Twelve-Month Follow-Up of Patients With Generalized Myasthenia Gravis Receiving BCMA-Directed mRNA Cell Therapy

We report the 12-month follow-up results of a phase 2 clinical of Descartes-08 ( NCT04146051 ), BCMA-directed RNA chimeric antigen receptor T-cell (rCAR-T) therapy for myasthenia gravis (MG) given as an outpatient treatment without lymphodepletion. In the Phase 2a part of the study, all 7 participants who received six weekly infusions of Descartes-08 exhibited clinically meaningful improvement in common MG severity scales (MG Composite, MG Activities of Daily Living, Quantitative MG scores, and Quality of Life 15-revised) at Month 3. At Month 9 follow-up, all participants continued to experience marked clinical improvements. Five out of seven participants maintained clinical improvement at Month 12. Of the two participants who experienced loss of clinical effect at Month 12 and were eligible for retreatment, one was retreated and had rapid improvement in clinical scores with minimal symptom expression which was ongoing at Month 6 of follow-up. All three participants with detectable anti-acetylcholine receptor (AChR) antibody levels at baseline experienced autoantibody reductions by Month 6, which deepened further by Month 9, and were maintained at Month 12. These data support continued development of Descartes-08 in myasthenia gravis and other autoantibody-associated autoimmune disorders.