CD40 agonistic-monovalent streptavidin fusion antibody for targeted neoantigen peptide delivery and potent cancer vaccination

Cancer vaccines targeting patient-derived neoantigens offer great promise for personalized cancer therapy but face challenges in achieving targeted delivery to antigen-presenting cells (APCs) to elicit robust and durable cancer-specific immune responses. We synthesized an anti-mouse CD40 agonistic-monovalent streptavidin fusion antibody (αCD40-mSAs), which enables targeted delivery of biotinylated neoantigen peptides to APCs in draining lymph nodes (dLNs). We confirmed mSA expression on the engineered antibody and its strong binding affinities to mouse CD40 and biotin. Advanced microscopy demonstrated that αCD40-mSAs enhances homing to dLNs and intracellular delivery of neoantigen peptides to critical APC subsets, such as cDC1. The potent agonistic effects of αCD40-mSAs on dendritic cell maturation, activation, and antigen presentation were verified through in vitro assays. Vaccination with αCD40-mSAs elicited robust cancer-specific CD8⁺ T cell responses, leading to significant tumor regression and prevention in a mouse tumor model. These results support αCD40-mSAs as an ‘all-in-one’ vaccine delivery platform with multifunctional immunopharmacological advantages and strong translational potential for personalized cancer vaccination.