Case Supports Soliris as Promising Treatment for Thymoma-associated MG

Soliris (eculizumab) may be a promising treatment option for patients with refractory myasthenia gravis (MG) associated with a tumor in the thymus gland, a case report suggests.

The case report study, “Eculizumab as a promising treatment in thymoma-associated myasthenia gravis,” was published in the journal Therapeutic Advances in Neurological Disorders.

MG is an autoimmune disease caused by the abnormal production of autoantibodies targeting proteins that are necessary for muscle contraction. Statistics indicate that approximately 15% of MG patients have a tumor in the thymus, the gland that produces immune T-cells.

MG patients with these types of tumors, known as thymomas, usually have a worse prognosis compared to other patient subgroups, with their disease sometimes becoming refractory, meaning the disease fails to respond to standard treatments. This has motivated the search for alternative therapies.

Soliris, marketed and developed by Alexion Pharmaceuticals, is an antibody that blocks signals from the immune system’s complement pathway that are thought to be involved in muscle damage in MG.

The therapy is approved for the treatment of patients with generalized MG, including those with refractory disease, in the U.S. and E.U. but little data exists about its use in MG patients with a history of thymoma.

In the study, investigators in Spain described the case of a woman with refractory MG associated with a thymoma who was successfully treated with Soliris.

The 25-year-old woman was transferred to the Bellvitge University Hospital in Barcelona after having experienced double vision, difficulty swallowing and speaking, and muscle weakness for two months.

Blood tests found she had MG autoantibodies circulating in her bloodstream, and a chest computed tomography scan revealed a mass on her chest that was suspected to be a thymoma.

She was started on pyridostigmine and oral prednisone, and was given two rounds of intravenous immunoglobulins and two of plasma exchange. However, due to the persistence of some symptoms, she was referred to a specialized MG clinic, where she underwent a thymectomy (surgical removal of the thymus).

“Unfortunately, the symptoms of MG deteriorated after thymectomy and the patient required immunoglobulins and plasma exchange, as well as an increased dose of prednisone,” the investigators wrote.

The patient was started on the immunosuppressant medication tacrolimus, but failed to respond to the medication. Other immunosuppressant treatments — rituximab, cyclophosphamide, and azathioprine — were also administered, leading to varying degrees of improvement and causing some serious side effects, including infections and thrombosis.

Physicians then decided to start treatment with Soliris, while monitoring the patient’s response using the quantitative myasthenia gravis (QMG) and the myasthenia gravis activities of daily living (MG-ADL) scales.

After eight weeks of treatment, her motor symptoms improved markedly. Soliris also lowered her QMG score by 9 points and her MG-ADL score by 3 points. Improvements following treatment with Soliris were particularly noticeable in her bulbar symptoms (symptoms affecting the head and neck).

Currently, the patient is still receiving Soliris every two weeks, in combination with lower doses of prednisone and azathioprine. After completing 48 weeks of treatment with Soliris, she has experienced no serious side effects associated with the medication.

“Although more data are required to determine the role of eculizumab in future therapeutic algorithms for MG, it is clear that new therapies such as this are urgently needed to remedy the considerable disease burden in [patients with refractory MG],” the researchers wrote.

“This report supports that eculizumab is a promising treatment in thymoma-associated MG,” they concluded.