Proprotein convertase subtilisin/kexin type 9 (PCSK9) regulates serum LDL cholesterol (LDL-C) by interacting with the LDL receptor (LDLR) and is an attractive therapeutic target for LDL-C lowering. We have generated a neutralizing anti-PCSK9 antibody, mAb1, that binds to an epitope on PCSK9 adjacent to the region required for LDLR interaction. In vitro, mAb1 inhibits PCSK9 binding to the LDLR and attenuates PCSK9-mediated reduction in LDLR protein levels, thereby increasing LDL uptake. A combination of mAb1 with a statin increases LDLR levels in HepG2 cells more than either treatment alone. In wild-type mice, mAb1 increases hepatic LDLR protein levels Ϸ2-fold and lowers total serum cholesterol by up to 36%: this effect is not observed in LDLR ؊/؊ mice. In cynomolgus monkeys, a single injection of mAb1 reduces serum LDL-C by 80%, and a significant decrease is maintained for 10 days. We conclude that anti-PCSK9 antibodies may be effective therapeutics for treating hypercholesterolemia.antibody ͉ LDL-C ͉ LDLR ͉ PCSK9 ͉ hypercholesterolemia P roprotein convertase subtilisin/kexin type 9 (PCSK9) has been implicated as an important regulator of LDL metabolism (1, 2). Human genetic studies provide strong validation for the role of PCSK9 in modulating LDL cholesterol (LDL-C) levels and the incidence of coronary heart disease (CHD) in man. Gain-of-function (GOF) mutations in the PCSK9 gene are associated with elevated serum LDL-C levels (Ͼ300 mg/dL) and premature CHD (3), whereas loss-of-function (LOF) mutations are associated with low serum LDL-C (Յ100 mg/dL) (4). Strikingly, subjects harboring the heterozygous LOF mutations exhibited an 88% reduction in the incidence of CHD over a 15-year period relative to noncarriers of the mutations (5). Moreover, despite a complete loss of PCSK9 and serum LDL-C of Ͻ20 mg/dL, the 2 subjects carrying compound heterozygote LOF mutations appear healthy (6, 7).PCSK9 belongs to the subtilisin family of serine proteases and consists of a prodomain, catalytic domain, and C-terminal V domain (8). Expressed highly in the liver, PCSK9 is secreted after autocatalytic cleavage of its zymogen form (1). The prodomain remains noncovalently associated with the catalytic domain and seems to inhibit further proteolytic enzyme activity (8, 9). Secreted PCSK9 modulates LDL-C levels by posttranslational downregulation of hepatic LDL receptor (LDLR) protein (1). The precise mechanism is unknown, but a direct interaction between repeat A of the LDLR EGF homology domain and the PCSK9 catalytic domain is required (10, 11). Proteolytic cleavage of the LDLR by PCSK9 does not occur (12, 13); rather, the PCSK9:LDLR complex is endocytosed and directed to the endosome/lysosome compartment for degradation (14, 15). Current understanding of the LDLR pathway asserts that apolipoprotein B (apoB) and E (apoE) containing lipoprotein particles endocytosed with the LDLR are transported to the acidic environment of the endosome, where they dissociate from the receptor and are subsequently catabolized in lysosomes, while t...

We report the discovery of potent benzamide inhibitors of 11beta-hydroxysteroid dehydrogenase (11beta-HSD1). The optimization and correlation of in vitro and in vivo metabolic stability will be described. Through modifications to our initial lead 2, we discovered pyridyl compound 13. This compound has a favorable pharmacokinetic profile across three species and showed a dose-dependent decrease in adipose 11beta-HSD1 activity in a monkey ex vivo pharmacodynamic model.

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These findings suggest that in the absence of classical apoptotic cell death, radiosensitivity is not predictably related to the p53 status of the cell. While both p53 and c-myc may be linked to the DNA damage response pathway, neither p53 nor c-myc are essential for growth arrest in response to ionizing radiation.

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