Therapeutic Effect of Colony Stimulating Factor 1 Receptor Kinase Inhibitor, JTE-952, on Methotrexate-Refractory Pathology in a Rat Model of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by inflammation and the destruction of bone and cartilage in affected joints. One of the unmet medical needs in the treatment of RA is to effectively prevent the structural destruction of joints, especially bone, which progresses because of resistance to conventional drugs that mainly have anti-inflammatory effects, and directly leads to a decline in the QOL of patients. We previously developed a novel and orally available type II kinase inhibitor of colony-stimulating factor-1 receptor (CSF1R), JTE-952. CSF1R is specifically expressed by monocytic-lineage cells, including bone-resorbing osteoclasts, and is important for promoting the differentiation and proliferation of osteoclasts. In the present study, we investigated the therapeutic effect of JTE-952 on methotrexate (MTX)-refractory joint destruction in a clinically established adjuvant-induced arthritis rat model. JTE-952 did not suppress paw swelling under inflammatory conditions, but it inhibited the destruction of joint structural components including bone and cartilage in the inflamed joints. In addition, decreased range of joint motion and mechanical hyperalgesia after disease onset were suppressed by JTE-952. These results suggest that JTE-952 is expected to prevent the progression of the structural destruction of joints and its associated effects on joint motion and pain by inhibiting CSF1/CSF1R signaling in RA pathology, which is resistant to conventional disease-modifying anti-rheumatic drugs such as MTX.

JTE-952 Suppresses Bone Destruction in Collagen-Induced Arthritis in Mice by Inhibiting Colony Stimulating Factor 1 Receptor.

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by synovial inflammation and structural destruction of the joints. Bone damage occurs in an early stage after onset and osteoclast activation plays a substantial role in its progression. Colony stimulating factor 1 receptor (CSF1R) is a receptor protein tyrosine kinase specifically expressed in monocytic-lineage cells such as macrophages and osteoclasts. Here, we investigated the effect of JTE-952, a novel CSF1R tyrosine kinase inhibitor, on osteoclast formation in vitro and on bone destruction in a mouse model of collagen-induced arthritis. JTE-952 completely inhibited osteoclast differentiation from human monocytes, with an IC50 of 2.8 nmol/L, and reduced osteoclast formation from the synovial cells of RA patients. Detectable levels of colony stimulating factor 1 (CSF1), a ligand of CSF1R, were observed in the synovial tissues of the arthritis model, similar to those observed in the pathology of human RA. JTE-952 significantly suppressed increases in the bone destruction score, the number of tartrate-resistant-acid-phosphatase-positive cells, and the severity of arthritis in the model mice. We also examined the efficacy of JTE-952 combined with methotrexate. This combination therapy more effectively reduced the severity of bone destruction and arthritis than monotherapy with either agent alone. In summary, JTE-952 potently inhibited human osteoclast formation in vitro and suppressed bone destruction in an experimental arthritis model, especially when combined with methotrexate. These results indicate that JTE-952 should strongly inhibit bone destruction and joint inflammation in RA patients and effectively prevent the progression of the structural destruction of joints.

Pharmacological Properties of JTE-952, an Orally Available and Selective Colony Stimulating Factor 1 Receptor Kinase Inhibitor.

Colony stimulating factor 1 (CSF1) receptor (CSF1R) is a receptor protein-tyrosine kinase specifically expressed in monocyte-lineage cells, such as monocytes and macrophages. In this study, we characterized the pharmacological properties of an azetidine compound, JTE-952 ((2S)-3-{[2-({3-[4-(4-cyclopropylbenzyloxy)-3-methoxyphenyl]azetidine-1-yl}carbonyl)pyridin-4-yl]methoxy}propane-1,2-diol), which is a novel CSF1R tyrosine kinase inhibitor. JTE-952 potently inhibited human CSF1R kinase activity, with a half maximal inhibitory concentration of 11.1 nmol/L, and inhibited the phosphorylation of CSF1R in human macrophages and the CSF1-induced proliferation of human macrophages. It also inhibited human tropomyosin-related kinase A activity, but only at concentrations 200-fold higher than that required to inhibit the activity of CSF1R in inducing the proliferation of human macrophages. JTE-952 displayed no marked inhibitory activity against other kinases. JTE-952 potently inhibited lipopolysaccharide-induced proinflammatory cytokine production by human macrophages and in whole blood. JTE-952 (≥3 mg/kg given orally) also significantly attenuated the CSF1-induced priming of lipopolysaccharide-induced tumor necrosis factor-alpha production in mice and arthritis severity in a mouse model of collagen-induced arthritis. Taken together, these results indicate that JTE-952 is an orally available compound with potent and specific inhibitory activity against CSF1R, both in vitro and in vivo. JTE-952 is a potentially clinically useful agent for various human inflammatory diseases, including rheumatoid arthritis.

A Novel TNF-α Converting Enzyme (TACE) Selective Inhibitor JTP-96193 Prevents Insulin Resistance in KK-Ay Type 2 Diabetic Mice and Diabetic Peripheral Neuropathy in Type 1 Diabetic Mice.

Tumor necrosis factor-α (TNF-α) converting enzyme/a disintegrin and metalloproteinase domain-containing protein 17 (TACE/ADAM17) is a key sheddase that releases TNF-α from its inactive precursor and is thought as a new drug target to inhibit TNF-α production. In the present study, pharmacological effects of a novel TACE selective inhibitor, JTP-96193, on type 2 diabetes and diabetic peripheral neuropathy (DPN) as its major complication was examined. Enzyme inhibitory activity of JTP-96193 on TACE and other ADAMs was measured in in vitro. High fat-induced obese mice and type 2 diabetic KK-Ay mice were used to evaluate the effect of JTP-96193 on insulin resistance. Finally, streptozotocin (STZ)-induced diabetic mice were treated with JTP-96193 to evaluate the sciatic motor nerve conduction velocities (MNCV). JTP-96193 selectively inhibited human TACE activity with IC50 value of 5.4 nM and showed more than 1800-fold selectivity against other matrix metalloproteinases. In mouse models of obesity and diabetes, JTP-96193 reduced the TNF-α release from the fat tissue and prevented development of diabetes and improved insulin resistance, respectively. Furthermore, JTP-96193 prevented delay of sciatic MNCV without any effects on blood glucose or insulin levels in STZ-induced diabetic mice. TACE inhibitor is effective on insulin resistance and DPN independent from glucose-lowering effect. These pharmacological properties of JTP-96193 may be helpful to treat type 2 diabetes accompanied by its microvascular complications.

Suppressive effect of an orally active MEK1/2 inhibitor in two different animal models for rheumatoid arthritis: a comparison with leflunomide.

OBJECTIVE AND DESIGN: To examine the effects of a mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2-inhibitor, JTP-74057, on inflammatory arthritis development, and compare its anti-arthritic effect with leflunomide. MATERIALS: Human, mouse, and rat peripheral blood mononuclear cells (PBMCs) were used. Lewis rats and DBA/1J mice were used for animal models. TREATMENT: JTP-74057 was tested between 0.1-100 nM in in-vitro studies. JTP-74057 (0.01-0.3 mg/kg) and leflunomide (2-10 mg/kg) were administered orally in vivo. METHODS: PBMCs were stimulated with lipopolysaccharide. Adjuvant-induced arthritis (AIA) and type II collagen-induced arthritis (CIA) was induced in Lewis rats or DBA1/J mice, respectively. RESULTS: JTP-74057 blocked tumor necrosis factor-α and interleukin-6 production from PBMCs. AIA and CIA development were suppressed almost completely by 0.1 mg/kg of JTP-74057 or 10 mg/kg of leflunomide. In the CIA, JTP-74057, but not leflunomide, suppressed collagen-reactive T-cell proliferation ex vivo, whereas leflunomide, but not JTP-74057, suppressed anti-collagen antibody production. CONCLUSIONS: JTP-74057 exerts potent anti-arthritic effects with a different profile from leflunomide, suggesting that JTP-74057 may be useful as a new therapeutic reagent in the treatment of rheumatoid arthritis.

Antitumor activities of JTP-74057 (GSK1120212), a novel MEK1/2 inhibitor, on colorectal cancer cell lines in vitro and in vivo.

The MAPK pathway is one of the most important pathways for novel anticancer drug development. We performed high-throughput screening for compounds that induce expression of p15INK4b, and identified JTP-74057 (GSK1120212), which is being evaluated in ongoing phase I, II and III clinical trials. We characterized its antitumor activities in vitro and in vivo. JTP-74057 strongly inhibited MEK1/2 kinase activities, but did not inhibit another 98 kinase activities. Treatment by JTP-74057 resulted in growth inhibition accompanied with upregulation of p15INK4b and/or p27KIP1 in most of the colorectal cancer cell lines tested. Daily oral administration of JTP-74057 for 14 days suppressed tumor growth of HT-29 and COLO205 xenografts in nude mice. Notably, tumor regression was observed only in COLO205 xenografts, and COLO205 was much more sensitive to JTP-74057-induced apoptosis than HT-29 in vitro. Treatment with an Akt inhibitor enhanced the JTP-74057-induced apoptosis in HT-29 cells. Finally, JTP-74057 exhibited an additive or a synergistic effect in combination with the standard-of-care agents, 5-fluorouracil, oxaliplatin or SN-38. JTP-74057, a highly specific and potent MEK1/2 inhibitor, exerts favorable antitumor activities in vitro and in vivo. Sensitivity to JTP-74057-induced apoptosis may be an important factor for the estimation of in vivo efficacy, and sensitivity was enhanced by an Akt inhibitor. These results suggest the usefulness of JTP-74057 in therapeutic applications for colorectal cancer patients.

Discovery of a Highly Potent and Selective MEK Inhibitor: GSK1120212 (JTP-74057 DMSO Solvate).

Inhibition of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK) represents a promising strategy for the discovery of a new generation of anticancer chemotherapeutics. Our synthetic efforts, beginning from the lead compound 2, were directed at improving antiproliferative activity against cancer cells as well as various drug properties. These efforts led to the discovery of N-{3-[3-cyclopropyl-5-(2-fluoro-4-iodophenylamino)-6,8-dimethyl-2,4,7-trioxo-3,4,6,7-tetrahydro-2H-pyrido[4,3-d]pyrimidin-1-yl]phenyl}acetamide dimethylsulfoxide solvate (GSK1120212, JTP-74057 DMSO solvate; 1), a selective and highly potent MEK inhibitor with improved drug properties. We further confirmed that the antiproliferative activity correlates with cellular MEK inhibition and observed significant antitumor activity with daily oral dosing of 1 in a tumor xenograft model. These qualities led to the selection of 1 for clinical development.

Therapeutic effect of camostat mesilate on Duchenne muscular dystrophy in mdx mice.

Duchenne muscular dystrophy is known to be caused by a defective gene of dystrophin, a 427-kDa cytoskeletal protein, but the effective therapeutic drug is presently unavailable. We previously reported that a trypsin-like protease designated as dystrypsin is markedly activated in the muscle microsomal fraction immediately before onset of the clinical signs in mdx mice, a dystrophin-deficient hereditary animal model for human Duchenne muscular dystrophy. In order to examine the possible participation of dystrypsin in the occurrence of the disease, we investigated the therapeutic effects of dystrypsin inhibitors on the occurrence and progress of muscular dystrophy. Here, we show that camostat mesilate, a low-molecular-weight inhibitor of trypsin-like proteases, including dystrypsin, is a candidate drug for Duchenne muscular dystrophy.