Adicet Bio, Inc. announced positive safety and efficacy data from the Company’s ongoing Phase 1 study of ADI-001 for the potential treatment of relapsed or refractory aggressive B-cell non-Hodgkin's lymphoma. Data highlights as of the May 4, 2023 data-cut date were as follows: Of the 24 efficacy-evaluable patients, 3 received ADI-001 at dose level 1 (DL1) (30 million CAR+ cells), 3 received ADI-001 at dose level 2 (DL2) (100 million CAR+ cells), 6 received ADI-001 at dose level 3 (DL3) (300 million CAR+ cells), 4 received two infusions of ADI-001 at DL3 (two doses of 300 million CAR+ cells, one on day 1 and the second dose on day 7 following a single lymphodepletion), and 8 received ADI-001 at dose level 4 (DL4) (1 billion CAR+ cells). Patients were heavily pretreated with a median of 4 prior lines of therapy (range 2-9), had relatively high tumor burden, and had a poor prognostic outlook based on their median International Prognostic Index (IPI) score.

50% of patients enrolled in the study had progressed on prior CAR T. ADI-001 treatment demonstrated a 71% ORR and 63% CR rate in the study across all dose levels. ADI-001 demonstrated an 83% ORR and 67% CR rate in heavily pre-treated patients (4 median prior lines of therapy) who had progressed on prior CAR T. ADI-001 demonstrated a 6-month CR rate consistent with autologous CAR T when factoring number of prior lines of therapy and percent of patients enrolled in the study who progressed on prior CAR T. Adicet selected the recommended Phase 2 dose (RP2D) as 1 billion CAR positive cells (DL4). At the RP2D (DL4) (with 4 median prior lines of therapy, 38% post-CAR T) the 6-month CR rate was 25%.

At this dose level, in patients who had progressed on prior CAR T, the CR rate was 67% and the 6-month CR rate was 33%. The expansion and persistence of ADI-001 at the RP2D exceed values reported for approved autologous CD19 CAR T cell therapy. DL4 demonstrated a mean Cmax of 483 cells/ul with a mean time-to-peak at approximately day 9 and demonstrated persistence through day 28 with a mean concentration of 21 cells/ul.

ADI-001 was generally well-tolerated in the study and there were no occurrences of dose-limiting toxicities or graft vs host disease (GvHD). Of the 24 patients evaluable for safety, there was 1 report of Grade 3 or higher CRS and 1 report of Grade 3 or higher ICANS. In May, the Company completed a Type B meeting with the FDA and expects to transition the ADI-001 program into a potentially pivotal Phase 2 study in post- CAR T LBCL in the first half of 2024.