Although PD-L1 expression, measured by immunohistochemistry, is an accepted and relevant biomarker of response to checkpoint inhibitors, it has been found to be unreliable in some cases [19] It is plausible that the patient’s metastasis may have contained heterogeneous tumor tissue, or the protein’s expression may have been downregulated, which can explain the efficacy of atezolizumab despite the observed PD-L1 negativity in the tumor sample. The gene discussed is CD274; the disease is neoplasm.