TLDR:
- Kyverna stock jumps after SPS trial shows strong mobility gains from single-dose CAR-T
- Mivacel meets all endpoints, supporting the first FDA approval in stiff person syndrome
- Phase 2 SPS data show durable benefit with no severe CAR-T safety signals
- Kyverna plans FDA filing in 2026 after breakthrough SPS registrational results
- Strong clinical data positions Kyverna as a leader in autoimmune CAR-T therapies
Kyverna Therapeutics, Inc. (KYTX) surged 23.52% to $10.85 after announcing positive topline results from its Phase 2 KYSA-8 trial.
Kyverna Therapeutics, Inc., KYTX
The trial evaluated its CAR T-cell therapy, mivocabtagene autoleucel (miv-cel), in patients with stiff person syndrome (SPS). The stock’s sharp rise reflects strong market reaction to what could be the first FDA-approved treatment for SPS.
Miv-cel Shows Statistically Significant Results in SPS Trial
The KYSA-8 trial enrolled 26 patients with confirmed SPS and unmet therapeutic needs. All participants received a single dose of miv-cel after standard lymphodepletion. The therapy met the primary endpoint, showing a 46% median improvement in timed 25-foot walk at Week 16.
81% of patients crossed the 20% clinical improvement threshold in mobility, reinforcing the treatment’s impact. Patients also recorded significant gains across secondary endpoints, including disability and stiffness indices. Of those using mobility aids at baseline, 67% no longer needed them post-treatment.
The trial also noted that 100% of patients discontinued all immunotherapies by Week 16. No rescue treatments were required, suggesting durable effects from a single infusion. These outcomes highlight MIV-Cel’s potential to reshape autoimmune disease care.
Safety Profile Remains Manageable with No Severe Neurotoxicity
Miv-cel demonstrated a favorable safety profile, critical for regulatory review and future adoption. No patients experienced high-grade cytokine release syndrome or CAR T-cell-related neurotoxicity. Most adverse events were mild to moderate and aligned with known effects of CAR T-cell therapies.
The most frequent issue observed was Grade 3 or 4 neutropenia, which remains manageable under standard supportive care. These findings suggest the therapy balances efficacy with safety, a key metric in severe autoimmune conditions. Continuous monitoring will further assess long-term tolerability.
With these safety results, miv-cel stands as a viable candidate for broader autoimmune use. The consistent safety across multiple endpoints and no life-threatening events bolster Kyverna’s regulatory strategy. These findings are expected to support their upcoming Biologics License Application submission.
FDA Approval Path Cleared with BLA Planned for 2026
Kyverna confirmed plans to submit its Biologics License Application (BLA) to the FDA in the first half of 2026. The therapy holds both Orphan Drug and Regenerative Medicine Advanced Therapy designations for SPS. These designations could help accelerate the regulatory timeline and review process.
SPS affects around 6,000 people in the U.S. and currently has no FDA-approved therapies. Current care relies on off-label immunotherapies and symptomatic treatments with limited long-term effectiveness. Miv-cel’s success presents a potential paradigm shift in how SPS is treated going forward.
Kyverna is also pursuing miv-cel in other autoimmune indications, including generalized myasthenia gravis. With supportive data from KYSA-8, the company solidifies its lead in the autoimmune CAR-T space. It also strengthens its position to become the first to bring CAR T-cell therapy into neuroimmunology.
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