Soliris Suitable for gMG Patients with Myasthenic Crisis and Thymoma-associated Disease, Study Suggests

Treatment with Soliris (eculizumab) leads to significant benefits in people with treatment-resistant generalized myasthenia gravis (gMG), including those with myasthenic crisis and thymoma-associated disease, a real-world study from Japan shows.

The data suggest that Soliris may be suitable for gMG patients with these features and who also check predefined eligibility criteria. Larger studies are needed to confirm which patients should be prescribed Soliris, the researchers said.

The study, “Suitable indications of eculizumab for patients with refractory generalized myasthenia gravis,” was published in the journal Therapeutic Advances in Neurological Disorders.

People with gMG, a progressive autoimmune disease, may experience several complications, exacerbations, and myasthenic crises, in which serious breathing difficulties frequently require hospitalization.

These patients typically fail to respond or are intolerant (refractory) to first-line therapies, including immunosuppressive therapies, high-dose intravenous immunoglobulin, and plasmapheresis.

Soliris, developed and marketed by Alexion Pharmaceuticals, is approved in the U.S., European Union and Japan to treat adults with refractory gMG who are positive for anti-acetylcholine receptor (AchR) antibodies.

The therapy, administered directly into the bloodstream, works by specifically blocking the activity of the C5 protein, a member of the complement system. This set of more than 30 proteins is part of the immune system that induces the damaging immune response seen in MG.

Soliris’ approval was based on positive data from the global Phase 3 REGAIN clinical trial (NCT01997229), a six-month, placebo-controlled trial involving 125 treatment-resistant gMG patients with anti-AchR antibodies.

While REGAIN and its open-label extension study (NCT02301624) highlighted the therapy’s benefits in this patient population, which gMG patients are more suitable to receive Soliris remains undetermined.

To clarify this, researchers evaluated the clinical data of 1,388 MG patients, including 12 (0.9%) treated with Soliris, followed at seven hospitals in Japan between January and December 2018 (immediately after Soliris’ approval in the country).

Disease severity was measured through the Quantitative MG (QMG) score, and the ability to perform daily living activities with the MG Activities of Daily Living (MG-ADL) score. Patient-reported improvements in quality of life also were assessed.

Among the 12 patients who received Soliris, 11 completed six months of treatment. Their mean age was 43 (range 22–67), with a disease onset between 12 and 66 years. Five had early onset MG, one had late-onset MG, and five developed MG associated with a thymoma — a tumor of the thymus, which is associated with the development of autoimmune diseases.

The remaining patient (a 36-year-old woman) had to discontinue treatment due to the development of nausea and vertigo immediately after the first Soliris injection.

All 11 patients had refractory, severe gMG with the presence of anti-AChR antibodies, and seven patients had previously experienced myasthenic crisis.

Soliris treatment led to fast and significant benefits, easing disease severity and improving the ability to perform daily life activities in all patients. The degree of these improvements was superior to those reported in the REGAIN trial, although the researchers cautioned that the enrollment criteria were different comparing the two studies.

Quality of life also was markedly improved. At six months, seven patients also were able to reduce their dose of prednisolone (an immunosuppressive therapy).

All but one patient did not need additional rescue therapy. Notably, the outcomes of the 11 patients who completed six months of Soliris treatment were significantly better than those of 20 patients with refractory gMG treated with rescue treatment alone.

“We demonstrate that [Soliris] provided remarkable benefits for refractory gMG in practical real-world experience as well as in the REGAIN study,” the researchers wrote.

Based on these findings, Soliris “should be preferentially selected for patients with MG who have undergone repeated myasthenic crises,” they added. The team also considered that thymoma-associated MG is an “appropriate indication” for Soliris treatment.

However, the investigators said that larger and longer prospective studies are required to confirm these data. The team is now conducting a multi-center study in Japan to identify biomarkers to predict refractory gMG patients more likely to benefit from Soliris treatment.