Venetoclax in Combination With Azacitidine (VEN/AZA) Followed by Donor Lymphocyte Infusion (DLI) for Patients With Very High-Risk Acute Myeloid Leukemia (AML) Undergoing Allogeneic Hematopoietic Cell Transplant (HCT)

Venetoclax will be given orally (PO) at the assigned doses of 50 or 100 mg once daily for 7, 14 or 21 days starting at day 1 of each 28-day cycle, for up to 12 cycles.

Azacitidine will be administered at a dose of 20mg/m\^2 once daily subcutaneously (SC) or intravenously (IV) for five days (Days 1-5) of each 28-day cycle.

"Donor lymphocyte infusions (DLI) may be administered at the discretion of the treating physician, if certain criteria are met. Participants may receive up to three (3) infusions of donor lymphocytes (a type of white blood cell) at the following dose levels and study timepoints:~* DLI 1: 1x10\^6 cluster of differentiation 3+ (CD3+) cells/kg, after cycle 3~* DLI 2: 5x10\^6 CD3+ cells/kg, after cycle 5, if there is persistent MRD~* DLI 3: 1x10\^7 CD3+ cells/kg, after cycle 7, if there is persistent MRD."