Haploidentical Hematopoietic Stem Cell Transplantation

Research subjects will undergo reduced intensity conditioning (Hydroxyurea, ATG, Fludarabine,
Thiotepa, Melphalan) followed by infusion of a peripheral blood stem cell graft collected
from haploidentical family donors that are CD34+ positively selected using the CliniMACS
device. Sirolimus will be used for GVHD prophylaxis and given for 9 months post-transplant
and then tapered off by one year

The use of the CliniMACS device for CD34 selection will be performed at CNMC through
cross-reference of the master file for CliniMACS CD34+ Reagent by Milteyni Biotech (BB-MF
8061).

CliniMACs is an electromechanical device intended to isolate certain cell subsets from mixed
cell populations. When used in combination with the CliniMACs CD34 reagent, it is possible to
prepare extremely pure populations of CD34+ cells with upwards of 5 logs depletion of
contaminating T cells within a closed and sterile system.

We intend to use this system to select cells from HLA haploidentical related donors who have
been mobilized with G-CSF prior to stem cell collection. Since previous investigations of
this strategy in adult patients have not translated into enhanced long term survival, we
intend to limit this protocol to patients under the age of 22 as they have more rapid immune
reconstitution.

Inclusion Criteria:

- First allogeneic transplant

- Age up to 22 years

- Patients with severe sickle cell disease (stroke, elevated TCD velocities, >2 acute
chest syndrome, ongoing chronic red cell transfusion > 6 months)

- Patients with transfusion dependent thalassemia and evidence of iron overload

- Patients must have a related donor that is HLA-matched at >/=4 of 8 but <8/8 HLA-A,
-B, -C and -DRB1

- Cardiac function: Shortening fraction >25%; ejection fraction >40%

- Estimated creatinine clearance greater than 50 mL/minute

- Pulmonary function: DLCO ≥40% (adjusted for hemoglobin) and FEV1≥50%, oxygen
saturation>91%

- Liver function: direct (conjugated) bilirubin < 2x the upper limit of normal and
ALT/AST < 2.5x the upper normal limit.

- Signed informed consent.

Exclusion Criteria:

- Life expectancy less than 6 months

- Patients with uncontrolled bacterial, viral or fungal infections (undergoing
appropriate treatment and with progression of clinical symptoms) within 1 month prior
to conditioning. Patients with febrile illness or suspected minor infection should
await clinical resolution prior to starting conditioning.

- Pregnant or breastfeeding patients

- Patients seropositive for the human immunodeficiency virus (HIV)

- Patient with active Hepatitis B or C determined by serology and/or NAAT

- Active hepatitis, bridging fibrosis or cirrhosis on liver biopsy (biopsy required for
patients on chronic transfusion therapy for > 1 year and evidence of iron overload
with ferritin >1000 ng/mL)

- Patients with suitable 8/8 HLA matched related and unrelated donors