Myasthenia gravis is a chronic autoimmune disorder characterized by muscle weakness and fatigue. The disorder leads to a breakdown of acetylcholine receptors at the neuromuscular junction which causes a failure of nerve cells to communicate with muscles. Acetylcholine is an abundant neurotransmitter in the nervous system and is critical for muscle control. When acetylcholine binds to its receptor at the neuromuscular junction, it leads to activation of the receptor and a contraction of the muscle. In myasthenia gravis, the body’s immune system mistakenly creates antibodies against the acetylcholine receptor which leads to their destruction and, subsequently, prevents the muscle from contracting. Myasthenia gravis can affect individuals of any age, but is most prevalent in women younger than 40, men older than 60, and affects approximately 14 – 40 per 100,000 individuals in the United States.
There is currently no cure or prevention for myasthenia gravis, however, treatment of the disorder can help alleviate symptoms and improve the quality of life of patients. Current treatments for the disorder are not effective in all patients, are poorly tolerated, and most of these treatments involve steroid-based therapeutics which have several side effects. As such, there is an unmet need for an effective treatment in a larger range of patients that is well-tolerated with low adverse side effects. Recently, the pharmaceutical company Argenxdeveloped a novel drug that appears to be effective in treating myasthenia gravis and will be up for consideration of approval by the Food and Drug Administration (FDA) by the end of 2021.
The novel drug is called Efgartigimod and it helps to prevent the body’s immune system-generated antibodies from attacking acetylcholine receptors. As discussed above, most patients with myasthenia gravis erroneously generate antibodies against acetylcholine receptors which leads to the impairments in muscle control that characterize the disease. Efgartigimod was designed to prevent the production and availability of the antibodies that are directed against acetylcholine receptors by finding and destroying the antibodies. In a first of its kind clinical trial with the drug, it was found that Efgartigimod was clinically effective in reducing the number of antibodies against acetylcholine receptors in patients with myasthenia gravis when compared to patients who were given placebo. Additionally, during the 26-week study, the drug was well tolerated in most patients with the majority of side effects being mild or moderate. Last, when the patients were asked to assess their daily living and quality of life before and after treatment, it was found that patients who were given the drug showed a significant improvement in quality of life compared to the placebo group.
This novel drug is the first of its kind to treat myasthenia gravis by blocking and degrading antibodies against the acetylcholine receptor. If the drug wins approval by the FDA, it will be much needed and welcomed treatment for patients living with myasthenia gravis.
Sources: Mayo Clinic; National Organization of Rare Diseases; Argenx; Efgartigimod; The Lancet
