460eP Ethnicity-based comparative analysis of progression free 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) combined with endocrine therapy, are the first-line treatment for hormone receptor-positive, HER2-negative metastatic breast cancer (HR+/HER2-MBC), with randomised controlled trials (RCTs) demonstrating improvements in progression-free survival (PFS). However under-representation of ethnically diverse populations in RCTs restricts ethnicity-specific outcome reporting. This systematic review and meta-analysis uses real-world evidence to study PFS with palbociclib, abemaciclib, and ribociclib across ethnic groups. Method(s): This was conducted in accordance with PRISMA guidelines using MEDLINE and Embase databases. 67, 29, and 20 studies were included in this systematic review and meta-analysis 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). PFS could not be meta-analysed due to limted hazard ratio (HR) reporting. Using a random-effects model, the median PFS was 27.7, 22.8, 21.0, and 14.1 months for WH, MX, AS, and BL patients, respectively. Abemaciclib 4715 patients (AS: 2429; WH: 2223; BL: 32; MX: 21; mean age ~62.4y) were included. Median PFS varied substantially across racial subgroups. WH population showed the longest PFS of 21.8 months, with the MX cohort showing the shortest of 6.0 months- reflecting later-line treatment. The median PFS for BL and AS patients was 17.0 and 13.0 months respectively. Ribociclib 4157 patients (WH: 2189; AS: 1514; BL: 131; MX: 323; mean age: 59.8y), were included. The median PFS calculated using a random-effects model was 32.3, 25.2, 24.1, and 10.8 months for the MX, AS, WH, and BL patient subgroups, respectively. Conclusion(s): This real-world meta-analysis demonstrates ethnic variation in PFS among patients with HR+/HER2 MBC treated with CDK4/6 inhibitors. The findings emphasise the need for ethnically diverse populations in studies and improved standardisation of reporting to better define the determinants of treatment response. 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