Cabaletta Bio CAR T-Cell Therapy Clears B Cells Without Chemotherapy in Autoimmune Trial

PHILADELPHIA, PA — October 25, 2025 — In early October, Cabaletta Bio reported compelling early data from its Phase 1/2 RESET-PV trial, demonstrating that its autologous CAR T-cell therapy, resecabtagene autoleucel (rese-cel), successfully eliminated overreactive B cells in patients with an autoimmune disease without requiring preconditioning chemotherapy.

The positive results, presented at the 2025 European Society of Gene & Cell Therapy conference, signal a potential path toward a less toxic and burdensome treatment regimen for autoimmune disorders. Following the announcement, Cabaletta’s stock price jumped from $2.40 to $3.25.

Chemotherapy-Free B Cell Depletion

The RESET-PV trial is investigating rese-cel in patients with pemphigus vulgaris (PV), a rare autoimmune disease that causes severe blistering.

• Efficacy: Two of the three patients treated achieved complete depletion of B cells after a single infusion of rese-cel without prior cytotoxic chemotherapy. A third patient saw substantial, though incomplete, B cell depletion.
• Clinical Response: All three patients showed substantial improvements on the Pemphigus Disease Area Index (a measure of disease severity) in the month following treatment.
• Reduced Burden: The three patients are currently off all immunomodulators and are tapering glucocorticoids, suggesting an immune reset effect.

Rese-cel is an autologous CAR T-cell therapy, where a patient’s own T cells are genetically modified to target and eliminate CD19-expressing B cells before being reinfused.

Favorable Tolerability Profile

The treatment was generally well-tolerated. Notably, there were no reported instances of immune effector cell-associated neurotoxicity syndrome (ICANS) in this cohort, a dangerous side effect that had been observed in a patient in a different rese-cel trial earlier this year.

“These data provide preliminary evidence that a single infusion of rese-cel without preconditioning can achieve complete B cell depletion and meaningful early clinical responses with a simplified regimen that can expand access to patients,” said David Chang, M.D., Cabaletta Chief Medical Officer.

Analysts were highly positive, with William Blair analyst Sami Corwin, Ph.D., noting that “The ability to eliminate preconditioning would be a colossal differentiator and would significantly decrease the treatment burden for patients.”

Cabaletta now plans to expand enrollment in the RESET-PV trial, potentially increase the dosage, and pursue chemotherapy-free regimens in its other ongoing autoimmune CAR T trials.