CD4 and glioblastoma: A phase I clinical study conducted in Japan indicated that WT1 peptide vaccine induced WT1-specific CD8+ T cells and CD4+ T cells and was tolerable in patients with WT1+ malignant glioma (9), and the phase II clinical trial further showed WT1 peptide vaccine was safe and produced a clinical response in patients with WT1/HLA-A*2402+ recurrent glioblastoma multiforme (10).