Eculizumab, sold under the trade name Soliris among others, is a medication used to treat paroxysmal nocturnal hemoglobinuria (PNH), atypical hemolytic uremic syndrome (aHUS), and neuromyelitis optica. In people with PNH, it reduces both the destruction of red blood cells and the need for blood transfusion, but does not appear to affect the risk of death. Eculizumab was the first drug approved for each of its uses, and its approval was granted based on small trials. It is given in a clinic by intravenous (IV) infusion.

Side effects include a risk for meningococcal infections and it is only prescribed to those who have enrolled in and follow a risk evaluation and mitigation strategy, which involves counseling people and ensuring that they are vaccinated. It is a humanized monoclonal antibody functioning as a terminal complement inhibitor.

It has been developed, manufactured, and marketed by Alexion Pharmaceuticals, which had patent exclusivity until 2017. Alexion started selling eculizumab in 2007 making $295 million in 2008 with its stock price rising 130% in 2010. In 2010, it was the most expensive drug in the world. It costs £340,200 (approximately €430,000) per year for ongoing treatment in the UK, $500,000 a year in Canada, and US$409,500 a year in the United States (2010). In 2015, it was the 4th most expensive medication in the US on a per person treated basis

Medical uses

Eculizumab is used to treat atypical hemolytic uremic syndrome (aHUS) and paroxysmal nocturnal hemoglobinuria (PNH). For people with PNH, it improves quality of life and decreases the need for blood transfusions but does not appear to affect the risk of death. It does not appear to change the risk of blood clots, myelodysplastic syndrome, acute myelogenous leukemia, or aplastic anemia. Eculizumab is also used to treat neuromyelitis Optica spectrum disorder in adults who are anti-aquaporin-4 (AQP4) antibody positive.

Eculizumab is administered in a doctor’s office or clinic by intravenous infusion.

Women should not become pregnant while taking eculizumab and pregnant women should take it only if it is clearly necessary.

Adverse effects

Eculizumab carries a black box warning for the risk of meningococcal infections and can only be prescribed by doctors who have enrolled in and follow a risk evaluation and mitigation strategy required by the FDA, which involves doctors counseling people to whom they are prescribing the drug, giving them educational materials, and ensuring that they are vaccinated, all of which must be documented.

Eculizumab inhibits terminal complement activation and therefore makes people vulnerable to infection with encapsulated organisms. Life-threatening and fatal meningococcal infections have occurred in people who received eculizumab. People receiving eculizumab have up to 2,000 times greater risk of developing invasive meningococcal disease. Due to the increased risk of meningococcal infections, meningococcal vaccination is recommended at least 2 weeks prior to receiving eculizumab, unless the risks of delaying eculizumab therapy outweigh the risk of developing a meningococcal infection, in which case the meningococcal vaccine should be administered as soon as possible. Both a serogroup A, C, W, Y conjugate meningococcal vaccine and a serogroup B meningococcal vaccine are recommended for people receiving eculizumab. Receiving the recommended vaccinations may not prevent all meningococcal infections, especially from nongroupable N. meningiditis. In 2017, it became clear that eculizumab has caused invasive meningococcal disease despite vaccination, because it interferes with the ability of antimeningococcal antibodies to protect against invasive disease.

The drug’s labels also carry warnings of severe anemia arising from the destruction of red blood cells as well as severe cases of blood clots forming in small blood vessels.

Headaches are very common adverse effects, occurring in more than 10% of people who take the drug.

Common adverse effects (occurring in between 1% and 10% of people who take the drug) include infections (pneumonia, upper respiratory tract infection, colds, and urinary tract infection), loss of white blood cells, loss of red blood cells, anaphylactic reaction, hypersensitivity reaction, loss of appetite, mood changes like depression and anxiety, a sense of tingling or numbness, blurred vision, vertigo, ringing in the ears, heart palpitations, high blood pressure, low blood pressure, vascular damage, peritonitis, constipation, upset stomach, swollen belly, itchy skin, increased sweating, blotches from small bleeds under the skin and skin redness, hives, muscle spasms, bone pain, back pain, neck pain, swollen joints, kidney damage, painful urination, spontaneous erections, general edema, chest pain, weakness, pain at the infusion site, and elevated transaminases.