Well‐Defined Mannosylated Polymer for Peptide Vaccine Delivery with Enhanced Antitumor Immunity

Peptide‐based cancer vaccines offer production and safety advantages but have had limited clinical success due to their intrinsic instability, rapid clearance, and low cellular uptake. Nanoparticle‐based delivery vehicles can improve the in vivo stability and cellular uptake of peptide antigens. Here, a well‐defined, self‐assembling mannosylated polymer is developed for anticancer peptide antigen delivery. The amphiphilic polymer is prepared by reversible addition‐fragmentation chain transfer (RAFT) polymerization, and the peptide antigens are conjugated to the pH‐sensitive hydrophobic block through the reversible disulfide linkage for selective release after cell entry. The polymer–peptide conjugates self‐assemble into sub‐100 nm micelles at physiological pH and dissociate at endosomal pH. The mannosylated micellar corona increases the accumulation of vaccine cargoes in the draining inguinal lymph nodes and facilitates nanoparticle uptake by professional antigen presenting cells. In vivo studies demonstrate that the mannosylated micelle formulation improves dendritic cell activation and enhances antigen‐specific T cell responses, resulting in higher antitumor immunity in tumor‐bearing mice compared to free peptide antigen. The mannosylated polymer is therefore a simple and promising platform for the delivery of peptide cancer vaccines. A well‐defined, self‐assembling mannosylated polymer provides straightforward formulation of multiple peptide antigens for effective antitumor activity.