CDK4 and neoplasm: Currently, a number of preclinical and clinical trials for iCPIs across all tumor types coupled with a second immunotherapeutic modality or combined with e.g., chemotherapy, targeted therapies, radiation therapy (RT), epigenetic modulators, inhibitors of histone deacetylases (HDAC), DNA methyltransferases (DNMT), or cyclin-dependent kinases 4 and 6 (CDK4/6), are conducted (13, 15).