Real-world first-line (1L) treatment selection for Australian patients (pts) with hormone receptor-positive advanced breast cancer (HR+ ABC).

Abstract

Background: CDK4/6 inhibitor (CDK4/6i) plus endocrine therapy (ET) is now standard 1L treatment for HR+ ABC. Whilst landmark trials demonstrate improvement in survival outcomes, real world treatment patterns and toxicities are limited. Methods: ARORA, a multi-site Australian registry, captures real-world data on pts with HR+ ABC including baseline characteristics, systemic therapy sequencing and treatment outcomes. Consecutive pts diagnosed between Jan 2020 and Jan 2024 were enrolled. Results: Data from 438 HR+ ABC pts with median follow up of 24.3 months were analysed. Median age was 64 yrs (IQR 54-74), with 64% ECOG 0-1 and 42% Charlson comorbidity index (CCI) 3. 44% of pts had visceral metastases and 19% had bone only metastases at diagnosis. 60% of pts had relapsed disease at a median time of 7.0 yrs (IQR 4.2-10). Of relapsed pts, 10% and 48% received neoadjuvant and adjuvant chemotherapy (CT) respectively, and 79% received adjuvant ET. 41% relapsed on or within 12 months of stopping adjuvant ET. Of the 426 (97%) HR+ ABC pts who received 1L treatment, 77% had CDK4/6i + ET, 14% ET alone, 5% CT and 5% CT then ET +/- CDK 4/6i. CDK4/6i selection was 46% palbociclib (PA), 35% ribociclib (RI), 13% abemaciclib (AB). Compared to pts who received 1L CDK4/6i+ET, pts who received 1L ET alone were older (78.5 vs 63.0 yrs, p