Interferon beta 1a (also interferon beta 1-alpha) is a cytokine 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. Some claims have been made that Interferons produce about an 18–38% reduction in the rate of MS relapses.

Interferon beta has not been shown to slow the advance of disability. Interferons are not a cure for MS (there is no cure); the claim is that interferons may slow the progress of the disease if started early and continued for the duration of the disease.

Interferon beta 1a is sold under the trade names Avonex (Biogen) and Rebif (Merck Serono), (Pfizer); CinnoVex (CinnaGen) is biosimilar.

Medical uses

Clinically isolated syndrome

The earliest clinical presentation of relapsing-remitting multiple sclerosis is the clinically isolated syndrome (CIS), that is, a single attack of a single symptom. During a CIS, there is a subacute attack suggestive of demyelination but the patient does not fulfill the criteria for diagnosis of multiple sclerosis. Treatment with interferons after an initial attack decreases the risk of developing clinical definite MS.