Small molecule inhibitors of PCSK9. SAR investigations of head and amine groups.

Our previous work on the optimization of a new class of small molecule PCSK9 mRNA translation inhibitors focused on empirical optimization of the amide tail region of the lead PF-06446846 (1). This work resulted in compound 3 that showed an improved safety profile. We hypothesized that this improvement was related to diminished binding of 3 to non-translating ribosomes and an apparent improvement in transcript selectivity.

Structural basis for selective stalling of human ribosome nascent chain complexes by a drug-like molecule.

The drug-like molecule PF-06446846 (PF846) binds the human ribosome and selectively blocks the translation of a small number of proteins by an unknown mechanism. In structures of PF846-stalled human ribosome nascent chain complexes, PF846 binds in the ribosome exit tunnel in a eukaryotic-specific pocket formed by 28S ribosomal RNA, and alters the path of the nascent polypeptide chain. PF846 arrests the translating ribosome in the rotated state of translocation, in which the peptidyl-transfer RNA 3'-CCA end is improperly docked in the peptidyl transferase center.

Small Molecule Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Inhibitors: Hit to Lead Optimization of Systemic Agents.

The optimization of a new class of small molecule PCSK9 mRNA translation inhibitors is described. The potency, physicochemical properties, and off-target pharmacology associated with the hit compound (1) were improved by changes to two regions of the molecule. The last step in the synthesis of the congested amide center was enabled by three different routes.

Correction: Selective stalling of human translation through small-molecule engagement of the ribosome nascent chain.

[This corrects the article DOI: 10.1371/journal.pbio.

Liver-Targeted Small-Molecule Inhibitors of Proprotein Convertase Subtilisin/Kexin Type 9 Synthesis.

Targeting of the human ribosome is an unprecedented therapeutic modality with a genome-wide selectivity challenge. A liver-targeted drug candidate is described that inhibits ribosomal synthesis of PCSK9, a lipid regulator considered undruggable by small molecules. Key to the concept was the identification of pharmacologically active zwitterions designed to be retained in the liver.

Selective stalling of human translation through small-molecule engagement of the ribosome nascent chain.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a key role in regulating the levels of plasma low-density lipoprotein cholesterol (LDL-C). Here, we demonstrate that the compound PF-06446846 inhibits translation of PCSK9 by inducing the ribosome to stall around codon 34, mediated by the sequence of the nascent chain within the exit tunnel. We further show that PF-06446846 reduces plasma PCSK9 and total cholesterol levels in rats following oral dosing.

Utility of a novel Oatp1b2 knockout mouse model for evaluating the role of Oatp1b2 in the hepatic uptake of model compounds.

We generated the organic anion transporting polypeptide (Oatp) 1b2 knockout (KO) mouse model and assessed its utility to study hepatic uptake using model compounds: cerivastatin, lovastatin acid, pravastatin, simvastatin acid, rifampicin, and rifamycin SV. A selective panel of liver cytochromes P450 (P450s) (Cyp3a11, Cyp3a13, Cyp3a16, Cyp2c29, and Cyp2c39) and transporters [Oatp1b2, Oatp1a1, Oatp1a4, Oatp1a5; organic anion transporter (Oat) 1, Oat2, Oat3; multidrug resistance gene 1 (Mdr1) a, Mdr1b; bile salt export pump, multidrug resistance associated protein (Mrp) 2, Mrp3; breast cancer resistance protein] were measured by reverse transcription-polymerase chain reaction in both KO and wild-type (WT) male mice. Male KO and WT mice received each model compound s.