CD19 Directed CAR T Therapy for Transformed Follicular Lymphoma: A CIBMTR Analysis

Transformed follicular lymphoma (tFL) is typically associated with chemotherapy resistance and a poor prognosis. There are limited data regarding outcomes after CD19-directed chimeric antigen receptor T-cell (CAR T) therapy in relapsed/refractory (R/R) tFL. A total of 923 adult patients with R/R tFL who received commercial CD19 CAR T therapy between 2017 and 2023 were identified in the Center for International Blood and Marrow Transplant Research registry. Median age was 64 years (range: 30-86) and median prior lines of therapy was 4 (range: 1-18). Most patients (78%) received axicabtagene ciloleucel, with 67% of patients having resistant disease at the time of CAR T infusion. At a median follow-up of 25 months (range: 1-72) from CAR T infusion, the 2-year overall survival (OS) was 57% (95% CI: 53-60) and progression-free survival (PFS) was 43% (95% CI: 40-47). The 2-year cumulative incidences of relapse or progression (rel/prog) and non-relapse mortality (NRM) were 47% (95% CI: 44-51) and 9% (95% CI: 7-11), respectively. The overall response rate to CAR T was 76%, with a complete response rate of 63%. Grade ≥ 3 cytokine release syndrome (CRS) was observed in 7.1% and grade ≥ 3 immune effector cell-associated neurologic syndrome (ICANS) in 21.6% of patients. Multivariable analysis suggested that resistant disease status at the time of CAR T, use of bridging therapy, and high comorbidity index ≥ 3 were associated with inferior PFS and OS. Older age ≥ 60 significantly increased the risk of NRM. Our study suggests that CD19 CAR T is effective and safe for tFL.