Any company that can develop a drug even partially effective against Alzheimer's disease will strike a gold mine. One analyst estimates the opportunity to be $20 billion, but most attempts so far have been costly failures. Think Pfizer ($PFE) and Johnson & Johnson's ($JNJ) bapineuzumab and Eli Lilly's ($LLY) solanezumab, both of which flamed out in late-stage trials. Don't think Sanofi ($SNY), though, because CEO Chris Viehbacher says the French drugmaker is not interested in going down that path until the science of the disease is better understood. "We really, at best, partially understand the cause of the disease. It's hard to come up with meaningful targets," he said. Story | More