Ten-Gram-Scale Total Synthesis of the Anticancer Drug Candidate E7130 to Supply Clinical Trials.

E7130 is a novel drug candidate with an exceedingly complex chemical structure of the halichondrin class, discovered by a total synthesis approach through joint research between the Kishi group at Harvard University and Eisai. Only 18 months after completion of the initial milligram-scale synthesis, ten-gram-scale synthesis of E7130 was achieved, providing the first good manufacturing practice (GMP) batch to supply clinical trials. This paper highlights the challenges in developing ten-gram-scale synthesis from the milligram-scale synthesis.

A landmark in drug discovery based on complex natural product synthesis.

Despite their outstanding antitumour activity in mice, the limited supply from the natural sources has prevented drug discovery/development based on intact halichondrins. We achieved a total synthesis of C52-halichondrin-B amine (E7130) on a >10 g scale with >99.8% purity under GMP conditions. Interestingly, E7130 not only is a novel microtubule dynamics inhibitor but can also increase intratumoural CD31-positive endothelial cells and reduce α-SMA-positive cancer-associated fibroblasts at pharmacologically relevant compound concentrations. According to these unique effects, E7130 significantly augment the effect of antitumour treatments in mouse models and is currently in a clinical trial. Overall, our work demonstrates that a total synthesis can address the issue of limited material supply in drug discovery/development even for the cases of complex natural products.

Total synthesis and stereochemistry of pinnatoxins B and C.

[Structure: see text] Pinnatoxins B and C were synthesized from diols (34R)-3b and (34S)-3a, respectively, in a stereochemically controlled manner. Through extensive analysis of the 1H NMR spectra of synthetic PnTXs B and C, the diagnostic NMR signals were first identified to differentiate (34S)- and (34R)-diastereomers and then used to establish the C34 configuration of natural PnTXs B and C as 34S and 34R, respectively.

E3024, 3-but-2-ynyl-5-methyl-2-piperazin-1-yl-3,5-dihydro-4H-imidazo[4,5-d]pyridazin-4-one tosylate, is a novel, selective and competitive dipeptidyl peptidase-IV inhibitor.

Dipeptidyl peptidase IV (DPP-IV) inhibitors are expected to become a useful new class of anti-diabetic agent. The aim of the present study is to characterize the in vitro and in vivo profile of E3024, 3-but-2-ynyl-5-methyl-2-piperazin-1-yl-3,5-dihydro-4H-imidazo[4,5-d]pyridazin-4-one tosylate, which is a novel imidazopyridazinone-derived DPP-IV inhibitor. E3024 inhibited recombinant human and mouse DPP-IV with IC50 values of approximately 100 nM. E3024 inhibited DPP-IV in human, mouse, rat and canine plasma with IC50 values of 140 to 400 nM. In contrast, E3024 did not inhibit DPP-8 or DPP-9 activity. Kinetic analysis indicated that E3024 is a competitive DPP-IV inhibitor. In Zucker fa/fa rats, E3024 (1 mg/kg) reduced glucose excursion after glucose load, with increases in plasma insulin and active glucagon-like peptide-1 levels. In fasted rats, this compound did not cause hypoglycemia. In a rat 4-week toxicological study, no notable changes were found at doses up to 750 mg/kg. The present preclinical studies indicate that E3024 is a novel selective DPP-IV inhibitor with anti-diabetic effects and a good safety profile.

Selective tissue factor/factor VIIa Inhibitor, ER-410660, and its prodrug, E5539, have anti-venous and anti-arterial thrombotic effects with a low risk of bleeding.

INTRODUCTION: Many anticoagulant drugs target factors common to both the intrinsic and extrinsic coagulation pathways, which may lead to bleeding complications. Since the tissue factor (TF)/factor VIIa complex is associated with thrombosis onset and specifically activates the extrinsic coagulation pathway, compounds that inhibit this complex may provide therapeutic and/or prophylactic benefits with a decreased risk of bleeding. MATERIALS AND METHODS: The in vitro enzyme profile and anticoagulation selectivity of the TF/VIIa complex inhibitor, ER-410660, and its prodrug E5539 were assessed using enzyme inhibitory and plasma clotting assays. In vivo effects of ER-410660 and E5539 were determined using a TF-induced, thrombin generation rhesus monkey model; a stasis-induced, venous thrombosis rat model; a photochemically induced, arterial thrombosis rat model; and a rat tail-cut bleeding model. RESULTS: ER-410660 selectively prolonged prothrombin time, but had a less potent anticoagulant effect on the intrinsic pathway. It also exhibited a dose-dependent inhibitory effect on thrombin generation caused by TF-injection in the rhesus monkey model. ER-410660 also reduced venous thrombus weights in the TF-administered, stasis-induced, venous thrombosis rat model and prolonged the occlusion time induced by arterial thrombus formation after vascular injury. The compound was capable of doubling the total bleeding time in the rat tail-cut model, albeit with a considerably higher dose compared to the effective dose in the venous and arterial thrombosis models. Moreover, E5539, an orally available ER-410660 prodrug, reduced the thrombin-anti-thrombin complex levels, induced by TF-injection, in a dose-dependent manner. CONCLUSION: Selective TF/VIIa inhibitors have potential as novel anticoagulants with a lower propensity for enhancing bleeding.

Antidiabetic and hypolipidemic effects of a novel dual peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist, E3030, in db/db mice and beagle dogs.

We investigated the antidiabetic effects of E3030, which is a potent dual activator of peroxisome proliferator-activated receptor (PPAR) alpha and PPARgamma, in an animal model of diabetes, C57BL/KsJ-db/db mice (db/db mice), and the lipidemic effects of E3030 in beagle dogs, whose PPARalpha and PPARgamma transactivation responses to E3030 were similar to those of humans. E3030 activated human PPARalpha, mouse PPARalpha, dog PPARalpha, human PPARgamma, mouse PPARgamma, and dog PPARgamma with EC(50) values of 65, 920, 87, 34, 73, and 34 nM, respectively, in the chimeric GAL4-PPAR receptor transactivation reporter assay. In db/db mice orally administered E3030 decreased blood glucose, triglyceride (TG), non-esterified fatty acids (NEFA), and insulin levels and increased blood adiponectin levels during a 14-day experimental period. Significant effects on blood glucose and adiponectin levels were observed at a dose of 3 mg/kg or greater. Furthermore, significant effects on blood TG, NEFA, and insulin levels were observed at doses of 1 mg/kg or more. An oral glucose tolerance test (OGTT) performed on Day 15 showed that E3030 at 3 mg/kg improved glucose tolerance in this model. Fourteen days of oral treatment with E3030 at a dose of 0.03 mg/kg or greater showed remarkable TG- and non high-density lipoprotein (non-HDL) cholesterol-lowering effects in beagle dogs. These results were similar to those observed for the PPARalpha agonist fenofibrate. E3030 also reduced apo C-III levels on Days 7 and 14, and elevated lipoprotein lipase (LPL) levels on Day 15. These results indicate that the TG- and non-HDL cholesterol-lowering actions of E3030 involve combined effects on reduction of apo C-III and elevation of LPL, resulting in increased lipolysis. The experimental results in animals suggest that E3030 has potential for use in the treatment of various aspects of metabolic dysfunction in type 2 diabetes, including dyslipidemia, hyperglycemia, hyperinsulinemia, and impaired glucose disposal.

Unified total synthesis of pteriatoxins and their diastereomers.

A unified total synthesis is reported to access all of the possible diastereomers of pteriatoxins A-C, with the use of an intramolecular Diels-Alder reaction as the key step to form the carbo-macrocyclic core structure. The C34/C35-diol protecting groups were found to have significant effects on both the exo/endo-selectivity and the exo-facial selectivity of the intramolecular Diels-Alder process.

Stereochemistry of pteriatoxins A, B, and C.

The C34 and C2' stereochemistry of pteriatoxins A-C has been established. The availability of all the stereoisomers via total synthesis has played an indispensable role.