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 adults with SPS aged 18–75 and inadequate response to prior immunomodulatory therapy.

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

• All patients discontinued immunotherapies prior to miv-cel infusion and had significant baseline disability.

• Baseline characteristics reflected real-world SPS, with 88% GAD65-positive and 12% glycine receptor-positive.

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

Efficacy results

• The trial met the primary endpoint (Timed 25-Foot Walk, median 46% improvement at week 16, p=0.0002) and all secondary endpoints with high statistical significance.

• 81% of patients achieved at least a 20% improvement in mobility; improvements were seen as early as week 4 and maintained through week 24.

• 67% of patients who required walking aids at baseline no longer needed them at week 16.

• Statistically significant improvements were observed across all secondary endpoints, including disability and SPS-specific symptom scales.

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