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Regressing Systemic Sclerosis?

Systemic sclerosis (scleroderma) is predominately characterized by fibrosis of tissue, including skin and the intima of small arteries. The pathogenesis is unknown, and therapy has had little success in halting or reversing the process. Relaxin is a human protein that fosters the growth and remodeling of the uterus and pelvic ligaments during pregnancy. In this industry-sponsored study, 64 patients with moderate-to-severe systemic sclerosis received placebo or treatment with recombinant human relaxin (25 microg/kg per day or 100 microg/kg per day), for at least 4 weeks.

The relaxin was delivered as a continuous subcutaneous infusion; the complete course of treatment was 24 weeks. Patients who received the 25-microg dosage had a statistically significant reduction in skin thickening, as measured by a modified Rodnan score (P=0.040 at 24 weeks); improved mobility; and improved ability to eat, compared with subjects who received placebo or 100 microg of relaxin. Adverse effects with relaxin included menometrorrhagia, reversible anemia, and irritation at the infusion site.

Comment: Any advance in treating this terrible disease is important, and the results from this study are very promising. While this study was well designed -- randomized, double-blinded, and controlled -- the number of patients enrolled was empirical rather than planned. Clinical trials that are larger and longer than this dose-finding, phase II-type study are needed to determine who will benefit most and how the drug should be used. It is not clear why the higher dose of relaxin produced effects no better than placebo, but this result suggests that 25 microg may not be the ideal dose either. Some patients developed antibodies to the treatment, but the presence of antibodies did not correlate with diminished efficacy.

— NH Shear

Published in Journal Watch Dermatology July 10, 2000

Citation(s):

Seibold JR et al. Recombinant human relaxin in the treatment of scleroderma: A randomized, double-blind, placebo-controlled trial. Ann Intern Med 2000 Jun 6 132 871-879.

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