Since the first approval of pembrolizumab (Keytruda) for patients with advanced or unresectable melanoma was announced in September 20148; the number of PD‐1/PD‐L1 inhibitors approved by the FDA has increased in recent years and PD‐1/PD‐L1 inhibitors, are being tested in clinical trials to extend their use to other solid tumors.9, 10, 11, 12, 13, 14. The gene discussed is PDCD1; the disease is melanoma.