233P Treatment pattern and outcomes for the first two lines of chemotherapy in patients diagnosed with metastatic triple-negative breast cancer, results from the Dutch SONABRE Registry

Abstract

We assessed the use and outcomes of first- and second-line chemotherapy in patients diagnosed with metastatic triple-negative breast cancer (mTNBC). All consecutively diagnosed patients with mTNBC in 2014-2020 in ten Dutch hospitals were retrieved from the SONABRE registry (NCT-03577197). Last follow-up was collected in 2022. The proportion of patients starting a specific line of therapy was assessed using the competing risk method. Median progression-free survival (PFS) and overall survival (OS) were calculated from start of chemotherapy using the Kaplan-Meier method. Of the 386 patients diagnosed with mTNBC, 72% started a first-line and 38% a second-line of chemotherapy. At start of first- and second-line chemotherapy, 29% and 25% had de novo mTNBC, 49% and 57% bone metastases, 66% and 71% visceral metastases and 9% and 15% central nervous system metastases. First- and second-line chemotherapy included capecitabine in respectively 32% and 34%, taxanes in 25% and 27%, other single-agent chemotherapy in 6% and 17%, an AC-containing regimens in 14% and 5% and other combination-chemotherapy in 23% and 17% of patients. Median PFS and OS were 5.9 and 11.7 months from starting first-line and 3.8 and 8.7 months from starting second-line chemotherapy. In real-world clinical practice, first- and second-line chemotherapy for mTNBC included most often the single-agent chemotherapies capecitabine and taxanes. The prognosis of patients with mTNBC is poor, with a median survival of less than a year from start of first-line chemotherapy.