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

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