Neonatal Fc receptor (FcRn) blockers are now an established class in generalized myasthenia gravis, and four products carry FDA-approved labeling. For regulatory, medical affairs and clinical teams, the way these labels differ on indicated populations, administration setting and safety language shapes competitive positioning, trial design for new indications, and the labeling a follow-on FcRn program can reasonably aim for.
The analysis below compares the current US prescribing information for Vyvgart, Vyvgart Hytrulo, Rystiggo and Imaavy. It covers indications and antibody-status restrictions, pediatric use, dosing regimens, route and site of administration, and how each label sets out its warnings, precautions and contraindications, with every point cited to the source labeling.
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FcRn blocker US labels compared: Vyvgart, Vyvgart Hytrulo, Rystiggo and Imaavy
The four neonatal Fc receptor (FcRn) blockers with FDA-approved labeling share a common core: each is indicated for generalized myasthenia gravis (gMG), each carries a Section 5 warning on infections that includes a recommendation against live vaccines, and none carries a Boxed Warning 109708396. Beyond that core, the labels differ in ways that matter for positioning and for labeling strategy on follow-on products:
- Indication breadth. Vyvgart Hytrulo adds chronic inflammatory demyelinating polyneuropathy (CIDP) 72. Imaavy adds warm autoimmune hemolytic anemia (wAIHA) and is the only one of the four labeled for pediatric patients (12 years and older) 97.
- Antibody-status restriction. After the May 2026 revisions, the two efgartigimod labels no longer limit gMG use to anti-AChR antibody-positive adults 11072126124. Rystiggo and Imaavy still require anti-AChR or anti-MuSK antibody positivity 8497.
- Route and regimen. The four products span IV weight-based cycles (Vyvgart), fixed-dose subcutaneous injection with a self-administration option (Vyvgart Hytrulo), weight-banded subcutaneous pump infusion by a healthcare provider (Rystiggo), and continuous IV maintenance every 2 or 4 weeks (Imaavy) 110728497.
- Warnings architecture. Rystiggo is the only label with a Section 5 warning for aseptic meningitis and the only one with no contraindications 8786. Imaavy's infection warning uniquely addresses latent viral reactivation and serious EBV-related events 99100.
Labels reviewed
| Product (nonproprietary name) | BLA | Current label revision | Initial US approval |
|---|---|---|---|
| Vyvgart (efgartigimod alfa-fcab) | 761195 12 | 5/2026 109 | 2021 109 |
| Vyvgart Hytrulo (efgartigimod alfa and hyaluronidase-qvfc) | 761304 32 | 5/2026 70 | 2023 70 |
| Rystiggo (rozanolixizumab-noli) | 761286 52 | 12/2025 83 | 2023 83 |
| Imaavy (nipocalimab-aahu) | 761430 66 | 08/2026 96 | 2025 96 |
Indications
| Product | gMG indication | Other indications | Age |
|---|---|---|---|
| Vyvgart | Adult patients with gMG; no antibody-status qualifier in the current Section 1 110 | None 109110 | Adults; pediatric safety and effectiveness not established 116 |
| Vyvgart Hytrulo | Adult patients with gMG; no antibody-status qualifier 72 | CIDP in adults 72 | Adults; pediatric safety and effectiveness not established 80 |
| Rystiggo | gMG in adults who are anti-AChR or anti-MuSK antibody positive 84 | None 8384 | Adults; pediatric safety and effectiveness not established 90 |
| Imaavy | gMG in adults and pediatric patients 12 years and older who are anti-AChR or anti-MuSK antibody positive 97 | wAIHA in adults and pediatric patients 12 years and older who are currently or previously treated with corticosteroids 97 | 12 years and older 97 |
The May 2026 efgartigimod indication change
The October 2025 Vyvgart label restricted use to adults with gMG "who are anti-acetylcholine receptor (AChR) antibody positive" 126125. The October 2025 Vyvgart Hytrulo label carried the same AChR qualifier for gMG alongside the CIDP indication 124122. Both current labels list Indications and Usage (Section 1) as a Recent Major Change dated 5/2026, and the current Section 1 text for both products describes adult gMG without an antibody qualifier 1091107072. As a result, the efgartigimod products are now the only FcRn blockers in this group whose gMG indication is not tied to AChR or MuSK serostatus.
Imaavy's wAIHA indication is also recent. Section 1.2 and the associated dosing and warnings sections are listed as Recent Major Changes dated 08/2026 96.
Dosing
| Product | Dose | Regimen structure | Subsequent treatment | Missed dose |
|---|---|---|---|---|
| Vyvgart (gMG) | 10 mg/kg IV for patients under 120 kg; fixed 1,200 mg (3 vials) for patients 120 kg or more 110 | Once weekly for 4 weeks per cycle 110 | Subsequent cycles based on clinical evaluation; no fixed maintenance schedule 110 | Up to 3 days after the scheduled time, then resume the schedule 110 |
| Vyvgart Hytrulo (gMG) | Fixed dose: 1,000 mg efgartigimod alfa/10,000 units hyaluronidase (prefilled syringe) or 1,008 mg/11,200 units (vial) 72 | Once weekly for 4 weeks per cycle 72 | Subsequent cycles based on clinical evaluation 72 | Up to 3 days, then resume the schedule 73 |
| Vyvgart Hytrulo (CIDP) | Same fixed doses as gMG 73 | Once weekly, ongoing (no cycle structure) 73 | Consider whether to continue if neurological symptoms worsen, since not all patients respond 73 | Up to 3 days, then resume the schedule 73 |
| Rystiggo (gMG) | Weight-banded: 420 mg (under 50 kg), 560 mg (50 to under 100 kg), 840 mg (100 kg or more) 84 | Once weekly for 6 weeks per cycle 84 | Based on clinical evaluation; safety of starting a new cycle sooner than 63 days from the start of the prior cycle not established 84 | Up to 4 days, then resume the schedule 84 |
| Imaavy (gMG) | 30 mg/kg IV loading dose, then 15 mg/kg IV 97 | Maintenance begins 2 weeks after the loading dose 97 | Every 2 weeks thereafter 97 | As soon as possible, then maintain the treatment interval 98 |
| Imaavy (wAIHA) | 30 mg/kg IV loading dose, then 30 mg/kg IV 97 | First subsequent dose 4 weeks after the loading dose 97 | Every 4 weeks thereafter 97 | As soon as possible, then maintain the treatment interval 98 |
Two dosing paradigms emerge. Vyvgart, Vyvgart Hytrulo (in gMG) and Rystiggo use discrete treatment cycles, with retreatment timing left to clinical evaluation 1107284. Imaavy uses a loading dose followed by fixed-interval maintenance, and Vyvgart Hytrulo in CIDP uses continuous once-weekly dosing 9773. For Vyvgart, the clinical studies section reports that subsequent cycles were started no sooner than 28 days after the last infusion of the prior cycle 119.
All four labels direct prescribers to evaluate the need for age-appropriate vaccines before starting treatment or a new cycle, and state that live vaccines are not recommended during treatment because IgG is transiently reduced 110728497.
Route of administration and presentations
| Product | Route | Administration time | Who administers | Presentations (Section 3) |
|---|---|---|---|---|
| Vyvgart | IV infusion only, diluted in 0.9% sodium chloride to 125 mL, through a 0.2-micron in-line filter 110111 | 1 hour 111 | Healthcare professional 111 | 400 mg/20 mL (20 mg/mL) single-dose vial 111 |
| Vyvgart Hytrulo | Subcutaneous only; do not give IV and do not dilute 72 | About 20 to 30 seconds (prefilled syringe); about 30 to 90 seconds (vial) 72 | Prefilled syringe: patient or caregiver after training. Vial: healthcare professional only, with a winged infusion set 727374 | 1,000 mg/10,000 units per 5 mL prefilled syringe; 1,008 mg/11,200 units per 5.6 mL vial 75 |
| Rystiggo | Subcutaneous infusion only, by infusion pump at up to 20 mL/hour; no dilution; do not flush the line 848586 | No fixed duration stated; maximum rate 20 mL/hour 8486 | Healthcare provider only 85 | 280 mg/2 mL, 420 mg/3 mL, 560 mg/4 mL and 840 mg/6 mL single-dose vials (140 mg/mL) 86 |
| Imaavy | IV infusion only, diluted in 0.9% sodium chloride to 250 mL (40 kg or more) or 100 mL (under 40 kg), through a 0.2-micron or smaller filter 979899 | At least 30 minutes (loading dose); at least 15 minutes (subsequent doses) 9799 | Healthcare professional 99 | 300 mg/1.62 mL and 1,200 mg/6.5 mL single-dose vials (185 mg/mL) 99 |
Vyvgart Hytrulo is the only product in the class with labeled self-administration, and only for the prefilled syringe 7273. Its abdominal injection instructions differ slightly by presentation (at least 2 inches from the navel for the syringe, 2 to 3 inches for the vial) 7374. Rystiggo is administered in the lower right or lower left abdomen below the navel, and the label specifies pump characteristics including occlusion alarm limits at the maximum setting, tubing no longer than 61 cm, and a 26-gauge or larger needle 85.
Post-dose observation periods also differ: 1 hour for Vyvgart, at least 30 minutes for Vyvgart Hytrulo, 15 minutes for Rystiggo, and 30 minutes for Imaavy 1127686100.
Contraindications and warnings
None of the four labels carries a Boxed Warning 109708396.
| Label element | Vyvgart | Vyvgart Hytrulo | Rystiggo | Imaavy |
|---|---|---|---|---|
| Contraindications | Serious hypersensitivity to efgartigimod alfa products or excipients (anaphylaxis, hypotension leading to syncope reported) 111 | Serious hypersensitivity to efgartigimod alfa products, hyaluronidase or excipients 75 | None 86 | History of serious hypersensitivity to nipocalimab-aahu or excipients (anaphylaxis, angioedema reported) 99 |
| Infections (with immunization) | 5.1 112 | 5.1 75 | 5.1 86 | 5.1, including latent viral activation (e.g., herpes zoster) and serious EBV-related events, one with fatal complications, in the gMG extension study 99100 |
| Hypersensitivity reactions | 5.2 112 | 5.2 7576 | 5.3 87 | 5.2 100 |
| Infusion- or injection-related reactions | 5.3 112 | 5.3 (infusion/injection-related) 76 | No separate subsection 87 | 5.3 101 |
| Aseptic meningitis | Not in Section 5 109 | Not in Section 5 71 | 5.2, serious drug-induced cases reported 87 | Not in Section 5 96 |
Infections and immunization
The infection warnings follow a shared template across all four labels: delay treatment in patients with an active infection, monitor for signs and symptoms of infection, and consider withholding the product if a serious infection occurs 112758699. The efgartigimod labels cite Study 1 data showing urinary tract infection in 10% versus 5% with placebo and respiratory tract infections in 33% versus 29% 11275. Imaavy's warning goes further. It adds risk of latent viral reactivation and describes serious Epstein-Barr virus-related events in the gMG extension study 99100.
Hypersensitivity and infusion reactions
The efgartigimod labels describe postmarketing anaphylaxis and hypotension leading to syncope with the IV product, occurring during or within 1 hour of administration 11276. Imaavy lists angioedema, anaphylaxis, rash, urticaria and eczema among observed hypersensitivity reactions and directs discontinuation of the infusion if a reaction occurs 100. Rystiggo's hypersensitivity warning cites angioedema and rash 87. Vyvgart, Vyvgart Hytrulo and Imaavy share language allowing rechallenge after mild to moderate infusion-related reactions with close observation, slower rates and premedication 11276101.
Aseptic meningitis and headache
Rystiggo alone carries an aseptic meningitis warning 87. Headache appears in all four labels only as an adverse reaction, not as a Section 5 item. Rystiggo reports severe headache in 5.3% of treated patients in Study 1 89, and Imaavy lists headache among its observed infusion-related reactions 101.
Other safety content outside Section 5
- Lipids. Imaavy reports lipid shifts as Section 6 laboratory findings. In gMG Study 1, 24% of patients shifted from normal to high fasting total cholesterol and 11% to high LDL cholesterol 103. None of the labels includes a lipid warning in Section 5 112758799.
- Pregnancy. All four labels address pregnancy in Section 8.1 rather than Section 5. The efgartigimod labels note that reduced maternal IgG may reduce passive protection of the newborn 11579. Rystiggo cites animal findings of increased embryonic death, reduced offspring body weight and impaired offspring immune function 8990. Imaavy cites placental ischemia associated with fetal loss in monkeys and possible reduction of infant passive immunity for 6 months or more 105.
Most common adverse reactions (Highlights)
| Product | Most common adverse reactions | Threshold |
|---|---|---|
| Vyvgart (gMG) | Respiratory tract infections, headache, urinary tract infection 109 | 10% or more 109 |
| Vyvgart Hytrulo (gMG and CIDP) | Injection-site reactions; plus the IV efgartigimod gMG profile above 70 | 15% or more for injection-site reactions; 10% or more for the IV profile 70 |
| Rystiggo (gMG) | Headache, infections, diarrhea, pyrexia, hypersensitivity reactions, nausea 83 | 10% or more 83 |
| Imaavy (gMG) | Respiratory tract infections, peripheral edema, muscle spasms 96 | 10% or more 96 |
| Imaavy (wAIHA) | Peripheral edema, diarrhea, pyrexia 96 | 10% or more 96 |
Takeaways for regulatory affairs teams
- Indication language is changing. Both efgartigimod labels dropped the AChR-positive qualifier in May 2026, and Imaavy added wAIHA in August 2026 1261101247296. Competitive labeling assessments built on 2025 labels are now out of date.
- Pediatric labeling is a differentiator. Imaavy is the only FcRn blocker in this group labeled for patients 12 years and older. The other three state that pediatric safety and effectiveness have not been established 971168090.
- Administration setting drives the regimen story. The four products cover every combination of IV and subcutaneous delivery with cyclic or continuous dosing. Only the Vyvgart Hytrulo prefilled syringe supports administration outside a healthcare setting 7273.
- Class labeling is consistent, but product-specific warnings are not. Infection and live-vaccine language is effectively harmonized across the class 1127586100. Aseptic meningitis (Rystiggo) and viral reactivation/EBV (Imaavy) are product-specific signals, and contraindication language ranges from none (Rystiggo) to hyaluronidase-inclusive hypersensitivity (Vyvgart Hytrulo) 87998675.