MMAP-08 CNS METASTATIC PATTERNS IN BREAST CANCER TREATED WITH SACITUZUMAB: PRELIMINARY RESULTS OF A RETROSPECTIVE ANALYSIS

Abstract BACKGROUND Sacituzumab is FDA approved for unresectable locally advanced or metastatic triple-negative or HR-positive/HER2-negative breast cancer in the metastatic setting. Sacituzumab’s ability to prevent or control CNS disease is not yet known. Thus, we investigated the patterns of CNS involvement in conjunction with Sacituzumab use in metastatic breast cancer. METHODS The Johns Hopkins Electronic Medical records from 4/2020-4/2024 were queried utilizing the following criteria: 1) Age ≥18 years; 2) Diagnosis and/or problem list including breast cancer; 3) ≥2 months of documented sacituzumab therapy. Patterns of disease progression, median progression-free (mPFS), and overall survival (mOS) was evaluated. RESULTS Forty-three female patients (49% White, 35% Black, 12% Asian, 2% Hispanic) were identified. Median age was 59 years (range 33-85). Sacituzumab was the median third-line therapy (range 1-10). Median time on sacituzumab was 4.4 months (range 2.1-15.6 [IQR 2.9-6.2]). Seven patients (16%) had preexisting CNS involvement: 5 brain/spine parenchymal, 1 leptomeningeal, and 1 with both. mPFS was 6.6 months (range 3.4-14.5) in the preexisting CNS disease group versus 4.0 months (range 1.3-16.4) in the group without prior CNS involvement (log-rank p=0.13). Visceral progressions were the most common (30; 70%), followed by bone (18; 42%), whereas CNS progression was only observed in 5 (12%). 2 (29%) patients with preexisting CNS disease developed further CNS progression (4.4 and 4.9 months after Sacituzumab commenced). mOS was 13.1 months (range 6.9-23.2) in the preexisting CNS disease group, versus 10.9 months (3.0-26.5) among patients without prior CNS involvement (log-rank p = 0.17). Five (14%) of known causes of death were neurologic. CONCLUSION This is a work-in-progress studying CNS metastatic patterns in metastatic breast cancer treated with Sacituzumab. Relatively low CNS progression rates were observed. Those with CNS involvement did not have shorter survival than those without. A detailed radiographic review of the metastasis cases is pending.