Kim Moran, Ph.D., MBA, Head of US Rare Diseases at UCB, discusses the two orphan drugs, rozanolixizumab and zilucoplan, which the company hopes to have approved shortly to treat myasthenia gravis.
Myasthenia gravis is a rare autoimmune disorder that targets the acetylcholine receptors (AChRs) in the muscle cells.
The primary symptom of MG is muscle weakness. This symptom commonly affects the voluntary muscles, particularly those controlling eyes and eyelids, facial expression, chewing, swallowing, and limb movements. As the disease progresses, weakness may extend to other muscles, including those involved in breathing, causing respiratory problems.
Treatment may include pyridostigmine, to increase acetylcholine availability at the neuromuscular junction. Doctors also use corticosteroids, immunosuppressants, monoclonal antibodies targeting B cells, and other immunomodulatory therapies.
This patient population needs more targeted therapies with fewer side effects. As Dr. Moran notes, two orphan drugs developed by UCB, rozanolixizumab and zilucoplan, are currently under review by the FDA.
Orphan Drug Data
Rozanolixizumab is a subcutaneous monoclonal antibody that targets the neonatal Fc receptor (FcRn) to treat adults with generalized myasthenia gravis who are anti-AChR or anti-muscle-specific tyrosine kinase (MuSK) antibody positive. Experts expect the FDA to make a decision in the second quarter of 2023. In the Phase 3 MycarinG study, rozanolixizumab significantly improved the Myasthenia Gravis-Activities of Daily Living (MG-ADL) scores by -3.37 in the 7mg/kg cohort (n=66) and -3.40 for the 10mg/kg cohort. (n=67). The placebo cohort experienced a reduction of -0.78 in MG-ADL scores (n=67). This data was recently published in Lancet Neurology.
Zilucoplan is a subcutaneous, self-administered macrocyclic peptide complement C5 inhibitor in development to treat ACHR-positive myasthenia gravis. Experts expect the FDA to make a decision in the latter half of 2023. In the Phase 3 RAISE study, zilucoplan (0.3 mg/kg once daily, subcutaneously) significantly improved the MG-ADL scores by -4.39 in (n=86) compare to -2.30 for the placebo cohort (n=88). This data was also recently published in Lancet Neurology.
As explained by Dr. Kimberly Moran, it is necessary to have two additional treatment options for myasthenia gravis, each with unique actions and delivery patterns, considering the complex and diverse patient population.
Rystiggo (rozanolixizumab-noli) was approved by the U.S. FDA on June 27, 2023.
To learn more about myasthenia gravis, go to checkrare.com/myasthenia-gravis/