CD8+ T Cell–Independent Tumor Regression Induced by Fc-OX40L and Therapeutic Vaccination in a Mouse Model of Glioma

Abstract Despite the growing number of preclinical and clinical trials focused on immunotherapy for the treatment of malignant gliomas, the prognosis for this disease remains grim. Although some promising advances have been made, the immune response stimulated as a result of immunotherapeutic protocols has been inefficient at complete tumor elimination, primarily due to our lack of understanding of the necessary effector functions of the immune system. We previously demonstrated that a tumor lysate vaccine/Fc-OX40L therapy is capable of inducing enhanced survival and tumor elimination in the GL261 mouse glioma model. The following experiments were performed to determine the mechanism(s) of action of this therapy that elicits a potent antitumor immune response. The evidence subsequently outlined indicates a CD8+ T cell–independent and CD4+ T cell–, NK cell–, and B cell–dependent means of prolonged survival. CD8+ T cell–independent tumor clearance is surprising considering the current focus of many cancer immunotherapy protocols. These results provide evidence for CD8+ T cell–independent means of antitumor response and should lead to additional examination of the potential manipulation of this mechanism for future treatment strategies.