patients require special treatment. We believe that, in the initial launch phases of SPS, there's going to be direct access to these patients through the existing academic centers and through the connections that we've already established through the clinical trial enrollment. That bridges over to the MG launch and the thinking about how we're thinking about these patients of the highest unmet need.
Many of them are refractory to the point that Dr. Muppidi was just outlining, and they are seeking additional therapy and additional treatments and secondary, you know, diagnosis and confirmatory diagnoses from these academic centers. We believe that these patients will be circulating and have access into these academic centers as well, which gives us a huge strength. We can build off the commercial footprint we're building with SPS and leverage that in terms of the initial launch of the myasthenia gravis patients as well. We think there's a lot of commercial synergies and are working hard through the clinical trial enrollment to set up these sites. This will give us a running start in terms of our commercialization as well.
Thank you. Our next question coming from the line of Sami Corwin with William Blair. Your line is now open.
Good morning. Congrats on the data and thanks for taking my questions. I was curious how many clinical trial sites you expect to have for the phase III trial. I think the prior question was trying to get at this. Dr. Muppidi, what percentage of your patients do you think would be good candidates for KYV-101 if this data held up through the phase III trial? Thank you.
Yeah. It's a great question. I think the challenge is that currently, you know, these are not available outside clinical trials. In general, about 5% - 10% of my patients' clinic would qualify for clinical trials. One of the challenges with the current clinical trial model that we have with phase III other novel therapies, not KYV-101, is that they cannot be on other novel therapies if they want to participate. Just to elaborate, for example, if you want to participate in a new FcRn therapy, then you couldn't be on a complement therapy or you couldn't be on FcRn therapy prior. Whereas with KYV-101, you know, as long as there is a brief washout period, they should be able to qualify.
In many ways, actually, it might be easier to recruit because patients see the degree of the response and we get more comfortable with the degree of response that we are seeing for patients. To put an exact number, that's a difficult one to say. Overall, I expect at least about 10% of the patients will likely qualify. Whether all of them will, you know, be eager and ready to participate, that's a very individual patient selection issue. I expect that number of patients to qualify for the study criteria.
Yeah. Maybe just following up quickly on your second point, Sami, we haven't disclosed a specific number of sites. As we talked about with the SPS trial recruitment, we believe in quality of sites and would rather have fewer sites and go deeper in that in terms of the relationships. We were able to recruit the SPS trial relatively quickly with only three sites. We're going to be taking, obviously, a broader approach with myasthenia gravis and going to a larger number of sites. We believe we can actually learn a lot from how we recruited the SPS trial to enroll this one as well.
Great. Thank you and congrats again.
Thanks, Sami.
Thank you. That will conclude the Q&A portion of today's call. I will now turn the call over to Warner for closing remarks.
Thank you all for joining us today. Today's presentation is available on our website. Dr. Muppidi's oral presentation will also be available for his talk at AANEM. It's an exciting time here at Kyverna . With the promising data we reported today, we're uniquely positioned to fundamentally change the treatment paradigm in generalized myasthenia gravis. Importantly, today's results increase our confidence in our registrational phase III superiority trial and our path to a BLA. Given the significant void that KYV-101 can fill in the large and growing MG market, we believe Kyverna Therapeutics is well-positioned to deliver on a compelling commercial opportunity. With the progress we made and the momentum ahead, we look forward to sharing more updates as we progress forward. Thanks again for joining us this morning.
This concludes today's conference call. Thank you for your participation. You may now disconnect.