IL21 and central nervous system cancer: We observed stronger T-cell reactivity, using IL-2/IL-15/IL-21, defined by IFN-γ production in blood from patients with grade III glioma as compared to blood from patients with grade II glioma (p = 0.045) using a single peptide epitope from survivin that has previously been reported to be immunodominant and to be presented by a broad range of MHC alleles [29] (Supplementary Fig. 4).