Renoprotective Effect of TP0472993, a Novel and Selective 20-Hydroxyeicosatetraenoic Acid Synthesis Inhibitor, in Mouse Models of Renal Fibrosis.

Kidney fibrosis is considered the essential pathophysiological process for the progression of chronic kidney disease (CKD) toward renal failure. 20-Hydroxyeicosatetraenoic acid (20-HETE) has crucial roles in modulating the vascular response in the kidney and the progression of albuminuria. However, the roles of 20-HETE in kidney fibrosis are largely unexplored. In the current research, we hypothesized that if 20-HETE has important roles in the progression of kidney fibrosis, 20-HETE synthesis inhibitors might be effective against kidney fibrosis. To verify our hypothesis, this study investigated the effect of a novel and selective 20-HETE synthesis inhibitor, TP0472993, on the development of kidney fibrosis after folic acid- and obstructive-induced nephropathy in mice. Chronic treatment with TP0472993 at doses of 0.3 and 3 mg/kg twice a day attenuated the degree of kidney fibrosis in the folic acid nephropathy and the unilateral ureteral obstruction (UUO) mice, as demonstrated by reductions in Masson's trichrome staining and the renal collagen content. In addition, TP0472993 reduced renal inflammation, as demonstrated by markedly reducing interleukin-1ß (IL-1ß) and tumor necrosis factor alpha (TNF-α) levels in the renal tissue. Chronic treatment with TP0472993 also reduced the activity of extracellular signal-regulated kinase 1/2 (ERK1/2) and signal transducer and activator of transcription 3 (STAT3) in the kidney of UUO mice. Our observations indicate that inhibition of 20-HETE production with TP0472993 suppresses the kidney fibrosis progression via a reduction in the ERK1/2 and STAT3 signaling pathway, suggesting that 20-HETE synthesis inhibitors might be a novel treatment option against CKD. SIGNIFICANCE STATEMENT: In this study, we demonstrate that the pharmacological blockade of 20-hydroxyeicosatetraenoic acid (20-HETE) synthesis using TP0472993 suppresses the progression of kidney fibrosis after folic acid- and obstructive-induced nephropathy in mice, indicating that 20-HETE might have key roles in the pathogenesis of kidney fibrosis. TP0472993 has the potential to be a novel therapeutic approach against chronic kidney disease.

Preclinical Metabolism and Disposition of TP0473292, a Novel Oral Prodrug of the Potent Metabotropic Glutamate 2/3 Receptor Antagonist TP0178894 for the Treatment of Depression.

TP0473292 is an adamantane carboxylic acid (ACA) ester prodrug for enhancing the oral bioavailability of the hydrophilic glutamate analog TP0178894, a novel metabotropic glutamate 2 and 3 receptor antagonist, and being developed as an antidepressant. TP0473292 showed high membrane permeability and rapid hydrolysis to TP0178894 in rat, monkey, and human liver S9 fractions, with a conversion rate of such that complete conversion by first-pass metabolism was expected. TP0473292 was also hydrolyzed in the intestinal, renal, and lung S9 fractions, coinciding with the result that TP0473292 was activated by carboxylesterase (CES) 1 and more efficiently by CES2. Despite the rapid hydrolysis of TP0473292 in the intestinal S9 fraction, TP0473292 achieved good oral bioavailability of poorly permeable TP0178894 (approximately 60%) in rats and monkeys, with no TP0473292 detected in the plasma, revealing that rapid hydrolysis in the intestine is not necessarily a disadvantage. We also confirmed the penetration of TP0178894 into the cerebrospinal fluid and its unmetabolized excretion in urine. The ester promoiety, ACA, was metabolized to chemically stable acyl glucuronide and excreted in urine in rats and monkeys, suggesting a low risk of idiosyncratic drug toxicity. TP0473292 and its metabolites did not show a drug-drug interaction potential via cytochrome P450 in humans. These results suggested that TP0473292 functions as an ideal oral prodrug in humans; this was later confirmed to be true in phase 1 clinical trials. Furthermore, ACA was firstly confirmed to be a useful promoiety for hydrophilic drugs to enhance their oral bioavailability. SIGNIFICANCE STATEMENT: Hydrolysis in the intestine reportedly has negative effects on the oral bioavailability of hydrophilic active metabolites of ester prodrugs. This study reports the preclinical pharmacokinetics of a hydrophilic metabotropic glutamate 2/3 receptor antagonist, TP0178894, and its ester prodrug TP0473292, which was found to act as an oral prodrug despite being activated predominantly in the intestine. Furthermore, this study firstly reports that adamantane carboxylic acid is useful as the ester promoiety of a prodrug for increasing lipophilicity and oral bioavailability.

Discovery of Novel Pyrazolylpyridine Derivatives for 20-Hydroxyeicosatetraenoic Acid Synthase Inhibitors with Selective CYP4A11/4F2 Inhibition.

20-Hydroxyeicosatetraenoic acid (20-HETE) is one of the major oxidized arachidonic acid (AA) metabolites produced by cytochrome P450 (CYP) 4A11 and CYP4F2 isozymes in the human liver and kidney. Numerous studies have suggested the involvement of 20-HETE in the pathogenesis of renal diseases, and suppression of 20-HETE production by inhibition of CYP4A11 and CYP4F2 may be an attractive therapeutic strategy for renal diseases. At first, we identified methylthiazole derivative 2 as a potent dual inhibitor of CYP4A11 and CYP4F2. An optimization study of a series of derivatives with a molecular weight of around 300 to improve aqueous solubility and selectivity against drug-metabolizing CYPs while maintaining the CYP4A11- and CYP4F2-inhibitory activities led to the identification of acetylpiperidine compound 11c. Compound 11c inhibited 20-HETE production in both human and rat renal microsomes and exhibited a favorable pharmacokinetic profile. Furthermore, 11c also significantly inhibited renal 20-HETE production in Sprague-Dawley rats after oral dosing at 0.1 mg/kg.

Prediction of a clinically effective dose of THY1773, a novel V1B receptor antagonist, based on preclinical data.

THY1773 is a novel arginine vasopressin 1B (V1B ) receptor antagonist that is under development as an oral drug for the treatment of major depressive disorder (MDD). Here we report our strategy to predict a clinically effective dose of THY1773 for MDD in the preclinical stage, and discuss the important insights gained by retrospective analysis of prediction accuracy. To predict human pharmacokinetic (PK) parameters, several extrapolation methods from animal or in vitro data to humans were investigated. The fu correction intercept method and two-species-based allometry were used to extrapolate clearance from rats and dogs to humans. The physiologically based pharmacokinetics (PBPK)/receptor occupancy (RO) model was developed by linking free plasma concentration with pituitary V1B RO by the Emax model. As a result, the predicted clinically effective dose of THY1773 associated with 50% V1B RO was low enough (10 mg/day, or at maximum 110 mg/day) to warrant entering phase 1 clinical trials. In the phase 1 single ascending dose study, TS-121 capsule (active ingredient: THY1773) showed favorable PKs for THY1773 as expected, and in the separately conducted phase 1 RO study using positron emission tomography, the observed pituitary V1B RO was comparable to our prediction. Retrospective analysis of the prediction accuracy suggested that the prediction methods considering plasma protein binding, and avoiding having to apply unknown scaling factors obtained in animals to humans, would lead to better prediction. Selecting mechanism-based methods with reasonable assumptions would be critical for the successful prediction of a clinically effective dose in the preclinical stage of drug development.

Pharmacological Characterization of TP0591816, a Novel Macrocyclic Respiratory Syncytial Virus Fusion Inhibitor with Antiviral Activity against F Protein Mutants.

Human respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in early childhood. However, no vaccines have yet been approved for prevention of RSV infection, and the treatment options are limited. Therefore, development of effective and safe anti-RSV drugs is needed. In this study, we evaluated the antiviral activity and mechanism of action of a novel macrocyclic anti-RSV compound, TP0591816. TP0591816 showed significant antiviral activities against both subgroup A and subgroup B RSV, while exerting no cytotoxicity. Notably, the antiviral activity of TP0591816 was maintained against a known fusion inhibitor-resistant RSV strain with a mutation in the cysteine-rich region or in heptad repeat B. Results of a time-of-addition assay and a temperature shift assay indicated that TP0591816 inhibited fusion of RSV with the cell membrane during viral entry. In addition, TP0591816 added after cell infection also inhibited cell-cell fusion. A TP0591816-resistant virus strain selected by serial passage had an L141F mutation, but no mutation in the cysteine-rich region or in heptad repeat B in the fusion (F) protein. Treatment with TP0591816 reduced lung virus titers in a dose-dependent manner in a mouse model of RSV infection. Furthermore, the estimated effective dose of TP0591816 for use against F protein mutants was thought to be clinically realistic and potentially tolerable. Taken together, these findings suggest that TP0591816 is a promising novel candidate for the treatment of resistant RSV infection.