Kyverna Therapeutics (KYTX) Study Result summary

Disease background and unmet need

• Stiff person syndrome (SPS) is a severe, progressive autoimmune disease with no FDA-approved therapies, leading to significant disability and high unmet medical need.

• 80% of SPS patients lose mobility and require walking aids or wheelchairs.

• Off-label treatments are commonly used but fail most patients and carry serious safety risks.

Study design and patient population

• KYSA-8 is a single-arm, multicenter, open-label phase II registrational trial enrolling 26 SPS patients aged 18–75 with inadequate response to prior immunomodulatory therapy.

• All patients had confirmed SPS, significant baseline disability, prior exposure to immunomodulatory therapies, and discontinued immunotherapies before a single miv-cel infusion.

• Patients received lymphodepletion followed by a single infusion of miv-cel at a target dose of 1 × 10^8 CAR T cells.

• The trial received Orphan Drug and RMAT designations, supporting a rapid path to BLA submission.

Efficacy results

• The trial met primary and all secondary endpoints with high statistical significance, including a 46% median improvement in the Timed 25-Foot Walk test at week 16 (p=0.0002), far exceeding the 20% threshold for clinical significance.

• 81% of patients achieved clinically meaningful improvement in mobility, and 67% of those using walking aids at baseline no longer needed them at week 16.

• Statistically significant improvements were observed across all secondary endpoints, including mRS, HAI, DSI, and HSS (all p-values < 0.0001).

• All patients remained free of immunotherapies through last follow-up, with no need for rescue therapy.