IDH1 Inhibition Using Ivosidenib as Maintenance Therapy for IDH1-mutant Myeloid Neoplasms Following Allogeneic Stem Cell Transplantation

Inclusion Criteria: * Pathologically confirmed diagnosis of IDH1(R132)-mutant acute myeloid leukemia (AML), myelodysplastic syndrome (MDS) or chronic myelomonocytic leukemia (CMML). IDH1 mutations could have been detected by any mutational technique at any prior point including at diagnosis or remission. * Between the ages of 18 and 75 years * Will undergo allogeneic hematopoietic stem cell transplantation (HSCT) for their malignancy. Conditioning may be either conventional myeloablative (MAC) or reduced intensity conditioning (RIC). * HSCT Donor will be one of the following: * 5/6 or 6/6 (HLA-A, B, DR) matched related donor * 7/8 or 8/8 (HLA-A, B, DR, C) matched unrelated donor. Matching in the unrelated setting must be at the allele level. * Haploidentical related donor, defined as ≥ 3/6 (HLA-A, B, DR) matched --≥ 4/6 (HLA-A, B, DR) umbilical cord blood (UCB). Matching in the UCB setting is at the antigen level. Recipients may receive either one or two UCB units. In the case of 2 UCB units, both units must have been at least 4/6 matched with the recipient. * ECOG performance status ≤ 2 * Participants must have normal organ and marrow function as defined below: * Absolute neutrophil count ≥ 1000/µL without growth factor support (e.g. GCSF) in the previous 7 days * Platelet count ≥ 50,000/µL without transfusional support in the previous 7 days * AST (SGOT), ALT (SGPT) and Alkaline phosphatase \< 3x institutional upper limit of normal (ULN) * Direct bilirubin …