The drug: Rebif
Generic: Interferon beta-1a
The company: Merck KGaA
Patent expiration date: Dec. 31, 2013
Estimated Global Sales 2012: $2.3 billion
The scoop: Rebif is one of those top-selling drugs that rivals shoot at when they're trying to advance a new standard of care for patients. Sanofi ($SNY) went gunning for Rebif in a head-to-head trial with its experimental new drug Lemtrada, coming up with a better score on delaying disease progression. That's a key measure for physicians and patients, though side effects could limit Lemtrada's entry. Novartis' ($NVS) Gilenya, meanwhile, has already been stealing market share. But where Biogen Idec ($BIIB) and Sanofi have been making major progress with new treatments, Merck KGaA has run into a buzzsaw of trouble on the MS front. Its program for the MS drug cladribine--once considered a leading late-stage program--became an epic failure that triggered a company-wide restructuring. Analysts concluded that its Serono acquisition was a bust. But Merck KGaA is still working in the field. An extended-release Rebif program is in Phase I, notes Evaluate Pharma, which could eventually help protect sales.