Interferon Beta for Multiple Sclerosis

Abstract

OBJECTIVE: To introducereaders to the use of a new agent, interferon beta-1b (IFNser), in the treatment of relapsing-remitting multiple sclerosis(RRMS). Therapeuticand economic issues surrounding IFNβser 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 IFNβser were included, as was toxicology information from the oncology population. DATA SYNTHESIS: IFNβser has recently been approved by the Food and Drug Administration for the treatmentof RRMS. Its exact mechanism of action is unknown, but it may downregulate interferon gamma (IFNγ) production and the IFNγ-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. IFNβser treatment resulted in a reduction in the annual exacerbationrate and a greater proportionof 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 scoreson the Kurtzke Expanded Disability Status Scale. Although many questions remain concerning IFNβser's long-term efficacy, its benefits in patients with other types of multiple sclerosis (MS), and its effect on progressionof disease and ultimate disability, IFNβser is the first treatment modality that has substantially altered the natural course of MS in a controlled clinical trial. CONCLUSIONS: IFNβser 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. IFNβser should be considered a definite improvementin RRMS treatment, although many therapeutic issues remain unanswered. Additional clinical trials are needed.