UCB Launches Zilbrysq for Generalized Myasthenia Gravis


Zilbrysq has a list price $1,047.19 for a 23 mg syringe. It is UCB’s second treatment for patients with myasthenia gravis.

UCB has launched Zilbrysq (zilucoplan) to treat patients with generalized myasthenia gravis, a chronic autoimmune disease that causes weakness in the skeletal muscles that worsens after periods of activity and improves after periods of rest. It is indicated for adult patients who are anti-acetylcholine receptor (AChR) antibody positive.

Zilbrysq is a daily, self-administered peptide inhibitor of C5 complement, which inhibits key components in the underlying pathophysiology of generalized myasthenia gravis. The dose and the price depend on the patient’s weight. The list price of a 23 mg syringe is $1,047.19. Zilbrysq is available through the specialty pharmacy PANTHERx Rare Pharmacy and through a Risk Evaluation and Mitigation Strategy (REMS) program because of the risk of serious meningococcal infections.

Kimberly Moran, Ph.D.

Kimberly Moran, Ph.D.

Kimberly Moran, Ph.D., senior vice president and head of U.S. Rare Diseases at UCB, told Formulary Watchthat Zilbrysq may offer a lower total cost of care relative to other existing complement inhibitors approved to treat generalized myasthenia gravis because it is self-administered. “Because Zilbrysq is the only generalized myasthenia gravis targeted therapy to be self-administered by eligible adult patients, the healthcare system incurs $0 of healthcare provider administration costs,” she said.

UCB executives point to a Milliman study of drug and administration costs of therapies to treat myasthenia gravis. Another C5 inhibitor, Alexion’s Soliris (eculizumab) is an intravenous administration with a drug cost per claim of $31,300 in 2022 and an administration cost per claim of $200. Annual drug costs based on patient claim counts in 2022 were $520,000 and an administration costs were $2,750. The Milliman study was commissioned by UCB.

UCB also provides the program ONWARD in which eligible patients have access to a dedicated Care Coordinator who will provide personalized support, tools, and resources to get started on treatment.

The FDA approved Zilbrysq in October 2023 based on safety and efficacy data from the phase 3 RAISE study, which demonstrated at week 12 that treatment with Zilbrysq resulted in clinically meaningful and statistically significant improvements in key generalized myasthenia gravis-specific outcomes compared with placebo in patients. The study met its primary endpoint with Zilbrysq showing a placebo-corrected mean improvement of 2.09 points in the Myasthenia Gravis Activities of Daily Living score at week 12. Additionally, treatment with Zilbrysq led to improvements in the Quantitative Myasthenia Gravis (QMG) total score, which is a 13-item categorical grading system that assesses muscle weakness.

The most common adverse reactions were injection site reactions, upper respiratory tract infection, and diarrhea. Results were published in The Lancet Neurology in May 2023.

Related: FDA Approves Rystiggo for Generalized Myasthenia Gravis

This is the second UCB treatment for generalized myasthenia gravis. In July 2023, UCB launched Rystiggo (rozanolixizumab-noli) in adult patients who are anti-acetylcholine receptor (AChR) or anti-muscle-specific tyrosine kinase (MuSK) antibody positive.

Rystiggo is a monoclonal antibody that targets the neonatal Fc receptor (FcRn). It has been designed to block the interaction of Fc receptor and immunoglobulin G (IgG) and reduce the concentration of IgG autoantibodies. It has a list price of $6,050 per vial. It is available at about 1,000 infusion sites in the United States, and UCB has also partnered with a network of specialty pharmacies with home infusion capabilities.

The approval of Rystiggo was based on data from a pivotal phase 3, which was published in The Lancet Neurology in May 2023.

The approvals of UCB’s therapies came just after the approval of another subcutaneous therapy for generalized myasthenia gravis: Argenx’s Vyvgart Hytrulo (efgartigimod alfa and hyaluronidase-qvfc). Vyvgart Hytrulo, however, is indicated only for those who are anti-AChR antibody positive.

Vyvgart intravenous was approved in December 2021, and, like Rystiggo, it binds to the neonatal Fc receptor (FcRn) to reduce circulating IgG. According to the Milliman study, Vyvgart intravenous had a cost per claim of $20,500 and administration cost of $220 in 2022. Annual drug costs based on patient claim counts in 2022 were $121,000, and the costs to administer were $1,070.

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