Soliris (eculizumab)

In AQP4-positive NMOSD, the immune system makes antibodies against aquaporin-4, a water channel protein on support cells in the optic nerve, spinal cord and brain. When these antibodies stick, they switch on the complement system, which damages the cells and causes the attacks, called relapses, that can lead to vision loss and weakness.

Eculizumab is a lab-made antibody that binds complement protein C5 and stops it from being split, blocking the last steps of the complement attack. The label says the exact way it works in NMOSD is unknown but is presumed to involve blocking the complement damage that AQP4 antibodies trigger^[1]. It does not lower the AQP4 antibodies themselves.

Soliris carries a boxed warning for serious meningococcal infections. It raises the risk of life-threatening or fatal infections caused by Neisseria meningitidis, even in people who have been vaccinated. Meningococcal vaccines for serogroups A, C, W, Y and B must be completed or updated at least 2 weeks before the first dose, unless waiting would be riskier. Soliris is available only through a restricted program called the ULTOMIRIS and SOLIRIS REMS, and patients carry a Patient Safety Card during treatment and for 3 months after the last dose^[1].

In the NMOSD trial, side effects more common on Soliris than placebo included upper respiratory tract infection (29% vs 13%), nasopharyngitis (21% vs 19%), diarrhea (16% vs 15%), back pain (15% vs 13%), dizziness (15% vs 13%), flu (11% vs 4%), sore throat called pharyngitis (10% vs 6%) and bruising (10% vs 4%)^[1].

The label also warns about other serious infections from bacteria such as Streptococcus pneumoniae and Haemophilus influenzae, and about infusion reactions, including allergic reactions^[1].

For NMOSD in adults, Soliris is given by IV infusion at 900mg once a week for the first 4 weeks, 1,200mg 1 week later for the fifth dose, then 1,200mg every 2 weeks. In adults the infusion runs over 35 minutes and should not go past 2 hours if it is slowed. Patients are watched for at least 1 hour afterward^[1].

Plasma exchange, a common treatment for NMOSD attacks, removes Soliris from the blood. After a session, an extra 300mg or 600mg dose is given within 60 minutes, depending on the last regular dose^[1].

The biosimilars Bkemv and Epysqli were approved for AQP4-positive NMOSD in adults in June 2026 and use the same dose^[6][7].

In its main trial, Soliris lowered the risk of a relapse by 94% compared with placebo.

Relapses: There were 3 relapses among 96 people on Soliris and 21 among 47 people on placebo.

Other results: Fewer hospital stays, fewer steroid courses for attacks and fewer plasma exchange treatments.

Who was studied: Adults with AQP4-positive NMOSD and frequent recent relapses, most of them also on other immune treatment.

Source: FDA label for Soliris, DailyMed, effective July 2026

The NMOSD dose is 900mg a week for 4 weeks, 1,200mg at week 5, then 1,200mg every 2 weeks, all by IV infusion.

Infusion time: About 35 minutes in adults, then at least 1 hour of observation.

Plasma exchange: An extra 300mg or 600mg dose follows each plasma exchange session.

Compared with PNH: The NMOSD dose is higher than the PNH maintenance dose of 900mg every 2 weeks.

Source: FDA label for Soliris, DailyMed, effective July 2026

It is not approved for AQP4-negative NMOSD.

What the label says: The approval covers adults who are anti-AQP4 antibody positive, and the PREVENT trial enrolled only AQP4-positive patients.

Next step: Ask your neurologist about testing and which options were studied in your antibody group.

Source: FDA label for Soliris, DailyMed, effective July 2026

Blocking C5 weakens the body's defense against meningococcal bacteria, and the label carries a boxed warning for that risk.

Timing: Meningococcal vaccines for serogroups A, C, W, Y and B are completed or updated at least 2 weeks before the first dose, unless waiting would be riskier.

Still at risk: Vaccines lower but do not remove the risk. Get emergency care for fever, headache with a stiff neck, a rash, confusion or eyes sensitive to light.

Safety card: Carry the Patient Safety Card during treatment and for 3 months after the last dose.

Source: FDA label for Soliris, DailyMed, effective July 2026

Both block complement C5 and come from Alexion; Ultomiris lasts longer, so infusions are every 8 weeks instead of every 2.

Trials: Soliris was tested against placebo in PREVENT. Ultomiris was tested in CHAMPION-NMOSD against the PREVENT placebo group, a comparison AstraZeneca says was used because a new placebo group was not considered ethical.

What this means: The 2 results cannot be ranked, and no trial has compared the drugs directly.

More: Ultomiris for NMOSD

Source: FDA label for Soliris, DailyMed; AstraZeneca, March 25, 2024

Yes. Bkemv and Epysqli added AQP4-positive NMOSD in adults to their labels in June 2026.

Same dose: They use 900mg weekly for 4 weeks, 1,200mg at week 5, then 1,200mg every 2 weeks.

Same warning: The meningococcal boxed warning applies, with separate REMS programs for each biosimilar.

Source: Bkemv label, DailyMed; Epysqli label, DailyMed

Yes, for people with commercial insurance.

Copay program: Alexion says eligible commercially insured patients enrolled in OneSource may pay as little as $0, and the program may help with some infusion costs.

Not eligible: Medicare, Medicaid and other federal or state plans. OneSource says it can point those patients to third-party resources.

Contact: Alexion OneSource at 1-888-765-4747.

Source: Alexion OneSource, Soliris financial assistance