Treatment patterns and clinical outcomes in chemotherapy-treated patients with HR+/HER2− metastatic breast cancer using real-world data in France and Germany

Limited real-world data exist on treatments for hormone receptor-positive/human epidermal growth factor receptor-2 negative (HR + /HER2 −) metastatic breast cancer (mBC) worldwide. We evaluated real-world survival outcomes and treatment patterns for patients with mBC who received chemotherapy (CT) in two European countries. This retrospective cohort study analysed anonymised data from adult patients with HR + /HER2 − mBC, who initiated ≥ 1 CT at any line of therapy (LoT) on/after their diagnosis, from one site in France and two in Germany, between 01/01/2016 and 28/02/2023. Primary outcomes were overall survival (OS) and time to next treatment or death (TTNTD) by CT line. Additionally, treatment patterns were reported. The study evaluated data for 339 French and 157 German patients; median (interquartile range [IQR]) age at first CT: 62 (51–71) years (France), 57 (49–67) years (Germany). In France, the median (IQR) OS and TTNTD at first CT were 20 (8–40) and 5 (3–7) months, decreasing to 7 (3–15) and 3 (2–5) months at fourth line, respectively. In Germany, these outcomes were 24 (9–NA) and 6 (3–9) months at first CT, decreasing to 7 (2–NA) and 3 (1–8) months by fourth line, respectively. In France, 91% of patients received a second LoT, 71% a third, and 53% a fourth. The most frequent first LoT was CT only (45%), followed by endocrine therapy (ET) + cyclin dependent kinase 4/6 inhibitors (CDK4/6i; 32%). In Germany, 90% of patients received a second LoT, 71% a third, and 48% a fourth, with the most common first LoT being ET + CDK4/6i (34%), followed by other regimens (29%) and CT only (24%). Prognosis in patients with HR + /HER2 − mBC receiving CT treatment remains poor, with a median OS < 2 years. Patients typically receive CT as first-line therapy with ET and CDK4/6i received in subsequent treatment lines.