However, recent in vivo studies in mouse models of KRAS-mutant colorectal cancer [7, 8], BRAFV600E-mutant melanoma [9], and triple-negative breast cancer [10] demonstrated that the combination of MEK inhibitors and antibodies targeting PD-1 or PD-L1 resulted in superior anti-tumor efficacy compared to single agents. This evidence concerns the gene PDCD1 and neoplasm.