Strategy for Research and Development of Antifungal Agents

The incidence of deep-seated mycosis has recently been increasing, while the number of clinically available antifungal agents is very limited and each agent has some drawbacks. We focused on the triazole class that is known to have good profiles as antifungal agents. After researching them, we found that CS-758 had excellent profiles in terms of antifungal spectrum, activity, and safety. Until this candidate was obtained, we experienced the following difficulties: (1) In vivo activity did not always reflect in vitro activity. (2) The relationship between in vivo activity and pharmacokinetic profile was important in selecting a candidate as an antifungal agent. (3) Suitable infection-models had to be established to predict clinical efficacy. (4) It was necessary to demonstrate superiority over marketed drugs to develop a novel agent. These experiences give us good ideas for future development of novel antifungal agents.