213P Real-world clinical outcomes associated with first-line palbociclib and aromatase inhibitor therapy among patients with HR+/HER2- advanced breast cancer in Europe

Palbociclib (PB), a cyclin-dependent kinase 4/6 inhibitor, has become a standard of care in HR+/HER2- advanced/metastatic breast cancer (ABC) in Europe since EMA approval in 2016. This study examines clinical characteristics and outcomes in ABC patients treated with PB and an aromatase inhibitor (AI) in routine clinical practice in Europe. A multicenter retrospective medical record review collected data on adult patients with HR+/HER2- ABC in Europe who received first-line PB+AI between September 2016 and July 2020. Sites screened all patients who received PB+AI during the study time frame and abstracted data for patients who met all eligibility criteria. We report here results from Germany, Spain and the UK; data from 4 additional European countries will be reported when data collection is complete. Study measures were descriptively analyzed, with the Kaplan-Meier method used to estimate real-world progression-free survival (rwPFS). Data were abstracted and analyzed for 668 patients from 47 sites. Median age at ABC diagnosis was 64.4 years (33.8% ≥70 yo), 99.6% were female, 82.9% were white, and median follow-up was 32.7 months. Of females (665), 14.1% were premenopausal at first-line PB+AI initiation. 38.5% of patients had de novo disease. At ABC diagnosis, 24.9% had bone only disease and 46.7% had visceral disease (Table). Objective response and clinical benefit rate were 35.8% and 80.7%, respectively. The median rwPFS (95% CI) was estimated to be 31.8 (27.7-35.4) months (Table). Table: 213PN%Total number of patients668100.0Age (years) at ABC diagnosis<5010115.150-6934151.1≥7022633.8Clinical stage at initial BC diagnosisStage I–III (resectable)38056.9Stage III–unresectable182.7Stage IV23935.8Unknown314.6Disease-free intervalDe novo25738.5≤12 months15222.8>12 months22133.1Unknown385.7Performance status at first-line016124.1117626.3≥2588.7Not recorded27340.9Objective response rate23935.8rwPFS, Kaplan–Meier estimateMonths (95% CI)Median31.8 (27.7-35.4)rwPFS rate% (95% CI)12 months77.2(73.8-80.3)24 months59.5(55.5-63.2)36 months45.2(41.0-49.4) Open table in a new tab This real-world study affirms the favorable clinical outcomes demonstrated for first-line PB+AI in the previous clinical trials and supports its utilization as frontline treatment for this patient population. This study presents pooled analysis of 3 European countries and variability in practice patterns and disease management may exist among countries.