A Canadian real world prospective observational study assessing the impact of hormone therapy ± targeted therapy in the treatment of HR+ HER2- advanced breast cancer

Abstract Purpose: Understanding real-world treatment patterns and their effectiveness in HR+ HER2- advanced breast cancer (aBC) in Canadian patients. Patient and Methods: This was an observational, prospective cohort study including men and pre-/peri-/postmenopausal women with HR+/HER2- aBC receiving endocrine therapy (ET) or ET+ targeted therapy (ET+TT). The primary objective was duration of treatment (DOT) with ET and ET+TT. Sequence of therapies, treatment patterns, and Overall Survival (OS) were also evaluated. Results: DOT was prolonged in patients receiving ET+TT compared to ET (median DOT: ET+TT 397 days vs ET 192 days; Log-Rank test p-value st (ET alone: 43.5% and ET+CDK4/6i: 43.3%) and 2nd line (ET alone: 36.3% and ET+CDK4/6i: 24.6%). Among patients who received at least one CDK4/6i in 1st, 2nd, or 3rd line, CDK4/6i were mostly administered in 1st line (61.9%) and 2nd line (38.5%). ClinicalTrials.gov ID: NCT02753686; Registration Date:20-04-2016 Conclusion: Results support current treatment recommendations of early introduction of CDK4/6i in HR+/HER2- aBC.