Objective: To define clinical and laboratory outcomes of longterm recombinant interferon-gamma (rIFN-gamma) treatment of patients with rheumatoid arthritis (RA).
Methods: Patients with RA (70) completing a 12-week multicenter double blind trial comparing rIFN-gamma with placebo were enrolled in a longterm prospective protocol evaluating rIFN-gamma in RA.
Results: The majority of patients sustained clinical improvement for one year. Eight (11%) patients with RA continued to receive rIFN-gamma after 5 years. One patient fulfilled remission criteria. rIFN-gamma was well tolerated with remarkably few suspected adverse drug reactions. Forty-seven (67%) patients discontinued rIFN-gamma because of lack of efficacy, 7 (10%) because of concurrent illnesses, 5 (7%) were not compliant to study protocol, 3 (4%) developed suspected adverse drug reactions for a total of 62 (89%) withdrawals over the 5 years of followup. Patients continuing rIFN-gamma treatment for 5 years had lower initial total leukocyte and neutrophil counts and higher hemoglobin and hematocrit levels than patients who discontinued rIFN-gamma during the 5-year followup.
Conclusions: Longterm treatment of RA with rIFN-gamma was generally well tolerated. Although many patients maintained sustained clinical improvement for at least one year, the main reason for discontinuing the drug over 5 years was the lack of continued benefit.