Uplizna (inebilizumab)
An approved treatment for IgG4-Related Disease.
The same compound appears under different names depending on the context. Here is how to identify Inebilizumab wherever you encounter it, plus the key facts at a glance.
- Generic name
- Inebilizumab
- Brand name
- Uplizna
- Development code
- MEDI-551
- Drug class
- Anti-CD19 monoclonal antibody
- Manufacturer
- Amgen (via its 2023 acquisition of Horizon Therapeutics)
- How it's taken
- Given as an intravenous infusion.
The first and only FDA-approved treatment for IgG4-related disease, approved for adults only. Inebilizumab targets CD19 on B cells, providing broader depletion than anti-CD20 therapies by also reaching plasmablasts, the cells that produce the disease-driving IgG4 antibodies. In the MITIGATE trial, only 10% of treated patients experienced flares versus 60% on placebo.
Where Inebilizumab fits
The only FDA-approved treatment for IgG4-related disease, a condition previously managed with off-label corticosteroids and rituximab. Inebilizumab's broader B-cell depletion (CD19 vs CD20) may provide advantages over rituximab by reaching plasmablasts. Also FDA-approved for AQP4 antibody-positive NMOSD (2020) and for AChR or MuSK antibody-positive generalized myasthenia gravis (December 2025). Trials are studying optimal duration of therapy and whether early treatment can prevent irreversible fibrotic organ damage.
How Inebilizumab works
IgG4-related disease is driven by an abnormal immune response in which B cells differentiate into IgG4-producing plasmablasts and plasma cells. These cells infiltrate organs, producing dense, tumor-like swelling and progressive fibrosis that can damage the pancreas, salivary glands, kidneys, and other organs.
Inebilizumab targets CD19, a protein found on B cells at all stages of development, including plasmablasts. This is a broader target than CD20 (used by rituximab), which is lost as B cells mature into antibody-producing plasmablasts. By reaching these CD19-positive plasmablasts, inebilizumab can deplete the specific cells responsible for producing the pathogenic IgG4 antibodies.
In the MITIGATE trial, inebilizumab dramatically reduced disease flares: only 10% of treated patients flared compared to 60% on placebo (87% relative risk reduction). Additionally, 57% of treated patients achieved flare-free, treatment-free complete remission. This trial led to the first FDA approval of any therapy for IgG4-related disease in April 2025.
Mechanism: Humanized monoclonal antibody targeting CD19 on B cells, providing broad B-cell depletion including plasmablasts and some plasma cells that drive IgG4-producing immune responses
Side effects and safety
The most common side effects include infections (upper respiratory, urinary tract), infusion-related reactions, and decreased immunoglobulin levels. Because inebilizumab depletes B cells, serious infections, including life-threatening or fatal ones, can happen during and after treatment, and an infusion is delayed if you have an active infection. Uplizna must not be used in people with active hepatitis B, active or untreated latent tuberculosis, or a past life-threatening reaction to an Uplizna infusion. Infusion reactions, including severe allergic reactions (anaphylaxis), can occur, so patients are watched during each infusion and for at least 1 hour afterward. Hepatitis B reactivation screening is required before starting therapy. Tuberculosis screening and immunoglobulin testing are also required before the first dose, and immunoglobulin levels should be monitored regularly. Inebilizumab also carries a warning for progressive multifocal leukoencephalopathy (PML), a rare brain infection. Live vaccines should be given at least 4 weeks before starting and are not recommended during treatment. It may cause fetal harm; the label advises effective contraception during treatment and for 6 months after the last dose. In the IgG4-RD trial, the most common side effects were urinary tract infections and low lymphocyte counts.
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 Inebilizumab
Given as an intravenous infusion. The dosing schedule consists of two 300-mg infusions (day 1 and day 15) followed by maintenance infusions every 6 months. Premedication with corticosteroids, antihistamines, and antipyretics is recommended to reduce infusion reactions.
Availability and cost
Only available as the brand-name product.
Help paying for Uplizna
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 may pay as little as $0 for UPLIZNA and infusion costs through the Amgen Commercial Co-Pay Program. Not for government insurance.
For: private insurance · source - Infusion cost help
The co-pay program can help with infusion (administration) costs. Residents of Massachusetts or Rhode Island are not eligible for administration support.
For: private insurance · source - Insurance and case manager help
A dedicated Patient Access Liaison helps with insurance approval, prior authorization and scheduling infusions.
For: private insurance, Medicare, Medicaid, TRICARE, no insurance, underinsured · source
Good to know: Official UPLIZNA pages do not describe a free drug program, and UPLIZNA was not on the Amgen Safety Net Foundation product list. Ask Amgen By Your Side about options if uninsured.
- From a charity · NORD RareCareIgG4-RD Medical Assistance fundOpen
Pays for: Medical and medication costs.
The foundation says: “Accepting Applications” - From a charity · NORD RareCareIgG4-RD Premium Copay Assistance fundOpen
Pays for: Insurance premiums and copays.
The foundation says: “Accepting Applications” - From a charity · The Assistance FundImmunoglobulin G4-Related Disease (IgG4-RD) fundOpen
Pays for: Copays, coinsurance, deductibles and other health-related expenses.
The foundation says: “OPEN — Accepting New Patients. TAF is currently accepting new patient enrollments for this program.”
Clinical trial results
The Phase 3 MITIGATE trial randomized patients with active IgG4-related disease to inebilizumab or placebo. The primary endpoint showed dramatic separation: only 10% of inebilizumab patients experienced a disease flare compared to 60% on placebo (hazard ratio 0.13, p<0.001). This represents an 87% reduction in flare risk. Additionally, 57% of inebilizumab patients achieved flare-free, treatment-free complete remission. These results led to FDA approval in April 2025.
Development history
Inebilizumab was originally developed by MedImmune (AstraZeneca) as MEDI-551. Viela Bio spun out from MedImmune and advanced it through clinical development, first gaining FDA approval for neuromyelitis optica spectrum disorder (NMOSD) in 2020. Horizon Therapeutics acquired Viela Bio in March 2021, and Amgen acquired Horizon in October 2023 and completed the IgG4-RD program. The MITIGATE trial results were presented at major medical conferences and led to FDA approval for IgG4-RD on April 3, 2025, making it the first and only approved treatment for this condition.
Explore IgG4-Related Disease trials
Common questions about Inebilizumab
▸What is Inebilizumab (Uplizna)?
The first and only FDA-approved treatment for IgG4-related disease, approved for adults only. Inebilizumab targets CD19 on B cells, providing broader depletion than anti-CD20 therapies by also reaching plasmablasts, the cells that produce the disease-driving IgG4 antibodies. In the MITIGATE trial, only 10% of treated patients experienced flares versus 60% on placebo.
▸How does Inebilizumab work?
IgG4-related disease is driven by an abnormal immune response in which B cells differentiate into IgG4-producing plasmablasts and plasma cells. These cells infiltrate organs, producing dense, tumor-like swelling and progressive fibrosis that can damage the pancreas, salivary glands, kidneys, and other organs.
Inebilizumab targets CD19, a protein found on B cells at all stages of development, including plasmablasts. This is a broader target than CD20 (used by rituximab), which is lost as B cells mature into antibody-producing plasmablasts. By reaching these CD19-positive plasmablasts, inebilizumab can deplete the specific cells responsible for producing the pathogenic IgG4 antibodies.
In the MITIGATE trial, inebilizumab dramatically reduced disease flares: only 10% of treated patients flared compared to 60% on placebo (87% relative risk reduction). Additionally, 57% of treated patients achieved flare-free, treatment-free complete remission. This trial led to the first FDA approval of any therapy for IgG4-related disease in April 2025.
▸What are the side effects of Inebilizumab?
The most common side effects include infections (upper respiratory, urinary tract), infusion-related reactions, and decreased immunoglobulin levels. Because inebilizumab depletes B cells, serious infections, including life-threatening or fatal ones, can happen during and after treatment, and an infusion is delayed if you have an active infection. Uplizna must not be used in people with active hepatitis B, active or untreated latent tuberculosis, or a past life-threatening reaction to an Uplizna infusion. Infusion reactions, including severe allergic reactions (anaphylaxis), can occur, so patients are watched during each infusion and for at least 1 hour afterward. Hepatitis B reactivation screening is required before starting therapy. Tuberculosis screening and immunoglobulin testing are also required before the first dose, and immunoglobulin levels should be monitored regularly. Inebilizumab also carries a warning for progressive multifocal leukoencephalopathy (PML), a rare brain infection. Live vaccines should be given at least 4 weeks before starting and are not recommended during treatment. It may cause fetal harm; the label advises effective contraception during treatment and for 6 months after the last dose. In the IgG4-RD trial, the most common side effects were urinary tract infections and low lymphocyte counts.
▸How is Inebilizumab taken?
Given as an intravenous infusion. The dosing schedule consists of two 300-mg infusions (day 1 and day 15) followed by maintenance infusions every 6 months. Premedication with corticosteroids, antihistamines, and antipyretics is recommended to reduce infusion reactions.
▸Is Inebilizumab FDA approved?
Yes, Inebilizumab (Uplizna) is FDA approved (2025) for the treatment of IgG4-Related Disease.
▸What is the first approved treatment for IgG4-related disease?
Inebilizumab (Uplizna) became the first and only FDA-approved treatment for IgG4-related disease in April 2025, based on the MITIGATE trial showing an 87% reduction in disease flare risk.
▸How does Uplizna work for IgG4-related disease?
Uplizna targets CD19 on B cells, depleting the immune cells that drive IgG4 overproduction and organ infiltration. Unlike rituximab (anti-CD20), it also reaches plasmablasts, the cells directly producing pathogenic IgG4 antibodies.
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.
- Amgen · April 3, 2025. Uplizna (inebilizumab-cdon) Approved as First Treatment for IgG4-Related Disease. https://www.amgen.com/newsroom/press-releases/2025/04/uplizna-inebilizumabcdon-is-now-the-first-and-only-fdaapproved-treatment-for-igg4related-disease
- New England Journal of Medicine. Inebilizumab in IgG4-Related Disease. https://www.nejm.org/doi/full/10.1056/NEJMoa2409712
- Amgen. Uplizna (inebilizumab) for IgG4-Related Disease. https://www.uplizna.com