In the past decade, immune checkpoint blockade (ICB), which targets inhibitory receptors on T cells, including programmed cell death 1 (PD-1) and cytotoxic T lymphocyte–associated protein 4 (CTLA4), has achieved great success in the treatment of melanoma, non–small cell lung cancer, and renal cell carcinoma (5). The gene discussed is PDCD1; the disease is renal cell carcinoma.