ZILBRYSQ is a first-of-its-kind complement C5 inhibitor approved for the treatment of gMG in adult patients who are anti-AChR Ab+1,2


Complement activation
in gMG

Generalized myasthenia gravis (gMG) is a chronic, unpredictable, autoimmune disease2

In gMG, pathogenic immunoglobulin G (IgG) autoantibodies attack key proteins, most commonly the acetylcholine receptor (AChR), in the neuromuscular junction (NMJ). This prevents AChR binding, reduces receptor density, and activates the complement system.1,2

Complement activation, resulting in the cleavage of C5 into C5a and C5b by C5 convertase.

In anti-AChR antibody positive (Ab+) gMG, binding of pathogenic autoantibodies to the AChR initiates complement activation2

  • Complement activation results in the cleavage of complement component 5 (C5) into C5a and C5b by C5 convertase1-3
  • C5a is a potent proinflammatory mediator, while C5b initiates the terminal complement pathway2
Activating the complement system and formation of a MAC.

Formation of the membrane attack complex (MAC) damages the NMJ2

  • Activation of C5b within the complement cascade contributes to MAC formation
  • This leads to the deposition of MAC on the post-synaptic membrane of the NMJ leading to damage and subsequent impaired synaptic transmission

Complement inhibition

ZILBRYSQ is a first-of-its-kind small peptide C5 inhibitor for the treatment of anti-AChR Ab+ gMG1,2

ZILBRYSQ provides complement inhibition.

Small macrocyclic peptide2

ZILBRYSQ is a first-of-its-kind, macrocyclic peptide that specifically targets the complement cascade.

Prevents the subsequent assembly of the MAC.

Prevents assembly of MAC2,3

ZILBRYSQ binds to C5 with high affinity and specificity, preventing C5 cleavage into C5a and C5b by C5 convertase. This prevents the subsequent assembly and activity of the MAC, providing complement inhibition.

The precise mechanism through which ZILBRYSQ exerts therapeutic effects in gMG is unknown.1

ZILBRYSQ Mechanism of Action



  1. ZILBRYSQ [Prescribing Information]. Smyrna, GA: UCB, Inc.
  2. Howard JF Jr, Bresch S, Genge A, et al; RAISE Study Team. Safety and efficacy of zilucoplan in patients with generalised myasthenia gravis (RAISE): a randomised, double-blind, placebo-controlled, Phase 3 study. Lancet Neurol. 2023;22(5):395-406. doi:10.1016/S1474-4422(23)00080-7
  3. Mantegazza R, Vanoli F, Frangiamore R, et al. Complement inhibition for the treatment of myasthenia gravis. ImmunoTargets Ther. 2022;9:317-331. doi:10.2147/ITT.S261414