[Initial clinical experience with ribociclib in advanced HR+/HER2- breast cancer in Uruguay].

Background: Ribociclib improves progression-free and overall survival (PFS and OS) in women with advanced HR+/HER2- breast cancer (BC), but real-world evidence in Uruguay is limited. Objective: To describe the clinical characteristics, outcomes, and safety profile of women with advanced HR+/HER2- breast cancer treated with ribociclib plus hormone therapy in Uruguay. Materials and methods: Observational, retrospective study. Demographic and clinical variables, type of hormone therapy, treatment duration, and adverse events were analyzed. Results: A total of 54 patients from public and private institutions were included, with a median age of 60 years. 67% relapsed after adjuvant treatment. Bone was the most common metastatic site (72%). Ribociclib was administered as first-line treatment in 81% of cases, and combined with aromatase inhibitors in 63%. The mean OS was 41.6 months and the mean PFS was 30 months; medians were not reached. Neutropenia was the most frequent adverse event (66%), followed by gastrointestinal toxicity (nausea 33%, diarrhea 28%) and skin toxicity (16%). One death due to pulmonary embolism was recorded, and QTc prolongation was documented in 5.6% of patients. Dose reduction was required in 20%, and one patient discontinued treatment due to skin toxicity. Conclusion: Ribociclib was well tolerated, with a safety profile consistent with the literature. This study provides relevant local evidence and supports its use in real-world settings. Longer follow-up is needed to more accurately assess OS and PFS outcomes.