Acquired resistance to anti-PD-1 ICI in patients with melanoma has been reported to be associated with defects in the pathways involving interferon-receptor–associated Janus kinase 1 (JAK1) or Janus kinase 2 (JAK2), as well as in the antigen-presenting protein beta-2-microglobulin (B2M) (36). The gene discussed is PDCD1; the disease is melanoma.