A proof-of-concept study showed that rAAV-mediated interferon β (IFNβ) expression suppressed colorectal cancer cells in a xenograft mouse model.356 In a non-randomized, non-blinded, retrospective human study, the addition of IFNβ to temozolomide therapy extended survival in glioblastoma (GBM) patients.357 Driving expression of IFNβ by rAAV-transduced (rAAV.IFNβ) tumor cells can overcome IFNβ’s short half-life and boost therapeutic efficacy, as evidenced in an invasive orthotopic xenograft GBM mouse model, where intracranial delivery almost doubled overall survival.358. This evidence concerns the gene IFNB1 and glioblastoma.