Fig. 1
From: Preclinical pharmacology characterization of HX009, a novel PD1 x CD47 Bi-specific antibody
HX009 structure and in vitro characterization. (A) Molecular structure of HX009: 2 × 2 symmetric BsAb molecule; (B) HX009 binding to the recombinant CD47 proteins of different species including human, cynomolgus monkey (upper) and mouse (lower), binding EC50 (half maximal effective concentration) were determined per four-parameter equation fitting curves; (C) competitive binding to CD47 single-positive (upper panel) or CD47-PD1 double positive (lower panel) cells by HX009. Labeled B6H12 (anti-CD47) was competed out by SIRPα-Fc, but not by HX009 (weakened binding) in single-positive cell assay, while it was competed out in double-positive cell assays by both SIPRα-Fc and HX009. (D) T-cell activation luciferase report assays: upper panel: HX009 had enhanced T-cell activation (cis-binding) over HX008 (4X), whereas the enhancement is diminished by an anti-SIRPα neutralizing antibody but not by CD47-Fc (soluble CD47). Lower panel: there was no enhancement of T-cell activation by HX008 and SIRPα-Fc combo treatment due to trans-binding.
