MT2025-35 Allogeneic Hematopoietic Stem Cell Transplantation Using Reduced Intensity Conditioning Treosulfan and Fludarabine, With Post-Transplant Cytoxan (PTCy) for the Treatment of Hematological Diseases

12 g/m2 administered intravenously over 2 hours on days -4, -3, and -2.

Fludarabine will be administered intravenously over 1 hour, every 24 hours on days -6 to -2. The daily dose of fludarabine will be determined by model-based dosing utilizing Bayesian methodology .

TBI 200 cGy will be administered as a single treatment on day -1 per current institutional guidelines.

Tacrolimus may be initiated on day +5 either PO or IV gtt , with a goal trough level of 5-10mg/mL and avoiding higher levels for the first two weeks post-transplant, as recent evidence demonstrated increased adverse events for levels over 10 mg/mL.

All patients begin mycophenolate mofetil (MMF) day +5 through day +35 if no acute GVHD or 7 days after engraftment, whichever is later.

Cyclophosphamide 40 mg/kg will be given as an IV infusion over 1-2 hours (depending on volume) on Days +3 post-transplant (between 60 and 72 hours after stem cell infusion) and on Day +4 post-transplant (approximately 24 hours after Day +3 cyclophosphamide).

Given on day 0.