Imaavy (nipocalimab)
An approved treatment for Myasthenia Gravis.
The same compound appears under different names depending on the context. Here is how to identify Nipocalimab wherever you encounter it, plus the key facts at a glance.
- Generic name
- Nipocalimab
- Brand name
- Imaavy
- Development code
- M281
- Drug class
- FcRn inhibitor
- Manufacturer
- Johnson & Johnson (Janssen)
- How it's taken
- Given as an intravenous (IV) infusion at an infusion center.
An FcRn blocker approved for generalized myasthenia gravis in patients 12 and older who are anti-AChR or anti-MuSK antibody positive. By lowering IgG antibodies that attack the neuromuscular junction, it reduces muscle weakness in adults and children 12 and older. In August 2026, the FDA also approved it as the first treatment for warm autoimmune hemolytic anemia, for patients 12 and older who are taking or have taken corticosteroids.
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Where Nipocalimab fits
Third FcRn blocker approved for generalized MG, indicated for both AChR and MuSK antibody-positive patients. Also being studied for maternal-fetal conditions.
How Nipocalimab works
Nipocalimab binds to the neonatal Fc receptor (FcRn), which normally recycles IgG antibodies back into circulation and extends their lifespan. By blocking this recycling, nipocalimab causes accelerated breakdown of all IgG antibodies, including the pathogenic autoantibodies that attack acetylcholine receptors or MuSK at the neuromuscular junction. This leads to reduced antibody levels and improvement in muscle strength.
Mechanism: Anti-FcRn monoclonal antibody that reduces pathogenic IgG autoantibodies by blocking the neonatal Fc receptor
Side effects and safety
In myasthenia gravis, the most common side effects were respiratory tract infections, swelling in the legs or feet (peripheral edema), and muscle spasms. In warm autoimmune hemolytic anemia, they were peripheral edema, diarrhea, and fever. Because it lowers IgG antibodies, it can raise the risk of infections, including reactivation of viruses like shingles. Allergic reactions (including anaphylaxis and angioedema) and infusion reactions (headache, flu-like symptoms, rash, nausea) can occur, so patients are watched for 30 minutes after each infusion. Live vaccines are not recommended during treatment. Cholesterol levels may rise.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Nipocalimab
Given as an intravenous (IV) infusion at an infusion center. For generalized myasthenia gravis: a first dose of 30 mg/kg, then 15 mg/kg every 2 weeks starting 2 weeks later. For warm autoimmune hemolytic anemia: 30 mg/kg every 4 weeks. Patients are watched for 30 minutes after each infusion for allergic or infusion reactions.
Availability and cost
Only available as the brand-name product.
FcRn blocker with additional development in maternal-fetal medicine indications. IV infusion every 2 weeks for MG (every 4 weeks for warm autoimmune hemolytic anemia) with specialty biologic pricing.
Help paying for Imaavy
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Copay help
Eligible commercially insured patients pay as little as $0 per infusion. Covers the drug and some infusion and monitoring costs; yearly maximum. No government insurance.
For: private insurance · source - Infusion cost help
Treatment Administration Cost Support helps with certain infusion administration and related monitoring costs for eligible commercially insured patients.
For: private insurance · source - Bridge or quick-start supply
IMAAVY withMe Access Program: for eligible commercial patients whose coverage is delayed more than 5 business days or denied.
For: private insurance · source - Free medicine program
Uninsured patients, or those whose insurance does not fully meet their needs, may get the medicine free for up to one year if they meet income and eligibility rules.
For: no insurance, underinsured, private insurance, Medicare, Medicaid · source
Good to know: Free-drug terms at PatientAssistanceInfo.com/IMM.
- From a charity · NORD RareCareMyasthenia Gravis Medical Assistance fundOpen
Pays for: Medical and medication costs.
The foundation says: “Accepting new applications and re-enrollments for current year” - From a charity · NORD RareCareMyasthenia Gravis Premium Copay Assistance fundOpen
Pays for: Insurance premiums and copays.
The foundation says: “Accepting new applications and re-enrollments for current year” - From a charity · TotalAssist (formerly PAN Foundation)Myasthenia Gravis fundOpen
Pays for: Out-of-pocket costs for approved medications, up to $10,000 per year. Requires Medicare, Medicaid or TRICARE.
- From a charity · The Assistance FundMyasthenia Gravis fundWaitlist
Pays for: Copays, coinsurance, deductibles and other health-related expenses.
The foundation says: “WAITLIST — Accepting Waitlist Patients. TAF is currently accepting requests to join the enrollment waitlist for this program. Waitlists a…”
Clinical trial results
The VIVACITY-MG3 Phase 3 trial demonstrated significant improvement in MG-ADL scores compared to placebo in adults who were anti-AChR or anti-MuSK antibody positive. In the trial, 88% of patients in the main analysis were AChR positive and 10% were MuSK positive.
Development history
Developed by Momenta Pharmaceuticals (acquired by Johnson & Johnson). Received FDA approval for generalized myasthenia gravis on April 29, 2025, for patients who are anti-AChR or anti-MuSK antibody positive. In August 2026, the FDA approved it for warm autoimmune hemolytic anemia, the first approved treatment for that condition, based on a 24-week, 118-patient placebo-controlled trial (NCT04119050) in which 24% of patients on the 30 mg/kg every-4-weeks dose had a durable hemoglobin response versus 8% on placebo. Also being studied for hemolytic disease of the fetus and newborn (HDFN).
Explore Myasthenia Gravis trials
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Nipocalimab in Trial Friend News and Guides
Common questions about Nipocalimab
▸What is Nipocalimab (Imaavy)?
An FcRn blocker approved for generalized myasthenia gravis in patients 12 and older who are anti-AChR or anti-MuSK antibody positive. By lowering IgG antibodies that attack the neuromuscular junction, it reduces muscle weakness in adults and children 12 and older. In August 2026, the FDA also approved it as the first treatment for warm autoimmune hemolytic anemia, for patients 12 and older who are taking or have taken corticosteroids.
▸How does Nipocalimab work?
Nipocalimab binds to the neonatal Fc receptor (FcRn), which normally recycles IgG antibodies back into circulation and extends their lifespan. By blocking this recycling, nipocalimab causes accelerated breakdown of all IgG antibodies, including the pathogenic autoantibodies that attack acetylcholine receptors or MuSK at the neuromuscular junction. This leads to reduced antibody levels and improvement in muscle strength.
▸What are the side effects of Nipocalimab?
In myasthenia gravis, the most common side effects were respiratory tract infections, swelling in the legs or feet (peripheral edema), and muscle spasms. In warm autoimmune hemolytic anemia, they were peripheral edema, diarrhea, and fever. Because it lowers IgG antibodies, it can raise the risk of infections, including reactivation of viruses like shingles. Allergic reactions (including anaphylaxis and angioedema) and infusion reactions (headache, flu-like symptoms, rash, nausea) can occur, so patients are watched for 30 minutes after each infusion. Live vaccines are not recommended during treatment. Cholesterol levels may rise.
▸How is Nipocalimab taken?
Given as an intravenous (IV) infusion at an infusion center. For generalized myasthenia gravis: a first dose of 30 mg/kg, then 15 mg/kg every 2 weeks starting 2 weeks later. For warm autoimmune hemolytic anemia: 30 mg/kg every 4 weeks. Patients are watched for 30 minutes after each infusion for allergic or infusion reactions.
▸Is Nipocalimab FDA approved?
Yes, Nipocalimab (Imaavy) is FDA approved (2025) for the treatment of Myasthenia Gravis.
▸What makes nipocalimab notable among MG treatments?
Nipocalimab is approved for both AChR and MuSK antibody-positive generalized MG, and it is the only FcRn blocker for MG approved for patients as young as 12. It is also approved for warm autoimmune hemolytic anemia. It is also being studied for hemolytic disease of the fetus and newborn, a unique additional indication.
▸How often is Imaavy infused?
For generalized myasthenia gravis, Imaavy starts with one IV infusion of 30 mg/kg, followed by 15 mg/kg every 2 weeks. For warm autoimmune hemolytic anemia, the dose is 30 mg/kg every 4 weeks.
▸What did the VIVACITY-MG3 trial show?
VIVACITY-MG3 demonstrated significant improvement in MG-ADL scores compared to placebo in adults who were anti-AChR or anti-MuSK antibody positive, measured over 24 weeks.
▸How does nipocalimab compare to other FcRn inhibitors?
Nipocalimab is the third FcRn blocker approved for gMG, after efgartigimod and rozanolixizumab. For MG it is given as an IV infusion every 2 weeks after a first loading dose (the others are given in treatment cycles) and is approved for patients 12 and older (versus adults only for some competitors).
▸What is the Imaavy withMe Access Program?
It helps eligible commercially insured patients get IMAAVY when coverage is delayed more than 5 business days or denied. Johnson & Johnson also offers copay help (as little as $0 per infusion for eligible commercially insured patients) and free medicine for up to one year for uninsured or underinsured patients who meet income rules.
▸Is nipocalimab approved for adolescents?
Yes. Nipocalimab (Imaavy) is approved for patients aged 12 and older with generalized myasthenia gravis who are anti-AChR or anti-MuSK antibody positive. This makes it one of the few targeted MG biologics available for adolescents.
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- U.S. Food and Drug Administration · 2026-08-25. FDA approves first drug for warm autoimmune hemolytic anemia. https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-first-drug-warm-autoimmune-hemolytic-anemia