Pertaining to the clinical testing of cell-free, neoepitope-based peptide vaccines, Keskin and colleagues recently reported a phase 1b PCV clinical trial in eight patients with glioblastoma, where specific CD4+ T-cell responses to a mutation-bearing sequence from Rho GTPase Activating Protein 35 (ARHGAP35), which is naturally processed and presented to the immune system, were demonstrated in one patient (72). Here, ARHGAP35 is linked to glioblastoma.