RT Journal Article SR Electronic T1 Pharmacologic Profile of the Adnectin BMS-962476, a Small Protein Biologic Alternative to PCSK9 Antibodies for Low-Density Lipoprotein Lowering JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 412 OP 424 DO 10.1124/jpet.114.214221 VO 350 IS 2 A1 Mitchell, Tracy A1 Chao, Ginger A1 Sitkoff, Doree A1 Lo, Fred A1 Monshizadegan, Hossain A1 Meyers, Daniel A1 Low, Simon A1 Russo, Katie A1 DiBella, Rose A1 Denhez, Fabienne A1 Gao, Mian A1 Myers, Joseph A1 Duke, Gerald A1 Witmer, Mark A1 Miao, Bowman A1 Ho, Siew P. A1 Khan, Javed A1 Parker, Rex A. YR 2014 UL http://jpet.aspetjournals.org/content/350/2/412.abstract AB Proprotein convertase subtilisin kexin-9 (PCSK9) is an important pharmacological target for decreasing low-density lipoprotein (LDL) in cardiovascular disease, although seemingly inaccessible to small molecule approaches. Compared with therapeutic IgG antibodies currently in development, targeting circulating PCSK9 with smaller molecular scaffolds could offer different profiles and reduced dose burdens. This inspired genesis of PCSK9-binding Adnectins, a protein family derived from human fibronectin-10th-type III–domain and engineered for high-affinity target binding. BMS-962476, an ∼11-kDa polypeptide conjugated to polyethylene glycol to enhance pharmacokinetics, binds with subnanomolar affinity to human. The X-ray cocrystal structure of PCSK9 with a progenitor Adnectin shows ∼910 Å2 of PCSK9 surface covered next to the LDL receptor binding site, largely by residues of a single loop of the Adnectin. In hypercholesterolemic, overexpressing human PCSK9 transgenic mice, BMS-962476 rapidly lowered cholesterol and free PCSK9 levels. In genomic transgenic mice, BMS-962476 potently reduced free human PCSK9 (ED50 ∼0.01 mg/kg) followed by ∼2-fold increases in total PCSK9 before return to baseline. Treatment of cynomolgus monkeys with BMS-962476 rapidly suppressed free PCSK9 >99% and LDL-cholesterol ∼55% with subsequent 6-fold increase in total PCSK9, suggesting reduced clearance of circulating complex. Liver sterol response genes were consequently downregulated, following which LDL and total PCSK9 returned to baseline. These studies highlight the rapid dynamics of PCSK9 control over LDL and liver cholesterol metabolism and characterize BMS-962476 as a potent and efficacious PCSK9 inhibitor.