Kyverna Therapeutics, Inc. (KYTX) announced positive data from its registrational Phase 2 KYSA-8 trial of mivocabtagene or miv-cel in patients with stiff person syndrome, marking a potential breakthrough for autoimmune CAR T-cell therapy.
Stiff person syndrome is a rare, progressive autoimmune neurological disorder characterized by muscle stiffness and painful spasms, often leading to severe disability, with no approved FDA therapies to date.
Miv-cel or formerly KYV-101 is a fully human, autologous CD19-targeting CAR T-cell therapy with CD28 co-stimulation, designed to deliver potency and tolerability. A single administration aims to achieve deep B-cell depletion and immune system reset, potentially enabling drug-free, disease-free remission in autoimmune diseases.The KYSA-8 trial enrolled 26 adult patients with Stiff person syndrome, who had inadequate response to prior therapies. Patients received a single infusion of Miv-cel. At the primary analysis time point of Week 16, patients experienced a median 46% improvement in the timed 25-foot walk, with 81% achieving more than a 20% improvement, a threshold considered clinically meaningful. Significant benefits were also observed across secondary measures, including disability scores, stiffness indices, and ambulation assessment.
Of the 12 patients, who required walking aids before treatment, two-thirds no longer needed assistance by Week 16. Importantly, all patients remained free of immunotherapies, and none required rescue therapy.
Miv-cel was generally well tolerated, with no high-grade cytokine release syndrome or ICANS reported. Based on these results, Kyverna plans to submit a BLA to the U.S. FDA in the first half of 2026.
Beyond KYV-101, Kyverna is advancing multiple first-in class cell therapy programs:
•KYSA-6 is KYV-101 in generalized myasthenia gravis, currently in a registrational Phase 2/3 trial. Interim Phase-2 data showed rapid and sustained reductions in MG-ADL and QMG scores. Updated Phase-2 data are expected in 2026 with Phase-3 enrolment planned by year-end 2025. •KYV-101 in multiple sclerosis- initiated Phase-1 studies, with recently presented data showing CAR T penetration into the CNS and improved disability scores.
•KYV-101 in rheumatoid arthritis- initiated Phase-1/2 study, with recently presented data demonstrating profound reductions in disease-associated autoantibodies and clinical activity in treatment-refractory RA.
•KYV-102, a next generation CD19 CAR T produced via Kyverna's proprietary whole blood rapid manufacturing process. IND filing is expected in the fourth quarter of 2025, designed to broaden access by eliminating apheresis and reducing cost of goods.
The company ended September 30, 2025, with cash and equivalents of $171.1 million, supplemented by an initial $25 million drawn from a $150 million loan facility, providing runway into 2027.
KYTX has traded in the range of $1.78 to $9.75 over the past year. The stock is currently trading in the pre-market at $12.25, up 39.52%, touching a new 52-week high.
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