Tumor-derived autophagosome vaccines combined with immune adjuvants mediate antitumor immune responses via the neoantigen pathway.

Vaccines composed of autophagosomes derived from tumor cells called DRibbles (DRiPs-containing blebs) are involved in the cross-presentation of tumor antigens, thus inducing cross-reactive T-cell responses against the tumor. Compared with traditional tumor lysate vaccines, autophagosome vaccines were found to be better sources of multiple tumor-associated antigens (TAAs) that activate antigen-specific T-cells. However, the involvement of tumor neoantigens in the immune responses of autophagosome vaccines remains unclear. The present study showed that exogenous autophagosome vaccines (DRibbles) combined with immune adjuvants (anti-OX40 antibody and ATP) can effectively activate functional T cells in vitro. Importantly, the combination of exogenous tumor-derived autophagosome vaccines and immune adjuvants was found to induce tumor regression in B16F10 and 4T1 tumor-bearing mice. The combination of autophagosome-enriched DRibbles with anti-OX40 antibody and ATP also exhibited optimal immune stimulation and antitumor efficiency in vivo. The effectiveness of exogenous DRibble vaccines was mainly due to their enhancement of tumor immunogenicity by increasing the presentation and release of tumor neoantigens. These findings suggest that this immunotherapeutic method may be effective in the treatment of cancer.