Antibody-based therapy against PD-1 (e.g., pembrolizumab, nivolumab, sintilimab) and PD-L1 (e.g., atezolizumab, avelumab, durvalumab) now represents part of standard care in the oncology clinic, though response rates vary across cancer types and the ideal biomarker to guide precision therapy is still lacking. The gene discussed is CD274; the disease is cancer.