Satralizumab, sold under the brand name Enspryng, is a humanized monoclonal antibody medication that is used for the treatment of neuromyelitis optica spectrum disorder (NMOSD), a rare autoimmune disease. The drug is being developed by Chugai Pharmaceutical, a subsidiary of Roche.

The most common side effects include the common cold (nasopharyngitis), headache, upper respiratory tract infection, inflammation of the lining of the stomach, rash, joint pain, extremity pain, fatigue and nausea.

Satralizumab regulates inflammation by inhibiting the interleukin-6 (IL-6) receptor, a key mediator of the immune response.

Satralizumab was approved for medical use in the United States in August 2020, and in the European Union in June 2021. The US Food and Drug Administration (FDA) considers it to be a first-in-class medication.

Satralizumab is indicated for the treatment of neuromyelitis optica spectrum disorder (NMOSD) in adults with a particular antibody – people who are anti-aquaporin-4 or AQP4 antibody-positive.

NMOSD is a rare autoimmune disease of the central nervous system that mainly affects the optic nerves and spinal cord. In people with NMOSD, the body's immune system mistakenly attacks healthy cells and proteins in the body, most often those in the optic nerves and spinal cord. Individuals with NMOSD typically have attacks of optic neuritis, which causes eye pain and vision loss. Approximately 50% of people with NMOSD have permanent visual impairment and paralysis caused by NMOSD attacks. Estimates vary, but NMOSD is thought to impact approximately 4,000 to 8,000 Americans.

NMOSD can be associated with antibodies that bind to a protein called aquaporin-4 (AQP4). Binding of the anti-AQP4 antibody appears to activate other components of the immune system, causing inflammation and damage to the central nervous system.

Vaccination with live-attenuated or live vaccines is not recommended during treatment and should be administered at least four weeks before starting satralizumab.