Abstract PS2-02-29: Real world evidence of systemic therapy in hormone receptor positive advanced breast cancer (HR+ ABC) in Australia - ARORA Registry

Abstract BACKGROUND: The incorporation of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) into first line (1L) systemic treatment for patients with HR+ ABC is now standard practice and leads to improved survival. However, there is a paucity of data on uptake of standard therapies and their associated toxicities in the real-world setting. Here, we present updated results from the ARORA registry. METHODS: ARORA is a secondary data use study of Australian patients aged ≥18 years and diagnosed with HR+ ABC after 1 Jan 2020. Prospective data is captured on patient characteristics, disease course, systemic therapy sequencing and treatment outcomes in routine clinical practice. Database lock for analysis was 19 May 2025. RESULTS: Data was analysed from 457 patients at 17 sites, with a median follow-up of 38.8 months. Median age was 64 years (24% ≥75 years). 65.6% were ECOG 0-1 and 2.8% had a BRCA1/2 pathogenic variant. 44.2% had liver or lung metastases, and 19% had bone-only disease. 60.4% had relapsed metastatic disease. Of these, 9.1% and 46.7% had received neoadjuvant and adjuvant chemotherapy respectively following early stage disease, and 75.2% had received adjuvant endocrine therapy (ET). 44.5% relapsed within 12 months of stopping adjuvant ET. 9 patients (2%) did not receive any systemic therapy for ABC. Of the 448 patients on 1L therapy, 335 (74.8%) received CDK4/6i + ET, 67 (15%) received ET alone and 41 (9.1%) received chemotherapy. Clinician preference for 1L CDK4/6i was palbociclib (32.6%), followed by ribociclib (27.2%) and abemaciclib (11.2%). Patients who received 1L ET alone were older (median 79 vs 63 years, 62.7% vs 18.5% ≥75 years), with poorer performance status (44.8% vs 8.7% ECOG ≥2) and more co-morbidities (29.8% vs 10.5% Charlson index ≥2). Conversely, those who received 1L chemotherapy were younger (median 58 years, 7.3% ≥75 years), with better performance status (46.3% vs 37.9% ECOG 0) and fewer co-morbidities (92.7% vs 88.9% Charlson index