Preclinical Characterization and Human Microdose Pharmacokinetics of ITMN-8187, a Nonmacrocyclic Inhibitor of the Hepatitis C Virus NS3 Protease

Application and synthesis of thiazole ring in clinically approved drugs

The development of heterocyclic derivatives has progressed considerably over the past few decades, and many new agents of synthetic and natural origin have been produced. Among heterocyclic compounds, thiazole is a unique five-membered heterocyclic motif characterized by nitrogen and sulfur atoms, which is widely used as an important core skeleton in a variety of pharmaceutically important compounds due to their diverse biological activities, such as antibacterial, antivirus, and antifungal. To the best of our knowledge, more than 90 thiazole-containing derivatives have been currently under clinical investigation, and some thiazole analogs have been approved to treat various diseases. As the potentially privileged scaffolds, thiazole derivatives can be further extensively explored to search for new drugs characterized by improved therapeutic efficacy and similar biological targets. This review aims to outline the applications and synthetic routes of some representative thiazole-containing drugs approved in the clinic, which may guide medicinal researchers to rationally design more effective thiazole-containing drug candidates.

Phase 0/microdosing approaches: time for mainstream application in drug development?

Phase 0 approaches - which include microdosing - evaluate subtherapeutic exposures of new drugs in first-in-human studies known as exploratory clinical trials. Recent progress extends phase 0 benefits beyond assessment of pharmacokinetics to include understanding of mechanism of action and pharmacodynamics. Phase 0 approaches have the potential to improve preclinical candidate selection and enable safer, cheaper, quicker and more informed developmental decisions. Here, we discuss phase 0 methods and applications, highlight their advantages over traditional strategies and address concerns related to extrapolation and developmental timelines. Although challenges remain, we propose that phase 0 approaches be at least considered for application in most drug development scenarios.

GP205, a new hepatitis C virus NS3/4A protease inhibitor, displays higher metabolic stability in vitro and drug exposure in vivo

NS3/4A serine protease is a prime target for direct-acting antiviral therapies against hepatitis C virus (HCV) infection. Several NS3/4A inhibitors have been widely used in clinic, while new inhibitors with better characteristics are still urgently needed. GP205 is a new macrocyclic inhibitor of NS3/4A with low nanomolar activities against HCV replicons of genotypes 1b, 2a, 4a, and 5a, with EC₅₀ values ranging from 1.5 to 12.8 nmol/L. In resistance selection study in vitro, we found resistance-associated substitutions on D168: The activity of GP205 was significantly attenuated against 1b replicon with D168V or D168A mutation, similar as simeprevir. No cross resistance of GP205 with NS5B or NS5A inhibitor was observed. Combination of GP205 with sofosbuvir or daclatasvir displayed additive or synergistic efficacy. The pharmacokinetic profile of GP205 was characterized in rats and dogs after oral administration, which revealed good drug exposure both in plasma and in liver and long plasma half-life. The in vitro stability test showed ideal microsomal and hepatic cells stability of GP205. The preclinical profiles of GP205 support further research on this NS3/4A inhibitor to expand the existing HCV infection therapies.