Distinct Cellular and Molecular Patterns in Pretreatment Peripheral Blood Are Associated with CAR T-cell Outcomes in Diffuse Large B-cell Lymphoma

Chimeric antigen receptor (CAR) T-cell therapy has revolutionized the treatment landscape for relapsed/refractory B-cell malignancies. Despite its success, approximately 60% of patients experience treatment failure, underscoring the need to better understand the determinants of response and resistance. We performed single-cell RNA sequencing of pretreatment peripheral blood samples and anti-CD19 CAR T-cell products from 57 diffuse large B-cell lymphomas (DLBCL), correlating molecular and cellular features with clinical outcomes. At the time of leukapheresis, responders presented elevated levels of CD16+ monocytes and CD4+ effector memory T cells. In contrast, nonresponders showed an inflammation-driven gene expression signature across T-cell and myeloid compartments, marked by upregulation of TNFα response signaling pathways. Notably, the presence of malignant or healthy B cells (13 of 57 patients) was strongly associated with a favorable response. These findings shed light on the immune landscape conducive to successful CAR T-cell therapy and offer a molecular framework for developing personalized tools to improve patient selection, stratification, and the design of next-generation CAR T-cell treatments. SIGNIFICANCE: Single-cell analysis of pretreatment peripheral blood from diffuse large B-cell lymphoma identified immune cell populations and genetic signatures correlated with CAR T-cell outcomes, informing patient selection, treatment strategies, and next-generation CAR T development.