Itacitinib for the Prevention of Graft Versus Host Disease

PRIMARY OBJECTIVE: I. To compare the 100-day acute grade 2-4 GvHD rate to matched controls. SECONDARY OBJECTIVES: I. To compare the 1-year rate of GvHD-free, relapse-free survival to matched controls. II. To assess the time to neutrophil and platelet engraftment. III. To assess the toxicity profile associated with this regimen. IV. To assess the incidence of severe grade 3-4 acute GVHD. V. To assess the incidence of limited, extensive, and moderate to severe chronic GVHD. VI. To assess the incidence of disease relapse. VII. To assess the incidence of non-relapse mortality. VIII. To assess overall survival and progression-free survival. IX. To assess immunosuppression discontinuation rate. TERTIARY OBJECTIVE (CORRELATIVE STUDY): I. Immune recovery and cytokines at various time points pre- and post- transplant OUTLINE: CONDITIONING: Patients receive busulfan intravenously (IV) over 3 hours on days -20, -13, and -6 to -3, thiotepa IV on day -7, and fludarabine IV over 1 hour on days -6 to -3. STEM CELL TRANSPLANT: Patients undergo stem cell transplant on day 0. GVHD PROPHYLAXIS: Patients receive cyclophosphamide IV over 3 hours on days 3 and 4. Patients also receive itacitinib orally (PO) once daily (QD) on days 5-60 in the absence of disease progression or unacceptable toxicity. Beginning day 5 after stem cell transplant, patients also receive tacrolimus IV over 24 hours until able to tolerate oral tacrolimus, whereby patients then receive tacrolimus PO twice daily (BID). After completion of study intervention, patients are followed up at days 100, 180, and 365 after stem cell transplant.