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)

PK-guided fludarabine dosing will be used for each of the 2 cycles, using the InsightRx DoseMeRx platform.

Cyclophosphamide will be administered Post-Transplant

Tacrolimus will be administered beginning on day +5

Mycophenolate mofetil (MMF) will be administered three times daily starting on day +5.

The dose and schedule of ATG will be determined according to the nomogram in Appendix A

Standard Regimen: Dexamethasone on days -68 to -64 and days -40 to -36.

Bortezomib on days -71, -68, -65, -61, -43, -40, -37, and -33

Rituximab on days -71, -58, -43, and -30.