The novel benzopyran class of selective cyclooxygenase-2 inhibitors-part I: the first clinical candidate.

In this manuscript, we report the discovery of the substituted 2-trifluoromethyl-2H-benzopyran-3-carboxylic acids as a novel series of potent and selective cyclooxygenase-2 (COX-2) inhibitors. 5c-(S) (SD-8381) was advanced into clinical studies due to its superior in vivo potency. The high plasma protein binding (>99% bound) of 5c-(S) has resulted in a surprisingly long human half life t(1/2)=360 h.

The novel benzopyran class of selective cyclooxygenase-2 inhibitors. Part 2: the second clinical candidate having a shorter and favorable human half-life.

In this Letter, we provide the structure-activity relationships, optimization of design, testing criteria, and human half-life data for a series of selective COX-2 inhibitors. During the course of our structure-based drug design efforts, we discovered two distinct binding modes within the COX-2 active site for differently substituted members of this class. The challenge of a undesirably long human half-life for the first clinical candidate 1t(1/2)=360 h was addressed by multiple strategies, leading to the discovery of 29b-(S) (SC-75416) with t(1/2)=34 h.

The novel benzopyran class of selective cyclooxygenase-2 inhibitors. Part III: the three microdose candidates.

In this manuscript, we report the discovery of the substituted 2-trifluoromethyl-2H-benzopyran-3-carboxylic acids as a novel series of potent and selective cyclooxygenase-2 (COX-2) inhibitors. We provide the structure-activity relationships, optimization of design, testing criteria, and human half-life data. The challenge of a surprisingly long half-life (t(1/2)=360 h) of the first clinical candidate 1 and human t(1/2) had been difficult to predict based on allometric scaling for this class of highly ppb compounds. We used a microdose strategy which led to the discovery of clinical agents 18c-(S), 29b-(S), and 34b-(S) with human half-life of 57, 13, and 11 h.

Pharmacology of PF-4191834, a novel, selective non-redox 5-lipoxygenase inhibitor effective in inflammation and pain.

5-Lipoxygenase (LOX) is an important arachidonic acid-metabolizing enzyme producing leukotrienes and other proinflammatory lipid mediators with potent pathophysiological functions in asthma and other inflammatory diseases. 4-(3-(4-(1-Methyl-1H-pyrazol-5-yl)phenylthio)phenyl)-tetrahydro-2H-pyran-4-carboxamide (PF-4191834) is a novel, selective non-redox 5-lipoxygenase inhibitor effective in inflammation and pain. In vitro and in vivo assays were developed for the evaluation of a novel 5-LOX inhibitor using conditions of maximal enzyme activity. PF-4191834 exhibits good potency in enzyme- and cell-based assays, as well as in a rat model of acute inflammation. Enzyme assay results indicate that PF-4191834 is a potent 5-LOX inhibitor, with an IC(50) = 229 +/- 20 nM. Furthermore, it demonstrated approximately 300-fold selectivity for 5-LOX over 12-LOX and 15-LOX and shows no activity toward the cyclooxygenase enzymes. In addition, PF-4191834 inhibits 5-LOX in human blood cells, with an IC(80) = 370 +/- 20 nM. This inhibitory concentration correlates well with plasma exposures needed for in vivo efficacy in inflammation in models of inflammatory pain. The combination of potency in cells and in vivo, together with a sustained in vivo effect, provides PF-4191834 with an overall pharmacodynamic improvement consistent with once a day dosing.

CJ-13610, an orally active inhibitor of 5-lipoxygenase is efficacious in preclinical models of pain.

Zileuton, a redox and iron chelator 5-lipoxygenase (5-LOX) inhibitor and, leukotriene receptor antagonists are presently used clinically in the long term treatment of asthma. Recent data implicate 5-LOX pathway in pain signaling. We report 5-LOX expression in the central nervous system (CNS) and analyze the pain efficacy of a new class of non redox, non iron chelating 5-LOX inhibitor. CJ-13610, 4-(3-(4-(2-methyl-1H-imidazol-1-yl) phenylthio) phenyl)-tetrahydro-2H-pyran-4-carboxamide, demonstrated antihyperalgesic activity in inflammatory pain models including the acute carrageenan model and the chronic inflammatory model using complete Freund's adjuvant. Following complete Freund's adjuvant stimulus leukotrieneB(4) concentration in the brain was elevated (9+/-1 ng/g, mean+/-S.E.M.) by about 3 times that of the control group (3+/-0.11, mean+/-S.E.M.). Hyperalgesia and leukotrieneB(4) concentration were both reversed following CJ-13610 treatment. Furthermore, we demonstrate CJ-13610 efficacy against osteoarthritis like pain using the rat medial meniscal transection model. CJ-13610 at oral doses of 0.6, 2 and 6 mg/kg/day reversed two modalities of pain in this model; tactile allodynia and weight bearing differential. Taken together, these data suggest that 5-LOX pathway and the leukotriene products are important mediators of pain.

Synthesis, crystal structure, and activity of pyrazole-based inhibitors of p38 kinase.

A series of pyrazole inhibitors of p38 mitogen-activated protein (MAP) kinase were designed using a binding model based on the crystal structure of 1 (SC-102) bound to p38 enzyme. New chemistry using dithietanes was developed to assemble nitrogen-linked substituents at the 5-position of pyrazoles. Calculated log D was used in tandem with structure-based design to guide medicinal chemistry strategy and improve the in vivo activity of a series of molecules. The crystal structure of an optimized inhibitor, 4 (SC-806), in complex with p38 enzyme was obtained to confirm the hypothesis that the addition of a basic nitrogen to the molecule induces an interaction with Asp112 of p38 alpha. A compound identified from this series was efficacious in an animal model of rheumatic disease.

A selective IKK-2 inhibitor blocks NF-kappa B-dependent gene expression in interleukin-1 beta-stimulated synovial fibroblasts.

NF-kappa B-induced gene expression contributes significantly to the pathogenesis of inflammatory diseases such as arthritis. I kappa B kinase (IKK) is the converging point for the activation of NF-kappa B by a broad spectrum of inflammatory agonists and is thus a novel target for therapeutic intervention. We describe a small molecule, selective inhibitor of IKK-2, SC-514, which does not inhibit other IKK isoforms or other serine-threonine and tyrosine kinases. SC-514 inhibits the native IKK complex or recombinant human IKK-1/IKK-2 heterodimer and IKK-2 homodimer similarly. IKK-2 inhibition by SC-514 is selective, reversible, and competitive with ATP. SC-514 inhibits transcription of NF-kappa B-dependent genes in IL-1 beta-induced rheumatoid arthritis-derived synovial fibroblasts in a dose-dependent manner. When the mechanism of NF-kappa B activation was evaluated in the presence of this inhibitor, several interesting observations were found. First, SC-514 did not inhibit the phosphorylation and activation of the IKK complex. Second, there was a delay but not a complete blockade in I kappa B alpha phosphorylation and degradation; likewise there was a slightly slowed, decreased import of p65 into the nucleus and a faster export of p65 from the nucleus. Finally, both I kappa B alpha and p65 were comparable substrates for IKK-2, with similar Km and Kcat values, and SC-514 inhibited the phosphorylation of either substrate similarly. Thus, the effect of SC-514 on cytokine gene expression may be a combination of inhibiting I kappa B alpha phosphorylation/degradation, affecting NF-kappa B nuclear import/export as well as the phosphorylation and transactivation of p65.

Radiosynthesis, in vitro validation, and in vivo evaluation of 18F-labeled COX-1 and COX-2 inhibitors.

UNLABELLED: In this article, we describe the radiosynthesis and evaluation of 18F-labeled cyclooxygenase (COX) inhibitors. 18F-SC63217 is selective to COX-1 and has a COX-1 inhibitory concentration of 50% (IC(50)) < 10 nmol/L and a COX-2 IC(50) > 100 micromol/L. 18F-SC58125 has IC(50) values of >100 micromol/L (COX-1) and <86 nmol/L (COX-2). METHODS: SC63217 and SC58125 were both labeled with 18F by nucleophilic displacement of a trimethylammonium triflate salt using a dedicated microwave cavity. Each compound was evaluated in vitro using a murine macrophage cell line (J774). COX-2 was stimulated in these cells by treatment with lipopolysaccharide and interferon-gamma. Both radiotracers were further investigated in vivo using rat biodistribution techniques. Brain uptake of the COX-2 inhibitor, 18F-SC58125, was further investigated by brain PET of a baboon. RESULTS: The in vitro studies showed that uptake of 18F-SC58125 was increased in stimulated cells and was totally inhibited by the addition of nonradioactive SC58125. In contrast, no increase in uptake was seen for 18F-SC63217. In the biodistribution experiments, 18F-SC63217 showed much higher uptake in the small intestine (an organ known to express high levels of COX-1) than did 18F-SC58125. Higher levels of 18F-SC58125 were observed in the kidney, an organ known to contain high levels of COX-2 rather than COX-1. 18F-SC58125 was retained in brain tissue. PET images of the baboon showed no regional distribution of the radiotracer in the brain. CONCLUSION: We have developed a radiosynthetic route that can yield 18F-labeled selective inhibitors of COX-1 or COX-2. Both compounds have been fully characterized in vitro and in vivo. Our results indicate that 18F-SC58125 has potential as a marker of COX-2 activity but that, because of high nonspecific binding, 18F-SC63217 was not a good choice as a marker of COX-1.