K. Jhaveri

Pts with HR+/HER2– mBC are typically treated with endocrine-based therapies (ET) until ET resistance develops, at which point Tx options are limited to CT-based regimens, and now antibody-drug conjugates (ADC). This real-world study aims to describe Tx patterns in pts with HR+/HER2– mBC treated with CT before the ADC era. This retrospective, observational study used the ConcertAI Patient360™ dataset of electronic medical record data of pts from the US. Pts (aged ≥18 years old) with HR+/HER2– mBC and initiating their first CT in the metastatic setting from Jan 2011 - Jun 2021 were included. Time to next Tx or death (TTNTD) was calculated for all pts and for pts subsequently treated with a second, third, and fourth CT. Index date was the start date of each CT. Pts (N=1545) included were female (99%) and White (76%); median age was 61 years. Most pts (80%) were treated in a community setting; 41%, 19%, and 18% received their first CT in 1L, 2L, and 3L, respectively. Sixty percent and 44% of pts had prior exposure to ET and CDK4/6i in the metastatic setting, respectively. Majority of pts received CT monotherapy across CT lines. Most used agents across CT lines are shown in the table; capecitabine and paclitaxel were most used in earlier lines of CT. Median TTNTD (95% CI) was 6.5 mo (5.9-7.1) in pts treated with first CT, and 6.4 mo (5.9-7.4), 4.6 mo (4.2-5.2), and 3.9 mo (3.5-4.3) in pts subsequently treated with a second (n=886), third (n=480), and fourth CT (n=260), respectively. In this real-world study, capecitabine and paclitaxel were most commonly used in earlier lines of CT. TTNTD decreased with each subsequent CT received, indicating a high unmet need for more efficacious treatment options for ET-resistant HR+/HER2– mBC.Table: 238PUse of CT agents in pts with HR+/HER2– mBCTreatment type*1st CT N=15452nd CT n=8863rd CT n=4804th CT n=260TaxanesPaclitaxel29%35%25%17%Docetaxel7%5%3%4%AnthracyclinesDoxorubicin11%7%12%11%Epirubicin<1%<1%1%<1%Platinum agentsCisplatin1%1%<1%<1%Carboplatin6%7%8%8%Pyrimidine analoguesCapecitabine45%30%22%16%Gemcitabine8%13%18%22%OtherEribulin3%11%19%20%Vinorelbine1%4%4%11%*The proportion of pts may add up to greater than 100% as the subgroups are not mutually exclusive. CT, chemotherapy; mBC, metastatic breast cancer; pts, patients. Open table in a new tab