Drug manufacturers are raising legal and trade concerns with FDA's plan to revoke a biologic's remaining exclusivity when it shifts to a license application in 2020. The Pharmaceutical Research and Manufacturers of America says the policy, proposed in recent FDA guidance, raises significant constitutional and international trade issues, and would harm incentives carefully crafted by Congress to encourage medical innovation. At issue is a draft guidance unveiled in March that says biologics approved under the Food, Drug and Cosmetic Act...