Real-world outcomes in patients (pts) with metastatic triple-negative breast cancer (mTNBC) treated with sacituzumab govitecan (SG) in 2L+ in the United States (US).

Abstract

e18879 Background: Pts with mTNBC have poor prognosis and limited treatment options. SG is an anti—Trop-2 antibody-drug conjugate approved in multiple countries for pts with mTNBC who received at least 1 prior systemic therapy and in the US for pts with pretreated HR+/HER2- mBC. In the pivotal phase 3 ASCENT study (NCT02574455), SG demonstrated superior efficacy over single-agent chemotherapy and a manageable safety profile in pts with mTNBCardia A, et al. NEJM. 2021). This study is, to our knowledge, the first to describe real-world treatment patterns and dosing with SG and its impact on clinical outcomes in pts with mTNBC in the US. Methods: This retrospective, observational cohort study used the ConcertAI Patient360™ dataset with additional curated electronic medical record data from the US. Pts (≥18 years) diagnosed with mTNBC as defined according to the current American Society of Clinical Oncology/College of American Pathologists guidelines (HER2 IHC0, 1, or 2/ISH-negative; ER/PR <1%) and initiating treatment with SG (index date) in 2L+ from April 2020 to May 2022 were included. Real-world clinical outcomes with SG and use patterns were assessed. Kaplan-Meier method was used to determine real-world overall survival (rwOS). Results: In total, 230 pts met the eligibility criteria and were included for analysis. All pts were female; 64% were White and 26% Black; median age was 60 years (IQR, 49-69); 71% of pts presented with ECOG performance status ≤1; 71% had visceral metastases and 7% had brain metastases at baseline. The median time from mBC diagnosis to SG treatment initiation was 11.8 months (IQR, 7.6-19.2). Most pts (66%) were treated in a community setting; 34%, 28%, 19%, and 20% of pts were treated with SG in the 2L, 3L, 4L, and 5L+ setting, respectively. Between 2020-2022, there was a trend in the distribution of SG use shifting to earlier line settings, see Table. Median starting dose was 10 mg/kg (IQR, 9.8-10.1). Median follow-up duration was 7.2 months (IQR, 3.9-11.1). Median rwOS (95% CI) from index date was 10 months (8.3-11.1) among all pts. Median rwOS (95% CI) was 13.9 months (9.79-not estimable) and 8.4 months (7.7-10.3) among pts treated with SG in 2L and in 3L+ setting, respectively. Analyses on real-world patterns of SG use are ongoing and additional results will be provided. Conclusions: Pts who were treated with SG in routine clinical practice were older, more ethnically diverse, and presented with worse performance status than pts enrolled in the ASCENT trial but demonstrated a similar survival benefit. The proportion of pts treated with 2L SG increased from 2020 to 2022, reflecting an expected dynamic of post approval drug uptake in routine practice. [Table: see text]