Accumulation of dysfunctional tumor-infiltrating PD-1+ DCs links PD-1/PD-L1 blockade immunotherapeutic response in cervical cancer.

Various predictive biomarkers are needed to select candidates for optimal and individualized treatments. Tumor-infiltrating immune cells have gained increasing interest in cancer research for the prediction of therapeutic response and survival. However, the role of dendritic cells (DCs) in PD-1 blockade immunotherapy remains unclear. In this study, we identified a population of PD-1+ DCs in the tumor microenvironment (TME) of cervical cancer (CC). The accumulation of PD-1+ DCs in cervical tumors was correlated with advanced stages, elevated preoperative squamous cell carcinoma antigen levels and lymph-vascular space invasion. PD-1 expression was induced on activated tumor-associated DCs (TADCs) in vitro compared with their resting counterparts. This PD-1+ DC population was characterized by reduced secretion of cytokines (IL-12, TNF-α, and IL-1β) and dysfunctional induction of T cell proliferation and cytotoxic reaction. PD-1 blockade significantly reinvigorated PD-1+ DCs to release IL-12, TNF-α, and IL-1β compared with PD-1- DCs. TILs from samples with higher PD-1+ DC infiltration could be induced to achieve a greater killing effect of PD-1 blockade treatment. Our findings suggested a role for PD-1+ DCs in immune surveillance dysfunction and CC progression. PD-1+ DC density in the TME may serve as a diagnostic factor for predicting the optimal beneficiaries of PD-1/PD-L1 blockade immunotherapy in CC.