Cabaletta Bio presents initial dose data from RESET-PV trial of rese-cel

Cabaletta Bio (CABA) presented initial dose data from the RESET-PV trial evaluating rese-cel at 1 x 106 cells/kg without preconditioning in three evaluable patients with pemphigus vulgaris. These data are being presented in a late-breaking clinical oral presentation by Samik Basu, M.D., Chief Scientific Officer at Cabaletta, at the ongoing 2025 European Society of Gene & Cell Therapy Annual Congress, which is being held in Seville, Spain, from October 7-10, 2025. The RESET-PV trial is the first study within Cabaletta’s RESET clinical development program to evaluate rese-cel without the use of cyclophosphamide and fludarabine as preconditioning agents. Because the RESET trials share consistent study design principles, including a single, weight-based dose of rese-cel, there is relevant context to interpret the translational data without preconditioning from the RESET-PV trial. As part of Cabaletta’s innovation strategy, data from this trial will help inform the potential removal of preconditioning in certain trials within the RESET program. In the late-breaking clinical oral presentation, key clinical and translational insights from the follow-up of the patients highlighted as of the data cut-off date of September 11, 2025, include: Rese-cel exhibited similar CAR T cell expansion and contraction kinetics relative to translational data reported from other RESET trials with preconditioning. All three patients experienced substantial depletion of B cells within the first month post-infusion, with patients 2 and 3 achieving complete peripheral B cell depletion. In these two patients, rapid reduction in autoantibodies to desmoglein was observed and the increase in peak B cell activating factor was within the range of patients dosed with rese-cel plus preconditioning from pre-infusion through the latest follow-up, suggestive of deep B cell depletion in the tissue. Rese-cel was generally well tolerated with no immune effector cell-associated neurotoxicity syndrome reported. After infusion, patient 1 experienced transient fever. Patient 2 required a course of steroids for a disease flare in the first two weeks following infusion after discontinuing immunomodulators. This steroid course was less intense than a previous course that was administered for a flare prior to infusion where limited impact on disease was observed. The patient has tapered the steroid dose to below the pre-infusion baseline dose at 3 months post-infusion. Meaningful early clinical responses were observed in all three patients starting in the first month post-infusion based on Pemphigus Disease Area Index score for skin, scalp and mucosal surfaces. From baseline to latest follow-up, PDAI activity scores improved as follows: Patient 1: 24 to 10; Patient 2: 83 to 3; Patient 3: 22 to 2. PDAI activity scores have formed the basis for the most recent regulatory approval in PV. Total PDAI scores were also reported to be consistent with the PDAI activity scores, including improvement in the PDAI damage scores, in the late-breaking clinical oral presentation. PDAI improvements were most significant in the two patients who experienced complete B cell depletion. All three patients remain off immunomodulators as of the data cut-off.