CMTM4 and neoplasm: Finally, given the reports about decreased tumor PD-L1 expression with CMTM4 deficiency (Burr et al, 2017; Mezzadra et al, 2017), and our result that CMTM4 KD tumor was more sensitive to PD-L1 blockade (Fig. 7D), CMTM4 can also be a predictive biomarker of response to immune checkpoint therapy.