A U.S. Court of Appeals affirmation of a lower court ruling requiring the FDA to grant Eagle Pharmaceuticals Inc.'s bendamustine infusion product, Bendeka, seven years of orphan drug exclusivity appears to resolve a key piece of uncertainty that had troubled Eagle and others in similar circumstances.

Drugs for rare diseases now account for 31% of R&D pipelines, up from 18% in 2010 and just 11% in 2005, according to a report from the Tufts Center for the Study of Drug Development. That's currently nearly 3,500 drugs in development, more than double the 1,530 in 2010.