A recent study published in Immunology and Inflammation found that a novel drug called S-1117 may be able to target the underlying autoimmune responses in patients with myasthenia gravis (MG).
Many patients with MG produce antibodies against the acetylcholine receptor (AChR), a protein that is critical for nervous system function. In most cases, these antibodies belong to the immunoglobulin G (IgG) class.
Currently, a subset of patients with MG do not respond to existing treatment options, meaning there is a need to develop new drugs for these individuals. Because S-1117 works by breaking down IgG antibodies, the investigators sought to determine whether this drug may be a potential therapeutic option for patients with MG.
The authors collected blood samples from 11 patients with AChR-MG to test their hypothesis. They found that when these samples were treated with S-1117, the drug was able to remove a portion of the antibody. This blocked some, but not all, of the antibody’s functional abilities.
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The drug did effectively prevent complement activation, which is the process by which anti-AcHR antibodies promote damage of the neuromuscular junction.
Notably, the study revealed that some patients with MG produce immunoglobulin M (IgM) antibodies instead of — or even in addition to — IgG antibodies, which could reduce their response to S-1117. In samples with a mix of IgG and IgM antibodies, an IgM-targeting molecule significantly reduced antibody function, both on its own and in combination with S-1117.
Though much more research is still needed, the authors explain, these findings suggest that S-1117 or similar drugs could emerge as an option for patients with MG in the future.
“Ultimately, comprehensive clinical trials will be required to evaluate therapeutic efficacy, long-term safety, and potential equivalence or superiority to existing approved treatments,” they concluded. “Such studies will be critical to define the clinical positioning of S-1117 in future therapeutic algorithms.”
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