Haploidentical Transplantation With Pre-Transplant Immunosuppressive Therapy for Patients With Sickle Cell Disease

All patients will receive an haploidentical hematopoietic stem cell transplant with the
following conditioning and GvHD prevention:

Pre-transplant immunosuppressive therapy:

2 cycles of Fludarabine and Dexamethasone x 5 days each cycle

Conditioning regimen:

rATG daily x 3 days, Fludarabine daily x 6 days and Busulfan daily x 4 days

GVHD prophylaxis:

Cyclophosphamide day +3 and +4, Tacrolimus and Mycophenolate mofetil

Inclusion criteria

- Diagnosis: Patients with sickle cell anemia (Hgb SS or SB° Thalassemia) with baseline
Hgb S more than 60%.

- Disease status:

- Significant neurologic event (stroke) or any neurological deficit lasting > 24 hours;
or increased transcranial Doppler velocity (>200 m/s).

- History of one or more episodes of acute chest syndrome (ACS) in the 2-year period
preceding enrollment despite the institution of supportive care measures (i.e. asthma
therapy and/or hydroxyurea).

- History of one or more severe vaso-occlusive pain crises per year in the 2-year period
preceding enrollment despite the institution of supportive care measures (i.e. a pain
management plan and/or treatment with hydroxyurea).

- Recurrent priapism requiring medical therapy.

- Osteonecrosis of two or more joints despite the institution of supportive care
measures.

- Prior treatment with regular RBC transfusion therapy, defined as receiving 8 or more
transfusions per year for > 1 year to prevent vaso-occlusive clinical complications
(i.e. pain, stroke, and acute chest syndrome)

- Echocardiograph finding of tricuspid valve regurgitation jet (TRJ) velocity ≥ 2.5
m/sec.

- Ages 1 to 30.

- Child Bearing Potential- Transplantation could be teratogenic and/or lethal to the
developing fetus. For this reason, women of child-bearing potential and men must agree
to use adequate contraception (hormonal or barrier method of birth control or
abstinence) prior to study entry and for six months following duration of study
participation. Should a woman become pregnant or suspect that she is pregnant while
participating on the trial, she should inform her treating physician immediately.

- Informed Consent/Assent: All subjects must have the ability to understand and the
willingness to sign a written informed consent.

- The recipient must have a related donor who is genotypically haploidentical on HLA-A,
B, C and DRB1 loci.

- No HLA matched sibling or 10/10 matched unrelated donor is available.

Exclusion criteria:

- Any uncontrolled illness including ongoing or active bacterial, viral or fungal
infection.

- Patients may not be receiving any other investigational agents, or concurrent
biological, chemotherapy, or radiation therapy.

- History of allergic reactions attributed to compounds of similar chemical or biologic
composition to any in the pre- or post-transplant regimen.

- Pregnant women are excluded from this study.

- Patients with any active malignancy are ineligible for this study, other than
non-melanoma skin cancers.

- Medical problem or neurologic/psychiatric dysfunction which would impair patient
ability to be compliant with the medical regimen and to tolerate transplantation or
would prolong hematologic recovery which in the opinion of the principal investigator
would place the recipient at unacceptable risk.

- Prior autologous or allogeneic transplant.

- Fully HLA-matched related or unrelated donor is available to donate.

- Non-Compliance: Subjects, who in the opinion of the investigator, may not be able to
comply with the safety monitoring requirements of the study.