Implementation of selective cyclin-dependent kinase 4/6 inhibitors (CDK4/6) in a group of metastatic luminal breast cancer patients in the brazilian public health system

Keywords

breast cancer - selective cyclin-dependent kinase 4/6 In - public health system

Introduction: Breast cancer is the most common type of cancer among women in Brazil, second only to non-melanoma skin cancer. In the case of advanced disease, even without a curative perspective, there are treatment options that aim not only to increase survival but also to relieve symptoms and improve or maintain quality of life. It is well established in the literature that patients with advanced disease who have not received prior treatments, express hormonal receptors, and are postmenopausal benefit from the addition of an aromatase inhibitor (AI) with a CDK4/6 inhibitor.

Objectives: To analyze progression-free survival and the safety of using AI combined with ribociclib (a CDK4/6 inhibitor) over 18 months in a group of 25 patients with metastatic luminal breast cancer in the first line of treatment.

Methods: This is an observational, longitudinal, retrospective study designed to evaluate progression-free survival and the safety of using ribociclib combined with AI in hormone receptor-positive, HER2-negative metastatic breast cancer patients in the first line of treatment at a public institution in Belo Horizonte, Minas Gerais, Brazil. Recruitment occurred in 2023, selecting 25 patients who had not been exposed to other systemic treatments in a metastatic setting and who agreed to participate in a partnership with Novartis, which committed to providing ribociclib to the 25 selected patients until disease progression, toxicity, or incorporation of the technology into the public health system. Data were collected anonymously from medical records, following the ethical principles defined by Resolution 196/96 on research involving human subjects in Brazil.

Results: The analysis included 24 female patients and 1 male patient, with a mean age of 56 years. After 18 months of follow-up, 16 patients (64%) continued using the therapeutic strategy, 6 patients (24%) experienced disease progression, and 3 patients (12%) had dose-limiting toxicities. Of the 16 patients currently on ribociclib, 9 (56.25%) are using 600 mg of the drug, and 7 (43.75%) have had dose reductions due to adverse effects, primarily afebrile neutropenia. No hepatic or QT interval toxicities were recorded.

Conclusion: The use of ribociclib combined with AI has proven to be a safe and beneficial therapeutic addition in controlling advanced breast cancer, with data consistent with previous randomized studies in a real-world setting

Corresponding author: Míria Rita Duarte (e-mail: [e-mail]).