Immune checkpoint inhibitors, such as the anti-cytotoxic T lymphocyte-associated protein 4 (CTLA-4) mAb ipilimumab (Bristol-Meyers Squibb) and the anti-programmed cell death protein 1 (PD1) mAbs nivolumab (Bristol-Meyers Squibb) and tremelimumab (Pfizer) remain in clinical trials for treatment of CRC (NCT02060188, NCT01975831, NCT02754856). The gene discussed is PDCD1; the disease is colorectal carcinoma.