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

Abstract

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 in vitro. In vivo 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 in vivo tool for antigenic peptide delivery.