UCB received approval from the US Food and Drug Administration (FDA) for Rystiggo (rozanolixizumab) as a treatment with generalized myasthenia gravis (gMG) who test positive for the anti-acetylcholine receptor (AChR) or anti-muscle-specific tyrosine kinase (MuSK) antibodies in adult patients. The FDA granted priority review status to Rystiggo depending on the positive results from the Phase 3 MycarinG study in gMG2. This large-scale study demonstrated that rozanolixizumab significantly improved gMG-specific outcomes, including daily activities such as breathing, talking, swallowing, and mobility.
Rystiggo is a subcutaneous infusion of rozanolixizumab, a IgG4 monoclonal antibody antibody that binds to the neonatal Fc receptor (FcRN) and reduces circulating IgG levels. It is the only FDA-approved treatment for adults with gMG who test positive for both anti-AChR and anti-MuSK antibodies, the most common subtypes of the condition. The FDA approval is supported by safety and efficacy data from the Phase 3 MycarinG study, published in The Lancet Neurology in May 2023.
The study's primary efficacy endpoint was the change in the MG-ADL total score at day 43. This measurement tool assesses the impact of gMG on daily functions related to eight signs or symptoms commonly affected in gMG. These functions include breathing, talking, swallowing, and mobility. The trial demonstrated a significant improvement in the MG-ADL total score for patients treated with rozanolixizumab (-3.4) compared to those on placebo (-0.8).
The study's secondary endpoint was the change in the QMG, a 13-item grading system that assesses muscle weakness. Again, rozanolixizumab demonstrated a statistically significant improvement in the QMG total score compared to placebo.
The most commonly reported side effects headache, infections, diarrhoea, pyrexia (fever), hypersensitivity reactions, and nausea.
Rystiggo is expected to be available commercially in the US during the third quarter of 2023.