A Phase 3, Randomized, Double-Blind, Placebo-Controlled, Multicenter Study of Ravulizumab in Adult and Adolescent Participants Who Have Thrombotic Microangiopathy (TMA) After Hematopoietic Stem Cell Transplant (HSCT)

• 12 years of age or older at time of consent/assent.

• Received HSCT within the past 12 months.

• Diagnosis of TMA that persists for at least 72 hours after initial management of any triggering agent/condition.

• A TMA diagnosis based on meeting the laboratory-based criteria during the Screening Period and/or ≤14 days prior to the Screening Period.

• Body weight ≥ 30 kilograms at Screening or ≤7 days prior to the start of the Screening Period (date of consent).

• Female participants of childbearing potential and male participants with female partners of childbearing potential must use highly effective contraception.

• Participants must be vaccinated against meningococcal infections if clinically feasible. Participants who cannot receive meningococcal vaccine should receive antibiotic prophylaxis. Participants \<18 years of age must be re-vaccinated against Haemophilus influenzae type b (Hib) and Streptococcus pneumoniae if clinically feasible.

• Participants or their legally authorized representative must be capable of giving signed informed consent or assent.