Interferon-alpha for maintenance of remission in Churg-Strauss syndrome: a long-term observational study.

BACKGROUND: Interferon-alpha has been successfully used for induction of remission in patients with Churg-Strauss syndrome, but data on its ability to prevent relapses and its safety during long-term use are lacking.

OBJECTIVES: To examine the safety and efficacy of interferon-alpha for mainten-ance of remission in Churg-Strauss syndrome.

PATIENTS AND METHODS: In a prospective open-label long-term observational study, 13 patients with CSS in stable remission received interferon-alpha (3 x 3 Mio. I.U/week s.c.) for maintenance of remission. Primary end point was the incidence of relapses. Secondary end points were the doses of concomitant prednisolone and the frequency adverse events.

RESULTS: After a median follow up of 64 month three patients were still on treatment with interferon-alpha all with a dose of 9 million units/week. In nine patients, interferon-alpha was discontinued for lack of efficacy (n=5), due to adverse events (n=2), or both (n=2) after median of 63 months (15-153) of therapy. A total of 3 major and 18 minor relapses occurred in 10 of the 13 patients with a median time to first relapse of 17 months (range 5-46). Sera of relapsing patients did not contain antibodies against interferon-alpha. In 6 relapsing patients treatment was switched to cyclophosphamide (n=4) or methotrexate (n=2). Four episodes of worsened asthmatic symptoms associated with a mild rise of blood eosinophils occurred in 3 patients and resolved following a transient increase of the oral prednisolone dosage. After 49 months one patient died probably due to a relapse. IFN-alpha was ceased prematurely, because of autoimmune-thyreoiditis in one, depression in another and cerebral leukoencephalopathy in two patients. Overall, 18 infectious episodes with need of antimicrobial treatment were observed.CONCLUSIONS. Recombinant interferon-alpha appears to be partially effective in the prevention of major relapses in patients with Churg-Strauss syndrome. Due to numerous side effects and infections during long-term administration its use should be restricted to patients with contraindications against conventional immunosuppressive therapies.