While RT dosage and fractioning equivalencies in small animals and humans are not well understood and more research is needed in this area, it would be interesting to combine the two-fractioned radiotherapy with novel IDO1-inhibitors as well as anti-PD-1 treatment in our animal model with fully immunocompetent rats and an infiltrative glioblastoma model, which has not been cultured in vitro for decades. The gene discussed is IDO1; the disease is glioblastoma.