Oncolytic adenovirus delivery of neoantigens sensitizes low-mutation tumors to anti-PD-1 therapy and prevents metastasis.

Neoantigen vaccines and oncolytic viruses are emerging immunotherapies that can reshape the tumor microenvironment (TME). However, tumors with low mutation burdens often respond poorly to immunotherapies because of their limited immunogenicity. Developing effective immunotherapy strategies for these types of tumors remains a significant challenge. In this study, we engineered oncolytic adenoviruses to accurately amplify neoantigen expression within tumor cells, which demonstrated superior efficacy compared to synthetic long peptide vaccines and showed enhanced effectiveness in a low mutation burden intrahepatic cholangiocarcinoma model. Building on this, we further developed NeoViron, which coexpresses neoantigens and Flt3L, a dendritic cell growth factor, to promote antigen presentation and T-cell infiltration simultaneously. NeoViron significantly inhibited tumor growth and prevented metastasis in intrahepatic cholangiocarcinoma animal models. Mechanistically, NeoViron enhanced the cytotoxicity of CD8+ T cells and promoted the expansion of CD69+ CD8+ tissue-resident memory T cells and TCF1+ CD8+ stem-like T cells to promote anti-tumor immunity and immune memory. When combined with anti-PD-1, it further enhances the cytotoxicity of tissue-resident memory T cells to eradicate solid tumors. These findings demonstrate that NeoViron can effectively sensitize low-mutation tumors to immunotherapy by increasing neoantigen expression and antigen-presentation efficacy, offering a promising strategy for cancer treatment, particularly for tumors with scarce neoantigens.