Identification of potent human anti-IL-IRI antagonist antibodies

Abstract

Interleukin-1 (IL-1) blockade by IL-1 receptor antagonist benefits some arthritis patients by reducing joint damage. This fact inspired us to develop antagonist human therapeutic antibodies against IL-1RI using phage libraries that display single-chain variable fragment (scFv) antibody fragments. Panning libraries against human IL-1RI generated 39 unique scFv-phage whose binding to IL-1RI was competed by IL-1 ligands. Fifteen of these scFv-phage, identified using IL-1RI-binding assays and dissociation rate ranking, were reformatted as scFv-Fc and IgG4 molecules. The ease of producing antibodies in the scFv-Fc format permitted rapid identification of four lead clones (C10, C13, C14, C15) that inhibit NF-κB nuclear translocation induced by IL-1. Reformatting these clones as IgG4 molecules increased their inhibition potency by ≤24-fold. C10 IgG4 is the most potent antagonist of IL-1α (26 nM IC 50) and IL-1β (18 nM IC50) in the NF-κB bioassay, although less potent than IL-1ra (∼0.4 nM IC50). C10 is the highest affinity clone for human IL-1RI (KD ∼60 nM). Flow cytometry indicates that several lead clones bind cell-surface cynomolgus or murine IL-1RI, characteristics advantageous for preclinical toxicology and efficacy studies. This study demonstrates the utility of scFv-Fc fusion proteins for rapid screening of clones derived from phage libraries to identify antibody leads with therapeutic potential.