Antigenic peptide delivery to antigen-presenting cells using a CD40-coiled coil affinity-based platform

Delivery of antigenic peptides to antigen presenting cells (APCs) such as dendritic cells (DCs) using monoclonal antibodies (mAbs) is an attractive approach to evoke antigen-specific T cell activation and improve drug efficacy. Peptide linkage to mAbs has previously been achieved through genetic fusion, chemical conjugation, nano-engineered platforms and high affinity peptides. In this study, we have developed a flexible antibody-peptide linking technology using oppositely charged coiled coil domains to non-covalently link peptides to mAbs. The technology comprises (1) an anti-CD40 mAb connected with negatively charged E domains and (2) an immunogenic OVA peptide (SIINFEKL) from ovalbumin used as a model antigenic peptide fused with positively charged K domains. Combining these constructs leads to the formation of complexes that can be targeted to CD40 expressed on cells. Proof of concept antibody constructs connected with E domains generated from transient expressions exhibited good manufacturability, binding, and stability attributes comparable to a control mAb. Also, optimal repeat lengths for coiled-coil oligomerization domains were identified in these studies. Binding kinetics studies showed that connecting E domains to mAbs do not impede Fc gamma and neonatal receptor interactions. Additionally, formation of stable complexes capable of binding CD40 expressing cells was demonstrated <i>in vitro. In vivo</i> functionality evaluations showed that treatment of human CD40 transgenic mice with complexes elicited expansion of OVA peptide-specific CD8+ T cells and potent antitumor effects superior to peptide monotherapies. Overall, these findings demonstrate that the technology has great potential for application as an <i>in vivo</i> tool for antigenic peptide delivery.