antigens together with a strong adjuvant. Despite the promise of this approach, the clinical efficacy currently remains modest. One method to elicit a more robust and durable immune response against a particular cancer is by targeting tumor antigens and adjuvants to antigen presenting macrophages and dendritic cells (DCs). [2,3] These cells normally encounter antigens at the site of peripheral vaccination, then subsequently mature, enter the lymphatic vessels and migrate to lymph nodes (LNs) to prime effector lymphocytes. [4] Over the past decades, considerable efforts have been made to generate DC-based cancer vaccines by maturing isolated DCs with adjuvants (e.g., toll-like receptor (TLR), agonists, cytokines, and molecules that facilitate DC maturation) and equipping them with tumor antigens in vitro to improve the efficiency of these cells. [5,6] However, ex vivo cell culture is expensive and a limited amount of DCs migrate to the LNs for the activation of antigen-specific T cells. Other widely investigated strategies for allophycocyanin (APC) targeting in vivo are to fuse antigens with antibodies or ligands that target APC surface markers, such as TLRs, CD205, CD207, CD11c, and major histocompatibility complex (MHC) II, or to generate nanoformulations modified with such antibodies or ligands to deliver the antigens. [2,7] Such designs often target APCs in peripheral tissues, whereas the LN APCs are a more desirable target. LNs contain a high number of resident APCs, so delivery of antigens and adjuvants to the LN is likely to increase uptake by APCs, resulting in enhanced vaccine efficiency. [8,9] In addition, resident APCs in LNs are phenotypically immature and capable of internalizing antigens and particles. [10] Thus, LN-resident APCs may be ideal targets for immunotherapeutic drugs.Nanoformulations loaded with tumor-specific antigens and adjuvants have proven highly beneficial in boosting vaccine efficiency. [11][12][13] Those nanoformulations with diameters larger than 100 nm are primarily utilized for the delivery of antigens to peripheral APCs, which subsequently migrate to the lymph nodes to activate T cells. [14] Antigen peptide degradation, rapid MHC I turnover, and the disassociation of peptide antigen from MHC molecules may all occur during translocation to Due to their ability to elicit a potent immune reaction with low systemic toxicity, cancer vaccines represent a promising strategy for treating tumors. Considerable effort has been directed toward improving the in vivo efficacy of cancer vaccines, with direct lymph node (LN) targeting being the most promising approach. Here, a click-chemistry-based active LN accumulation system (ALAS) is developed by surface modification of lymphatic endothelial cells with an azide group, which provide targets for dibenzocyclooctyne (DBCO)-modified liposomes, to improve the delivery of encapsulated antigen and adjuvant to LNs. When loading with OVA 257-264 peptide and poly(I:C), the formulation elicits an enhanced CD8 + T cell response in vivo, resulting in ...