CDK4/6 inhibitors are a class of drugs that target particular enzymes, called CDK4 and CDK6. CDK stands for cyclin-dependent kinase, and it is an enzyme that is important for cell division. CDK4/6 inhibitors interrupt signals that stimulate the proliferation of malignant (cancerous) cells.
  Certain cancers, for example, hormone receptor-positive breast cancer, are more likely to have disturbances in CDK4/6, and CDK 4/6 inhibitors may form part of the treatment protocol. Most often, CDK4/6 inhibitors are given synergistically with hormonal therapy (such as an aromatase inhibitor or fulvestrant), although the CDK4/6 inhibitor abemaciclib may be used alone to treat hormone receptor-positive, HER2-negative metastatic breast cancer in pre-treated patients.
  Research suggests CDK4/6 inhibitors may increase the time people have before cancer spreads. More evidence is needed to determine their impact on overall survival.
  Common side effects include fatigue and gastrointestinal dis...