EXTH-01. INTRATHECAL DELIVERY OF DENDRITIC CELL VACCINE ERADICATES TUMOR GROWTH AND PROTECTS AGAINST LEPTOMENINGEAL DISEASE RE-INOCULATION IN HER2+ AND TRIPLE NEGATIVE BREAST CANCER LMD XENOGRAFT MODELS

Abstract BACKGROUND Leptomeningeal disease (LMD) occurs in approximately 5% of patients with breast cancer and has a median survival 2-4 months. We found loss the anti-HER2 anti-HER3 CD4 Th1 immune responses patients. In pre-clinical clinical trials, administration class II HER2 peptide-pulsed dendritic cell vaccine (HER2-DCV) partially restores pathologic complete HER2+ Here, we examined intrathecal (IT) delivery HER2/HER3-DCV cancer-associated LMD immunocompetent animal models. METHODS Luciferase-labeled TUBO cells were injected into cisterna magna BALB/c mice to produce LMD. used our Murine Ommaya (mimics an reservoir patients) for IT DCVs CSF. RESULTS AND DISCUSSION cancer-LMD randomized following groups: 1) HER2-DCV 2) HER3-DCV 3) IT. The untreated (control) group was 15 days. All groups given DCV prolonged (p< 0.001). Interestingly, HER2-/HER3-DCV able rescue (71% 28% triple negative cancer-LMD) showed tumor regression. Some surviving subsequent rechallenge. CSF, evidence CD4+ CD8+ T-cells infiltration, robust IFN-g IL18 response upon treatment. CONCLUSIONS Our preclinical data supported trial (submitted)