Risk factors for CAR‐T cell manufacturing failure among DLBCL patients: A nationwide survey in Japan

Summary For successful chimeric antigen receptor T (CAR‐T) cell therapy, CAR‐T cells must be manufactured without failure caused by suboptimal expansion. In order to determine risk factors for CAR‐T cell manufacturing failure, we performed a nationwide cohort study in Japan and analysed patients with diffuse large B‐cell lymphoma (DLBCL) who underwent tisagenlecleucel production. We compared clinical factors between 30 cases that failed (7.4%) with those that succeeded ( n = 378). Among the failures, the proportion of patients previously treated with bendamustine (43.3% vs. 14.8%; p < 0.001) was significantly higher, and their platelet counts (12.0 vs. 17.0 × 10 4 /μL; p = 0.01) and CD4/CD8 T‐cell ratio (0.30 vs. 0.56; p < 0.01) in peripheral blood at apheresis were significantly lower than in the successful group. Multivariate analysis revealed that repeated bendamustine use with short washout periods prior to apheresis (odds ratio [OR], 5.52; p = 0.013 for ≥6 cycles with washout period of 3–24 months; OR, 57.09; p = 0.005 for ≥3 cycles with washout period of <3 months), low platelet counts (OR, 0.495 per 10 5 /μL; p = 0.022) or low CD4/CD8 ratios (<one third) (OR, 3.249; p = 0.011) in peripheral blood at apheresis increased the risk of manufacturing failure. Manufacturing failure remains an obstacle to CAR‐T cell therapy for DLBCL patients. Avoiding risk factors, such as repeated bendamustine administration without sufficient washout, and risk‐adapted strategies may help to optimize CAR‐T cell therapy for DLBCL patients.