Oral biomimetic virus vaccine hydrogel for robust abscopal antitumour efficacy

Remarkable progress has been made in tumour immunotherapy in recent decades. However, the clinical outcomes of therapeutic interventions remain unpredictable, largely because of inefficient immune responses. To address this challenge and optimise immune stimulation, we present a novel administration route for enhancing the bioavailability of immunotherapeutic drugs. Our approach involves the development of an oral tumour vaccine utilising virus-like particles derived from the Hepatitis B virus core (HBc) antigen. The external surfaces of these particles are engineered to display the model tumour antigen OVA, whereas the interiors are loaded with cytosine phosphoguanosine oligodeoxynucleotide (CpG ODN), resulting in a construct called CpG@^OVAHBc with enhanced antigenicity and immune response. For oral delivery, CpG@^OVAHBc is encapsulated in a crosslinked dextran hydrogel called CpG@^OVAHBc@Dex. The external hydrogel shield safeguards the biomimetic virus particles from degradation by gastric acid and proteases. Upon exposure to intestinal flora, the hydrogel disintegrates, releasing CpG@^OVAHBc at the intestinal mucosal site. Owing to its virus-like structure, CpG@^OVAHBc exhibits enhanced adhesion to the mucosal surface, facilitating uptake by microfold cells (M cells) and subsequent transmission to antigen-presenting cells. The enzyme-triggered release of this oral hydrogel ensures the integrity of the tumour vaccine within the digestive tract, allowing targeted release and significantly improving bioavailability. Beyond its efficacy, this oral hydrogel vaccine streamlines drug administration, alleviates patient discomfort, and enhances treatment compliance without the need for specialised injection methods. Consequently, our approach expands the horizons of vaccine development in the field of oral drug administration.