Robust CAR T-cell expansion and superior outcomes in DLBCL patients in complete response at infusion

Historically, the presence of measurable disease has been considered essential to stimulate CAR T-cell expansion and persistence. However, the kinetics of CAR T cells in patients achieving complete response (CR) before infusion remain poorly understood. This study aimed to evaluate the outcomes and CAR T-cell kinetics in relapsed/refractory diffuse large B-cell lymphoma (DLBCL) patients stratified by pre-infusion disease status. In this retrospective analysis of 87 patients treated at a single institution, 23 (26.4%) were in CR and 64 (73.6%) were in non-CR prior to CAR T-cell infusion. Patients in CR exhibited significantly better progression-free survival (PFS) and overall survival compared to non-CR patients. Peripheral blood CAR T-cell kinetics, including the proportion and absolute counts of CAR T cells, CD4+ CAR T cells and CD8+ CART cells, showed no significant differences between CR and non-CR groups. These findings were consistent across different CAR T-cell products, whether 4-1BB- or CD28-based. Moreover, an analysis of patients achieving complete metabolic response (CMR) by PET-CT confirmed comparable CAR T-cell expansion and persistence in both CMR and non-CMR patients. Our findings demonstrate that CAR T-cell therapy achieves robust expansion and favourable survival outcomes in CR patients, even in the absence of measurable disease.