CDK4 and breast cancer: The upcoming protocol at Brown University Oncology Group and Lifespan Cancer Institute that has been under development as a result of this research is entitled "BrUOG 387: Phase Ib investigator-initiated trial of heat shock protein 90 inhibitor TAS-116 (pimitespib) combined with cyclin-dependent kinase 4/6 inhibitor palbociclib in advanced breast cancer progressing on palbociclib and treatment-refractory solid tumors with retinoblastoma (Rb) deficiency".