Ribociclib in HR+/HER2-Advanced or Metastatic Breast Cancer Patients

Objective: To review the chemistry, pharmacology, pharmacokinetics, safety, and efficacy of ribociclib (LEE011, Kisqali) in hormone receptor-positive/human epidermal growth factor receptor-2-negative (HR+/HER2-) metastatic breast cancer. Data Sources: A PubMed search was performed using the terms 'Ribociclib', 'Kisqali', and 'LEE011' between May 2018 and November 2018. References of published articles and reviews were also assessed for additional information. Study Selection and Data Extraction: English-language preclinical and clinical studies on the chemistry, pharmacology, pharmacokinetics, safety, and efficacy of ribociclib were evaluated. Data Synthesis: Ribociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, is Food and Drug Administration (FDA) approved in combination with endocrine therapy for treatment of HR+/HER2- advanced or metastatic breast cancer in premenopausal/perimenopausal and postmenopausal women. Three phase III trials have evaluated ribociclib in combination with endocrine therapy, including letrozole, anastrozole, tamoxifen, and fulvestrant. These studies found that ribociclib 600 mg/d, 21 days on, 7 days off, leads to a significantly greater median progression-free survival (PFS), ranging from 8 to 13 months. Ribociclib is well tolerated in elderly patients, maintains health-related quality of life, and significantly reduces pain scores. The dose-limiting toxicities found in phase I studies were neutropenia, thrombocytopenia, and QTc prolongation. Common adverse effects seen in phase III trials include neutropenia, leukopenia, nausea, diarrhea, vomiting, and fatigue. Relevance to Patient Care and Clinical Practice: Literature on the safety and efficacy of ribociclib as well as its place in therapy in comparison to other FDA-approved CDK4/6 inhibitors for breast cancer is discussed. Conclusions: Ribociclib, when added to endocrine therapy, significantly improves PFS and has manageable toxicity in premenopausal/perimenopausal and postmenopausal women with HR+/HER2- advanced breast cancer.