Donor Lymphocyte Infusion After Allogeneic Hematopoietic Cell Transplantation for High-Risk Hematologic Malignancies

The DLI will be given on Day +7 (Day +21 for dose level -1). If a recipient participant is deemed too critically ill/unstable to receive DLI on the protocol specified day, the DLI will be delayed up to 4 days at the discretion of the PI and given within this time frame once the recipient participant s clinical status has stabilized or improved. If the DLI cannot be given during this time frame, the recipient participant will be taken off study and not considered evaluable for DLT, outcomes, or adverse events since the experimental intervention will not have been given.

HLA-matched: 50 mg/kg IV once daily over 2 hours on days +3 and +4a Cyclophosphamide will be dosed according to ideal body weight. HLA haploidentical: 25 mg/kg IV once daily over 2 hours on days +3 and +4a Cyclophosphamide will be dosed according to ideal body weight.

AUC targeted dose based on busulfan test dose, with a default dose of 130 mg/m2/day, given as IV infusion over 3 hours each day for 4 days Transplant days -6 through day -3

15 mg/kg orally or IV three times daily (max 1000 mg/dose) starting on day +5, continued through day +35. Dosing will be according to actual body weight.

40 mg/m2 IV infusion over 30-60 minutes once daily for 4 days Transplant days -6 through -3

Loading dose of 6 mg orally given on day +5 (calculated based on actual body weight, maximum initial dose 6 mg), then maintenance dose starting at 2 mg orally daily on day +6 with dose adjustments to maintain a trough of 5-12 ng/ml, continued through day +70 with no taper. Doses should be modified as appropriate for drug interactions.