Programmed cell death protein-1 (PD-1) checkpoint blockade has emerged as a remarkable immunotherapy in pilot GBM clinical trials, yet the durability of patient remission remains largely unpredictable due to heterogeneous tumor immune microenvironments of GBM patients (Cloughesy et al., 2019; Di Tomaso et al., 2010). The gene discussed is PDCD1; the disease is neoplasm.