Additionally, the advent of novel agents, including phosphatidylinositol-3-kinase (PI3K)/Akt and mammalian target of rapamycin (mTOR) pathway inhibitors (buparlisib, everolimus, and pictilisib), CDK4/6 inhibitors (palbociclib, ribociclib and abemaciclib), antibody-drug conjugates (trastuzumab-deruxtecan), and immune checkpoint inhibitors (pembrolizumab) have revolutionized the BC treatment landscape [7–11]. This evidence concerns the gene CDK4 and breast cancer.