Interferon beta for multiple sclerosis

OBJECTIVE: To introduce readers to the use of a new agent, interferon beta-1b (IFN beta ser), in the treatment of relapsing-remitting multiple sclerosis (RRMS). Therapeutic and economic issues surrounding IFN beta ser are discussed, as are its pharmacology, clinical efficacy, adverse effects, and dosage guidelines. DATA SOURCES: A MEDLINE search was used to identify pertinent literature, including clinical trials and reviews. STUDY SELECTIONS: All available trials were reviewed. DATA EXTRACTION: Since trials evaluating subcutaneously administered interferon beta are sparse, clinical trials evaluating intrathecal IFN beta ser were included, as was toxicology information from the oncology population. DATA SYNTHESIS: IFN beta ser has recently been approved by the Food and Drug Administration for the treatment of RRMS. Its exact mechanism of action is unknown, but it may downregulate interferon gamma (IFN gamma) production and the IFN gamma-stimulated major histocompatibility complex antigen expression, and/or augment T-suppressor cell function. Primary adverse effects include flu-like symptoms, fever, chills, myalgia, sweating, and injection-site reactions. Clinical efficacy has been investigated in 372 ambulatory patients with RRMS. IFN beta ser treatment resulted in a reduction in the annual exacerbation rate and a greater proportion of exacerbation-free patients. Burden of central nervous system disease was also significantly reduced in treated patients. However, no reductions were detected on the Scripps Neurologic Rating Scale or with confirmed endpoint scores on the Kurtzke Expanded Disability Status Scale. Although many questions remain concerning IFN beta ser's long-term efficacy, its benefits in patients with other types of multiple sclerosis (MS), and its effect on progression of disease and ultimate disability, IFN beta ser is the first treatment modality that has substantially altered the natural course of MS in a controlled clinical trial. CONCLUSIONS: IFN beta ser is not a cure for MS, but it is well tolerated and patients with RRMS have shown significant improvements in exacerbation rates and burden of central nervous system disease. IFN beta ser should be considered a definite improvement in RRMS treatment, although many therapeutic issues remain unanswered. Additional clinical trials are needed.