258P Real-world (rw) outcomes in patients (pts) with hormone receptor-positive and human epidermal growth factor receptor-2-negative (HR+/HER2-) metastatic breast cancer (mBC) treated with chemotherapy (CT) in France

This is the authors' abstract. We don't add key points for this paper.

Endocrine therapy (ET) combined with CDK4/6 inhibitors (CDK4/6i) is the standard of care for HR+/HER2- mBC pts. However, efficacy is limited due to acquired ET resistance, after which treatment options are limited to CT and, more recently, antibody-drug conjugates. This rw study describes patient characteristics, treatment patterns and survival outcomes in HR+/HER2- mBC pts initiating at least first (1st)CT in France and Germany. This is an interim analysis of adults with HR+/HER2- mBC initiating CT (Jan 2016 - Feb 2023) for mBC at the Institut de Cancérologie de l'Ouest in France. Germany data will be assessed in the final analyses. Demographics, clinical characteristics, and treatments were described using descriptive statistics. Kaplan-Meier method was used to describe rw overall survival (OS) for 1st to 4th CT line, separately, from each line start. 339 pts were analysed: 99% were female, 28% had de novo mBC, with median age of 62 years at 1st CT. Prior to 1st CT start, 43% received CDK4/6i and 52% ET for mBC. 61%, 39% and 24% had records of subsequent second, 3rd and 4th CT line, respectively. Most pts received CT as monotherapy: paclitaxel and capecitabine were the most used agents followed by eribulin and cyclophosphamide. Median rwOS was 19.9, 12.3, 8.1 and 7.2 months (mo) from 1st, 2nd, 3rd and 4th CT line, respectively (Table).Table: 258PrwOS by CT line1st CT2nd CT3rd CT4th CTN Pts33920713283N Deaths24115110259Median rwOS in moInterquartile range19.9 (8.0-38.7)12.3 (5.7-24.1)8.1 (4.3-18.5)7.2 (2.9-15.1)6 moN2681448139Survival[95% Confidence interval (CI)]80% [75-84]73% [67-79]66% [58-74]55% [45-68]12 moN206923719Survival[95% CI]63% [58-68]50% [44-58]35% [27-45]34% [24-47]18 moN1644923-Survival[95% CI]54% [49-60]33% [27-41]26% [19-35]24 moN11233--Survival[95% CI]42% [36-47]25% [19-33]32 moN5311--Survival[95% CI]26% [22-32]15% [10-23] Open table in a new tab HR+/HER2- mBC pts initiating CT in France showed poor survival, decreasing with each subsequent CT line. There is still a high unmet need for improved treatment options in this population.