Real-world data comparing third and subsequent line regimens for treatment of metastatic triple-negative breast cancer in the United States.

Abstract

e18765 Background: Eribulin is a commonly prescribed regimen for metastatic triple negative breast cancer (mTNBC) patients pre-treated with one or more chemotherapy regimens, although no clear survival benefit has been shown when compared to treatment of physician's choice (TPC) [1]. Here, using real-world oncology data we compare the impact of treatment with Eribulin vs. other common chemotherapies as third and subsequent lines of therapy on overall survival and post-treatment hospitalizations. Methods: We performed a retrospective cohort study of third and subsequent lines (3L+) treatment of patients with mTNBC between 1/2016 and 6/2021 using administrative claims data from the Anthem Cancer Care Quality Program. Real-world overall survival (rwOS) was defined as time from diagnosis to death. Real-world overall survival (rwOS) was defined as time from diagnosis to death. A Cox model with inverse probability of treatment weighting was used to adjust for age, ECOG, socioeconomic status, comorbidity, and liver and bone metastatic sites. Median rwOS was estimated using the weighted Kaplan-Meier method. Adjusted hazard ratios (aHR) were estimated using weighted Cox proportional hazards models. Results: We identified 210 (52%) individuals with mTNBC who received Eribulin (E) for 3L+, compared to 189 patients treated with other chemotherapies (O), which include carboplatin+gemcitabine, nab-paclitaxel, vinorelbine, paclitaxel, carboplatin and nab-paclitaxel+atezolizumab, ordered by frequency. We found no significant difference in any of the demographic and clinical features tested between the groups (Table). Median rwOS in the E group was 6.4 months, compared to 7.6 months in the O group (p-value = 0.4). In adjusted survival analyses to known confounders, E showed no significant difference in mortality (aHR: 1.09, 95% Confidence Interval [CI]: 0.87-1.37, p-value = 0.46). Furthermore, we found no significant difference in hospitalizations following the treatment between the E to the O group (36% vs. 39%, p-value = 0.6), length of stay (7 vs. 8 days, p-value = 0.8) and classes of associated severe adverse events. Conclusions: Our analysis of real-world oncology data aligns with National Institute for Health and Care Excellence (NICE) recent recommendation in showing no survival benefit or reduction in post-treatment adverse events when treating with Eribulin at 3L+ in metastatic TNBC patients.[Table: see text]