Metastatic luminal B HER2-negative breast cancer (HR+/HER2- mBC) occupies a leading place in the global structure of morbidity and mortality among women. The current gold standard of first-line treatment is the combination of CDK4/6 inhibitors with aromatase inhibitors, among which ribociclib with letrozole is distinguished. According to the MONALEESA-2 study, the addition of ribociclib to letrozole significantly increased the median overall survival to 63.9 months, reducing the risk of death by 24%. The safety profile of the combination is manageable, and the development of adverse events led to the interruption of therapy only in 7.5% of cases. A study of the actual clinical practice of CompLEEment-1 also confirmed the safety and effectiveness of the combination. Maintaining and improving the quality of life is one of the main tasks in the treatment of patients with HR+/HER2- mBC. According to the MONALEESA-2 study, the addition of ribociclib significantly affects the maintenance of quality of life and leads to a decrease in the intensity of pain syndrome. The published data allowed us to assign a combination of ribociclib and letrozole 4 points on the ESMO-MCBS scale. The safety of long-term use of the combination in the first line of treatment illustrated by clinical observation. The patient's progression-free survival during therapy was 40 months, which significantly exceeds the data of the MONALEESA-2 and CompLEEment-1 studies. The maximum effect (partial response according to RECIST 1.1 -40%) achieved after 24 weeks and persisted for 24 months. Clinically, the patient noted a decrease in the severity of the pain syndrome after 8 weeks of therapy. Against the background of therapy, it was possible to maintain the quality of life without sacrificing antitumor efficacy.

For patients with the metastatic subtype of luminal HER-2-negative (HR+/HER2-) breast cancer (mBC) in the absence of visceral crisis, the gold standard of treatment is a combination of CDK4/6 inhibitors and aromatase inhibitors, regardless of their menopausal status and the sites of metastasis. The effectiveness of this approach was confirmed in the MONARCH, PALOMA, MONALEESA study cycles for the drugs abemaciclib, palbociclib and ribociclib, respectively. Metastasis in the central nervous system (CNS) in breast cancer complicates the treatment of patients and leads to the search for new approaches to the choice of therapy. To date, neurosurgical and radiosurgical techniques are actively used, however, drug therapy still stands for the leading positions. Data on the use of CDK4/6 inhibitors or aromatase inhibitors in patients with CNS metastases are limited. Most studies did not include patients with CNS metastases, only PALOMA-2,3 and MONALEESA-3 studies allowed the inclusion of patients with either “inactive” CNS metastases or after exposure to local treatment methods (for example, radiosurgery, radiotherapy, or surgery). In the study of real clinical practice of combined endocrine therapy with ribociclib (CompLEEment-1) allowed the inclusion of patients with active brain metastases (n = 51), while the subgroup analysis demonstrated the benefits of using a combination of ribociclib and aromatase inhibitors in patients in this difficult clinical situation. In the article, the authors review the available data from randomized clinical trials and real clinical practice, and also illustrate with their own observation.