Mivocabtagene Autoleucel Shows Durable 1-year Benefit in SPS, gMG

According to a new announcement, Kyverna Therapeutics reported positive one-year data from the KYSA-8 trial (NCT06588491) of mivocabtagene autoleucel (miv-cel; KYV-101; Kyverna Therapeutics) in stiff person syndrome (SPS) and updated longer-term data from the KYSA-6 trial (NCT06193889) in generalized myasthenia gravis (gMG).¹ In the 26-patient KYSA-8 cohort, median improvement in the Timed 25-Foot Walk (T25FW) reached 49% at month 12, compared with 46% at week 16 (P <.0001).¹ All seven patients treated in the KYSA-6 phase 2 cohort achieved clinically meaningful improvement in MG-ADL and QMG scores at week 24.¹

Miv-cel is a fully human, autologous CD19-directed CAR T-cell therapy incorporating CD28 co-stimulation, one of three Kyverna programs across autoimmune neurologic disease holding FDA Regenerative Medicine Advanced Therapy designation, alongside gMG and non-active secondary progressive multiple sclerosis (naSPMS). No FDA-approved therapy currently exists for SPS, a rare, progressive autoimmune disorder in which up to 80% of patients develop mobility loss. Kyverna has treated more than 100 patients across its autoimmune disease programs using a validated, established manufacturing process.¹

"After a single dose of miv-cel, the sustained improvements observed in mobility, stiffness and other disease-specific measures, together with a well-tolerated profile, underscore its potential to deliver significant, long-lasting benefit to patients with SPS," Amanda Piquet, MD, FAAN, director of autoimmune neurology at the University of Colorado Anschutz School of Medicine and lead investigator of the KYSA-8 trial, said in a statement.¹

Miv-cel sustains motor function gains in stiff person syndrome at 1 year

KYSA-8 is a single-arm, open-label, phase 2 registrational trial enrolling patients with treatment-refractory SPS who received a single infusion of miv-cel following lymphodepletion.² Among the 26 patients evaluated at 12 months, median improvement on the T25FW reached 49%, compared with 46% at week 16, with the effect reaching statistical significance (P <.0001).¹

A total of 95% of patients sustained a clinically meaningful improvement, defined as a reduction of more than 20% from baseline, and one-third completed the T25FW in under 5 seconds.¹ Of the 12 patients who required a walking aid before treatment, 67% no longer needed assistance at the latest follow-up.¹ In total, 92% of patients remained free of chronic immunotherapies through the one-year assessment, consistent with a durable, single-dose treatment effect rather than ongoing immunosuppression.¹

Miv-cel produces meaningful gMG improvement without high-grade CRS or ICANS

In the seven-patient KYSA-6 phase 2 cohort (NCT06193889), all patients achieved clinically meaningful improvement in MG-ADL and QMG scores at week 24, with mean reductions of 8.3 and 11.7 points, respectively.³ Improvement was maintained through 1 year or longer among the five patients who reached this follow-up point, and 57% maintained minimal symptom expression, defined as an MG-ADL score of 0 to 1.¹

All seven patients remained free of immunotherapies at week 24, and 86% (6 of 7) remained off immunosuppressants at the most recent follow-up.¹ Across both trials, no high-grade cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome, or immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome occurred, with miv-cel well tolerated through 1 year of follow-up.¹

"In SPS, we continue to see powerful evidence that a single dose of miv-cel has the potential to reset the immune system, reverse disease progression, and free patients from chronic immunotherapies, delivering sustained clinical benefit and a well-tolerated safety profile," said Naji Gehchan, MD, chief medical and development officer of Kyverna.¹

Kyverna is advancing miv-cel across three FDA RMAT-designated indications, including naSPMS, positioning the CD19 CAR T platform within a broader field of autoimmune cell therapies now progressing through registrational study. Phase 3 KYSA-6 enrollment is expected to complete in mid-2027, and the company's rolling BLA submission covering SPS remains on track for completion in the fourth quarter of 2026.¹

REFERENCES:

1. Kyverna Therapeutics reports positive one-year data further demonstrating best-in-class potential of miv-cel in stiff person syndrome and generalized myasthenia gravis. News release. Kyverna Therapeutics. September 24, 2026. Accessed September 24, 2026. https://ir.kyvernatx.com/news-releases/news-release-details/kyverna-therapeutics-reports-positive-one-year-data

2. A study of anti-CD19 chimeric antigen receptor T-cell (CD19 CAR T) therapy in subjects with treatment refractory stiff person syndrome (KYSA-8). ClinicalTrials.gov identifier: NCT06588491. Accessed September 24, 2026. https://clinicaltrials.gov/study/NCT06588491

3. A study of anti-CD19 chimeric antigen receptor T-cell therapy in patients with generalized myasthenia gravis (KYSA-6). ClinicalTrials.gov identifier: NCT06193889. Accessed September 24, 2026. https://clinicaltrials.gov/study/NCT06193889