Initially, three studies were completed in vitro in a preclinical model of human glioblastoma to demonstrate that engineered PD-1-deficient EGFRvIII CAR T cells (132, 133), or CD133-specific CAR T cells (134) showed similar levels of cytokine secretion and improved proliferation and cytotoxicity in vitro and enhanced tumor growth inhibition in a mouse model of glioma in situ. The gene discussed is PDCD1; the disease is neoplasm.