Biogen Idec Inc has seen its market value quadruple in three years to more than $100 billion on the back of its successful multiple sclerosis drugs. The Massachusetts-based company, which made headlines last week when it announced better-than-expected clinical trial results for its experimental Alzheimer’s drug, aducanumab, said that it will drop Idec from its name as of Monday and adopt a new logo. Chief Executive George Scangos says that going forward he will keep Biogen focused on developing drugs for some of the hardest-to-treat diseases.