Real-world treatment patterns and clinical outcomes among patients with HR+/HER2- advanced/metastatic breast cancer receiving palbociclib in Brazil: IRIS study.

e13088 Background: Palbociclib was approved for hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) advanced/metastatic breast cancer (aBC/mBC) in Brazil in 2018. Worldwide studies explore palbociclib's real-world use and outcomes; however, this data is not available for Brazilian patients. IRIS Brazil study aimed to describe demographic/clinical characteristics, treatment and clinical outcomes of adult female patients who have received palbociclib as first-line treatment for HR+/HER2- aBC/mBC in private healthcare institutions in Brazil. Methods: This retrospective descriptive study included females aged 18 years or older diagnosed with HR+/HER2- aBC/mBC and those who had received palbociclib as their initial line of therapy. The study analyzed variables such as demographics, clinical characteristics, treatment history, palbociclib combinations, and clinical outcomes. Progression-free survival (PFS) and overall survival (OS) were calculated using Kaplan-Meier estimates at 6- and 12-month time points. Results: A total of 121 patients were included in the study. The mean age was 54.4 years, and 82 (67.7%) were menopausal at diagnosis. A total of 51 patients (42.1%) were treated with palbociclib + fulvestrant, while 67 (55.8%) were treated with palbociclib + aromatase inhibitors. The majority of patients (n = 79; 65.3%) did not require any dose adjustments. Among the 40 patients (33.1%) who required dose adjustments, the main reason was adverse events/toxicity (n = 36; 90%). The PFS rates at 6 and 12 months were 78% and 60%, respectively. The OS rates at 6 and 12 months were 86% and 70%, respectively. Conclusions: Results from this initial real-world assessment of clinical outcomes in Brazil suggest that Palbociclib combinations exhibit favorable effectiveness in treating HR+/HER2- aBC/mBC disease, as measured by PFS and OS rates.