A prospective natural history study and biorepository for patients with myasthenia gravis (EXPLORE-MG2)

ABSTRACT

Objective: To define clinical features, disease course, and collect biospecimens in patients with myasthenia gravis (MG), including understudied subgroups such as seronegative, muscle-specific kinase antibody (MuSK), and LRP4 antibody positive MG. Background: The MG Rare Disease Clinical Research Network (MGNet) was funded by the National Institutes of Health (NIH) to gain better understanding of the clinical course of MG and develop improved approaches to diagnosis and treatment. As part of this initiative a multicenter prospective natural history study and biorepository was developed Exploring Outcomes and Characteristics of Myasthenia Gravis 2 (EXPLORE-MG2). Design/Methods: EXPLORE-MG2 is a web-based observational registry that incorporates NIH recommended common data elements for MG. Key eligibility criteria include ≥18 years old;diagnosed with MG within 2-years of study enrollment based on clinical presentation and seropositivity for MG associated autoantibodies, and/or abnormal neurophysiology test or positive edrophonium test. Biospecimen collection focuses on immunosuppressive naïve patients and rare MG subgroups. Participants will be followed for at least 2-years with study visits occurring approximately every 6 months in the context of usual clinical care. The study has been open to enrollment since January 2021 with 6 sites currently activated/participating. Results: A total of 62 patients have been enrolled and 152 biospecimens were collected as of 10/1/2021. The mean age was 57 years (range 20-84);47% were female, 66% were acetylcholine receptor antibody-positive, 16% were MuSK MG, and 18% were seronegative. Enrollment of new participants and follow-up of existing participants are ongoing to reach our current goal of 400 enrolled participants. We will present updated enrollment data and demographics at the meeting. Conclusions: The EXPLORE-MG2 study is active after a COVID-19 pandemic related delay. Samples and clinical data will be available to researchers for current and future investigation. Data from EXPLORE-MG2 will improve clinical trial readiness for future studies and facilitate development of treatment-responsive biomarkers.