Inhibition of plasma kallikrein by a highly specific active site blocking antibody

J Biol Chem. 2014 Aug 22;289(34):23596-608. doi: 10.1074/jbc.M114.569061. Epub 2014 Jun 26.


Plasma kallikrein (pKal) proteolytically cleaves high molecular weight kininogen to generate the potent vasodilator and the pro-inflammatory peptide, bradykinin. pKal activity is tightly regulated in healthy individuals by the serpin C1-inhibitor, but individuals with hereditary angioedema (HAE) are deficient in C1-inhibitor and consequently exhibit excessive bradykinin generation that in turn causes debilitating and potentially fatal swelling attacks. To develop a potential therapeutic agent for HAE and other pKal-mediated disorders, we used phage display to discover a fully human IgG1 monoclonal antibody (DX-2930) against pKal. In vitro experiments demonstrated that DX-2930 potently inhibits active pKal (Ki = 0.120 ± 0.005 nM) but does not target either the zymogen (prekallikrein) or any other serine protease tested. These findings are supported by a 2.1-Å resolution crystal structure of pKal complexed to a DX-2930 Fab construct, which establishes that the pKal active site is fully occluded by the antibody. DX-2930 injected subcutaneously into cynomolgus monkeys exhibited a long half-life (t½ ∼ 12.5 days) and blocked high molecular weight kininogen proteolysis in activated plasma in a dose- and time-dependent manner. Furthermore, subcutaneous DX-2930 reduced carrageenan-induced paw edema in rats. A potent and long acting inhibitor of pKal activity could be an effective treatment option for pKal-mediated diseases, such as HAE.

Keywords: Antibody Engineering; Enzyme Inhibitor; Inflammation; Kallikrein; Protease.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies / immunology*
  • Catalytic Domain
  • Crystallography, X-Ray
  • Enzyme-Linked Immunosorbent Assay
  • Humans
  • Kallikreins / blood
  • Kallikreins / immunology*
  • Molecular Sequence Data
  • Rats
  • Rats, Sprague-Dawley
  • Surface Plasmon Resonance


  • Antibodies
  • Kallikreins

Associated data

  • PDB/4OGX
  • PDB/4OGY
  • PDB/4PUB