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Landmark results could pave the way for miv-cel to become the first FDA-approved CAR T-cell therapy for autoimmune disease; Company on track to submit BLA for stiff person syndrome in 1H 2026
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Miv-cel achieved statistically significant clinical benefit across all primary and secondary endpoints, reversing disability and eliminating immunotherapies after a single dose
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Miv-cel was generally well-tolerated with no high-grade CRS or ICANS observed
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SPS is a debilitating, progressive autoimmune disease with no FDA-approved therapies
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Company to host webcast today, December 15, 2025 at 8 am ET
EMERYVILLE, Calif., Dec. 15, 2025 (GLOBE NEWSWIRE) -- Kyverna Therapeutics, Inc. (Nasdaq: KYTX), a clinical-stage biopharmaceutical company focused on developing cell therapies for patients with autoimmune diseases, today announced positive topline data from KYSA-8, its registrational Phase 2 trial of mivocabtagene autoleucel (‘miv-cel’, formerly KYV-101), a fully human, autologous CD19-targeting CAR T-cell therapy with CD28 co-stimulation, in stiff person syndrome (SPS).
“We are very pleased to share transformative topline data in stiff person syndrome, which 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,” said Warner Biddle, Chief Executive Officer of Kyverna Therapeutics. “Today’s results further cement our leadership position in the autoimmune CAR T field and add to the growing body of evidence supporting miv-cel’s potential to fundamentally shift the treatment paradigm in autoimmune diseases. We look forward to submitting our BLA for SPS in the first half of 2026 with the goal of bringing this novel therapy to patients and physicians who desperately need an effective treatment for this devastating and progressive disease.”
KYSA-8 Clinical Trial Summary and Topline Data Highlights
KYSA-8 is a single-arm registrational Phase 2 trial in which patients with SPS, who had an inadequate response with non-approved treatment options, received a single dose of miv-cel. A total of 26 patients were dosed and followed through the primary analysis time point (Week 16) with additional follow-up thereafter.
“Today’s topline data represent a significant breakthrough in the treatment of stiff person syndrome, demonstrating miv-cel’s ability to reverse progressive disability in a debilitating disease that has no approved therapies,” said Naji Gehchan, Chief Medical and Development Officer of Kyverna Therapeutics. “With a single dose, miv-cel achieved highly statistically significant and sustained improvements in overall disability, mobility, and stiffness, while enabling all patients to remain free of immunotherapies. In addition, miv-cel demonstrated a well-tolerated and manageable safety profile. We believe these unprecedented results, which support our BLA submission, will have a profound impact on patients. We want to thank the patients, their families and the healthcare providers for participating in this important trial.”
About KYSA-8 Trial Design
The registrational Phase 2 KYSA-8 trial is an open-label, single-arm, multicenter study evaluating the safety and efficacy of miv-cel in patients with SPS. A total of 26 adult patients with SPS were dosed in the trial. Key inclusion criteria included a confirmed SPS diagnosis, stiffness index ≥2, and inadequate response to prior immunomodulatory therapies.
Patients received lymphodepletion with cyclophosphamide and fludarabine followed by a single infusion of miv-cel at a target dose of 1×108 CAR T cells. The primary endpoint was the change from baseline in the T25FW at Week 16. Secondary endpoints included the change from baseline in mRS, HAI, DSI, and HSS. Patients will be followed for one year.
About Stiff Person Syndrome (SPS)
SPS is a rare, progressive neurologic autoimmune disease characterized by muscle stiffness and painful muscle spasms, impacting mobility and gait. Stiffness, rigidity, and spasms in the torso, arms, and legs lead to progressive disability causing up to 80% of patients to lose mobility1-3. SPS has been shown to lead to permanent disability and increased risk of mortality3. Most patients with SPS have antibodies to glutamic acid decarboxylase 65 (GAD65) or the glycine receptor, which disrupt normal inhibitory neurotransmission, contributing to the hallmark symptoms of SPS. There are currently no FDA-approved treatments for SPS. Current treatment options include symptomatic treatments, off-label immunotherapies, such as intravenous immunoglobulin (IVIg), rituximab and plasmapheresis, as well as physical, speech, occupational therapy, supportive care, and psychiatric therapy; however, the majority of patients have inadequate or no response to these treatment options.
About mivocabtagene autoleucel (miv-cel)
Mivocabtagene autoleucel (miv-cel’, formerly KYV-101) is a fully human, autologous CD19-targeting CAR T-cell therapy with CD28 co-stimulation, designed for potency and tolerability, which is under investigation for B-cell-driven autoimmune diseases. With a single administration, miv-cel has potential to achieve deep B-cell depletion and immune system reset to deliver durable drug-free, disease-free remission in autoimmune diseases.
About Kyverna Therapeutics
Kyverna Therapeutics, Inc. (Nasdaq: KYTX) is a clinical-stage biopharmaceutical company focused on liberating autoimmune patients through the curative potential of cell therapy. Kyverna’s lead autologous CD19-targeting CAR T-cell therapy candidate, miv-cel (mivocabtagene autoleucel, KYV-101), has demonstrated the potential to fundamentally change the treatment paradigm across multiple B-cell-driven autoimmune diseases.
Kyverna is advancing its potentially first-in-class neuroimmunology franchise with its recently completed registrational trial in stiff person syndrome and an ongoing registrational trial for generalized myasthenia gravis. The Company is also harnessing other KYSA trials and investigator-initiated trials, including in multiple sclerosis and rheumatoid arthritis, to inform the next priority indications. Additionally, its next generation pipeline includes CAR T-cell therapies deploying novel innovations to improve patient access and experience.
1 Rakocevic G, et al. BMC Neurol. 2019;19:1.
2 Dalakas MC. Nat Rev Neurol. 2024;20(10):587-601.
3 Duddy ME, Baker MR. Front Neurol Neurosci. 2009;26:147-165.