The Discovery of VX-745: A Novel and Selective p38α Kinase Inhibitor.

The synthesis of novel, selective, orally active 2,5-disubstituted 6H-pyrimido[1,6-b]pyridazin-6-one p38α inhibitors is described. Application of structural information from enzyme-ligand complexes guided the selection of screening compounds, leading to the identification of a novel class of p38α inhibitors containing a previously unreported bicyclic heterocycle core. Advancing the SAR of this series led to the eventual discovery of 5-(2,6-dichlorophenyl)-2-(2,4-difluorophenylthio)-6H-pyrimido[1,6-b]pyridazin-6-one (VX-745).

Structure-guided design of potent and selective pyrimidylpyrrole inhibitors of extracellular signal-regulated kinase (ERK) using conformational control.

The Ras/Raf/MEK/ERK signal transduction, an oncogenic pathway implicated in a variety of human cancers, is a key target in anticancer drug design. A novel series of pyrimidylpyrrole ERK inhibitors has been identified. Discovery of a conformational change for lead compound 2, when bound to ERK2 relative to antitarget GSK3, enabled structure-guided selectivity optimization, which led to the discovery of 11e, a potent, selective, and orally bioavailable inhibitor of ERK.

Structure-based design of 3-aryl-6-amino-triazolo[4,3-b]pyridazine inhibitors of Pim-1 kinase.

A series of substituted 3-aryl-6-amino-triazolo[4,3-b]pyridazines were identified as highly selective inhibitors of Pim-1 kinase. Initial exploration identified compound 24 as a potent, selective inhibitor, limited in its utility by poor solubility and permeability. Understanding the unusual ATP-binding site of the Pim kinases and X-ray crystallographic data on compound 24 led to design improvements in this class of inhibitor.

Flipped out: structure-guided design of selective pyrazolylpyrrole ERK inhibitors.

The Ras/Raf/MEK/ERK signal transduction is a key oncogenic pathway implicated in a variety of human cancers. We have identified a novel series of pyrazolylpyrroles as inhibitors of ERK. Aided by the discovery of two distinct binding modes for the pyrazolylpyrrole scaffold, structure-guided optimization culminated in the discovery of 6p, a potent and selective inhibitor of ERK.

CORES: an automated method for generating three-dimensional models of protein/ligand complexes.

We describe a new, automated method for building 3D models of small-molecule ligands complexed with proteins. Modeling templates are constructed from frameworks (i.e.

A minimalist approach to fragment-based ligand design using common rings and linkers: application to kinase inhibitors.

We present a novel method for stepwise scaffold assembly that integrates fragment-by-fragment ligand design approaches with high-throughput virtual library screening (COREGEN). As an extension of our earlier studies of common features present in drug molecules, we investigate the hypothesis that most pharmaceutically interesting ligands can be expressed in terms of the ring-linker frameworks that comprise them. Analysis of 119 published kinase inhibitors from at least 18 different targets illustrates that a basis set of 4 rings and 8 linkers is sufficient to describe approximately 90% of ring and linker occurrences, respectively.

BREED: Generating novel inhibitors through hybridization of known ligands. Application to CDK2, p38, and HIV protease.

In this work we describe BREED, a method for the generation of novel inhibitors from structures of known ligands bound to a common target. The method is essentially an automation of the common medicinal chemistry practice of joining fragments of two known ligands to generate a new inhibitor. The ligand-bound target structures are overlaid, all overlapping bonds in all pairs of ligands are found, and the fragments on each side of each matching bond are swapped to generate the new molecules.

Kinase inhibitors and the case for CH...O hydrogen bonds in protein-ligand binding.

Although the hydrogen bond is known to be an important mediator of intermolecular interactions, there has yet to be an analysis of the role of CH...