Currently, the mainstay of drug treatment for luminal HER2-negative metastatic metastatic breast cancer is endocrine therapy combined with targeting therapy with CDK4/6 tumor enzyme inhibitors. Ribociclib, palbociclib and abemociclib, which are currently registered in the Russian Federation, are widely used in oncological medical organisations. The presented clinical observation demonstrates a case of medical care using ribociclib as therapy for metastatic breast cancer in a female patient with early recurrence. The duration of use of the recommended antitumor drug therapy regimen is conditioned by the high efficacy of the treatment regimen, satisfactory level of drug safety ensuring preservation of the patient’s quality of life, and comfortable way of application.