title: Inhibition of plasma kallikrein by a highly specific active site blocking antibody.
abstract: 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.
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Jon A
authors: JA
authors: Kenniston
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Ryan R
authors: RR
authors: Faucette
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Diana
authors: D
authors: Martik
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Stephen R
authors: SR
authors: Comeau
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Allison P
authors: AP
authors: Lindberg
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Kris J
authors: KJ
authors: Kopacz
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Gregory P
authors: GP
authors: Conley
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Jie
authors: J
authors: Chen
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Malini
authors: M
authors: Viswanathan
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Niksa
authors: N
authors: Kastrapeli
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Janja
authors: J
authors: Cosic
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Shauna
authors: S
authors: Mason
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Mike
authors: M
authors: DiLeo
authors: Beryllium, Bainbridge Island, Washington 98110, and.
authors: Jan
authors: J
authors: Abendroth
authors: Biokin, Watertown, Massachusetts 02472.
authors: Petr
authors: P
authors: Kuzmic
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Robert C
authors: RC
authors: Ladner
authors: Beryllium, Bainbridge Island, Washington 98110, and.
authors: Thomas E
authors: TE
authors: Edwards
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Christopher
authors: C
authors: TenHoor
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Burt A
authors: BA
authors: Adelman
authors: From the Dyax Corp., Burlington, Massachusetts 01803.
authors: Andrew E
authors: AE
authors: Nixon
authors: From the Dyax Corp., Burlington, Massachusetts 01803, dsexton@dyax.com.
authors: Daniel J
authors: DJ
authors: Sexton
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology*; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007610:Kallikreins / Q000097:blood / Q000276:immunology*; D008969:Molecular Sequence Data; D051381:Rats; D017207:Rats, Sprague-Dawley; D020349:Surface Plasmon Resonance
chemical_list: D000906:Antibodies; D007610:Kallikreins
keywords: Antibody Engineering; Enzyme Inhibitor; Inflammation; Kallikrein; Protease