The recent FDA approval of Vyvgart (efgartigimod) for generalized myasthenia gravis (gMG) marks the first drug approval for Argenx. Vyvgart is designed specifically for adults who test positive for the anti-acetylcholine receptor (AChR) antibody.
An article recently published in Endpoints News celebrates another first. Vyvgart is the first drug to be validated in the FcRn inhibitor class.
Efforts behind the development of an FcRn inhibitor, one of a new class of drugs, came about due to a lack of treatment options for gMG patients. Science Advances notes that FcRn (neonatal crystallizable fragment receptor) provides intracellular protection for immunoglobulin G (IgG).
FcRn recycles IgG antibodies by causing them to avoid lysosomal decay. This is an undesirable process that would eventually render the antibodies useless.
About generalized Myasthenia Gravis (gMG)
The disease, gMG, results from an autoantibody of the immunoglobulin G (IgG) type that interrupts the signals between muscle cells and nerves (neuromuscular junction). The muscles can no longer contract, normally leading to a weakness that is potentially life-threatening.
According to Tim Van Hauwermeiren, Argenx CEO, 65,000 people in the United States are affected by myasthenia gravis. The generalized form affecting multiple organs of the body occurs in approximately eighty-five percent of gMG patients. Time to progression is generally eighteen months with patients experiencing difficulty with speech, breathing, and swallowing.
About the Study
The results of the Vyvgart study showed a response by 68% of patients in the first treatment cycle versus 30% of patients assigned to a placebo.
The FDA noted that along with Vyvgart’s reduction in IgG levels, there may be a corresponding risk of infections. The majority of side effects were headaches and infections in the respiratory or urinary tract.
CEO Van Hauwermeiren commented that the before and after of Vyvgart reminds him of a sledgehammer versus a scalpel. Prior to Vyvgart’s approval, doctors had only steroids, surgery, or chemotherapy as options for treating gMG. Now they have a “scalpel” that removes the autoantibody precisely.
James Howard, the principal investigator of the study, predicts that this new therapy will reduce the gMG disease burden, and offers a new treatment going forward.
Currently, there are over one hundred IgG-related autoimmune disorders and Argenx believes that the majority can be addressed by an FcRn antagonist.