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 infused with CART cells (median 81 days after leukapheresis) and were 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-γ and TNF-α). 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.