Discovery of Clinical Candidate 1-{[(2S,3S,4S)-3-Ethyl-4-fluoro-5-oxopyrrolidin-2-yl]methoxy}-7-methoxyisoquinoline-6-carboxamide (PF-06650833), a Potent, Selective Inhibitor of Interleukin-1 Receptor Associated Kinase 4 (IRAK4), by Fragment-Based Drug Design.

Through fragment-based drug design focused on engaging the active site of IRAK4 and leveraging three-dimensional topology in a ligand-efficient manner, a micromolar hit identified from a screen of a Pfizer fragment library was optimized to afford IRAK4 inhibitors with nanomolar potency in cellular assays. The medicinal chemistry effort featured the judicious placement of lipophilicity, informed by co-crystal structures with IRAK4 and optimization of ADME properties to deliver clinical candidate PF-06650833 (compound 40). This compound displays a 5-unit increase in lipophilic efficiency from the fragment hit, excellent kinase selectivity, and pharmacokinetic properties suitable for oral administration.

Recent developments in targeting protein misfolding diseases.

Protein misfolding is an emerging field that crosses multiple therapeutic areas and causes many serious diseases. As the biological pathways of protein misfolding become more clearly elucidated, small molecule approaches in this arena are gaining increased attention. This manuscript will survey current small molecules from the literature that are known to modulate misfolding, stabilization or proteostasis.

Small molecules that target protein misfolding.

Protein misfolding is a process in which proteins are unable to attain or maintain their biologically active conformation. Factors contributing to protein misfolding include missense mutations and intracellular factors such as pH changes, oxidative stress, or metal ions. Protein misfolding is linked to a large number of diseases such as cystic fibrosis, Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and less familiar diseases such as Gaucher's disease, nephrogenic diabetes insipidus, and Creutzfeldt-Jakob disease.

Discovery of WAY-260022, a Potent and Selective Inhibitor of the Norepinephrine Transporter.

The potency and selectivity of a series of 1-{(1S)-2-[amino]-1-[3-(trifluoromethoxy)phenyl]ethyl}cyclohexanol analogues are described. These compounds were prepared to improve in vitro metabolic stability and achieve brain penetration. Compound 13 (WAY-260022, NRI-022) was found to be a potent inhibitor of norepinephrine reuptake and demonstrated excellent selectivity over the serotonin and dopamine transporters.

Novel synthesis and structural characterization of a high-affinity paramagnetic kinase probe for the identification of non-ATP site binders by nuclear magnetic resonance.

To aid in the pursuit of selective kinase inhibitors, we have developed a unique ATP site binder tool for the detection of binders outside the ATP site by nuclear magnetic resonance (NMR). We report here the novel synthesis that led to this paramagnetic spin-labeled pyrazolopyrimidine probe (1), which exhibits nanomolar inhibitory activity against multiple kinases. We demonstrate the application of this probe by performing NMR binding experiments with Lck and Src kinases and utilize it to detect the binding of two compounds proximal to the ATP site.

Structure-activity relationships of the cycloalkanol ethylamine scaffold: discovery of selective norepinephrine reuptake inhibitors.

Further exploration of the cycloalkanol ethylamine scaffold, of which venlafaxine ( 1) is a member, was undertaken to develop novel and selective norepinephrine reuptake inhibitors (NRIs) for evaluation in a variety of predictive animal models. These efforts led to the discovery of a piperazine-containing analogue, 17g (WY-46824), that exhibited potent norepinephrine reuptake inhibition, excellent selectivity over the serotonin transporter, but no selectivity over the dopamine transporter. Synthesis and testing of a series of cyclohexanol ethylpiperazines identified ( S)-(-)- 17i (WAY-256805), a potent norepinephrine reuptake inhibitor (IC 50 = 82 nM, K i = 50 nM) that exhibited excellent selectivity over both the serotonin and dopamine transporters and was efficacious in animal models of depression, pain, and thermoregulatory dysfunction.

Identification of a novel class of selective Tpl2 kinase inhibitors: 4-Alkylamino-[1,7]naphthyridine-3-carbonitriles.

We have previously reported the discovery and initial SAR of the [1,7]naphthyridine-3-carbonitriles and quinoline-3-carbonitriles as Tumor Progression Loci-2 (Tpl2) kinase inhibitors. In this paper, we report new SAR efforts which have led to the identification of 4-alkylamino-[1,7]naphthyridine-3-carbonitriles. These compounds show good in vitro and in vivo activity against Tpl2 and improved pharmacokinetic properties.

Synthesis of pyrazolo[1,5-alpha]pyrimidinone regioisomers.

This work describes two distinct routes to prepare pyrazolo[1,5-alpha]pyrimidin-7-ones and two distinct routes to prepare pyrazolo[1,5-alpha]pyrimidin-5-ones. Use of 1,3-dimethyluracil as the electrophile in the preparation of the pyrimidin-5-one regioisomer represents a correction of previously reported results. Also, a novel reaction to prepare this isomer was identified and the reaction mechanism elucidated.

Inhibition of Tpl2 kinase and TNFalpha production with quinoline-3-carbonitriles for the treatment of rheumatoid arthritis.

The synthesis and structure-activity studies of a series of quinoline-3-carbonitriles as inhibitors of Tpl2 kinase are described. Potent inhibitors of Tpl2 kinase with selectivity against a panel of selected kinases in enzymatic assays and specificity in cell-based phosphorylation assays in LPS-treated human monocytes were identified. Selected inhibitors with moderate activity in human whole blood assay effectively inhibited LPS/D-Gal induced TNFalpha release when administered intraperitoneally in mice.

Inhibition of Tpl2 kinase and TNF-alpha production with 1,7-naphthyridine-3-carbonitriles: synthesis and structure-activity relationships.

The synthesis and structure-activity studies of a series of 6-substituted-4-anilino-[1,7]-naphthyridine-3-carbonitriles as inhibitors of Tpl2 kinase are described. The early exploratory work described here may lead to the discovery of compounds with significant therapeutic potential for treating rheumatoid arthritis and other inflammatory diseases.