CYCLIN-DEPENDENT KINASE INHIBITORS - NEW THERAPEUTIC OPTION FOR PATIENTS WITH HORMONE-DEPENDENT HER2-NEGATIVE BREAST CANCER: CLINICAL EXPERIENCE

Background. In the vast majority of patients with suspected metastasis of breast cancer (BC), the luminal type of tumor - hormone sensitive (HR+) with no significant expression of the epidermal growth factor receptor (HER2-) is diagnosed at presentation. The sequential application of various variants of endocrine therapy provides a significant increase in the overall and disease-free survival in such patients, while maintaining a sufficiently high quality of life. Over time, however, the disease progresses due to the development of resistance to the treatment. The appearance of drugs with direct effect on the cell cycle regulators has given rise to a new stage in the treatment of patients with advanced HR+ HER2-BC. Ribociclib (Kisqaly, LEE001) is an oral, highly selective cyclin-dependent kinase inhibitor (CDK4/6), which stops the progression of the cell cycle at the G1/S phase. Description of the clinical case. Postmenopausal woman with BC was diagnosed with generalization of the process with the presence of bone metastases and visceral lesions 3 years after the end of adjuvant therapy with letrozole. In this clinical experience, we confirmed the rapid response to ribociclib therapy in combination with letrozole. A partial response was recorded after 3 months (tumor reduction by 31%) with further reduction of the tumor by 42% after 6 month of treatment. Clinically significant improvement in the quality of life and relief of pain in the bones was noted already at 8th week of therapy. The tolerability of therapy was satisfactory. Conclusion. Oral high selective CDK4/6 inhibitor ribociclib is an excellent therapeutic option for patients with hormone-dependent HER2-negative advanced breast cancer in real clinical practice.

CDK4/6, metastatic hormone-dependent HER2-negative breast cancer, endocrine therapy, cyclin-dependent kinase inhibitors, CDK4/6, ribocyclob