Section 07 · Monograph

Efgartigimod

Reviewed Nov 2026FDA label

VyvgartFcRn blocker

Indications

Generalized myasthenia gravis (gMG) in adult patients — VYVGART and VYVGART Hytrulo are approved for all serotypes of adult gMG, including anti-AChR antibody-positive, anti-MuSK antibody-positive, anti-LRP4 antibody-positive, and triple seronegative patients, following an FDA label expansionFDA-labeled
Chronic inflammatory demyelinating polyneuropathy (CIDP) in adults — VYVGART Hytrulo (subcutaneous efgartigimod alfa/hyaluronidase) onlyFDA-labeled

Human IgG1 antibody Fc-fragment (fusion protein, not a whole antibody) engineered for increased affinity to the neonatal Fc receptor (FcRn) at both neutral and acidic pH
Competitively blocks IgG from binding FcRn within endosomes, preventing IgG recycling back into circulation and instead routing IgG for lysosomal degradation
Produces a rapid, reversible reduction in circulating total IgG levels, including pathogenic autoantibodies that drive neuromuscular junction damage in gMG
Does not directly target the autoantibody itself but broadly lowers total IgG, which is the basis for infection risk and reduced vaccine antibody titers during treatment
Efficacy demonstrated even in seronegative gMG patients, suggesting a broader IgG-mediated pathophysiology beyond currently identifiable autoantibodies

VYVGART (IV): 10 mg/kg (up to 1,200 mg for patients ≥120 kg) infused intravenously over approximately 1 hour, once weekly for 4 infusions per treatment cycle
Subsequent treatment cycles administered based on clinical evaluation; cycles separated by a minimum of 28 days between cycle start dates
VYVGART Hytrulo (subcutaneous, coformulated with recombinant human hyaluronidase): fixed dose of 1,008 mg efgartigimod alfa/43,200 units hyaluronidase, injected subcutaneously into the abdomen over approximately 30-90 seconds, once weekly for 4 doses per cycle
VYVGART Hytrulo prefilled syringe available for at-home patient/caregiver self-injection after training
For CIDP, VYVGART Hytrulo initial 4-week cycle followed by maintenance dosing every 2 weeks based on clinical evaluation
Delay dosing in patients with an active infection until the infection resolves

Known serious hypersensitivity to efgartigimod alfa or any excipient (reactions have included anaphylaxis and hypotension leading to syncope)

Reduces effectiveness of other FcRn-binding therapeutics such as IVIG and monoclonal antibodies with a human IgG Fc domain — closely monitor or consider discontinuing efgartigimod if such a medication is clinically essential
May reduce circulating levels of vaccine-induced or passively-administered antibodies
Live and live-attenuated vaccines: administer before starting therapy when possible
Concurrent immunosuppressants increase cumulative infection risk

Screen for active infection prior to each cycle; delay dosing until infection resolves
Baseline and periodic CBC with differential given reported lymphocyte/neutrophil decreases
Monitor for hypersensitivity/infusion reactions during and for approximately 1 hour after IV infusion
Assess MG-ADL and QMG scores (or CIDP disability scales) to track clinical response
Update immunizations prior to initiating therapy
Monitor injection sites for local reactions with subcutaneous formulation

No adequate human data on use during pregnancy; efgartigimod is an IgG-Fc fragment expected to cross the placenta, increasing with gestational age
Animal reproduction studies in monkeys showed no adverse developmental effects at exposures up to ~10x the maximum recommended human dose
Because the drug lowers maternal IgG, it may theoretically reduce passive transfer of protective maternal antibodies to the fetus/neonate
A pregnancy exposure registry is available for patients exposed during pregnancy
No data on presence in human milk, effects on breastfed infants, or milk production