Ribociclib is another selective CDK4/CDK6 inhibitor, and its safety and efficacy in children was firstly tested in a phase I study including patients with malignant rhabdoid tumors, neuroblastoma, and other solid tumors [119], and subsequently in the arms A and B of the AcSé-ESMART Trial (NCT02813135) in combination with topotecan-temozolomide or everolimus, respectively, in children with advanced malignancies [50]. This evidence concerns the gene CDK4 and neuroblastoma.