A Novel Antigen Design Strategy to Isolate Single‐Domain Antibodies that Target Human Nav1.7 and Reduce Pain in Animal Models

Abstract Genetic studies have identified the voltage‐gated sodium channel 1.7 (Na_v1.7) as pain target. Due to the ineffectiveness of small molecules and monoclonal antibodies as therapeutics for pain, single‐domain antibodies (V_HHs) are developed against the human Na_v1.7 (hNa_v1.7) using a novel antigen presentation strategy. A 70 amino‐acid peptide from the hNa_v1.7 protein is identified as a target antigen. A recombinant version of this peptide is grafted into the complementarity determining region 3 (CDR3) loop of an inert V_HH in order to maintain the native 3D conformation of the peptide. This antigen is used to isolate one V_HH able to i) bind hNa_v1.7, ii) slow the deactivation of hNa_v1.7, iii) reduce the ability of eliciting action potentials in nociceptors, and iv) reverse hyperalgesia in in vivo rat and mouse models. This V_HH exhibits the potential to be developed as a therapeutic capable of suppressing pain. This novel antigen presentation strategy can be applied to develop biologics against other difficult targets such as ion channels, transporters and GPCRs.