FDA Approves Rystiggo for Generalized Myasthenia Gravis

The FDA has approved UCB’s Rystiggo (rozanolixizumab-noli) to treat adults with generalized myasthenia gravis (gMG). It is be indicated for patients who are positive for the anti-acetycholine receptor (AChR) or the anti-muscle-specific tyrosine kinase (MuSK) antibody.

Generalized myasthenia gravis is a chronic and unpredictable autoimmune disease that causes weakness in the skeletal muscles, including those in the arms and legs and those involved in breathing. The condition worsens with activity. People living with gMG can experience a variety of symptoms, including drooping eyelids, double vision, and difficulty in swallowing, chewing and talking. It is estimated that there are two to seven people in every 10,000 that have myasthenia gravis, according to the Muscular Dystrophy Association.

Rystiggo is a subcutaneous (under the skin) monoclonal antibody that targets the neonatal Fc receptor (FcRn). It has been designed to block the interaction of Fc receptor and Immunoglobulin G (IgG), accelerating the catabolism of antibodies and reducing the concentration of IgG autoantibodies. It will be commercially available in the third quarter of 2023 and will have a list price of $6,050 per vial. For patients without insurance, the company offers financial assistance.

Rystiggo is the only FDA-approved treatment in adults who are both anti-AChR and anti-MuSK antibody-positive gMG, the two most common subtypes of generalized myasthenia gravis. This approval follows the approval of a subcutaneous version of Argenx’s Vyvgart Hytrulo (efgartigimod alfa and hyaluronidase-qvfc). Vyvgart Hytrulo, however, is indicated only for those who are anti-AChR antibody positive.

Related: FDA Approves Subcutaneous Vyvgart for Myasthenia Gravis

“gMG can cause unpredictable fluctuations in severity and frequency of symptoms, which are often debilitating and can substantially impact the lives of patients. People living with gMG often face treatment options that are broad-acting, and that have traditionally only offered symptomatic relief,” lead investigator Vera Bril, M.D., professor of Medicine (Neurology), University of Toronto, Director of the Neuromuscular Section, Division of Neurology, University of Toronto and University Health Network, Toronto, said in a press release. “There is a significant need for new, innovative treatment options to reduce the day-to-day burden of gMG.”

The approval was based on data from the pivotal phase 3, published in The Lancet Neurology in May 2023. A statistically significant difference was seen in the MG-ADL total score change in patients receiving Rystiggo. MG-ADL is a measurement tool that assesses the impact of generalized myasthenia gravis on daily functions of eight signs or symptoms that are typically affected in generalized myasthenia gravis. The secondary endpoint was the change between treatment groups in the QMG, a 13-item categorical grading system that assesses muscle weakness. A statistically significant difference was seen with patients who received Rystiggo.

The most common adverse reactions were headache, infections, diarrhea, pyrexia, hypersensitivity reactions, and nausea.