The one-trial, two-trial conundrum

BETHESDA, Md. - Often FDA advisory panel meetings shed light on issues beyond the specific drugs under consideration. At last week's meetings of the Peripheral and Central Nervous Systems Drugs Advisory Committee, high-ranking FDA officials shed light on the agency's cautious thinking about the need for multiple trials to support an NDA.

In response to questions from panel members on Friday, Robert Temple, chief of FDA's division of drugs, conceded that in some cases drugs can be approved on the basis of a single trial. But he said that the rule is that two or more trials are required. "The usual way we say it is: You need two studies, but sometimes you don't. If a study is very powerful, if it has internal replication, then one study can be enough."...