Kyverna Therapeutics said it has produced one-year data supporting an FDA submission path for its rare autoimmune CAR-T program. The company highlighted positive long-term findings in patients with stiff person syndrome, an ultra-rare condition characterized by painful muscle spasms and stiffness. The update positions Kyverna’s program as moving from early efficacy observations toward longer-duration durability—an important threshold for regulatory evaluation in autoimmune indications where durability and safety profiles must be established. Market reaction in this kind of readout typically centers on whether the one-year signal can support broader labeling or at least accelerate the probability of favorable review outcomes in subsequent regulatory steps.