Imaavy

Imaavy (nipocalimab-aahu) is a prescription infusion medicine used to treat generalized myasthenia gravis (gMG) and warm autoimmune hemolytic anemia (wAIHA) in adults and children 12 years of age and older. It belongs to a class of medicines called neonatal Fc receptor (FcRn) blockers, and it is given into a vein every 2 or 4 weeks depending on the condition treated.

Key facts about Imaavy

• Generic name: nipocalimab-aahu
• Drug class: neonatal Fc receptor (FcRn) blocker
• Treats: generalized myasthenia gravis; warm autoimmune hemolytic anemia
• How it is given: intravenous infusion by a healthcare provider
• Dosing schedule: every 2 weeks for gMG; every 4 weeks for wAIHA
• Most common side effects: respiratory tract infection, peripheral edema, muscle spasms (gMG); peripheral edema, diarrhea, fever (wAIHA)
• First FDA approved: 2025 for gMG; wAIHA indication added August 2026
• Made by: Janssen Biotech, Inc., a Johnson & Johnson company
• Generic available: no

Imaavy is FDA-approved to treat two autoimmune conditions in adults and children 12 years and older. It is used for generalized myasthenia gravis in people who test positive for anti-acetylcholine receptor (AChR) or anti-muscle-specific tyrosine kinase (MuSK) antibodies, and for warm autoimmune hemolytic anemia in people currently or previously treated with corticosteroids.

• Generalized myasthenia gravis (gMG) in adults and children 12 years and older who are anti-AChR or anti-MuSK antibody positive. This is an autoimmune condition that causes muscle weakness.
• Warm autoimmune hemolytic anemia (wAIHA) in adults and children 12 years and older who are currently taking, or have previously taken, corticosteroids. This is an autoimmune condition in which the immune system destroys your own red blood cells. Read more about warm autoimmune hemolytic anemia.

Imaavy was first approved by the FDA in 2025 for generalized myasthenia gravis. The warm autoimmune hemolytic anemia indication was added in August 2026. There is no generic version of Imaavy.

Imaavy is a targeted therapy that works by blocking the neonatal Fc receptor (FcRn), which lowers the level of immunoglobulin G (IgG) antibodies in your blood. FcRn normally protects IgG antibodies from being broken down, keeping them in circulation. In gMG and wAIHA, some of these IgG antibodies are harmful, so reducing them reduces the attack on your own body.

In generalized myasthenia gravis, the harmful antibodies attack the connection between nerves and muscles, causing weakness. In warm autoimmune hemolytic anemia, they attach to red blood cells and mark them for destruction. Imaavy lowers both the total IgG level and the level of these specific harmful antibodies.

Imaavy is given by a healthcare provider as an infusion into a vein (intravenous infusion). Your first infusion lasts at least 30 minutes and later infusions last at least 15 minutes. You will be monitored during the infusion and for 30 minutes afterward. Imaavy is not a medicine you inject yourself at home.

• Imaavy is diluted with sodium chloride (salt water) solution before it is given.
• It is infused through a filter with a pore size of 0.2 micrometers or less.
• Your healthcare provider will watch you for reactions during the infusion and for 30 minutes after each infusion is finished.
• Imaavy is not given through the same intravenous line at the same time as other medicines.

Do not receive Imaavy if you have had a serious allergic reaction to nipocalimab-aahu or to any of the ingredients in Imaavy. These reactions have included anaphylaxis and angioedema. See the ingredients list at the end of this page.

Imaavy can cause serious side effects including infections, allergic reactions, and infusion-related reactions. You should not receive live vaccines during treatment. These warnings apply to everyone receiving Imaavy, whether it is being used to treat generalized myasthenia gravis or warm autoimmune hemolytic anemia.

Infections

Because Imaavy lowers IgG antibody levels, it may increase your risk of infections, including serious infections. If you have an active infection, your healthcare provider will treat the infection or delay your infusion until the infection has cleared.

Tell your healthcare provider right away if you get any symptoms of infection, including:

• fever
• chills
• shivering
• cough
• sore throat
• fever blisters
• burning when you urinate
• trouble breathing

In the main gMG study, 43% of people treated with Imaavy reported an infection. Across that study and its extension study, 71% of the 186 people treated reported at least one infection, and serious infections were reported in 7% of people. In the wAIHA study, 45% of people treated with Imaavy reported an infection, and across that study and its extension study, 71% of the 113 people treated reported an infection, with serious infections reported in 12%.

Reactivation of viruses already in the body

People treated with Imaavy may be at increased risk of a virus that is already in the body becoming active again (latent viral infection), such as shingles (herpes zoster). In the extension period of the gMG study, 2 people had serious reactions related to Epstein-Barr virus (EBV) infection, and 1 of those people had fatal complications. Tell your healthcare provider if you have ever had shingles or mono (mononucleosis caused by Epstein-Barr virus).

Allergic (hypersensitivity) reactions

Allergic reactions including swelling under the skin (angioedema), severe whole-body allergic reaction (anaphylaxis), rash, hives (urticaria), and eczema have happened in people treated with Imaavy. These reactions can happen during your infusion or up to a few weeks afterward.

Tell your healthcare provider and get emergency medical help right away if you get any of these symptoms during or after your infusion:

• swelling of your face, lips, mouth, tongue, or throat
• trouble swallowing or breathing
• hives
• itchy rash
• chest pain or tightness

Infusion-related reactions

Tell your healthcare provider right away if you get any of the following symptoms during or within a few days after your infusion:

• headache
• rash
• nausea
• fatigue
• dizziness
• chills
• flu-like symptoms
• redness of the skin

If you have a reaction during your infusion, your healthcare provider may slow the infusion down, give you medicine before your next infusion, or stop the infusion if the reaction is severe.

Live vaccines

You should not receive live vaccines during treatment with Imaavy. Because Imaavy causes a temporary drop in IgG levels, live vaccines are not recommended while you are being treated, and it is not known how well other vaccines will work during treatment. Your healthcare provider will check whether you need any age-appropriate vaccines before you start Imaavy. Tell any healthcare provider that you are receiving Imaavy before you have a vaccination.

Before receiving Imaavy, tell your healthcare provider about all of your medical conditions, including if you:

• have had an allergic reaction to Imaavy. Ask your healthcare provider if you are not sure.
• have or have had any recent infections, or have any symptoms of infection.
• have or have had shingles (herpes zoster) or mono (mononucleosis caused by Epstein-Barr virus).
• have recently received or are scheduled to receive a vaccine (immunization).
• are pregnant or plan to become pregnant.
• are breastfeeding or plan to breastfeed.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Imaavy may affect the way some medicines work.

Pregnancy

It is not known whether Imaavy will harm your unborn baby, and there is only limited information on its use during pregnancy. In animal studies, giving nipocalimab-aahu to pregnant monkeys caused reduced blood flow to the placenta (placental ischemia) and was linked with pregnancy loss at both doses tested.

Because Imaavy lowers the amount of IgG passed from a mother to her baby before birth, a baby exposed to Imaavy in the womb may have reduced natural protection against infection (passive immunity) for 6 months or longer. Babies should be monitored for serious infection, vaccines may not work as well, and the risks and benefits of live vaccines should be considered before they are given.

There is a pregnancy safety study for Imaavy. If you receive Imaavy during pregnancy, or become pregnant while receiving it, your healthcare provider should report the exposure by contacting Janssen at 1-800-526-7736 or through www.imaavy.com.

Breastfeeding

Nipocalimab-aahu passes into human colostrum and breast milk, based on limited information from a study of 13 pregnant women. There is not enough information to know what effect this has on a breastfed baby, and there is no information on whether Imaavy affects milk production. Talk to your healthcare provider about the best way to feed your baby during treatment.

The most common side effects of Imaavy in people with generalized myasthenia gravis are respiratory tract infection, swelling in the hands, ankles, or feet (peripheral edema), and muscle spasms. In people with warm autoimmune hemolytic anemia, the most common side effects are peripheral edema, diarrhea, and fever (pyrexia).

Common Imaavy side effects in generalized myasthenia gravis

• infection in the parts of your body you use for breathing (respiratory tract infection)
• swelling in your hands, ankles, or feet (peripheral edema)
• muscle spasms

The table below shows side effects reported in at least 5% of people treated with Imaavy in the main gMG study, and more often than with placebo.

Common Imaavy side effects in warm autoimmune hemolytic anemia

• swelling in your hands, ankles, or feet (peripheral edema)
• diarrhea
• fever (pyrexia)

The table below shows side effects reported in at least 5% of people treated with Imaavy in the wAIHA study, and more often than with placebo.

Other side effects reported in 5% or fewer people in the wAIHA study were pneumonia (5% with Imaavy and 5% with placebo), nausea (3.8% with Imaavy and 2.6% with placebo), and trouble sleeping (1.3% with Imaavy and 0% with placebo).

Changes in blood tests

Imaavy can raise cholesterol levels. In the gMG study, 24% of people treated with Imaavy had a rise in total cholesterol from normal to high (240 mg/dL or above), and 11% had a rise in LDL cholesterol from normal to high (160 mg/dL or above). These changes peaked at Week 4, then decreased and leveled off by Week 24. In the wAIHA study, 2.3% of people had a rise in total cholesterol from normal to high, and LDL cholesterol stayed below 160 mg/dL in everyone at Week 24.

These are not all of the possible side effects of Imaavy. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088. See the full list of Imaavy side effects.

Imaavy improved symptoms compared with placebo in both approved conditions. In generalized myasthenia gravis, it improved scores measuring daily function and muscle weakness over 24 weeks. In warm autoimmune hemolytic anemia, 23.7% of people treated with Imaavy achieved a durable rise in hemoglobin compared with 7.7% on placebo.

Generalized myasthenia gravis

gMG Study 1 (NCT04951622) was a 24-week study in which 196 adults were randomly assigned to receive either Imaavy or placebo, on top of their usual myasthenia gravis treatment. The main measure was the Myasthenia Gravis Activities of Daily Living (MG-ADL) score, which rates 8 everyday functions affected by the condition, with higher scores meaning more difficulty.

• MG-ADL score fell by an average of 4.7 points with Imaavy compared with 3.3 points with placebo, a difference of 1.5 points (p=0.002).
• Quantitative Myasthenia Gravis (QMG) score, which measures muscle weakness, fell by an average of 4.9 points with Imaavy compared with 2.1 points with placebo, a difference of 2.8 points (p<0.001).

A separate 24-week study in 7 children aged 12 to 16 years with AChR-positive gMG found side effects similar to those seen in adults.

Warm autoimmune hemolytic anemia

The wAIHA Study (NCT04119050) compared Imaavy 30 mg/kg every 4 weeks with placebo over 24 weeks in adults who had been diagnosed with wAIHA for at least 3 months, had a hemoglobin level below 10 g/dL, and had evidence of red blood cell destruction. The main measure was a durable hemoglobin response, defined as reaching a hemoglobin level of 10 g/dL or higher along with a rise of at least 2 g/dL from the starting level, held across at least three consecutive visits over a minimum of 28 days, without needing rescue treatment.

• 23.7% of people treated with Imaavy (9 out of 38) achieved a durable hemoglobin response, compared with 7.7% of people on placebo (3 out of 39), a difference of 16.0 percentage points (one-sided p=0.015).
• Fatigue, measured with the FACIT-Fatigue questionnaire, improved by an average of 2.95 points with Imaavy compared with a fall of 0.56 points with placebo.

The dose of Imaavy is 30 mg/kg for the first infusion in both approved conditions, but the schedule then differs. For generalized myasthenia gravis, the dose drops to 15 mg/kg every 2 weeks starting 2 weeks later. For warm autoimmune hemolytic anemia, the dose stays at 30 mg/kg every 4 weeks starting 4 weeks later.

Imaavy dosage for generalized myasthenia gravis (adults and children 12 years and older)

Imaavy dosage for warm autoimmune hemolytic anemia (adults and children 12 years and older)

Notes:

• Imaavy must be diluted with 0.9% Sodium Chloride Injection before it is given. For people who weigh 40 kg or more, the total volume infused is 250 mL. For people 12 years and older who weigh less than 40 kg, the total volume infused is 100 mL.
• The safety and effectiveness of Imaavy have not been established in children under 12 years of age for either condition.
• No dose adjustment is needed for people with kidney (renal) or liver (hepatic) impairment.

What should I do if I miss a dose?

If you miss a scheduled infusion, you should receive your next dose as soon as possible. Your healthcare provider will then restart your regular schedule, keeping the same interval between doses.

Imaavy can reduce how well certain other medicines work. Because Imaavy blocks the neonatal Fc receptor, it lowers levels of medicines that also bind to that receptor, including immunoglobulin products, monoclonal antibodies, and other antibody-based medicines containing a human IgG Fc region.

• Your healthcare provider will watch closely for signs that these medicines are not working as well as expected.
• If you need to take one of these medicines long term, your healthcare provider may consider stopping Imaavy and using a different treatment instead.
• Imaavy is not broken down by liver enzymes called cytochrome P450 enzymes, so interactions with medicines that affect those enzymes are unlikely.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

Imaavy is stored and prepared by your healthcare provider, so you will not need to store it at home. Unopened vials are kept in a refrigerator at 2°C to 8°C (36°F to 46°F) in the original carton to protect them from light. Vials must not be frozen or shaken.

Once diluted, the solution should be given straight away where possible. If it is not used immediately, it is protected from light and can be refrigerated for no more than 24 hours, and must be used or thrown away within 12 hours of preparation or of being taken out of the refrigerator, including the time it takes to infuse.

Imaavy may cost as little as $0 for eligible patients through the IMAAVY withMe program. The program provides two separate savings offers: Medicine Cost Support for the cost of the medicine and Treatment Administration Cost Support for certain infusion administration and related monitoring costs. See IMAAVY withMe Savings Program for more details.

The full Imaavy prescribing information, also called the package insert or label, is published by the FDA and was most recently revised in August 2026 to add the warm autoimmune hemolytic anemia indication. It is written for healthcare professionals and contains complete details on dosing, preparation, clinical studies, and safety.

You can read the full Imaavy prescribing information, or ask your pharmacist or healthcare provider for a copy.

Active ingredient: nipocalimab-aahu

Inactive ingredients: arginine hydrochloride, histidine, L-histidine monohydrochloride monohydrate, methionine, polysorbate 80, sucrose, and water for injection.

Imaavy is manufactured by Janssen Biotech, Inc., Horsham, PA 19044, USA, a Johnson & Johnson company. For more information, call 1-800-526-7736 or go to www.imaavy.com.