A Phase 2A Study of ALXN1007 in Participants With Newly Diagnosed Acute Lower Gastrointestinal Graft-Versus-Host Disease

Exclusion Criteria

• •Participants with a body weight \> 140 kg (for Cohorts dosing 20 mg/kg of ALXN1007 and higher only).
• •Participants with signs and symptoms of chronic GVHD.
• •Participants with an active uncontrolled infection.
• •Participants who test positive for Clostridium difficile (C. difficile) at Screening.
• •Participants with relapsed/persistent malignancy requiring rapid immune suppression withdrawal.
• •Participants who received an unplanned (not part of the original transplant therapy plan) donor lymphocyte infusion.
• •Participants who received previous systemic treatment for acute GVHD, except for a maximum of 3 days (72 hours) of 2 mg/kg corticosteroid therapy.
• •Participants with unresolved veno-occlusive disease of the liver.
• •Participants with creatinine clearance \<40 milliliters (mL)/minute at Screening, as calculated by the Cockcroft-Gault formula.
• •Participants known to be infected with human immunodeficiency virus (HIV), hepatitis B, or hepatitis C.
• •Participants known to have an uncontrolled thyroid disorder.
• •Participants who are pregnant, breast feeding, or sexually active and unwilling to use effective birth control for the duration of the study.
• •Participants who participated in any other investigational drug trial or had exposure to any other investigational agent, device, or procedure \<4 weeks prior to Screening and throughout the entire trial, with the exception of investigational drugs administered prophylactically for cytomegalovirus (CMV) post allogeneic HCT.