473eP Ethnicity-based comparative analysis of overall survival in 30,000 HR+/HER2- metastatic breast cancer patients treated with CDK4/6 inhibitors (palbociclib, ribociclib, abemaciclib): A real-world meta-analysis

Abstract

Background: Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) with endocrine therapy, are the first-line treatment for hormone receptor-positive, HER2-negative metastatic breast cancer (HR+/HER2-MBC). Yet, ethnically diverse populations remain underrepresented in randomised clinical trials (RCTs) reporting overall survival (OS), limiting ethnicity-specific outcome assessment. This study analyses real-world evidence to evaluate OS across ethnic groups treated with palbociclib, abemaciclib or ribociclib. Method(s): This was conducted in accordance with PRISMA guidelines using MEDLINE and Embase databases. 67, 29 and 20 studies were included for palbociclib, abemaciclib and ribociclib, respectively. Result(s): Palbociclib 23786 patients (Asian (AS): 18124; White (WH): 4581; Black (BL): 347; Mixed Ethnicity (MX): 734; mean age: 57y). Formal meta-analysis of OS was not feasible. Using a random-effects model to account for between-study variability, the median OS was 61.8, 60.5, and 27.1 months for AS, WH and MX patients, respectively. OS data was unavailable for BL patients. Abemaciclib 4715 patients (AS: 2429; WH: 2223; BL: 32; MX: 21; mean age ~62.4y), heterogeneity precluded pooled OS analysis. Median OS was 37.6 months for WH patients and 25.2 months for AS patients. Survival data for BL and MX groups were immature at the time of analysis. Ribociclib 4157 patients (WH: 2189; AS: 1514; BL: 131; MX: 323; mean age: 59.8y) were included. OS data showed maturity across several subgroups. The longest Median OS of 63.9 months was seen in WH patients primarily driven by follow-up results from the MONALEESA trials. Median OS was 58.7 and 36.7 months in AS and BL patients respectively, while OS was not reached for MX patients. Conclusion(s): This real-world meta-analysis provides an evaluation of ethnic variation in OS with CDK4/6 inhibitors in HR+/HER2-MBC. Perpetual heterogeneity suggests that factors beyond ethnicity, such as study design and patient characteristics, influence outcomes. The findings emphasise the need for ethnically diverse populations in studies and improved standardisation of outcome reporting. Legal entity responsible for the study: Olivia Benny. Funding(s): Has not received any funding. Disclosure: All authors have declared no conflicts of interest. Copyright © 2026