Safety and efficacy of recombinant gamma interferon in the treatment of systemic sclerosis.

OBJECTIVE: To evaluate the safety and efficacy of recombinant gamma interferon (rIFN gamma) in the treatment of patients with systemic sclerosis.
METHODS: Sixteen patients with systemic sclerosis were treated with r-IFN gamma, 60 micrograms m-2 (low dose, n = 10) and 150 micrograms m-2 (high dose, n = 6), three times weekly in an open phase I/II trial of eight months duration. The patients were stratified in low and high dose according to the severity and the extent of scleroderma; the two groups were comparable.
RESULTS: The treatment was well tolerated. The most common side effects, almost certainly related to r-IFN gamma, were fever, chills, dizziness, headache, and severe flu-like syndrome with decreasing intensity with the time of treatment. Severe aphthous stomatitis (n = 1), ventricular tachycardia (n = 1), severe oesophageal ulcers due to gastro-oesophageal reflux (n = 1), disease exacerbation alone with frank arthritis and slight pericardial effusion (n = 1), and inability to conform to the requirements of the study (n = 1) were the reasons for discontinuing treatment. Side effects and degree of response were evident during the first five months of treatment. A significant decrease in mean skin thickness score was observed and was higher in the high dose group. Reactive oxygen species of peripheral neutrophils and soluble interleukin-2 receptor serum concentrations were higher than those of normal individuals at study entry and decreased in parallel with clinical improvement.
CONCLUSIONS: Treatment of systemic sclerosis patients with r-IFN gamma was relatively safe and well tolerated for doses as high as 150 micrograms m-2 three times weekly. Side effects and the degree of response can be seen during the first months of therapy and can be used as predictors of ultimate toxicity or response. The drug seems to be effective in treating cutaneous scleroderma.