An all-in-one adjuvanted therapeutic cancer vaccine targeting dendritic cell cytosol induces long-lived tumor suppression through NLRC4 inflammasome activation

Therapeutic cancer vaccines (TCVs) should induce robust tumor-specific T cell responses. To achieve this, TCVs incorporate T cell epitopes and strong adjuvants. Here, we report an all-in-one adjuvanted cancer vaccine platform, which targets intracellular compartment of antigen presenting cells and subsequently induces effective cytotoxic T cell responses. We screened a novel peptide (DCpep6) that specifically binds and tranmits into CD11c+ cells through in vivo phage biopanning. We then engineered a protein-based TCV (DEF) consisting of DCpep6 (D), an optimized HPV E7 tumor antigen (E), and a built-in flagellin adjuvant (F) as a single molecule. DEF was stably expressed and each component was functional. In vivo administered DEF rapidly biodistributed in draining LNs and internalized into CD11c+ cells. DEF immunization elicited strong anti-tumor T cell responses and provided long-term survival of TC-1 tumor implanted mice. The DEF-mediated anti-tumor effect was abolished in NLRC4−/− mice. Taken together, we propose a protein-based all-in-one TCV platform that intracellularly co-delivers tumor antigen and inflammasome activator to DCs to induce long-lasting anti-tumor T cell responses.