Kyverna Therapeutics announces topline data from registrational KYSA-8 trial

Kyverna Therapeutics (KYTX) announced topline data from KYSA-8, its registrational Phase 2 trial of mivocabtagene autoleucel, a fully human, autologous CD19-targeting CAR T-cell therapy with CD28 co-stimulation, in stiff person syndrome. 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 with additional follow-up thereafter. Efficacy: After a single dose, miv-cel achieved statistically significant benefits on primary and all secondary efficacy endpoints at Week 16: Primary Endpoint: Miv-cel demonstrated a robust and sustained improvement in mobility with a highly statistically significant improvement in timed 25-foot walk. The median improvement was 46% at Week 16 as compared to baseline. 81% of patients exceeded a 20% improvement in T25FW, a threshold considered clinically meaningful. Secondary Endpoints: highly statistically significant benefit was also achieved across all secondary endpoints, including the Modified Rankin Scale, Distribution-of-stiffness Index, Hauser Ambulation Index, and Heightened Sensitivity Scale. Of the 12 patients who required a walking aid-device prior to treatment, 67% no longer needed assistance to walk at Week 16. 100% of patients remained free of immunotherapies, and no patients required rescue therapy as of the last follow up, highlighting miv-cel’s potential to provide unprecedented clinical benefit while significantly reducing or eliminating chronic treatment burden. Miv-cel was well-tolerated, with no high-grade cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome observed. Grade 3/4 neutropenia, a known adverse event associated with CAR T treatments, was observed in certain patients and was manageable. Based on these data, Kyverna plans to submit a Biologics License Application to the FDA for SPS in the first half of 2026. It has received both Regenerative Medicine Advanced Therapy and Orphan Drug designations for miv-cel in this indication. The Company also plans to share the full SPS data set at a medical conference in 2026.