Optimization of a series of novel, potent and selective Macrocyclic SYK inhibitors.

Spleen tyrosine kinase (SYK) is a non-receptor cytoplasmic kinase. Due to its pivotal role in B cell receptor and Fc-receptor signalling, inhibition of SYK has been a target of interest in a variety of diseases. Herein, we report the use of structure-based drug design to discover a series of potent macrocyclic inhibitors of SYK, with excellent kinome selectivity and in vitro metabolic stability. We were able to remove hERG inhibition through the optimization of physical properties, and utilized a pro-drug strategy to address permeability challenges.

Virtual Screening in the Cloud Identifies Potent and Selective ROS1 Kinase Inhibitors.

ROS1 rearrangements account for 1-2% of non-small cell lung cancer patients, yet there are no specifically designed, selective ROS1 therapies in the clinic. Previous knowledge of potent ROS1 inhibitors with selectivity over TrkA, a selected antitarget, enabled virtual screening as a hit finding approach in this project. The ligand-based virtual screening was focused on identifying molecules with a similar 3D shape and pharmacophore to the known actives. To that end, we turned to the AstraZeneca virtual library, estimated to cover 1015 synthesizable make-on-demand molecules. We used cloud computing-enabled FastROCS technology to search the enumerated 1010 subset of the full virtual space. A small number of specific libraries were prioritized based on the compound properties and a medicinal chemistry assessment and further enumerated with available building blocks. Following the docking evaluation to the ROS1 structure, the most promising hits were synthesized and tested, resulting in the identification of several potent and selective series. The best among them gave a nanomolar ROS1 inhibitor with over 1000-fold selectivity over TrkA and, from the preliminary established SAR, these have the potential to be further optimized. Our prospective study describes how conceptually simple shape-matching approaches can identify potent and selective compounds by searching ultralarge virtual libraries, demonstrating the applicability of such workflows and their importance in early drug discovery.

Novel potent and selective pyrazolylpyrimidine-based SYK inhibitors.

Hybridisation of amino-pyrimidine based SYK inhibitors (e.g. 1a) with previously reported diamine-based SYK inhibitors (e.g. TAK-659) led to the identification and optimisation of a novel pyrimidine-based series of potent and selective SYK inhibitors, where the original aminomethylene group was replaced by a 3,4-diaminotetrahydropyran group. The initial compound 5 achieved excellent SYK potency. However, it suffered from poor permeability and modest kinase selectivity. Further modifications of the 3,4-diaminotetrahydropyran group were identified and the interactions of those groups with Asp512 were characterised by protein X-ray crystallography. Further optimisation of this series saw mixed results where permeability and kinase selectivity were increased and oral bioavailability was achieved in the series, but at the expense of potent hERG inhibition.

Alternative to LRRK2-IN-1 for Pharmacological Studies of Parkinson's Disease.

BACKGROUND/AIMS: LRRK2 (leucine-rich repeat protein kinase 2) is one of the most commonly accepted genes associated with Parkinson's disease (PD). The overexpression of disease-associated mutations in LRRK2 is toxic to the cells, while reduction or elimination of LRRK2 expression promotes cell health and growth. Thus, the identification of an LRRK2 inhibitor with good physiochemical and pharmacokinetic properties is of great interest for the treatment of PD. METHODS: In this study, we have investigated LRRK2 compounds, LRRK2-IN-1 and Compound 1, in vitro and in vivo to determine how suitable they are as a selective LRRK2 tool compound. RESULTS: We report that Compound 1, patented by GSK, is a potent and selective LRRK2 inhibitor with good blood-brain barrier permeability as reflected by its high brain to plasma ratio in rats. In addition, Compound 1 can significantly promote neurite outgrowth in a primary cortical culture, indicating an optimistic cellular function of this compound in a biological system. In contrast, LRRK2-IN-1 is a less selective LRRK2 inhibitor and has low brain penetration. Furthermore, LRRK2-IN-1 is cyto- and genotoxic, while Compound 1 does not exhibit any toxicity. CONCLUSIONS: These results suggest that Compound 1 may be a superior tool compound than LRRK2-IN-1 to advance future pharmacological research on LRRK2.

Potent and Selective Inhibitors of the Epidermal Growth Factor Receptor to Overcome C797S-Mediated Resistance.

The epidermal growth factor receptor (EGFR) harboring activating mutations is a clinically validated target in non-small-cell lung cancer, and a number of inhibitors of the EGFR tyrosine kinase domain, including osimertinib, have been approved for clinical use. Resistance to these therapies has emerged due to a variety of molecular events including the C797S mutation which renders third-generation C797-targeting covalent EGFR inhibitors considerably less potent against the target due to the loss of the key covalent-bond-forming residue. We describe the medicinal chemistry optimization of a biochemically potent but modestly cell-active, reversible EGFR inhibitor starting point with sub-optimal physicochemical properties. These studies culminated in the identification of compound 12 that showed improved cell potency, oral exposure, and in vivo activity in clinically relevant EGFR-mutant-driven disease models, including an Exon19 deletion/T790M/C797S triple-mutant mouse xenograft model.

The identification of novel orally active mGluR5 antagonist GSK2210875.

The identification of novel orally active mGluR5 antagonist GSK2210875 is described.

The identification of a selective dopamine D2 partial agonist, D3 antagonist displaying high levels of brain exposure.

The identification of a highly selective D(2) partial agonist, D(3) antagonist tool molecule which demonstrates high levels of brain exposure and selectivity against an extensive range of dopamine, serotonin, adrenergic, histamine, and muscarinic receptors is described.

Dopamine D3 receptor antagonists: the quest for a potentially selective PET ligand. Part one: lead identification.

The synthesis and SAR of a new series of potent and selective dopamine D(3) receptor antagonists is reported.

The identification of beta-hydroxy carboxylic acids as selective MMP-12 inhibitors.

A new class of selective MMP-12 inhibitors have been identified via high throughput screening. Crystallization with MMP-12 confirmed the mode of binding and allowed initial optimization to be carried out using classical structure based design.

5-HT7 Receptor Antagonists with an Unprecedented Selectivity Profile.

Selective leads: In this study, we generated a new series of serotonin 5-HT7 receptor antagonists. Their synthesis, structure-activity relationships, and selectivity profiles are reported. This series includes 5-HT7 antagonists with unprecedented high selectivity for the 5-HT7 receptor, setting the stage for lead optimization of drugs acting on a range of neurological targets.

Identification of novel glycine sulfonamide antagonists for the EP1 receptor.

A high-throughput screen targeting the EP(1) receptor identified non-acidic glycine sulfonamide derivative 2a with a pK(i) of 6.2. Analogue synthesis allowed a thorough investigation of the structure-activity relationship (SAR) and led to a 100-fold increase in recombinant potency.

Identification of novel pyrazole acid antagonists for the EP1 receptor.

The discovery, synthesis and structure-activity relationship (SAR) of a novel series of EP1 receptor antagonists is described. Pyrazole acid 4, identified from a chemical array, had desirable physicochemical properties, an excellent in vitro microsomal inhibition and cytochrome P450 (CYP450) profile and good exposure levels in blood. This compound had an ED50 of 1.3 mg/kg in a rat pain model. A range of more potent analogues in the in vitro assay was identified using efficient array chemistry. These EP1 antagonists have potential as agents in the treatment of PGE2 mediated pain.