Daratumumab and Donor Lymphocyte Infusion in Treating Participants With Relapsed Acute Myeloid Leukemia After Stem Cell Transplant

Inclusion Criteria: * AML relapse following Allo-HSCT (Morphological relapse, or MRD positive verified by flow cytometry, cytogenetics, and molecular mutations) * Relapsed/Refractory AML must not be candidates for available therapies known to be effective for treatment of their AML. * MDS transformed to AML following Allo-HCT * Patients who received a 10/10 HLA-matched allogeneic HCT either from sibling donors or unrelated donors or atleast a 5/10 haploidentical transplant. * Engraftment must have occurred as defined by platelet (PLT) count \> 20,000/µL and ANC * 0.5 * Eastern Cooperative Oncology Group (ECOG) performance status \< 3 * Creatinine clearance \> 40 ml/min (calculated or measured) * Aspartate aminotransferase (AST) \< 3 x upper limit of normal (ULN), alanine aminotransferase (ALT) \< 3 x ULN * Total bilirubin \< 1.5 x ULN * Off calcineurin inhibitors for at least 2 weeks * Prednisone dose ≤ 20 mg/day * Patients with proliferative disease can be cytoreduced with cytotoxic chemotherapy at Investigator discretion, but there should be at least a 14 day window between start of cytoreductive therapy and start of daratumumab * Blast count ˂20K/day (hydrea use is allowed) Exclusion Criteria: * No demonstrable evidence of donor chimerism (˂ 55% donor CD3 or CD33 chimerism) * Patients with a molecular mutation without chromosomal abnormalities or declining chimerisms (MRD status must be verified by surface marker and mutational analyses) * Active graft-versus-host di…