Study: NCT06412497

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Rituximab
Description: For patients with EBV IgG seropositivity or EBV PCR positivity on pre-transplant evaluations, Rituximab 375 mg/m2 is given IV once on day -14 (+/-2 day) in the outpatient setting. Pre-medicate 30 minutes prior to rituximab with methylprednisolone (1 mg/kg) IV, acetaminophen 15 mg/kg (maximum 650mg) IV or PO and diphenhydramine 1 mg/kg (maximum 50mg) IV or PO.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Rituximab
Description: For patients with EBV IgG seropositivity or EBV PCR positivity on pre-transplant evaluations, Rituximab 375 mg/m2 is given IV once on day -14 (+/-2 day) in the outpatient setting. Pre-medicate 30 minutes prior to rituximab with methylprednisolone (1 mg/kg) IV, acetaminophen 15 mg/kg (maximum 650mg) IV or PO and diphenhydramine 1 mg/kg (maximum 50mg) IV or PO.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Rabbit ATG
Description: Rabbit ATG will be administered at doses and days indicated above, infused through a 0.22 micrometer filter over 4-6 hours. Pre-medicate 30 minutes prior to ATG infusion with methylprednisolone 1 mg/kg IV, (max dose = 125 mg), acetaminophen 15 mg/kg dose (max dose = 650 mg) enterally and diphenhydramine 1 mg/kg/dose (max dose = 50 mg) enterally or IV.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Rabbit ATG
Description: Rabbit ATG will be administered at doses and days indicated above, infused through a 0.22 micrometer filter over 4-6 hours. Pre-medicate 30 minutes prior to ATG infusion with methylprednisolone 1 mg/kg IV, (max dose = 125 mg), acetaminophen 15 mg/kg dose (max dose = 650 mg) enterally and diphenhydramine 1 mg/kg/dose (max dose = 50 mg) enterally or IV.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Cyclophosphamide
Description: Cyclophosphamide 14.5 mg/kg is be given as a 2-hour infusion on day -6. If the patient is obese (actual body weight (ABW) \>/= 125% of the ideal body weight (IBW)), cyclophosphamide should be dosed using the adjusted body weight (AdjBW): 0.5(ABW-IBW) + IBW. Uroprotection with MESNA (14.5 mg/kg/day) in IV continuous infusion will be provided per institutional guidelines. Hyperhydration is not required for 14.5 mg/kg cyclophosphamide doses.~Cyclophosphamide will be administered at 50 mg/kg using ABW over 2 hours on days +3 and +4. If the patient is obese (ABW \>/= 125% of the ideal body weight (IBW)), cyclophosphamide should be dosed using the adjusted body weight (AdjBW): 0.5(ABW-IBW) + IBW. Uroprotection with MESNA (50 mg/kg/day) in IV continuous infusion as well as hyperhydration will be provided per institutional guidelines.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Cyclophosphamide
Description: Cyclophosphamide 14.5 mg/kg is be given as a 2-hour infusion on day -6. If the patient is obese (actual body weight (ABW) \>/= 125% of the ideal body weight (IBW)), cyclophosphamide should be dosed using the adjusted body weight (AdjBW): 0.5(ABW-IBW) + IBW. Uroprotection with MESNA (14.5 mg/kg/day) in IV continuous infusion will be provided per institutional guidelines. Hyperhydration is not required for 14.5 mg/kg cyclophosphamide doses.~Cyclophosphamide will be administered at 50 mg/kg using ABW over 2 hours on days +3 and +4. If the patient is obese (ABW \>/= 125% of the ideal body weight (IBW)), cyclophosphamide should be dosed using the adjusted body weight (AdjBW): 0.5(ABW-IBW) + IBW. Uroprotection with MESNA (50 mg/kg/day) in IV continuous infusion as well as hyperhydration will be provided per institutional guidelines.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Fludarabine
Description: For all patients, fludarabine dosing will be model-based using Bayesian methodology IV every 24 hours on days -6 to -3 with a cumulative area under the curve (cAUC) of 20 mg\*hr/L.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Fludarabine
Description: For all patients, fludarabine dosing will be model-based using Bayesian methodology IV every 24 hours on days -6 to -3 with a cumulative area under the curve (cAUC) of 20 mg\*hr/L.

Intervention type: RADIATION
Group type: EXPERIMENTAL
Intervention: Total Body Irradiation
Description: For patients age \>/= 25 years, with myelodysplasia, or clonal hematopoiesis, total body irradiation will be 4 Gy, provided in two fractions on day -1. For all other patients, total body irradiation will be 2 Gy provided in a single fraction on day -1.~Each dose of 2 Gy will be given at a dose rate between 1 and 1.9 Gy/minute prescribed to the midplane of the patient at the level of the umbilicus.

Intervention type: RADIATION
Group type: EXPERIMENTAL
Intervention: Total Body Irradiation
Description: For patients age \>/= 25 years, with myelodysplasia, or clonal hematopoiesis, total body irradiation will be 4 Gy, provided in two fractions on day -1. For all other patients, total body irradiation will be 2 Gy provided in a single fraction on day -1.~Each dose of 2 Gy will be given at a dose rate between 1 and 1.9 Gy/minute prescribed to the midplane of the patient at the level of the umbilicus.

Intervention type: BIOLOGICAL
Group type: EXPERIMENTAL
Intervention: Cell Infusion
Description: On day 0 the cells will be infused per cell source specific institutional guidelines.

Intervention type: BIOLOGICAL
Group type: EXPERIMENTAL
Intervention: Cell Infusion
Description: On day 0 the cells will be infused per cell source specific institutional guidelines.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Post-Transplant G-CSF
Description: Beginning on day +5, patients will receive G-CSF SQ or IV 5 micrograms/kg once daily until post-nadir ANC \> 1500/μL for 3 consecutive days or \>3000/μL for 1 day.