A Study of Immune Suppression Treatment for People With Sickle Cell Disease or β-Thalassemia Who Are Going to Receive an Allogeneic Hematopoietic Cell Transplantation (HCT)

Inclusion Criteria

• •Age ≥ 2 and ≤ 50 years
• •Suitable haploidentical donor.
• •Performance score ≥ 70% by Karnofsky Performance Scale or 0 to 1 by ECOG (age \> 16 years), or Lansky Play-Performance Scale ≥ 70% (age ≤ 16 years).
• •Adequate major organ system function as demonstrated by:
• •* For patients ≥ 18 years of age:
• •* eGFR ≥ 50 mL/min by Cockcroft-Gault formula Formula: ((140 - Age) x Weight (kg)) / (72 x Serum Creatinine (mg/dL) Female Adjustment: Multiply result by 0.85
• •* For patients \< 18 years of age:
• •* Serum creatinine clearance: glomerular filtration rate \[GFR\]) must be \>50 mL/min/1.73 m2 as calculated by the Schwartz formula
• •Conjugated (direct) bilirubin less than 3x upper limit of normal.
• •ALT or AST ≤ 3 times institutional upper limit of normal.
• •Left ventricular ejection fraction ≥ 50%.
• •Diffusing capacity for carbon monoxide (DLCO) ≥ 50% predicted, corrected for hemoglobin. For children \< 7 years of age who are unable to perform PFT, oxygen saturation \> 92% on room air by pulse oximetry.
• •For SCD patients: HbSS, HbSC, HbS/β° with one or more of the following complications:
• •* Acute chest syndrome: 2 or more episodes in the 2 years preceding enrollment
• •* Vaso-occlusive episodes: 3 or more episodes in the 2 years preceding enrollment
• •* Recurrent priapism: 2 or more episodes in the 2 years preceding enrollment
• •* History of osteomyelitis or osteonecrosis
• •* Cerebrovascular disease:
• •Imaging evidence of prior overt or silent stroke
• •History of a neurologic event resulting in focal neurologic deficits lasting \> 24 hours
• •Abnormal transcranial Doppler: Timed average maximum mean velocity ≥ 200 cm/sec in terminal portion of the carotid or proximal portion of the middle cerebral artery or \> 185 cm/sec plus evidence of intracranial vasculopathy if imaging TCD is used
• •* Pulmonary hypertension: Confirmed by right heart catheterization with mean pulmonary arterial pressure ≥ 25 mmHg or mean pulmonary vascular resistance \> 2 Wood units
• •* Red blood cell alloimmunization (\> 3 alloantibodies)
• •For thalassemia patients: Any genotype, with all of the following:
• •* Onset of red blood cell transfusion dependence during the first 3 years of life
• •* RBC transfusion history \> 225 mL/kg/year or \> 15 lifetime RBC transfusions
• •* Pre-transfusion hemoglobin ≤ 7 g/dL
• •* Hepatosplenomegaly
• •Patient or the patient's legal representative, parent(s) or guardian should be able to provide written informed consent. Assent of a minor if participant's age is at least seven and less than eighteen years.
• •For sexually active men and women of childbearing potential, must agree to use a form of contraception considered effective and medically acceptable by the Investigator.