“Carry-Over” Effect of CDK4/6 Inhibitors in Adjuvant Therapy for Hormone Receptor (HR)-Positive/HER2-Negative Early Breast Cancer: Clinical Evidence and Molecular Approach

: From a biological perspective, the review proposes that the "carry-over" effect should not be considered a uniform class effect, but rather the result of a sequence of events modulated by pharmacological selectivity (CDK4 vs. CDK6 and additional targets), the induction of cellular senescence, and immunomodulatory effects that could favor the control of micrometastases. In addition, elements that influence interpretation and the need to optimize adherence and toxicity management to "materialize" the benefit in a potentially curable context are discussed.