Abstract Details

Title Long-term remission with rituximab in refractory generalized myasthenia gravis

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) S12 - Interventional/Observational Studies of Neuromuscular Diseases (4:00 PM-4:08 PM)

Poster/Presentation
Number 001

Background RTX is a therapeutic option in MG, especially in patients without adequate response, either due to severity, refractoriness or inability to reduce doses of basal immunosuppressive drugs.

Objective To assess long-term efficacy of rituximab (RTX) in the treatment of refractory generalized myasthenia gravis (MG).

Design/Methods

A retrospective study was performed in adult patients with refractory generalized MG referred to our center from January/2015 to October/2020 with a follow-up of at least 24 months. Anti-acetylcholine receptor (AChR) and anti-muscle-specific kinase (MuSK) autobodies were analyzed. The Myasthenia Gravis Status and Treatment Intensity (MGSTI) score was used to assess outcomes, and CD19/CD20+ B-cell counts were serially monitored.

Results

Sixteen MG patients (13 = female; mean age = 45 years) treated with RTX were included. They were previously studied with autoimmune antibodies (AChR = 8 and MuSK = 8), and presented a median MGFA score of 4A-B. Patients were undergoing treatment with 2 immunosuppressants and they had received at least one cycle of intravenous immunoglobulin (10 requiring intensive care). Low-dose RTX protocols were used during induction (7 = 2000 mg, 7 = 1000 mg and 2 = 1500 mg), and only 5 patients received maintenance doses. During follow-up, all patients maintained undetectable CD20 levels at 6 and 12 months after induction, without new relapses. All patients presented MGFA-PIS and MGSTI scores ≤2; the earlier the treatment with RTX was initiated, the faster the score was reached.

Conclusions RTX is an effective therapeutic option, both in MG MuSK (being the 1st option in this case) and in refractory AChR. In our series, high doses of RTX induction or regular maintenance were not required to achieve undetectable CD20, attain remission or achieve minimal basal immunosuppressive treatment. Early initiation of RTX in selected patients could be associated with a more rapid and sustained clinical response over time.

Authors/Disclosures
Juan I. Castiglione, MD (FLENI) PRESENTER	Dr. Castiglione has nothing to disclose.
Fabio Adrian Barroso, MD	Fabio Adrian Barroso, MD has nothing to disclose.
Patricio Brand, MD (FLENI)	Dr. Brand has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Biogen.
	No disclosure on file
Alejandro Kohler	No disclosure on file