New guidance on myasthenia gravis from international experts

Movement disorders

By Michael Woodhead

5 Nov 2020

New international consensus guidance for management of myasthenia gravis (MG) includes updated recommendations on thymectomy and the use of agents such as rituximab and eculizumab.

An international panel of experts convened by the Myasthenia Gravis Foundation of America has updated its initial 2016 guidance, and the new treatment recommendations also cover MG associated with immune checkpoint inhibitor treatment.

The Task Force said the results of several new trials of MG treatment have been published since the initial 2016 guidance statement, and the new recommendations reflect the latest evidence.

For example, they now recommend that for generalised MG patients with AChR-Ab, aged 18-50 years, thymectomy should be considered early in the disease to improve clinical outcomes and to minimise immunotherapy requirements and need for hospitalisations for disease exacerbations.

In addition, “thymectomy should be strongly considered in patients with AChR-Ab+ generalised MG if they fail to respond to an initial adequate trial of immunotherapy or have intolerable side effects from that therapy,” they advise.

Recommendations on rituximab are unchanged, but the new statement notes that although the efficacy of rituximab in refractory AChR-Ab+ MG is uncertain, it is an option if patients fail or do not tolerate other IS agents.

For methotrexate the recommendation is that it may be considered as a steroid-sparing agent in patients with generalised MG who have not tolerated or responded to other steroid-sparing agents that are better supported by RCT data.

The new consensus guidance recommends that eculizumab should be considered in the treatment of severe, refractory, AChR-Ab+ generalised MG.  However the guidance notes that the place of eculizumab in the treatment of MG is evolving and it should be considered after trials of other immunotherapies have been unsuccessful in meeting treatment goals.

The 2020 consensus statement also provides guidance on the risk of new or worsening MG in patients using immune checkpoint inhibitors (ICIs).

The advise that pre-existing MG does not constitute an absolute contraindication to the use of ICIs in patients with well-controlled disease but it may be prudent to avoid combined therapy, and close clinical monitoring is mandatory.

“Early aggressive treatment with high-dose steroids in combination with plasma exchange or IVIg may be required in patients who develop overt MG while on ICIs,” the guidance states.

New recommendations are also provided for early immunosuppression of ocular MG.

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