PDCD1 and glioblastoma: A recent clinical study of patients with GBM showed that neoadjuvant PD-1 blockade induced the expansion of TCF7+ progenitor exhausted T cells expressing markers of proliferation and cytolytic activity as well as GZMK+ T cells expressing PDCD1 (PD-1), HAVCR2 (TIM-3), and IFNG suggestive of activation and terminal differentiation with antigen specificity (12).