Moreover, four out of six patients were recurrence-free at 25 months after vaccination while the two with cancer recurrence were subjected to subsequent anti-PD-1 therapy and exhibited a complete cancer regression.499 In a phase Ib clinical trial, Keskin et al.500 demonstrated that neoantigen-specific infiltrating T cells express co-inhibitory receptors following cancer vaccination in glioblastoma patients, providing a rationale for neoantigen vaccines and immune-checkpoint blockade combination therapy. Here, PDCD1 is linked to cancer.