Zilbrysq for AChR-positive gMG now commercially available in US

List price for approved daily injection therapy set at $1,047.19 per syringe

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by Steve Bryson, PhD |

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Zilbrysq (zilucoplan), a new treatment for adults with generalized myasthenia gravis (gMG) who test positive for antibodies against the acetylcholine receptor (AChR), is now commercially available in the U.S., with a list price likely to exceed $30,000 for a 30-day supply.

Approved by the U.S. Food and Drug Administration (FDA) in October of last year, the subcutaneous (under-the-skin) injection therapy is available by prescription as a ready-to-use, pre-filled syringe for once-daily self-administration by patients or caregivers. It will be dispensed by the specialty pharmacy PANTHERx Rare Pharmacy, as selected by the therapy’s developer UCB, the company announced in a press release.

The list price of Zilbrysq has now been set at $1,047.19 per 23 mg syringe, UCB stated on its U.S. website. The company noted that the amount patients will pay will vary based on their weight, and will be dependent on the individual’s prescription drug coverage.

“UCB aimed to price Zilbrysq to be the lowest cost complement inhibitor treatment for the U.S. gMG population overall,” the press release states.

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Approved injection therapy dispensed by specialty pharmacy PANTHERx

Zilbrysq’s U.S. launch comes approximately five months after that of Rystiggo (rozanolixizumab-noli), another gMG therapy developed by UCB. Rystiggo was approved by the FDA in June 2023 for patients with antibodies against AChR or muscle-specific tyrosine kinase, known as MuSK.

Both Zilbrysq and Rystiggo are included in ONWARD, a personalized support program from UCB that’s in place to help patients and caregivers in various aspects of their treatment journey.

ONWARD will provide patients with a dedicated care coordinator who can provide tools and resources for getting started on Zilbrysq. The care coordinators will offer help on understanding insurance coverage, and on specifics of the therapy, such as “refresher injection coaching and information on symptom tracking,” per the release. Patients and caregivers can visit http://www.UCBONWARD.com or call 1-844-ONWARD to access the program.

“Now that Zilbrysq is approved and commercially available, the ONWARD program will be in place to provide further care and support for those navigating the complexities of this disease,” the release states.

In MG, the communication between nerves and muscles is disrupted by self-reactive antibodies, most commonly those targeting the AChR protein. The binding of antibodies to the AChR protein can trigger the activation of the complement system — a group of immune proteins that normally help defend the body against harmful microbes. Such activation contributes to the damage that drives the disease.

Zilbrysq is designed to specifically target a complement protein called C5, in the same way as other approved treatments for AChR-positive gMG, including Soliris (eculizumab) and Ultomiris (ravulizumab-cwvz).

Unlike Soliris and Ultomiris, which are administered as an infusion directly into the bloodstream under the guidance of a healthcare professional, Zilbrysq is given by once-daily subcutaneous injections that can be administered by caregivers or patients after proper training.

Zilbrysq’s approval was supported by data from a 12-week Phase 3 trial called RAISE (NCT04115293), which enrolled 174 adults with anti-AChR-positive gMG.

Compared with a placebo, Zilbrysq significantly reduced MG symptom severity and the impact of these symptoms on daily living, as measured by the MG Activities of Daily Living (MG-ADL) scale. The therapy also outperformed the placebo on quality of life assessments and other measures of MG severity. Moreover, recent analyses of trial data showed that Zilbrysq was consistently effective across different patient subgroups.

The most common Zilbrysq-related side effects included injection site reactions, upper respiratory tract infections, and diarrhea. The therapy also has a boxed warning noting that it may cause a potentially life-threatening meningococcal bacterial infection.

Given that risk, healthcare providers who prescribe Zilbrysq must enroll in Zilbrysq REMS, a restricted risk evaluation and mitigation strategy (REMS) program.