Study of Sacituzumab Govitecan With Atropine to Improve Tolerability in Advanced TNBC and HR+/HER2- Breast Cancer

After signing the informed consent form (ICF) and confirmation of eligibility, participants with mTNBC or mHR(+)/HER2(-) breast cancer will receive sacituzumab govitecan administered as intravenous infusion (IV) at dose of 10 mg/kg on D1 and D8 of each 21-day cycle until unacceptable toxicity, disease progression, withdrawal of consent, death, or study termination, whichever occurs first. Atropine will be administered 0.5 mg SC as premedication 10 minutes before each infusion of sacituzumab govitecan on D1 and D8 of each 21-day cycle during the first two treatment cycles (consider extending to the next cycles at the discretion of the physician). To improve hematologic tolerability, G-CSF will be used as a supportive medication during the first 2 cycles of sacituzumab govitecan. The use of G-CSF beyond the second treatment cycle will be at the discretion of the Investigator.