Study of Itacitinib for the Prophylaxis of Graft-Versus-Host Disease and Cytokine Release Syndrome After T-cell Replete Haploidentical Peripheral Blood Hematopoietic Cell Transplantation

Inclusion Criteria: Patients must meet the following criteria within 30 days prior to Day 0 unless otherwise noted. * Diagnosis of a hematological malignancy listed below: * Acute myelogenous leukemia (AML) in complete morphological remission (based on International Working Group (IWG) Criteria) * Acute lymphocytic leukemia (ALL) in complete morphological remission (MRD negative, based on IWG Criteria) * Myelodysplastic syndrome with ≤ 5% blasts in bone marrow. * Non-Hodgkin's lymphoma (NHL) or Hodgkin's disease (HD) in 2nd or greater complete or partial remission. * Planned treatment is myeloablative or reduced intensity conditioning followed by T Cell-replete peripheral blood haploidentical donor transplantation * Available human leukocyte antigen (HLA)-haploidentical donor who meets the following criteria: * Blood-related family member, including (but not limited to) sibling, offspring, cousin, nephew, or parent. Younger donors should be prioritized. * At least 18 years of age * HLA-haploidentical donor/recipient match by at least low-resolution typing per institutional standards. * In the investigator's opinion, is in general good health, and medically able to tolerate leukapheresis required for harvesting hematopoietic stem cells (HSC). * No active hepatitis. * Negative for human T-cell lymphotrophic virus (HTLV) and human immunodeficiency virus (HIV). * Not pregnant. * Safety Lead-In Phase: For the first three patients, the donor must consent…