Kouichi Uoto

A New Water‐soluble Camptothecin Derivative, DX‐8951f, Exhibits Potent Antitumor Activity against Human Tumors in vitro and in vivo

CPT‐11, a semisynthetic derivative of camptothecin, exhibited strong antitumor activity against lymphoma, lung cancer, colorectal cancer, gastric cancer, ovarian cancer, and cervical cancer. CPT‐11 is a pro‐drug that is converted to an active metabolite, SN‐38, in vivo by enzymes such as carboxylesterase. We synthesized a water‐soluble and non‐pro‐drug analog of camptothecin, DX‐8951f. It showed both high in vitro potency against a series of 32 malignant cell lines and significant topoisomerase I inhibition. The anti‐proliferative activity of DX‐8951f, as indicated by the mean GI50 value, was about 6 and 28 times greater than that of SN‐38 or SK&F 10486‐A (Topotecan), respectively. These three derivatives of camptothecin showed similar patterns of differential response among 32 cell lines, that is, their spectra of in vitro cytotoxicity were almost the same. The antitumor activity of three doses of DX‐8951f administered i.v. at 4‐day intervals against human gastric adenocarcinoma SC‐6 xenografts was greater than that of CPT‐11 or SK&F 10486‐A. Moreover, it overcame P‐glycoprotein‐mediated multi‐drug resistance. These data suggest that DX‐8951f has a high antitumor activity and is a potential therapeutic agent.

Discovery of novel thieno[2,3-d]pyrimidin-4-yl hydrazone-based inhibitors of Cyclin D1-CDK4: Synthesis, biological evaluation and structure-activity relationships. Part 2

The design, synthesis and evaluation of novel thieno[2,3-d]pyrimidin-4-yl hydrazone analogues as cyclin-dependent kinase 4 (CDK4) inhibitor are described. Focusing on the optimization of the heteroaryl moiety at the hydrazone with substituted phenyl groups, 4-[(methylamino)methyl]benzaldehyde (22) and 5-isoindolinecarbaldehyde (24) (6-tert-butylthieno[2,3-d]pyrimidin-4-yl)hydrazone derivatives have been identified. In this paper, the potency, selectivity profile and structure-activity relationships of our synthetic compounds are discussed.

Discovery of novel thieno[2,3-d]pyrimidin-4-yl hydrazone-based inhibitors of Cyclin D1-CDK4: synthesis, biological evaluation, and structure-activity relationships.

The synthesis and evaluation of new analogues of thieno[2,3-d]pyrimidin-4-yl hydrazones are described. 2-Pyrdinecarboxaldehyde [6-(tert-butyl)thieno[2,3-d]pyrimidine-4-yl]hydrazone derivatives have been identified as cyclin-dependent kinase 4 (CDK4) inhibitors. The potency, selectivity profile, and structure-activity relationship of this series of compounds are discussed.

Discovery of DS-5272 as a promising candidate: A potent and orally active p53–MDM2 interaction inhibitor

We have published p53-MDM2 interaction inhibitors possessing a novel dihydroimidazothiazole scaffold. Although our lead compound 1 showed strong antitumor activity with single oral administration on a xenograft model using MV4-11 cells harboring wild-type p53, it needed a higher dose (200mg/kg) for distinct efficacy. We executed further optimization with the aim of improvement of potency and physicochemical properties. Thus optimal compounds were furnished by introducing fluorine moieties onto the phenyl ring at the C-6 position and the pyrrolidine part at the C-2 substituent; and modifying the terminal piperazine to 4,7-diazaspiro[2,5]octane variants. Furthermore, replacing 4-chlorophenyl on the C-5 position with pyridyl variant decreased nonspecific cytotoxicity significantly. Our exploration afforded DS-5272 indicating excellent antitumor efficacy from a dose of 25mg/kg on SJSA-1 xenografted models with high safety and good PK profiles, which has appropriate potency as a clinical candidate.

Inhibition of ergosterol synthesis by novel antifungal compounds targeting C-14 reductase

The limited number of clinically available antifungal drugs for life-threatening fungal infections has produced an increased demand for new agents. In the course of our screening for novel antifungals, we identified aminopiperidine derivatives which exhibit antifungal activities against the major pathogenic yeasts. Thin layer chromatography (TLC) analysis of the extracted non-saponifiable lipids from Candida albicans showed that these compounds inhibited the ergosterol production in the late step of the synthesis pathway. The results of an LC/Q-Tof MS analysis showed that abnormal sterols including predicted ignosterol, which is known to be accumulated in C. albicans ERG24 deleted mutant, were accumulated in C. albicans treated with one of these derivatives (Compound 1b). Furthermore, the partial disruption of the cell membrane of C. albicans treated with compound 1b was observed by electron microscopy analysis, suggesting its inhibition of ergosterol synthesis. Additionally, a genetic approach demonstrated that ERG24 gene would be responsible for the resistance of Saccharomyces cerevisiae against Compound 1b, strongly indicating that the enzyme targeted by Compound 1b is Erg24p. From all these data, we concluded that these aminopiperidine derivatives are novel antifungal compounds inhibiting C-14 reduction in the ergosterol synthesis pathway.

Design, synthesis and SAR of novel ethylenediamine and phenylenediamine derivatives as factor Xa inhibitors.

We previously reported on a series of cyclohexanediamine derivatives as highly potent factor Xa inhibitors. Herein, we describe the modification of the spacer moiety to discover an alternative scaffold. Ethylenediamine derivatives possessing a substituent at the C1 position in S configuration and phenylenediamine derivatives possessing a substituent at the C5 position demonstrated moderate to strong anti-fXa activity. Further SAR studies led to the identification of compound 30 h which showed both good in vitro activity (fXa IC(50) = 2.2 nM, PTCT2 = 3.9 μM) and in vivo antithrombotic efficacy.