Itacitinib for the Treatment of Bronchiolitis Obliterans Syndrome After Donor Hematopoietic Cell Transplant

PRIMARY OBJECTIVE: I. To assess the safety of itacitinib in patients with bronchiolitis obliterans syndrome (BOS) after allogeneic hematopoietic cell transplantation (HCT). SECONDARY OBJECTIVES: I. To assess treatment failure at 3 months and 6 months. II. To assess change in symptom-based lung score at 3 months and 6 months. III. To assess change in the St. George Respiratory Questionnaire and Study Short Form 36 at 3 months and 6 months. IV. To assess change in the Lee chronic graft versus host disease (GVHD) symptom scale at 3 months and 6 months post-treatment. V. To assess change in 6-minute walk test at 3 months and 6 months. VI. To assess failure-free survival at 6 months. VII. To assess non-relapse mortality at 6 months. VIII. To assess overall survival at 6 months. OUTLINE: Patents receive itacitinib orally (PO) once daily (QD) for up to 1 year in the absence of disease progression or unacceptable toxicity.