On Wednesday, U.S. regulators approved Tecfidera, a new multiple sclerosis drug made by Biogen Idec Inc. It is widely expected to become the No. 1 oral treatment for the disease, with annual sales topping $3 billion. Tecfidera activates a chemical pathway in the body known as Nrf2 that helps protect nerve cells from damage and inflammation. Biogen said it will launch the drug within the coming days. Read the full story.