Introduction:Cyclin dependent kinase (CDK) 4/6 inhibitors are oral drugs that include Abemaciclib, Ribociclib and Palbociclib. These drugs target the CDK4/6, that acts as a converging point for different growth proliferation and growth arrest signals in the cell cycle regulation. CDK 4/6 inhibitors block it, to cause cell growth arrest leading to tumor cell death. These drugs are only used for breast cancer that is hormone receptor positive, in association with an endocrine therapy that varies from anti estrogen, aromatase inhibitors and selective estrogen receptor modulator. Common side effects include hematological toxicity, QT elongation for Ribociclib and digestive toxicity for Abemaciclib. Less common side effects include cutaneous toxicity. In fact, vitiligo-like lesions have been described with the use of Ribociclib.