Toshito Nakagawa

5-Hydroxyindole-2-carboxylic Acid Amides: Novel Histamine-3 Receptor Inverse Agonists for the Treatment of Obesity

Obesity is a major risk factor in the development of conditions such as hypertension, hyperglycemia, dyslipidemia, coronary artery disease, and cancer. Several pieces of evidence across different species, including primates, underscore the implication of the histamine 3 receptor (H(3)R) in the regulation of food intake and body weight and the potential therapeutic effect of H(3)R inverse agonists. A pharmacophore model, based on public information and validated by previous investigations, was used to design several potential scaffolds. Out of these scaffolds, the 5-hydroxyindole-2-carboxylic acid amide appeared to be of great potential as a novel series of H(3)R inverse agonist. Extensive structure-activity relationships revealed the interconnectivity of microsomal clearance and hERG (human ether-a-go-go-related gene) affinity with lipophilicity, artificial membrane permeation, and basicity. This effort led to the identification of compounds reversing the (R)-alpha-methylhistamine-induced water intake increase in Wistar rats and, further, reducing food intake in diet-induced obese Sprague-Dawley rats. Of these, the biochemical, pharmacokinetic, and pharmacodynamic characteristics of (4,4-difluoropiperidin-1-yl)[1-isopropyl-5-(1-isopropylpiperidin-4-yloxy)-1H-indol-2-yl]methanone 36 are detailed.

Design and synthesis of an androgen receptor pure antagonist (CH5137291 ) for the treatment of castration-resistant prostate cancer

A series of 5,5-dimethylthiohydantoin derivatives were synthesized and evaluated for androgen receptor pure antagonistic activities for the treatment of castration-resistant prostate cancer. Since CH4933468, which we reported previously, had a problem with agonist metabolites, novel thiohydantoin derivatives were identified by applying two strategies. One was the replacement of the alkylsulfonamide moiety by a phenylsulfonamide to avoid the production of agonist metabolites. The other was the replacement of the phenyl ring with a pyridine ring to improve in vivo potency and reduce hERG affinity. Pharmacological assays indicated that CH5137291 (17b) was a potent AR pure antagonist which did not produce the agonist metabolite. Moreover, CH5137291 completely inhibited in vivo tumor growth of LNCaP-BC2, a castration-resistant prostate cancer model.

Stronger uricosuric effects of the novel selective URAT1 inhibitor UR-1102 lowered plasma urate in tufted capuchin monkeys to a greater extent than benzbromarone

Urate-lowering therapy is indispensable for the treatment of gout, but available drugs do not control serum urate levels tightly enough. Although the uricosurics benzbromarone and probenecid inhibit a urate reabsorption transporter known as renal urate transporter 1 (URAT1) and thus lower serum urate levels, they also inhibit other transporters responsible for secretion of urate into urine, which suggests that inhibiting URAT1 selectively would lower serum urate more effectively. We identified a novel potent and selective URAT1 inhibitor, UR-1102, and compared its efficacy with benzbromarone in vitro and in vivo. In human embryonic kidney (HEK)293 cells overexpressing URAT1, organic anion transporter 1 (OAT1), and OAT3, benzbromarone inhibited all transporters similarly, whereas UR-1102 inhibited URAT1 comparably to benzbromarone but inhibited OAT1 and OAT3 quite modestly. UR-1102 at 3–30 mg/kg or benzbromarone at 3–100 mg/kg was administered orally once a day for 3 consecutive days to tufted capuchin monkeys, whose low uricase activity causes a high plasma urate level. When compared with the same dosage of benzbromarone, UR-1102 showed a better pharmacokinetic profile, increased the fractional excretion of urinary uric acid, and reduced plasma uric acid more effectively. Moreover, the maximum efficacy of UR-1102 was twice that of benzbromarone, suggesting that selective inhibition of URAT1 is effective. Additionally UR-1102 showed lower in vitro potential for mechanisms causing the hepatotoxicity induced by benzbromarone. These results indicate that UR-1102 achieves strong uricosuric effects by selectively inhibiting URAT1 over OAT1 and OAT3 in monkeys, and could be a novel therapeutic option for patients with gout or hyperuricemia.

Discovery of potent and selective histamine H3 receptor inverse agonists based on the 3,4-dihydro-2H-pyrazino[1,2-a]indol-1-one scaffold

A novel series of potent histamine H(3) receptor inverse agonists based on the 3,4-dihydro-2H-pyrazino[1,2-a]indol-1-one scaffold has been discovered. Several compounds display high selectivity over other histamine receptor subtypes and have favorable physicochemical properties, low potential for CYP450 enzyme inhibition and high metabolic stability in microsomal preparations. (R)-2-Cyclopropylmethyl-8-(1-isopropyl-piperidin-4-yloxy)-3-methyl-3,4-dihydro-2H-pyrazino[1,2-a]indol-1-one (8t) showed good in vivo efficacy after per os application in an acute rat dipsogenia model of water intake.

Structure–activity relationships of bioisosteric replacement of the carboxylic acid in novel androgen receptor pure antagonists

A series of 5,5-dimethylthiohydantoin derivatives were synthesized and evaluated for androgen receptor pure antagonistic activities for the treatment of hormone refractory prostate cancer. CH4933468 (32d) with a sulfonamide side chain not only exhibited antagonistic activity with no agonistic activity in the reporter gene assay but also inhibited the growth of bicalutamide-resistant cell lines. This compound also inhibited tumor growth of the LNCaP xenograft in mice dose-dependently.

Biological properties of androgen receptor pure antagonist for treatment of castration-resistant prostate cancer: Optimization from lead compound to CH5137291†

Castration‐resistant prostate cancer (CRPC) is still dependent on androgen receptor (AR) signaling. We previously reported that a novel nonsteroidal AR pure antagonist, CH4933468, which is a thiohydantoin derivative with a sulfonamide side chain, provided in vitro proof of concept but did not in vivo.

Metabolites of alectinib in human: their identification and pharmacological activity

Two metabolites (M4 and M1b) in plasma and four metabolites (M4, M6, M1a and M1b) in faeces were detected through the human ADME study following a single oral administration of [14C]alectinib, a small-molecule anaplastic lymphoma kinase inhibitor, to healthy subjects. In the present study, M1a and M1b, which chemical structures had not been identified prior to the human ADME study, were identified as isomers of a carboxylate metabolite oxidatively cleaved at the morpholine ring. In faeces, M4 and M1b were the main metabolites, which shows that the biotransformation to M4 and M1b represents two main metabolic pathways for alectinib. In plasma, M4 was a major metabolite and M1b was a minor metabolite. The contribution to in vivo pharmacological activity of these circulating metabolites was assessed from their in vitro pharmacological activity and plasma protein binding. M4 had a similar cancer cell growth inhibitory activity and plasma protein binding to that of alectinib, suggesting its contribution to the antitumor activity of alectinib, whereas the pharmacological activity of M1b was insignificant.

CH5137291, an androgen receptor nuclear translocation-inhibiting compound, inhibits the growth of castration-resistant prostate cancer cells

Resistance of prostate cancer to castration is currently an unavoidable problem. The major mechanisms underlying such resistance are androgen receptor (AR) overexpression, androgen-independent activation of AR, and AR mutation. To address this problem, we developed an AR pure antagonist, CH5137291, with AR nuclear translocation-inhibiting activity, and compared its activity and characteristics with that of bicalutamide. Cell lines corresponding to the mechanisms of castration resistance were used: LNCaP-BC2 having AR overexpression and LNCaP-CS10 having androgen-independent AR activation. VCaP and LNCaP were used as hormone-sensitive prostate cancer cells. In vitro functional assay clearly showed that CH5137291 inhibited the nuclear translocation of wild-type ARs as well as W741C- and T877A-mutant ARs. In addition, it acted as a pure antagonist on the transcriptional activity of these types of ARs. In contrast, bicalutamide did not inhibit the nuclear translocation of these ARs, and showed a partial/full agonistic effect on the transcriptional activity. CH5137291 inhibited cell growth more strongly than bicalutamide in VCaP and LNCaP cells as well as in LNCaP-BC2 and LNCaP-CS10 cells in vitro. In xenograft models, CH5137291 strongly inhibited the tumor growth of LNCaP, LNCaP-BC2, and LNCaP-CS10, whereas bicalutamide showed a weaker effect in LNCaP and almost no effect in LNCaP-BC2 and LNCaP-CS10 xenografts. Levels of prostate-specific antigen (PSA) in plasma correlated well with the antitumor effect of both agents. CH5137291 inhibited the growth of LNCaP tumors that had become resistant to bicalutamide treatment. A docking model suggested that CH5137291 intensively collided with the M895 residue of helix 12, and therefore strongly inhibited the folding of helix 12, a cause of AR agonist activity, in wild-type and W741C-mutant ARs. In cynomolgus monkeys, the serum concentration of CH5137291 increased dose-dependently and PSA level decreased 80% at 100 mg/kg. CH5137291 is expected to offer a novel therapeutic approach against major types of castration-resistant prostate cancers.

SAT0356 The Therapeutic Efficacy of the Novel Uricosuric Agent UR-1102 for Hyperuricemia and Gout

Background Control of blood uric acid is important for the treatment of gout. The clinical potential of a selective uric acid transporter 1 (URAT1) inhibitor as a drug for hyperuricemia and gout remains unknown because currently available uricosuric drugs block renal uric acid reabsorption by inhibiting not only URAT1 but also other transporters responsible for renal tubular uric acid secretion, such as OAT1 or OAT3. We have identified a highly selective URAT1 inhibitor, UR-1102, which is now under clinical trial for gout. Objectives In this study, we examined the therapeutic potential of selective URAT1 inhibition with UR-1102 by comparing it with benzbromarone, a traditional non-selective URAT1 inhibitor, in vitro and in vivo with cebus monkeys, an animal model that has similar purine metabolism and urinary uric acid excretion to humans. Methods The inhibitory effects of UR-1102 and benzbromarone on URAT1, OAT1, OAT3 and ABCG2 were evaluated in vitro using CHO cells that over-express these transporters. UR-1102 at 3, 10, and 30 mg/kg or benzbromarone at 3, 10, 30, and 100 mg/kg were administered orally once a day to cebus monkeys for 3 consecutive days (n=6, cross-over study). Plasma and urinary excretion of uric acid and creatinine were measured at regular time intervals. Fractional excretion of uric acid (FEUA) was calculated from those values. Results UR-1102 exhibited significantly more potent and highly selective (Ki values for URAT1 were >100 smaller than other transporters) URAT1 inhibition than benzbromarone in vitro, while benzbromarone inhibited URAT1, OAT1, OAT3 and ABCG2 dose-dependently as reported in the literature. The average plasma uric acid concentration for the control group was 3.6 +/- 0.2 mg/dL and FEUA was 8.8% +/- 0.4% on day 3 (0–8 hours after 3rd administration) in the cebus monkeys. Benzbromarone showed dose-dependent and significant reduction of plasma uric acid concentration (3.4, 3.0, 2.8, and 2.7 mg/dL at 3, 10, 30, and 100 mg/kg, respectively) and increase of FEUA (10.3%, 14.5%, 18.5%, and 20.6% at 3, 10, 30, and 100 mg/kg, respectively). UR-1102 also showed the dose-dependent and significant effects on plasma uric acid reduction (2.5, 2.4, and 1.8 mg/dL at 3, 10, and 30 mg/kg, respectively) and increase of FEUA (22.6%, 35.4%, and 42.1% at 3, 10, and 30 mg/kg, respectively). The effects were more apparent for UR-1102 at a lower dose. Moreover, comparing the submaximal dose of UR-1102 at 30 mg/kg with benzbromarone at 100 mg/kg, the effects were significantly higher for UR-1102 than for benzbromarone (plasma uric acid concentration: 1.8 +/- 0.2 mg/dL vs 2.7 +/- 0.2 mg/dL, p<0.01 and FEUA: 42.1% +/- 4.4% vs 20.6% +/- 2.3%, p<0.05). Conclusions Hypouricemic and uricosuric effects were more potent for UR-1102 than for benzbromarone in both dose and maximum efficacy in cebus monkeys. This may be due to the high selectivity of UR-1102 for URAT1. UR-1102 would have greater efficacy as a therapeutic drug for gout/hyperuricemia than benzbromarone. Disclosure of Interest S. O. Ahn Employee of: C&C Research Laboratories, N. Horiba Employee of: Chugai Pharmaceutical Co., Ltd., S. Ohtomo Employee of: Chugai Pharmaceutical Co., Ltd., K. J. Lee Employee of: C&C Research Laboratories, K. H. Kim Employee of: C&C Research Laboratories, B. H. Kim Employee of: C&C Research Laboratories, J. Kiyokawa Employee of: Chugai Pharmaceutical Co., Ltd., M. Yamane Employee of: Chugai Pharmaceutical Co., Ltd., H. Ikegami Employee of: Chugai Pharmaceutical Co., Ltd., T. Nakagawa Employee of: Chugai Pharmaceutical Co., Ltd., H.-H. Hwang Employee of: JW Pharmaceutical corp., J.-H. PARK Employee of: JW Pharmaceutical corp., J. Y. Cha Employee of: JW Pharmaceutical corp., J. Tanaka Employee of: Shin Nippon Biomedical Laboratories, Ltd., T. Kake Employee of: Chugai Pharmaceutical Co., Ltd.

In vitro metabolism of alectinib, a novel potent ALK inhibitor, in human: contribution of CYP3A enzymes

Abstract 1. The in vitro metabolism of alectinib, a potent and highly selective oral anaplastic lymphoma kinase inhibitor, was investigated. 2. The main metabolite (M4) in primary human hepatocytes was identified, which is produced by deethylation at the morpholine ring. Three minor metabolites (M6, M1a, and M1b) were also identified, and a minor peak of hydroxylated alectinib (M5) was detected as a possible precursor of M4, M1a, and M1b. 3. M4, an important active major metabolite, was produced and further metabolized to M6 by CYP3A, indicating that CYP3A enzymes were the principal contributors to this route. M5 is possibly produced by CYP3A and other isoforms as the primary step in metabolism, followed by oxidation to M4 mainly by CYP3A. Alternatively, M5 could be oxidized to M1a and M1b via an NAD-dependent process. None of the non-CYP3A-mediated metabolism appeared to be major. 4. In conclusion, this study suggests that involvement of multiple enzymes in the metabolism of alectinib reduces its potential for drug–drug interactions.