Unmet need for previously untreated metastatic triple-negative breast cancer: a real-world study of patients diagnosed from 2011 to 2022 in the United States

BACKGROUND: This real-world study describes the treatment landscape evolution after targeted therapy approval and associated survival outcomes for previously untreated metastatic triple-negative breast cancer (mTNBC) in the United States. PATIENTS AND METHODS: This retrospective analysis used de-identified electronic health record-derived data of patients diagnosed with mTNBC (January 2011-July 2022; index date was first-line 1L treatment start date). Patient characteristics, treatment patterns, real-world overall survival (rwOS), and time to next treatment or death (TTNTD) were determined. Outcomes before (2011-2017, early cohort) and after (2018-2022, late cohort) targeted therapy approval were evaluated. RESULTS: Among 2004 eligible patients, 21% were classified as Black, 13% had Eastern Cooperative Oncology Group performance status ≥2, and 63% were diagnosed with recurrent disease; median age was 60 years. First-line chemotherapy-only (single- and multiple-agent chemotherapy) use decreased with the introduction of targeted therapies from 96% before 2018 to 65% between 2019 and 2022. From 2019, 33% of patients received programmed death-(ligand) 1 inhibitor-based regimen; ~2% received poly (ADP-ribose) polymerase inhibitors. Median 1L treatment duration was 2.6 months and this did not change over time. Of all 1L patients, 34% died before second-line (2L) and 51% subsequently received 2L treatment. Median (95% CI) 1L rwOS and TTNTD were 11.3 (10.7-12.0) months and 4.3 (4.1-4.6) months, respectively. Median 1L 5-year survival 95% CI showed statistically significant but small improvement from the early (10.9 10.3-11.6 months) to late cohort (11.9 10.7-13.1 months; HR 95% CI, 0.87 0.78-0.96). CONCLUSION: This analysis demonstrated that, despite changes in care over time, survival improvements were not clinically meaningful; thus, a substantial unmet need for more efficacious treatments in previously untreated patients with mTNBC remains.