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The combination of hormone therapy and CDK4/6 inhibitors has become the reference treatment for hormone-dependent and HER2-negative metastatic breast cancers without rapidly progressive disease. Numerous phase II and III randomized trials with abemaciclib, palbociclib, and ribociclib have demonstrated a clear benefit in terms of progression-free survival and, in some cases, overall survival, both in first-line treatment and more advanced lines of treatment. Given that 20 to 30 percent of patients treated with hormone therapy alone are likely to subsequently relapse, it was only logical that these treatments should be offered in an adjuvant setting. Clinical trials are ongoing, although a study of patients at high risk of relapse has already produced positive outcomes on relapse-free survival. These results have led the FDA to approve the use of abemaciclib in combination with hormone therapy for this indication.