891 Beta-adrenergic Blockade Licenses the Use of Immunotherapy in Primary and Metastatic Brain Tumors

Abstract Brain tumors present a unique challenge to in the context of immunotherapy, as these patients are immunosuppressed not just at the tumor but also outside the CNS. The systemic immunosuppression observed in brain tumor patients limits the capacity of the immune system to respond to immunotherapy. Brain tumor patients, particularly those with metastatic disease, represent a patient population that is on the rise and in need of targeted treatment approaches. Through this work we present a novel axis of immunosuppression in brain tumor patients and demonstrate that overactive adrenergic signaling is a major barrier to immunotherapeutic success. Our data indicate that combining beta-adrenergic blockade with immunotherapy provides a survival benefit in the setting of brain tumors, where immunotherapy alone has proven ineffective. Using the SEER-Medicaid database, we retrospectively examined outcomes in patients with melanoma and lung adenocarcinoma brain metastasis who received checkpoint blockade therapy alone vs those concurrently on beta-blocker therapy. We found that patients receiving combination therapy showed increased overall survival compared to those receiving checkpoint blockade alone. We then validated these findings in preclinical models of both glioma and melanoma brain metastases, demonstrating that combining immunotherapy and propranolol, a widely-prescribed FDA-approved beta-blocker, extended survival. Moving forward, we suggest that combination therapy with propranolol and immunotherapy, particularly checkpoint blockade, represents a promising translational treatment platform for patients with primary or metastatic intracranial malignancies.