Safety and Efficacy of Itacitinib in Combination With Corticosteroids for Treatment of Graft-Versus-Host Disease in Pediatric Subjects

Inclusion Criteria

• Male and female participants: 12 to < 18 years old (Cohort 1), 6 to < 12 years old (Cohort 2), 2 to < 6 years old (Cohort 3), Weighing > 8 kg to < 2 years old (Cohort 4), and 28 days old to weighing ≤ 8 kg (Cohort 5).
• Undergone 1 allogeneic hematopoietic stem cell transplantation (allo-HSCT) from any donor and source for hematological malignancies or disorders. Recipients of myeloablative and reduced-intensity conditioning regimens are eligible.
• Clinically suspected Grade II to IV aGVHD as per Mount Sinai Acute GVHD International Consortium (MAGIC) criteria, occurring after allo-HSCT and any GVHD prophylactic medication.
• Evidence of myeloid engraftment.

Exclusion Criteria

• More than 1 allo-HSCT.
• Received more than 2 days of systemic corticosteroids for aGVHD before the first study drug administration.
• Presence of GVHD overlap syndrome.
• Presence of an active uncontrolled infection.
• Known HIV infection.
• Active hepatitis B virus (HBV) or hepatitis C virus (HCV) infection that requires treatment or at risk for HBV reactivation.
• Evidence of relapsed primary disease or have been treated for relapse after the allo-HSCT was performed.
• Any corticosteroid therapy for indications other than GVHD at doses > 1 mg/kg once daily of methylprednisolone (or equivalent) within 7 days of the first study drug administration.
• Receipt of live (including attenuated) vaccines or anticipation of need for such vaccines during the study.
• Receipt of JAK inhibitor therapy after allo-HSCT for any indication.
• Treatment with any other investigational agent, device, or procedure within 21 days (or 5 half-lives, whichever is greater) of enrollment.