Effect of regulation reform on clinical trials for registering novel therapeutic agents in Taiwan: a chronological analysis.

The registration process for new drugs is crucial in the clinical application of medicines. Previously, the registration of imported novel therapeutic agents in Taiwan depended considerably on their approvals in developed countries. The Taiwanese government enacted Article 38-1 of the Regulations for Registration of Medicinal Products in September 2009. According to the new submission criteria, approvals may be exempted if the number of Taiwanese participants in the clinical trials fulfills the required threshold. The present study compared the profiles of clinical trials of novel therapeutic agents before and after the enactment of this regulation in terms of over-threshold trials, structural types, and therapeutic areas across phases. The outcome-whether the liberalization of the submission criteria functioned as an incentive to launch clinical trials in Taiwan-was also evaluated. The results revealed that the number of clinical trial applications increased after the reformed regulation was enacted, even after the over-threshold criteria were considered; however, the increase disappeared for phase III trials. Most clinical trials were for chemical products and antineoplastic agents across all phases and study periods before and after the enactment of Article 38-1. Furthermore, the increase in the number of international clinical trials conducted in Taiwan was not directly caused by the regulation reform because the percentage of investigational products fulfilling the exemption criteria did not increase. These paradoxical results were interpreted in several aspects, referring particularly to the well-established infrastructure for launching clinical trials as well as the integral environment of medical services in Taiwan.

Antiangiogenic activities and cisplatin-combined antitumor activities of BPR0L075.

BACKGROUND: Antimitotic tubulin-binding BPR0L075 is structurally analogous to the vascular-disrupting combretastatin A-4. MATERIALS AND METHODS: In vitro/in vivo models of endothelial cells cultures, Matrigel plug assay, tumor-bearing nude mice, and murine leukemia cells-inoculated mice were utilized to evaluate BPR0L075 for antiangiogenic and antitumoral activity spectra. RESULTS: BPR0L075 concentration-dependently inhibited proliferation and migration of human umbilical vein endothelial cells (HUVECs), disrupted capillary tube formations of HUVECs and rat aorta endothelial cells, and suppressed in vivo VEGF-mediated angiogenesis in Matrigel plugs in mice. Besides inhibiting the colony growth of cancer cells, BPR0L075 suppressed growth of subcutaneously-xenografted human lung, colorectal, and cervical solid tumors in nude mice. Combination treatments of BPR0L075 plus cisplatin, compared to either agent alone, demonstrated a stronger growth inhibition against the tumor xenografts in nude mice and longer lifespan in the leukemia mice. CONCLUSION: BPR0L075 is an antitumoral and antiangiogenic agent and potentiates the anticancer activity of cisplatin.

(2S,4S)-1-[2-(1,1-dimethyl-3-oxo-3-pyrrolidin-1-yl-propylamino)acetyl]-4-fluoro-pyrrolidine-2-carbonitrile: a potent, selective, and orally bioavailable dipeptide-derived inhibitor of dipeptidyl peptidase IV.

A series of 2-[3-[2-[(2S)-2-cyano-1-pyrrolidinyl]-2-oxoethylamino]-3-methyl-1-oxobutyl]-based DPP-IV inhibitors with various monocyclic amines were synthesized. The structure-activity relationships (SAR) led to the discovery of potent DPP-IV inhibitors, having IC(50) values of <100 nM with excellent selectivity over the closely related enzymes, DPP-II, DPP8, DPP9 and FAP (IC(50)>20 microM). Of these compounds, the analogues 12a, 12h and 12i exhibited a long-lasting ex vivo DPP-IV inhibition in rats.

Discovery of 2-[5-(4-chloro-phenyl)-1-(2,4-dichloro-phenyl)-4-ethyl-1H-pyrazol-3-yl]-1,5,5-trimethyl-1,5-dihydro-imidazol-4-thione (BPR-890) via an active metabolite. A novel, potent and selective cannabinoid-1 receptor inverse agonist with high antiobesity efficacy in DIO mice.

By using the active metabolite 5 as an initial template, further structural modifications led to the identification of the titled compound 24 (BPR-890) as a highly potent CB1 inverse agonist possessing an excellent CB2/1 selectivity and remarkable in vivo efficacy in diet-induced obese mice with a minimum effective dose as low as 0.03 mg/kg (po qd) at the end of the 30-day chronic study. Current SAR studies along with those of many existing rimonabant-mimicking molecules imply that around the pyrazole C3-position, a rigid and deep binding pocket should exist for CB1 receptor. In addition, relative to the conventional carboxamide carbonyl, serving as a key hydrogen-bond acceptor during ligand-CB1 receptor interaction, the corresponding polarizable thione carbonyl might play a more critical role in stabilizing the Asp366-Lys192 salt bridge in the proposed CB1-receptor homology model and inducing significant selectivity for CB1R over CB2R.

Cytotoxic prenylflavanones from Taiwanese propolis.

Two new prenylflavanones, propolin A (2) and propolin B (3), were isolated and characterized from Taiwanese propolis. Both compounds were found to have cytotoxic properties against three cancer cell lines. DNA content analyses and DNA fragmentation indicated that propolin A (2) efficiently induced apoptosis in cancer cell lines, but had no effect on the cell cycle program. Furthermore, both propolin A (2) and B (3) are potential antioxidant agents and show strong scavenging effects against most types of free radicals.