CMTM6 and gastric cancer: Recent studies confirmed that in a variety of cancers, PD-L1 and CMTM6 are coexpressed, including gastric cancer (Li et al., 2020), liver cancer (Liu et al., 2020a), head and neck squamous cell carcinoma (Chen et al., 2020), and lung cancer (Gao et al., 2019; Koh et al., 2019; Shang et al., 2020; Wang et al., 2020a; Zugazagoitia et al., 2019).