Allogene Therapeutics, Inc. presented long-term follow up data from the Phase 1 ALPHA/ALPHA2 trials of ALLO-501/501A in patients with relapsed/refractory (r/r) large B-cell lymphoma (LBCL) at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois. These data will also be presented in a poster session at the European Hematology Association (EHA) Hybrid Congress on June 9, 2023. The updated analysis of ALPHA/ALPHA2 examined data from 12 CAR T-naïve patients with r/r LBCL who received a single dose of ALLO-501/501A manufactured using the Alloy™ process following a lymphodepletion regimen (FCA90) comprised of fludarabine (30 mg/m2/day x 3 days) and cyclophosphamide (300 mg/m2/day x 3 days) plus ALLO-647 (30 mg/day x 3 days).

The median time from enrollment to the start of therapy was three days and all 12 patients were followed through a minimum of six months (data cutoff April 20, 2023). As of the data cutoff, 7 of 12 (58%) patients achieved a CR and five (42%) maintained a CR through Month 6. Of the five patients who were in CR at 6 months, four (80%) remained in CR. The fifth patient had disease progression at 24 months.

The median duration of response was 23.1 months with three patients remaining in remission for over 24 months and the longest remaining in remission for over 31 months. A safety analysis of 33 CAR T-naïve LBCL patients receiving Alloy™ process ALLO-501/501A product candidates at any dose and lymphodepletion schedule, including the 12 patients treated with the Phase 2 regimen, was also conducted. Treatment was generally well tolerated with no incidences of Grade 3 or greater cytokine release syndrome, and no cases of immune effector cell-associated neurotoxicity syndrome or graft versus host disease.

Cytopenias and infections were manageable and comparable to the experience with autologous CAR T cell therapies in patients with r/r LBCL. The ALPHA/ALPHA2 Phase 1 trials were designed to assess the safety, tolerability, and preliminary efficacy at increasing dose levels of ALLO-501 and ALLO-501A, allogeneic CAR T cell product candidates that target CD19. In addition to exploring cell doses, these studies evaluated various doses of ALLO-647, Allogene's proprietary lymphodepleting antibody designed to prevent premature rejection of AlloCAR T cells.

Allogene is currently enrolling the potentially pivotal Phase 2 ALPHA2 trial of ALLO-501A in LBCL and expects to complete enrollment in the first half of 2024.