UCB received approval on Oct. 17, 2023, for Zilbrysq® (zilucoplan) injection for treating adults who have generalized myasthenia gravis (gMG) that is positive for acetylcholine receptor (AChR) antibodies. A complement 5 (C5) inhibitor, is administered by subcutaneous (SC) injections by the patient or caregiver once every day at dosages that depend on the patient’s weight. Due to potentially fatal meningococcal infections that may be associated with the use of Zilbrysq, it has a boxed warning and a Medication Guide, as well as a risk evaluation and mitigation strategy (REMS) which limits its access to certified prescribers and dispensers. All patients should be vaccinated against meningitis at least two weeks prior to beginning treatment with Zilbrysq. UCB launched Zilbrysq upon approval. Distribution and pricing are not yet available. Complete prescribing information including the patient Medication Guide is here.

At a Glance

• Brand (Generic) Name: Zilbrysq (zilucoplan)
• Manufacturer: UCB
• Date Approved: Oct. 17, 2023
• Indication: to treat gMG in adult patients who are AChR antibody-positive
• Dosage Forms Available: single-dose syringes prefilled with 16.6mg, 23mg, or 32.4mg of Zilbrysq
• Launch Date: Upon approval
• Estimated Annual Cost: Not available
• Caused by an autoimmune reaction that damages neuromuscular junctions (parts of muscles where nerve signals are received), gMG results in muscle weakness in multiple muscle groups.
• Around 10% of patients may have potentially life-threatening involvement of the muscles used for breathing. Additional symptoms may include double vision, drooping eyelids, and difficulty swallowing, chewing and talking.
• Up to 60,000 Americans are estimated to have MG, which is more common among women than men with a global prevalence of 100 to 350 cases per one million people.
• Women generally are diagnosed with the condition in early adulthood, but cases in men usually are not discovered until after the age of 50 years old.
• Approximately 85% of patients who have MG have the generalized type and the majority of patients (about 85%) also have AChR antibodies.
• By blocking the complement protein C5, Zilbrysq is believed to decrease activity at neuromuscular junctions.
• Approval of Zilbrysq was based on the Phase III study, RAISE, that showed it was statistically significant vs. placebo for improvements in MG-specific efficacy outcomes, the Myasthenia Gravis-Activities of Daily Living (MG-ADL) and the Quantitative Myasthenia Gravis (QMG) scores, reported by patients and clinicians from baseline to week 12.
• Because using Zilbrysq may be associated with an increased risk of serious meningococcal infections, along with its REMS, it has a boxed warning and a patient Medication Guide about potentially life-threatening meningitis that may occur during its use. Vaccinations against meningitis infections must be given at least two weeks before therapy begins.
• The risk for infections is increased with complement inhibitors, especially bacterial infections, such as Neisseria meningitidis and Streptococcus pneumoniae.
• Because using Zilbrysq may cause pancreatitis, amylase, and lipase levels should be determined before therapy starts and regularly during treatment.
• Other drugs approved to treat gMG in patients who are AChR antibody-positive include Alexion’s intravenously (IV) infused complement inhibitors Soliris^® (eculizumab) and Ultomiris^® (ravulizumab-cwvz) and Argenx’s neonatal Fc receptor (FcRn) blockers Vyvgart^® (efgartigimod alfa-fcab) and Vyvgart^® Hytrulo (efgartigimod alfa/hyaluronidase-qvfc). Vyvgart is administered as an IV infusion and Vyvgart Hytrulo, which was approved on June 20, 2023, is administered as a SC infusion over approximately 30 to 90 seconds once weekly for four weeks.
• Rystiggo^® (rozanolixizumab-noli – UCB) is an FcRn blocker approved in June 2023. It decreases pathogenic Immunoglobulin G (IgG) autoantibodies for the treatment of gMG in adult patients who are AChR or anti-muscle-specific tyrosine kinase (MuSK) antibody positive. It is administered via a SC infusion pump over 20 to 30 minutes once weekly for six weeks. The infusion must be prepared and infused by a healthcare professional.
• Zilbrysq was granted Orphan Drug Designation for the treatment of gMG.