Abstract PD13-09: A Real-World Multicenter Study in China: Efficacy and Safety of Sacituzumab Govitecan in Heavily Pretreated HER2-Negative Metastatic Breast Cancer Patients and Brain Metastases

Abstract Background: Sacituzumab govitecan (SG), the first Trop-2-targeting antibody-drug conjugate (ADC), has shown improved PFS and OS in pre-treated mTNBC and HR+/HER2− metastatic breast cancer (MBC) patients in trials like ASCENT and TROPiCS-02. Despite its approval in China, real-world data on SG efficacy and safety in Chinese HER2− MBC patients remain limited. This multicenter study evaluated SG in this population. Methods: Retrospective data were collected from three hospitals on HER2− MBC patients who received SG treatment between June 2023 and December 2024, and completed at least one imaging assessment. Outcomes included real-world progression-free survival (rwPFS), objective response rate (ORR), disease control rate (DCR), real-world overall survival (rwOS), and safety. Results: A total of 58 HER2− metastatic breast cancer patients treated with SG were included, with a median age of 52.5 years. The median number of prior lines of therapy in the metastatic setting was 3 (range: 1-10). SG was administered in the second line for 31% of patients and in the third or later lines for 69%. The cohort included 43 TNBC patients (74.1%) and 15 HR+/HER2− patients (25.9%), with metastatic sites involving the liver (55.2%), bone (53.3%), lung (41.4%), and brain (20.6%). At a median follow-up of 11.0 months, the overall population showed an ORR of 34.5%, a DCR of 81.0%, a median rwOS of 16.32 months, a 6-month rwOS rate of 77.6%, and a median rwPFS of 4.41 months. In mTNBC patients, the ORR was 34.8%, DCR was 79.1%, median rwPFS was 4.97 months, and median rwOS was 16.32 months. In HR+/HER2− patients who received a median of 2 lines of prior endocrine therapy and 2 lines of chemotherapy, the ORR was 33.33%, DCR was 86.6%, median rwPFS was 4.41 months, and median rwOS was not reached. Among 12 patients with baseline brain metastases (11 TNBC, 1 HR+/HER2−BC), including 3 with stable brain metastases without prior radiotherapy, 5 with stable brain metastases post-radiotherapy, and 4 with newly diagnosed active brain metastases without radiotherapy, the ORR was 25%, DCR was 91.6%, median rwPFS was 5.43 months, and median rwOS was 17.50 months. The intracranial objective response rate (icORR) was 41.6%, and the median intracranial PFS (icPFS) was 14.9 months. Two patients received concurrent chemoradiotherapy, with one achieving intracranial complete response (CR) and one intracranial partial response (PR), both remaining free of intracranial progression with icPFS 14.9 months. Safety analysis showed that neutropenia (51.7%) and diarrhea (22.4%) were the most common adverse events (AEs), with grade 3+ incidences of 15.5% and 6.9%, respectively. Febrile neutropenia occurred in 1.7% of patients. Prophylactic granulocyte colony-stimulating factor (G-CSF) was used in 36.2% of patients. Nine patients (15.5%) received long-acting G-CSF as primary prophylaxis, and none of these patients experienced grade 3+ neutropenia. Conclusions: This RWS expands real-world evidence of SG in Chinese advanced TNBC and HR+/HER2− breast cancer, confirming its efficacy and manageable safety. SG showed robust disease control in both subgroups, notably in patients with brain metastases, who showed better outcomes than the overall population, suggesting potential blood-brain barrier permeability of SG. This provides a new therapeutic option for patients with brain metastases lacking effective treatments. Compared with global trials, lower incidences of neutropenia and diarrhea were observed, possibly reflecting improved supportive care, especially that prophylactic G-CSF use clinically reduced the incidence and severity of SG-related neutropenia. Future studies should explore SG plus local therapies for brain metastases and standardized G-CSF prophylaxis to optimize outcomes. Citation Format: X. Liang, S. Guohong, P. Yong, L. Zhijun, L. Huiping. A Real-World Multicenter Study in China: Efficacy and Safety of Sacituzumab Govitecan in Heavily Pretreated HER2-Negative Metastatic Breast Cancer Patients and Brain Metastases abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PD13-09.