Despite a good concordance between these tests [6], PD-L1 expression remains an imperfect biomarker of response to PD-1 blocking immunotherapies, as many patients with PD-L1 expression in the tumor do not respond to treatment while a subset of patients with PD-L1-negative tumors will respond to PD-1 blockade [7,8]. The gene discussed is CD274; the disease is neoplasm.