BACKGROUND: Glioblastoma is a fatal disease despite aggressive multimodal therapy. PD-1 blockade, a therapy that reinvigorates hypofunctional exhausted CD8 T cells (T
METHODS: Single-cell RNA sequencing was performed on flow sorted tumor-infiltrating lymphocytes from female C57/BL6 mice implanted with each model, with and without PD-1 blockade therapy. CD8
RESULTS: The CD8 T-cell compartment of the models is composed of heterogenous CD8 T
CONCLUSIONS: Here, we describe that dysfunctional CD4 T cells are associated with terminal CD8 T-cell exhaustion, suggesting CD4 T cells impact PD-1 blockade efficacy by controlling the severity of exhaustion. Given that CD4 lymphopenia is frequently observed in patients with glioblastoma, this may represent a basis for resistance to PD-1 blockade. We demonstrate that CD40 agonism may circumvent a dysfunctional CD4 compartment to improve PD-1 blockade responsiveness, supporting a novel synergistic immunotherapeutic approach
