Kyverna Therapeutics reported that its patient-specific CD19 CAR-T therapy achieved statistically significant benefits in a registrational trial for stiff person syndrome (SPS), meeting the study’s primary and all secondary endpoints. The company said the data improved walking ability and other clinical measures and plans a U.S. marketing application in the first half of 2026. Stiff person syndrome is a rare, autoimmune neurological disorder marked by painful muscle stiffness and spasms; the condition currently lacks approved disease-modifying therapies. Kyverna characterized the results as strong enough to support a regulatory filing and commercialization strategy focused on an unmet rare-disease indication.