Personalized Peptide Cancer Vaccine Combined With Immunotherapy Achieved 80% Tumor Regression in Liver Cancer Models

Neoantigen peptides were identified through tumor mutation screening of the murine Hepa1-6 HCC cell line. Seven high-immunogenicity peptides were selected and combined with clinical-grade Poly(I:C) adjuvant to create NeoVAC. Efficacy was tested in an orthotopic (liver-implanted) HCC mouse model, alone and combined with anti-PD-1 antibody. The tumor immune microenvironment was analyzed by single-cell RNA sequencing, tetramer flow cytometry, and immunofluorescence. Tumor-killing capacity of CD8+ TRMs was verified in both mouse and human patient-derived cancer cells.

Hepatocellular carcinoma is the third leading cause of cancer death worldwide, and most patients are diagnosed too late for surgery. Current immunotherapy (PD-1 blockade alone) has limited response rates in liver cancer. This study shows that combining a personalized peptide vaccine with immunotherapy dramatically improves outcomes by recruiting specialized immune cells that remain in the liver long-term. The 80% regression rate and evidence of immune memory are exceptional for an aggressive cancer.

Personalized cancer vaccines are one of the most promising frontiers in oncology, with mRNA-based neoantigen vaccines (like Moderna's partnership with Merck for melanoma) gaining attention. This study demonstrates that peptide-based vaccines can be equally powerful when combined with checkpoint inhibitors. The identification of CD8+ tissue-resident memory T cells as the key effector population provides a measurable biomarker for predicting treatment success and could guide the design of future combination immunotherapy trials.

All efficacy data are from mouse models, which may not predict human responses. The orthotopic model uses a single mouse cell line (Hepa1-6), limiting diversity. Patient-derived cell validation was done in vitro, not in patients. The seven neoantigen peptides are specific to the mouse tumor line — human patients would require individualized peptide selection. Manufacturing personalized vaccines for each patient is logistically complex and expensive. Long-term durability of the immune response was not assessed beyond the study timeframe.