CDK4 and Ewing sarcoma: In addition to in brain tumors, preclinical studies have been demonstrated that CDK4/6 inhibitors effectively arrest cell cycle progression and tumor growth in several cancers, including hepatocellular carcinoma [41,42], synovial sarcoma [43], gastric cancers [22], non–small cell lung cancer [44], Ewing’s sarcoma [45], multiple myeloma [20], and aggressive germinal center-derived B-cell lymphoma [46].