TIGIT and PD-1 Mark Intratumoral T Cells with Reduced Effector Function in B-cell Non-Hodgkin Lymphoma.

Checkpoint blockade can reverse T-cell exhaustion and promote antitumor responses. Although blocking the PD-1 pathway has been successful in Hodgkin lymphoma, response rates have been modest in B-cell non-Hodgkin lymphoma (NHL). Coblockade of checkpoint receptors may therefore be necessary to optimize antitumor T-cell responses. Here, characterization of coinhibitory receptor expression in intratumoral T cells from different NHL types identified TIGIT and PD-1 as frequently expressed coinhibitory receptors. Tumors from NHL patients were enriched in CD8+ and CD4+ T effector memory cells that displayed high coexpression of TIGIT and PD-1, and coexpression of these checkpoint receptors identified T cells with reduced production of IFNγ, TNFα, and IL2. The suppressed cytokine production could be improved upon in vitro culture in the absence of ligands. Whereas PD-L1 was expressed by macrophages, the TIGIT ligands CD155 and CD112 were expressed by lymphoma cells in 39% and 50% of DLBCL cases and in some mantle cell lymphoma cases, as well as by endothelium and follicular dendritic cells in all NHLs investigated. Collectively, our results show that TIGIT and PD-1 mark dysfunctional T cells and suggest that TIGIT and PD-1 coblockade should be further explored to elicit potent antitumor responses in patients with NHL. ©2019 American Association for Cancer Research.