Immunosuppressants
Carol L. Koski, M.D., Principal Author
Approximately 10-15% of patients fail to respond to IVIG, corticosteroids, or plasma exchange therapy. Some patients develop significant side effects and may benefit from the administration of various other immunosuppressive agents to induce improvement. (Joint Task Force, 2005) Several immunosuppressive agents are currently being used. They include:
- anti-CD 20 (rituximab)
- azathioprine
- cyclophosphamide
- cyclosporin
- etanercept
- interferon-a
- interferon-ß1a
- mycophenolate mofetil
No random controlled trials however have been reported for any immunosuppressive agent except for azathioprine. In a small trial with 14 patients, no additional benefit was seen when azathioprine was added to an initial prednisone regimen. (Dyck, 1985) It should be noted that in this trial, the dose of azathioprine was small and the duration of treatment was short.
A small crossover trial of interferon-ß1a in only 10 patients did not detect a significant benefit. (Hadden, 1999) A non-randomized open study of IM IFN-ß1a at 30 µg weekly showed that 7 out of 20 patients had clinical improvement, 10 patients remained stable, and 3 patients worsened. (Vallat, 2003). An open study of IFN-a showed a benefit in 9 of 14 treatment-resistant patients. (Gorson, 1998)
The newer immunosuppressive agents (mycophenolate mofetil and rituximab) may have better efficacy and/or safety, but some anecdotal experience suggests that only 20% of CIDP patients may respond. (Gorson, 1998)
A recent small study of weekly low-dose oral methotrexate in 10 patients with other-wise treatment-resistant CIDP showed improvement in strength by at least two points on the MRC sum score in 7 patients while three patients worsened. Only two patients showed an improvement in disability; however, both were also receiving corticosteroid therapy. (Fialho, 2006)
In general, the newer immunosuppressive agents need to be tested in controlled trials before establishing efficacy. They are powerful drugs and they should be used only by physicians experienced in immunosuppressive therapy. Many of them come with Black Box Warnings. Their side effect profiles are listed in the Treatment Issues - Immunosuppressants section, linked below.
