Study of Ravulizumab in Pediatric Participants With HSCT-TMA

Inclusion Criteria:

1. 1 month of age up to < 18 years of age at the time of signing the informed consent.
2. Received HSCT within the past 12 months.
3. Diagnosis of TMA that persists despite initial management of any triggering condition.
4. Body weight ≥ 5 kilograms.
5. Female participants of childbearing potential and male participants with female partners of childbearing potential must use highly effective contraception starting at Screening and continuing until at least 8 months after the last dose of ravulizumab.
6. Participants must be vaccinated against meningococcal infections if clinically feasible, according to institutional guidelines for immune reconstitution after HSCT. Participants must be re-vaccinated against Haemophilus influenzae type b and Streptococcus pneumoniae if clinically feasible, according to the institutional guidelines for immune reconstitution after HSCT. All participants should be administered coverage with prophylactic antibiotics according to institutional post-transplant infection prophylaxis guidances, including coverage against Neisseria meningitidis for at least 2 weeks after meningococcal vaccination. Participants who cannot receive meningococcal vaccine should receive antibiotic prophylaxis coverage against Neisseria meningitidis the entire Treatment Period and for 8 months following the final dose of ravulizumab.

Exclusion Criteria:

1. Known familial or acquired 'a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13' deficiency (activity < 5%).
2. Known Shiga toxin-related hemolytic uremic syndrome.
3. Positive direct Coombs test.
4. Diagnosis or suspicion of disseminated intravascular coagulation.
5. Known bone marrow/graft failure.
6. Diagnosis of veno-occlusive disease (VOD).
7. Human immunodeficiency virus (HIV) infection (evidenced by HIV-1 or HIV-2 antibody titer).
8. Unresolved meningococcal disease.
9. Presence of sepsis requiring vasopressor support.
10. Pregnancy or breastfeeding.
11. Hypersensitivity to murine proteins or to 1 of the excipients of Ravulizumab.
12. Previously or currently treated with a complement inhibitor.