New treatments for myasthenia: a focus on antisense oligonucleotides.

Autoimmune myasthenia gravis (MG) is a neuromuscular disorder caused by autoantibodies directed against the acetylcholine receptor (AChR). Current symptomatic therapy is based on acetylcholinesterase (AChE) drugs. The available long-term current therapy includes steroids and other immunomodulatory agents. MG is associated with the production of a soluble, rare isoform of AChE, also referred as the "read-through" transcript (AChE-R). Monarsen (EN101) is a synthetic antisense compound directed against the AChE gene. Monarsen was administered in 16 patients with MG and 14 patients achieved a clinically significant response. The drug is now in a Phase II study. Further investigations are required to confirm its long-term effects.