Early trials in glioblastoma largely administered systemic or intra-tumoural cytokines, with development limited by significant toxicity with only modest clinical benefit.79,80 Arguably the most promising of these, IFN-γ, possesses anti-proliferative, anti-angiogenic and pro-apoptotic functions and is able to increase antigen presentation through upregulation of MHC Class I and II, as well as mediating immune cell infiltration.81 However, IFN-γ also induces PD-L1 expression as well as promoting T-reg development. The gene discussed is IFNG; the disease is glioblastoma.