Characteristics of premanufacture CD8+T cells determine CAR-T efficacy in patients with diffuse large B-cell lymphoma

In this study, 58 r/r DLBCL patients treated with tandem CD19/CD20 CAR T cells. Twenty-seven patients had durational responses for more than 24 months, and the median PFS was 21.7 months. But 15 patients still did not have an objective response, and 11 patients relapsed within 1 year. The analysis found that CD8+TSCM cells with higher frequency and stronger activation ability in CART products were the key to achieving clinical sustained objective response. Bulk-RNA-seq results confirmed that CD8+CART cells in CR group had higher expression of memory-related genes and transcription factors and lower expression of activation/depletion related genes than those in PD patients. Naive CD8 cells also showed similar differential expression in apheresis. The use of Naive cells as the source cell population for CART preparation could partially improve CART function, but could not completely reverse it. It is suggested that the resistance of DLBCL to tandem CD19/CD20 CAR T cell therapy may be caused by the decreased function and the loss of expression of memory genes of the source Naive T cells. Sequencing samples were collected from 5-6 PD patients with significantly reduced killing efficacy in previous efficacy experiments, and CR patients with disease characteristics similar to Resistant patients. CAR T cell products of these patients were divided into CD8 positive and CD4 positive，apheresis cells from the same patients were divided into Naive CD8 positive T cells, Naive CD4 positive T cells, non-naive CD4 positive T cells, and non-CD8 positive T cells for performed bulk RNA-seq. CR patient: patient who achieved complete remission after TanCAR7 T cell therapy PD patient: patient who had progressive disease after TanCAR7 T cell therapy