This study is a single-arm open phase II clinical trial. It aims to observe the effectiveness and safety of Sacituzumab Govitecan combined with head radiotherapy in the treatment of Her2-negative breast cancer brain metastases, and to search for a more effective treatment option for Her2-negative breast cancer brain metastases. Patients were treated with Sacituzumab Govitecan 10mg/kg every 21 days as a treatment cycle, which was infused intravenously on day 1 and day 8, and the treatment was continued until the disease progressed or unacceptable toxicity occurred. Radiotherapy was administered after the second infusion of Sacituzumab Govitecan, on day 9 after the start of this regimen. The radiotherapy regimen was: brain metastases at a dose of 60 Gy/20 doses. For lesions located adjacent to the brainstem and optic nerve, 54 Gy/20 doses were given. For patients with ≥5 lesions, whole-brain radiotherapy at 40 Gy/20 doses was synchronized with radiotherapy to localized brain metastases.
