CDK4 and pancreatic neoplasm: Of note, the combination of palbociclib and gemcitabine was investigated in the study as mentioned earlier, but the therapeutic efficacy of gemcitabine has been reported to be influenced by tumor immune microenvironment during pancreatic cancer therapy (Halbrook et al., 2019), which further highlights the importance of appropriate models in evaluating the CDK4/6-targeted combinational strategy.