Using a Pregnancy-Related Hormone, Relaxin, to Treat Scleroderma

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The summary below is from the full report titled "Recombinant Human Relaxin in the Treatment of Scleroderma. A Randomized, Double-Blind, Placebo-Controlled Trial." It is in the 6 June 2000 issue of Annals of Internal Medicine (volume 132, pages 871-879). The authors are J.R. Seibold, J.H. Korn, R. Simms, P.J. Clements, L.W. Moreland, M.D. Mayes, D.E. Furst, N. Rothfield, V. Steen, M. Weisman, D. Collier, F.M. Wigley, P.A. Merkel, M.E. Csuka, V. Hsu, S. Rocco, M. Erikson, J. Hannigan, W.S. Harkonen, and M.E. Sanders.

What is the problem and what is known about it so far?

Scleroderma is a disease of unknown cause that produces fibrosis (hardening or scarring) of the connective tissue in the skin, blood vessels, and internal organs. This results in a tight, shiny appearance of the skin and potentially life-threatening abnormalities of the lungs, heart, kidneys, and digestive tract. Scleroderma can be mild or severe and there is no current effective treatment. Relaxin is a pregnancy-related hormone that blocks the development of fibrous tissue, so some experts suspect it might be useful in treating diseases, such as scleroderma, where fibrosis is a problem.

Why did the researchers do this particular study?

To find out if relaxin could be useful in treating patients who have scleroderma.

Who was studied?

68 patients who had had moderate to severe scleroderma for less than 5 years.

How was the study done?

Each study patient was randomly assigned to get a low dose (25 [g/kg of body weight per day] or a high dose (100 µg/kg of body weight per day) of relaxin, or placebo. Relaxin was given continuously from a pump through a needle placed under the skin, for a total of 24 weeks. The placebo looked like the relaxin and was given using the same type of pump but contained no active ingredient. The researchers then measured how severely each person's skin was affected by scleroderma using an accepted scoring system. They also did special tests of lung function, hand motion, and ability to perform tasks of daily living.

What did the researchers find?

Patients who got the lower dose of relaxin had significantly better skin scores than those who got placebo. All other measures also suggested benefit from the lower dose of relaxin. In contrast, patients who got the higher dose of relaxin did no better than those who got placebo. Side effects related to relaxin were mild and included heavy menstrual bleeding, anemia or low red blood counts, and irritation or infection at the site where the needle entered the skin.

What were the limitations of the study?

This study does not tell us whether this therapy would help patients with less severe scleroderma or those who have had the disease longer than 5 years. The study also does not tell us the effects of relaxin treatment for more than 24 weeks or whether the disease gets worse again after the low dose of relaxin is stopped.

What are the implications of the study?

Relaxin at a dose of 25 µg/kg of body weight per day may be an effective option for treating patients with moderate to severe scleroderma who have had their disease for less than 5 years.