The Gray Area of Dueling Immunity: Clinical Challenges in Treating Concurrent Multiple Sclerosis and Primary Brain Tumor (P6.127)

Objective: The CNS is a specialized immune compartment noted for decreased expression of MHC molecules, paucity of lymphatic drainage, and low level immune-surveillance by circulating white blood cells. Primary brain tumors drive and thrive in this immunosuppressed microenvironment. In sharp contrast, multiple sclerosis (MS) is characterized by increased CNS circulation of auto-reactive T-cells directed against brain parenchyma. Concurrence of the conditions has been reported since 1938 debating a causal relationship, although rare contiguity is noted between MS and tumor lesions. Background: The significant dueling immune challenges to diagnosis, treatment, and MRI surveillance heightens the intrigue of the microenvironmental balance. Design/Methods: Here, we present a case of 8-years pre-existing untreated MS prior to diagnosis of medulloblastoma in a 43-year-old-male. The patient presented the ED with symptoms reminiscent of MS flare but failed treatment with IV solumedrol prompting brain imaging, revealing right infratentorial mass. The patient was initiated on glatiramer acetate, a lesser immunomodulatory MS therapy, prior to the planned blood-brain-barrier (BBB) compromising tumor treatment course. Results: The patient was CSF negative for dissemination, underwent subtotal resection of medulloblastoma (nodular/desmoplastic, SHH pathway activation, TP53-wildtype), followed by concurrent craniospinal irradiation with 6-weekly cycles of vincristine, and consolidation therapy with 4-monthly cycles of cisplatin/cyclophosphamide. Conclusions: Surveillance with alternating MRI of the CNS-axis demonstrated only mild progression of MS plaques, no recurrence of medulloblastoma, and stable clinical exam noted for moderate chemotherapy-induced peripheral neuropathy 13-months post-operatively. Here we present the first reported case of medulloblastoma concurrent with MS and detail the clinical and ethical challenges that should be considered in these patients. We discuss avoiding severe immunosuppressive therapy which might promote neoplastic progression, recognizing risk for BBB disruption to exacerbate demyelination and keen CNS MRI surveillance for tumor vs plaque stability. Disclosure: Dr. Malik has nothing to disclose. Dr. Kazmi has nothing to disclose. Dr. Vadakara has nothing to disclose. Dr. Mongelluzzo has nothing to disclose. Dr. Gatson has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Novocure (Optune).