MMDA-18 CLINICAL OUTCOMES WITH SACITUZUMAB GOVITECAN IN BREAST CANCER-ASSOCIATED LEPTOMENINGEAL METASTASIS
Aileen Hsi, Akshara Singareeka Raghavendra, Rashmi Krishna Murthy, Catherine Garcia Stangherlin, Barbara O’BrienAbstract
Background
Treatment options for breast cancer leptomeningeal metastasis (LM), especially in HER2-negative disease, are limited. Sacituzumab govitecan (SG) is active in metastatic breast cancer, but its efficacy in LM is poorly defined. We evaluated outcomes with SG in patients treated after LM diagnosis.
Methods
We retrospectively identified patients with breast cancer LM treated with SG from 2020-2025. Only those who started SG after LM diagnosis were included. Progression-free survival (PFS) was defined from first SG dose to progression or death, overall survival (OS) from first SG dose to death or last follow-up, and survival from the last SG dose was also assessed.
Results
Five patients were included. The median age at LM diagnosis was 55 years. Four of five patients had a KPS 70 or higher, with one not documented. All five had HER2-negative disease and CSF-confirmed LM. Three had brain metastases, and all five had extra-CNS disease at SG initiation. Patients were heavily pretreated (median 3 prior lines; range, 1-4). Prior LM-directed therapies included CNS radiation in five patients (three with proton craniospinal irradiation) and intrathecal therapy in three. Three patients had prior trastuzumab deruxtecan. The median time from LM diagnosis to SG initiation was 9.1 months (range, 1.5-28.4). Median time on SG was 4.6 months (range, 0.9-30.3). Best imaging response was stable disease in four evaluable patients; one had no post-treatment scans. Median PFS was 4.6 months (range, 1.5-27.0), median OS was 7.5 months (range, 1.9-34.9), and median survival from the last SG dose was 3.6 months (range, 1.0-5.2), as estimated by Kaplan-Meier.
Conclusions
SG demonstrated limited clinical activity in breast cancer LM, with disease stabilization in a subset. Outcomes should be interpreted cautiously in this small, heavily pretreated cohort. Prospective studies are needed to better define its role.