How is eosinophilic granulomatosis with polyangiitis (EGPA) treated?
A variety of immunosuppressive drugs (drugs that suppress the immune system) are used to treat EGPA. The doctor will choose the drug based on how the EGPA is affecting the patient--whether it is mild (for instance, affecting the skin or joint), or potentially life-threatening.
Corticosteroids such as prednisone or prednisolone are the most commonly used treatments. People who have a mild disease (those whose disease does NOT affect the nervous system, heart, kidneys, intestinal tract, or show other features of severe disease) might do extremely well on corticosteroid therapy alone. Once the patient has a dramatic improvement on this drug, the dosage is reduced to the lowest amount that keeps the disease under control.
People with EGPA that affects critical organs are usually treated with corticosteroids combined with another immunosuppressive drug, such as cyclophosphamide (Cytoxan®), methotrexate, or azathioprine (Imuran®).
These drugs are also used to treat other medical conditions. Azathioprine is used to prevent organ transplant rejection and is also a treatment for rheumatoid arthritis and lupus. High doses of cyclophosphamide and methotrexate are used to treat certain types of cancer. In vasculitis, these drugs are given at doses that are 10 to 100 times lower than that used to treat cancer in order to suppress the immune system.
All immunosuppressive drugs can have side effects. Each drug can have its own side effects, so it is very important to watch for them. A person with EGPA may tolerate these drugs at first; however, this may not last. This is why it’s so important to watch for side effects, even after the patient stops taking the drug. Blood tests are also used to evaluate the illness itself.
The goal of treatment is to stop all damage that comes from EGPA; this is known as "remission." Once the disease begins to improve, the doctor slowly reduces the corticosteroid dose, and eventually hopes to stop it completely. Stopping it completely may be difficult if a person has significant asthma, as the airways can be very sensitive to corticosteroids.
If cyclophosphamide is used for severe EGPA, it is often only given until the patient goes into remission (usually around 3 to 6 months); the patient is then switched to another immunosuppressive agent, such as methotrexate or azathioprine, to maintain remission.
The duration of maintenance immunosuppressive drug depends on the patient. In most instances, it is given for least one to two years before the doctor considers slowly reducing the dosage and eventually stopping it.