8-K: Kyverna's Miv-cel Shows Positive Phase 2 SPS Trial Data

Kyverna Therapeutics announced positive topline data from its registrational Phase 2 KYSA-8 trial of mivocabtagene autoleucel (miv-cel) in stiff person syndrome, demonstrating statistically significant clinical benefit across all primary and secondary endpoints.

Summary

• Positive topline data from the KYSA-8 registrational Phase 2 trial of mivocabtagene autoleucel (miv-cel, formerly KYV-101), a fully human, autologous CD19 CAR T-cell therapy, in stiff person syndrome (SPS) was announced.
• Miv-cel achieved statistically significant clinical benefit across all primary and secondary endpoints, reversing disability scores.
• Patients remained free of immunotherapies as of the last follow-up.
• The data supports a Biologics License Application (BLA) submission expected in 1H 2026.
• Miv-cel has the potential to become the first and only approved therapy in SPS and the first CAR T-cell therapy for an autoimmune disease.
• The KYSA-8 trial was an open-label, single-arm, multicenter study with 26 patients aged 18 to 75 years, diagnosed with SPS and an inadequate response to immunomodulatory therapy.
• The primary endpoint, change from baseline in Timed 25-Foot Walk (T25FW) at 16 weeks, showed a statistically significant improvement (P=0.0002).
• 81% of patients achieved a clinically meaningful 46% improvement in T25FW at Week 16.
• Secondary endpoints, including Modified Rankin Scale, Distribution of Stiffness Index, Hauser Ambulation Index, and Heightened Sensitivity Scale, all showed statistically significant benefit (P<0.0001 for each).
• Of 12 patients who required a walking aid device prior to treatment, 67% (8/12) no longer needed assistance to walk at Week 16.
• The safety profile was well-tolerated and manageable, with no high-grade Cytokine Release Syndrome (CRS) or Immune effector cell-Associated Neurotoxicity Syndrome (ICANS) observed.
• 24 patients (92%) experienced any grade CRS (10 Grade 1, 14 Grade 2), and 3 patients (12%) experienced any grade ICANS (all Grade 1).
• 16 patients (62%) had Grade 3/4 neutropenia, a known adverse event associated with CAR T treatments, which was manageable and resolved for the majority within 28 days of infusion.
• The initial priority addressable market in the U.S. for miv-cel in SPS is estimated at ~2.0 to 2.5k patients (30-40% of total diagnosed), with a total addressable market of ~5.5k patients (90% of total diagnosed) out of ~6,000 total U.S. diagnosed SPS patients.

Sentiment

Score: 9

Explanation: The filing reports highly positive, statistically significant topline data from a registrational Phase 2 trial for a debilitating disease with no approved therapies. The safety profile is manageable, and the company has a clear path to BLA submission, indicating a strong potential for market entry and significant commercial opportunity. This represents a major breakthrough for the company and patients.

Positives

• Miv-cel achieved statistically significant clinical benefit across all primary and secondary endpoints in the KYSA-8 trial for Stiff Person Syndrome (SPS).
• The therapy reversed disability scores and enabled patients to remain free of immunotherapies through the last follow-up.
• Miv-cel demonstrated a well-tolerated and manageable safety profile, with no high-grade Cytokine Release Syndrome (CRS) or Immune effector cell-Associated Neurotoxicity Syndrome (ICANS).
• The positive data supports a Biologics License Application (BLA) submission in 1H 2026, indicating a clear and rapid path to market.
• Miv-cel has the potential to be the first and only FDA-approved therapy for SPS and the first CAR T-cell therapy for an autoimmune disease, addressing a significant unmet medical need.
• The estimated addressable market for miv-cel in the U.S. for SPS patients is substantial, with ~2.0-2.5k priority patients and ~5.5k total diagnosed patients.
• The current financial position is expected to support the SPS BLA filing, the ongoing Phase 3 trial for generalized myasthenia gravis (gMG), and pre-launch activities.

Negatives

• 16 patients (62%) experienced Grade 3/4 neutropenia, a known adverse event associated with CAR T treatments, although these events were manageable and mostly resolved within 28 days.

Risks

• Forward-looking statements are subject to risks and uncertainties, including factors described in the company's most recent Annual Report on Form 10-K and Quarterly Reports on Form 10-Q.
• Actual results could differ materially and adversely from those anticipated or implied in forward-looking statements.
• The company undertakes no obligation to update or revise forward-looking statements.
• Estimates made by independent parties relating to industry market size and other data involve assumptions and limitations, and the company has not independently verified their accuracy or completeness.
• Results from named-patient basis access (e.g., Individueller Heilversuch in Germany) are not a substitute for, or intended to replace, clinical trials and are not expected to be used as the basis for marketing approval by regulatory agencies like the U.S. Food and Drug Administration (FDA).

Future Outlook

Kyverna Therapeutics expects to submit a Biologics License Application (BLA) for miv-cel in Stiff Person Syndrome (SPS) in the first half of 2026. The company anticipates miv-cel could become the first and only approved therapy for SPS and the first CAR T-cell therapy for an autoimmune disease, laying the groundwork for expansion into broader indications. The current financial position is expected to support the SPS BLA filing, the ongoing Phase 3 trial for generalized myasthenia gravis (gMG), and pre-launch activities. An Investigational New Drug (IND) application for KYV-102 was filed in Q4 2025.

Management Comments

• Miv-cel achieved statistically significant clinical benefit across all primary and secondary endpoints, reversing disability scores; patients remained free of immunotherapies as of last follow up; data supports BLA submission expected in 1H 2026.
• The first completed registration-enabling CAR T trial for autoimmune disease could pave the way for miv-cel to become the first and only approved therapy in SPS and CAR T-cell therapy for autoimmune disease.
• There is a valuable commercial opportunity in SPS, supported by attractive market dynamics and a focused commercialization strategy.
• The first-to-market opportunity in SPS lays the foundation for expansion into broader indications.
• Today's results represent a breakthrough in SPS, potentially making miv-cel the first and only approved therapy in SPS and CAR T for autoimmune disease.
• SPS data solidifies Kyverna's leadership in autoimmune CAR T.
• The company has conviction in delivering on a valuable commercial opportunity in SPS.
• There is a promising path to achieving a first-in-class neuroimmunology CAR T franchise.

Industry Context

The positive topline data for miv-cel in Stiff Person Syndrome (SPS) positions Kyverna Therapeutics as a potential first-mover in the autoimmune CAR T-cell therapy space, an area with significant unmet medical need and no FDA-approved therapies for SPS. This development could establish a new treatment paradigm for severe autoimmune diseases, potentially expanding the application of CAR T technology beyond oncology. The company's focus on a scalable CDMO model and targeting academic centers aligns with strategies for specialized, high-value therapies in rare diseases.

Comparison to Industry Standards

• SPS is a debilitating, progressive autoimmune disease with no FDA-approved therapies, highlighting a significant unmet medical need compared to other conditions with established treatment protocols.
• Miv-cel's achievement of statistically significant clinical benefit across all primary and secondary endpoints, reversing disability scores, and enabling patients to remain free of immunotherapies, sets a high benchmark for efficacy in a disease with limited treatment options.
• The safety profile, with no high-grade Cytokine Release Syndrome (CRS) or Immune effector cell-Associated Neurotoxicity Syndrome (ICANS), is favorable when compared to some CAR T therapies used in oncology, which can have more severe safety concerns.
• The potential for miv-cel to be the first and only approved therapy in SPS and the first CAR T-cell therapy for an autoimmune disease represents a significant advancement, potentially establishing a new standard of care where none currently exists.

Stakeholder Impact

• Shareholders: Highly positive impact due to strong clinical data, potential first-to-market approval, and significant commercial opportunity, which could lead to increased valuation and future revenue streams.
• Patients (SPS): Transformative impact by offering a potential first and only approved therapy for a debilitating disease with no current FDA-approved treatments, reversing disability and eliminating the need for chronic immunotherapies.
• Healthcare Providers: Provides a novel and potentially highly effective treatment option for Stiff Person Syndrome, addressing a significant unmet medical need.
• Employees: Positive impact through the success of a key pipeline asset, potentially leading to growth and stability for the company.

Next Steps

• Submit Biologics License Application (BLA) for miv-cel in SPS in 1H 2026.
• Continue the ongoing Phase 3 trial for generalized myasthenia gravis (gMG).
• Engage in pre-launch activities for miv-cel in SPS.
• Further develop KYV-102, for which an IND was filed in Q4 2025.
• Expand into broader indications for miv-cel beyond SPS.

Key Dates

Recommendation

The announcement of highly statistically significant positive topline data from a registrational Phase 2 trial for miv-cel in Stiff Person Syndrome (SPS) is a major de-risking event for Kyverna Therapeutics. SPS is a severe autoimmune disease with no FDA-approved therapies, presenting a substantial unmet medical need and a significant first-to-market opportunity. The robust efficacy across all primary and secondary endpoints, coupled with a well-tolerated safety profile, strongly supports a Biologics License Application (BLA) submission in 1H 2026. This positions miv-cel to potentially become the first and only approved therapy for SPS and the first CAR T-cell therapy for an autoimmune disease, opening up a new therapeutic class. The estimated addressable market is meaningful, and the company's financial position is stated to support key upcoming milestones. This news represents a transformative breakthrough with high potential for future revenue and market leadership, making it a strong buy recommendation for investors.

Keywords

Kyverna Therapeutics, miv-cel, KYV-101, Stiff Person Syndrome, SPS, CAR T-cell therapy, autoimmune disease, Phase 2 trial, KYSA-8, topline data, BLA submission, FDA approval, CD19 CAR T, neuroimmunology, biotechnology, clinical trial results