Identification of public neoantigens with broad HLA class I coverage as candidates for off-the-shelf cancer vaccine development in colorectal cancer

Introduction Shared neoantigens derived from recurrent mutations represent promising targets for off-the-shelf (OTS) cancer immunotherapies; however, their clinical utility is often constrained by population-specific HLA diversity and variable immunogenicity. There remains a need for population-tailored neoantigen panels with broad HLA coverage and functional validation. Methods We developed a colorectal cancer (CRC)–specific OTS neoantigen panel by integrating TCGA mutation data with HLA class I binding predictions across 68 alleles (18 HLA-A, 34 HLA-B, and 16 HLA-C), covering both Asian and Caucasian populations. Candidate neoantigens were evaluated in a Vietnamese CRC cohort (n = 67) based on mutation and HLA matching. Functional immunogenicity was assessed in patient-derived CD8⁺ T cells using IFN-γ ELISpot assays and single-cell RNA sequencing. Results The resulting panel comprised 73 recurrent nonsynonymous mutations, each generating at least one predicted HLA-I–restricted neoepitope, achieving >90% population coverage in both Asian and Caucasian groups. In the Vietnamese CRC cohort, 58% of patients harbored at least one matched neoantigen, with mutation frequency strongly correlating with predicted HLA presentation, particularly for HLA-A alleles. Functional validation in seven patients demonstrated robust CD8 + T-cell responses against TP53_R273H. Neoantigen-reactive T cells exhibited transcriptional signatures consistent with cytotoxic effector function and stem-like memory phenotypes. Discussion These findings identify TP53_R273H as a clinically relevant shared neoantigen in CRC and support the translational feasibility of a population-tailored OTS neoantigen panel. Our integrative computational and experimental framework highlights the importance of combining population-level HLA coverage with functional validation to advance broadly applicable neoantigen-based immunotherapies.