The frequency of differentiated CD3+CD27-CD28- T cells predicts response to CART cell therapy in diffuse large B-cell lymphoma.

Background: Chimeric antigen receptor T (CART) cell therapy targeting the B cell specific differentiation antigen CD19 has shown clinical efficacy in a subset of relapsed/refractory (r/r) diffuse large B cell lymphoma (DLBCL) patients. Despite this heterogeneous response, blood pre-infusion biomarkers predicting responsiveness to CART cell therapy are currently understudied. Methods: Blood cell and serum markers, along with clinical data of DLBCL patients who were scheduled for CART cell therapy were evaluated to search for biomarkers predicting CART cell responsiveness. Findings: Compared to healthy controls (n=24), DLBCL patients (n=33) showed significant lymphopenia, due to low CD3⁺CD4⁺ T helper and CD3-CD56⁺ NK cell counts, while cytotoxic CD3⁺CD8⁺ T cell counts were similar. Although lymphopenic, DLBCL patients had significantly more activated HLA-DR⁺ (P=0.005) blood T cells and a higher frequency of differentiated CD3⁺CD27-CD28-(28.7 ± 19.0% versus 6.6 ± 5.8%; P<0.001) T cells. Twenty-six patients were infusedwithCART cells (median 81 days after leukapheresis) andwere analyzed for the overall response (OR) 3 months later. Univariate and multivariate regression analyses showed that low levels of differentiated CD3⁺CD27-CD28-T cells (23.3 ± 19.3% versus 35.1 ± 18.0%) were independently associated with OR. This association was even more pronounced when patients were stratified for complete remission (CR versus non-CR: 13.7 ± 11.7% versus 37.7 ± 17.4%, P=0.001). A cut-off value of ≤ 18% of CD3⁺CD27-CD28-T cells predicted CR at 12 months with high accuracy (P<0.001). In vitro, CD3⁺CD8⁺CD27-CD28-compared to CD3⁺CD8⁺CD27⁺CD28⁺ CART cells displayed similar CD19⁺ target cell-specific cytotoxicity, but were hypoproliferative and produced less cytotoxic cytokines (IFN-g and TNF-a). CD3⁺CD8⁺ T cells outperformed CD3⁺CD4⁺ T cells 3-to 6-fold in terms of their ability to kill CD19⁺ target cells. Interpretation: Low frequency of differentiated CD3⁺CD27-CD28-T cells at leukapheresis represents a novel pre-infusion blood biomarker predicting a favorable response to CART cell treatment in r/r DLBCL patients. [ABSTRACT FROM AUTHOR]