Interferon beta-1a (also interferon beta-1-alpha) is a drug in the interferon family used to treat multiple sclerosis (MS). It is produced by mammalian cells while Interferon beta-1b is produced in modified E. coli. Interferons have been shown to have about a 18–38% reduction in the rate of MS relapses, and to slow the progression of disability in MS patients. None of the products on the market is a cure, but patients today who start early on Interferons may beneficially alter the natural course of the disease. There are two principal competitors in the market for this drug and one biosimilar one: Avonex Rebif CinnoVex