Abstract
BACKGROUND
Sacituzumab-govitecan (SG) is an antibody drug conjugate (ADC) with activity against breast cancer brain metastases (BCBM). Efficacy and safety information of SG with stereotactic radiosurgery (SRS) is limited. Reports suggest SRS with ADCs may increase risk of symptomatic radiation necrosis (SRN).
METHODS
Patients treated with SG from 2020-2023 were reviewed. Patients had BCBM prior to SG and received SRS for active BM within 6 months of SG. Patients with prior leptomeningeal disease (LMD) were excluded. Kaplan-Meier method was used to estimate overall survival (OS), intracranial PFS (CNS-PFS), extracranial PFS (EC-PFS), local control (LC) and distant intracranial control (DIC). RESULTS: Between 2020-2023, 121 lesions were treated over 25 courses in 14 patients. Median follow up was 28.6 months. Median age was 60 (range 30-72). Five (36%) patients had neurologic symptoms, 7 (50%) were HR+. Eleven (9%) lesions received fractionated SRS (fSRS) and 110 (91%) single-fraction. Median dose for single fraction was 24 Gy (range 16-24), and for fSRS was 27 Gy (range 20-30) in median 5 fractions (range 3-5). Seventy-seven (63%) received SRS concurrent with SG. The median gross tumor volume (GTV) was 0.047 cc (range 0.007-17.4) and median planning target volume (PTV) was 0.14 cc (0.032-30). Six (5%) lesions were treated post-operatively. Median OS was 8.4 months (95% CI 4.2-not reached), with 12-month rate of 48%. Median CNS-PFS was 4.2 months (95% CI 1.9-6.3), with 12-month rate of 11%. Median EC-PFS was 4.4 months (95% CI 1.4-8.1), with 12-month rate of 17%. Twelve-month LC from SRS was 91%. Median DIC from SRS was 4.2 months (95% CI 2.1-7.5) with 12-month DIC rate of 12%. Two patients developed LMD. SRN occurred in 1 lesion, which received SRS prior to SG. CONCLUSIONS: SRS and SG demonstrated excellent local control and no increased risk of RN. Prospective investigation is warranted.