Naturally Occurring Canine Glioma as a Model for Novel Therapeutics

Background: Current animal models of glioma are limited to small animal models, which are less predictive of treatment of human disease. Canines often develop gliomas de novo, but the natural history of the disease is not well described. Objective: We provide data for naturally occurring canine gliomas; evaluating medical and surgical therapies. Methods: We reviewed medical records of pet dogs with a presumptive diagnosis of glioma from MRI imaging that underwent surgery as part of the Canine Brain Tumor Clinical Trials Program. Breed, age, sex, median progression-free, and overall survival times and cause of death were recorded for multivariate analysis. Results: Ninety five dogs (56 male; mean age = 8.3 years) were included, but nine were excluded as final pathology was non-neoplastic. Gross total resection was reported in 81 cases based on postoperative MRI. Seventy had high-grade tumors (grade III or IV). Eighty three dogs presented with seizures, being the most common presenting clinical sign. Median survival after surgery was 723 days (95% CI 343-1103) for grade II tumors, 301 days (197-404) for grade III and 200 days (126-274) for grade IV (p = .009 Kaplan-Meier survival analysis; Log Rank test). Age (cox regression, p = .14) or sex (Kaplan-Meier test, p = .22) did not predict survival. Conclusions: This study establishes normative data for a model exploiting dogs with naturally occurring glioma, which can be used to test novel therapies prior to translation to human trials. Further work will focus on the effects of different therapies, including chemotherapy, radiation therapy, and immunotherapy.