Inebilizumab: anti-CD19 antibody for NMOSD
Inebilizumab (brand name Uplizna) is a humanised, afucosylated monoclonal IgG1 antibody that binds to the B cell surface antigen CD19. The substance was approved in 2020 in the USA and 2022 in the EU for the treatment of neuromyelitis optica spectrum disorder (NMOSD) in adults with aquaporin 4 IgG positive status. NMOSD is a rare, severe autoimmune disease of the central nervous system that can lead to recurrent vision loss and transverse myelitis.
Compared with anti-TNF substances or B cell depleting anti-CD20 antibodies such as rituximab, inebilizumab targets a broader spectrum of B cells, including plasmablasts and some plasma cells, since CD19 is expressed in a larger part of the B cell lineage than CD20. Clinically this results in longer suppression of pathogenic antibody production.
Mechanism of action
CD19 is a co-receptor of the B cell antigen receptor and is expressed from the pro-B cell stage to short-lived plasma cells. Inebilizumab binds to CD19 and triggers elimination of B cells primarily via antibody-dependent cellular cytotoxicity (ADCC). Afucosylation of the Fc portion enhances binding to FcγRIIIa on NK cells and thereby boosts effector function.
The treatment causes rapid and almost complete depletion of B cells in peripheral blood. The reduction of pathogenic plasmablasts decreases production of aquaporin 4 IgG autoantibodies, which attack astrocytes in the CNS in NMOSD.
Because CD19 is also expressed by plasmablasts, inebilizumab covers an immunologically more important population than anti-CD20. B cell repopulation is delayed, which permits twice-yearly dosing.
Indications
- Neuromyelitis optica spectrum disorder (NMOSD): in adult patients with aquaporin 4 IgG positive status to reduce relapses
- IgG4-related disease (IgG4 RD): approved in the USA since 2024, under EU evaluation
- Research indications: trials are ongoing in generalised myasthenia gravis and systemic lupus erythematosus
Inebilizumab is not approved for aquaporin 4 negative NMOSD or for multiple sclerosis. Accurate diagnosis with serological confirmation of AQP4 antibodies is a prerequisite.
Dosing and administration
Initial dose: 300 mg intravenously on day 1 and day 14 (two initial infusions).
Maintenance dose: 300 mg intravenously every 6 months.
The infusion is given over at least 90 minutes. Before each dose, premedication with methylprednisolone, an H1 antihistamine and an antipyretic is given to prevent infusion reactions.
Requirements before starting therapy:
- Hepatitis B screening and antiviral prophylaxis if at risk of reactivation
- Quantitative immunoglobulin profile and differential blood count
- Updated vaccination status, complete live vaccines before starting
- Pregnancy test, counselling on contraception
- Tuberculosis screening
Side effects
Very common: urinary tract infections, respiratory tract infections, arthralgia, back pain.
Common: infusion reactions (headache, nausea, dizziness, rash), lymphopenia, neutropenia, raised liver transaminases, hypogammaglobulinaemia.
Uncommon: herpes reactivations (zoster, simplex), severe infections, anaphylactic reactions, depressive symptoms, sleep disturbances.
Rare and very rare: progressive multifocal leukoencephalopathy (PML, theoretically possible, not yet reported in NMOSD studies), hepatitis B reactivation, severe hypogammaglobulinaemia with frequent infections.
Important safety aspects:
- Infusion reactions mostly occur with the first dose and are well controlled by premedication
- Lymphopenia and low immunoglobulin levels are common, clinically significant hypogammaglobulinaemia is less frequent
- Reassess therapy with repeated severe infections
- Consider PML in case of cerebral symptoms such as visual disturbance, personality change or neurological deficits
Interactions
- Other immunosuppressants and biologics: additive immunosuppression, careful indication; combinations are mostly not established outside clinical trials
- Live vaccines: contraindicated during therapy and for several months afterwards
- Inactivated vaccines: possible but with reduced efficacy; ideally before starting therapy
- Anti-CD20 pretreatment (rituximab, ocrelizumab): possible additive B cell suppression, judge clinical relevance individually
Special considerations
Pregnancy: data are limited. If clinically required, individual benefit-risk assessment. Women of childbearing potential should use reliable contraception during therapy and for at least 6 months after the last infusion. IgG antibodies cross the placenta especially in the third trimester, which can lead to B cell depletion in the newborn.
Breastfeeding: data lacking. Given the molecular weight a relevant transfer to milk is unlikely and gastrointestinal degradation likely. Individual decision.
Vaccinations: ideally complete at least 4 weeks before starting therapy (live vaccines) or 2 weeks (inactivated vaccines). Only inactivated vaccines are possible during therapy.
Renal impairment: no specific adjustments required.
Patient card: inebilizumab is part of a controlled risk management. Patients should receive a treatment card and present it in emergencies.
Quality of life and adherence: the twice-yearly infusion is often a relief for patients with chronic disease. It improves quality of life as no daily medication is required.
Related substances
- Glofitamab, bispecific antibody against CD20 and CD3
- Golimumab, anti-TNF antibody
- Methotrexate, classic immunosuppressant
- Canakinumab, IL-1 beta antibody for autoinflammatory syndromes
Frequently asked questions
How does inebilizumab differ from rituximab?
Both deplete B cells, but via different antigens. Rituximab binds CD20 and does not capture all plasmablasts, since CD20 is no longer expressed in late B cell stages. Inebilizumab binds CD19, covering a broader population including plasmablasts. Clinically, inebilizumab significantly reduces relapses in NMOSD studies.
How quickly does the therapy work?
B cell depletion is measurable within days. Clinical protection from relapses is seen over weeks to months. In the registration study (N MOmentum) inebilizumab significantly reduced relapses in the first 6 months versus placebo.
Which vaccinations am I allowed?
Inactivated vaccines such as influenza, tetanus, pneumococci or COVID-19 are generally possible, although the response may be attenuated. Live vaccines such as measles, mumps, rubella, varicella or yellow fever are contraindicated during therapy; they should be completed before starting if possible.
How long do I need treatment?
NMOSD is a chronic disease, and therapy is usually continued long term to prevent relapses. The decision to stop or pause is made individually with neurology, often after several years of stability.
Sources
- EMA Uplizna (inebilizumab) EPAR
- BfArM Federal Institute for Drugs and Medical Devices
- AWMF guidelines neurology and NMOSD
- Gelbe Liste inebilizumab monograph
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