IL13 and glioblastoma: Some trials involved the use of an IL-13 immunotoxin, containing a truncated version of Pseudomonas exotoxin, highly cytotoxic to renal cancer cells and other human solid tumours.17 Indeed, IL-13 immunotoxin has been used in a Phase III clinical trial with glioblastoma patients, showing small but significant effects on survival.18 These IL-13 immunotoxin-based strategies might bind indistinctly IL13Rα2 or IL13Rα1 receptors.