Vorinostat Dose-escalation After Allogeneic Hematopoietic Cell Transplantation

The objective of this study is to evaluate the maximum tolerated (MTD) of vorinostat used in combination with low-dose azacitidine after allogeneic hematopoietic cell transplantation (alloHCT) for prevention of relapse of childhood myeloid malignancies.

Inclusion Criteria: 1. Patient is 1 year to 21 years of age. 2. Patient has a diagnosis of AML, MDS, MDS/AML, MPAL, or JMML. Note: patients are allowed to have received a HMA or HDACi prior to undergoing alloHCT. 3. Patient has undergone allogeneic hematopoietic cell transplantation (no restrictions on conditioning regimen, donor or stem cell source, or GVHD prophylaxis regimen). 4. Patient and/or parent(s) or legal guardian(s) are capable of understanding the study, including potential benefits and risks, and sign written informed consent. Age-appropriate assent will be obtained. 5. Female patient of childbearing potential has a negative screening pregnancy test (urine or serum, as per local institutional standard). 6. Female patient with infant(s) agrees not to breastfeed her infant(s) while on study. 7. Patient of child-bearing potential (male and female) agrees to use effective method of contraception during the study. Exclusion Criteria: 1. Patient is enrolled on a clinical trial with investigational post-transplant medications. Note: trials involving defibrotide, post-transplant cyclophosphamide, and Lactobacillus plantarum are permitted. Other trials involving investigational medications that aren't leukemia or GVHD-directed may also be permitted after consultation with the overall PI. 2. Patient has a planned administration of non-protocol chemotherapy, radiation therapy, donor leukocyte infusion, or immunotherapy during the planned study period. 3. Patient has a known allergy to azacitidine or vorinostat. 4. Patient has chronic myelogenous leukemia. 5. Concomitant use of coumarin-derived anticoagulants or valproic acid. \-