Cabaletta Bio, Inc. reported positive initial clinical data from each of the first two patients dosed with CABA-201 in the Phase 1/2 RESET-Myositis and RESET-SLE trials. Cabaletta designed CABA-201, a 4-1BB-containing fully human CD19-CAR T cell investigational therapy, to deeply and transiently deplete CD19-positive B cells following a one-time infusion that may enable a reset of the immune system with the potential for durable remission without chronic therapy in patients with autoimmune diseases. Cabaletta is advancing four Phase 1/2 RESET trials evaluating CABA-201 within a total of ten cohorts with six patients in each cohort.

All cohorts are evaluating the same single, weight-based dose of 1 x 106 cells/kg, following a preconditioning regimen of fludarabine and cyclophosphamide consistent with the dosing regimen used in the academic experience, without a dose escalation requirement. As of May 28, 2024, the data cut-off date, one patient treated in the immune-mediated necrotizing myopathy (IMNM) cohort in the RESET-Myositis trial had completed three months of follow-up and one patient enrolled in the systemic lupus erythematosus (SLE) non-renal cohort in the RESET-SLE trial had completed one month of follow-up. The patient with IMNM is a 33-year-old male with a two-year history of disease, positive for anti-SRP antibody and who had prior disease-specific therapy that included IVIg, rituximab, methotrexate and glucocorticoids.

The patient with SLE is a 26-year-old male with a six-year history of disease, positive for anti-dsDNA antibody and who had prior disease specific therapy that included cyclophosphamide, voclosporin, belimumab, tacrolimus, mycophenolate mofetil, hydroxychloroquine and glucocorticoids. Both patients were administered a one-time infusion of CABA-201 at 1 x 106 cells/kg, following a preconditioning regimen of fludarabine and cyclophosphamide. The primary endpoint of each trial is safety and tolerability within 28 days of infusion.

Secondary endpoints include translational assessments and clinical outcomes.