DR-18 to Prevent or Treat Acute Myeloid Leukemia or Myelodysplastic Syndrome Relapse After Hematopoietic Cell Transplantation, the DR. DREAM Trial

Inclusion Criteria: * ≥ 18 years of age (no upper age limit) * The most recent HCT was from a 10/10 human leukocyte antigen (HLA)-matched related or unrelated donor (assessed at HLA-A, B, C, DR, DQ) * Evidence of blood count recovery at any time post-HCT defined as absolute neutrophil count (ANC) ≥ 0.5 x 10\^9/L for ≥ 3 consecutive days and platelets ≥ 30 x 10\^9/L (independent of granulocyte colony-stimulating factor \[G-CSF\] or platelet transfusions for 5 days). (Blood count recovery may not be sustained.) * Absent, stable or reducing immune suppression in the preceding 4 weeks without GvHD flares * Karnofsky performance status (KPS) ≥ 80% * Agrees to use a suitable method of contraception during study treatment and for 4 months after the last dose of DR-18 * Capable of providing informed consent * GROUP 1: Documented persistent or recurrent measurable residual AML or MDS after HCT, defined as bone marrow blasts \< 5% by morphology (unless suspected to be regenerative) and malignant bone marrow blasts \< 5% by flow cytometry. * Note: MRD (\< 5% malignant blasts) must be detected with flow cytometry testing at University of Washington Medical Center (UWMC)/Fred Hutchinson Cancer Center (Fred Hutch) clinical laboratory * GROUP 1: Absence of circulating malignant blasts detected by the complete blood count (CBC) * GROUP 1: Absence of extramedullary disease * GROUP 1: Post-HCT restaging never detected overt relapse or disease persistence, defined as ≥ 5% (non-regenerative)…