Haploidentical PBMC Transplant for Severe Congenital Anemias

Nonmyeloablative allogeneic peripheral blood stem cell (PBSC) transplants are currently being investigated in phase I/II trials assessing engraftment, efficacy, and toxicity at a number of transplant centers. Our ongoing protocol for patients with severe congenital anemias, particularly sickle cell disease (SCD), and an HLA-matched sibling donor has had excellent preliminary results. None of the patients who engrafted had sickle-related events or any evidence of graft versus host disease (GVHD). There was no significant toxicity associated with the conditioning regimen.

Our main limitation has been a lack of HLA-matched sibling donors in the majority of patients. We performed a study in which patients with severe SCD who lacked a suitable donor underwent a search for a matched unrelated donor or umbilical cord donor. The vast majority of patients were not found to have an appropriate alternative donor. We therefore seek to develop a safe nonmyeloablative regimen to be applied to the haploidentical setting so that family members can serve as donors and greatly expand the donor pool.

In this protocol, we propose PBSC transplantation in patients with SCD and thalassemia, considered at high risk for complications from or ineligible for standard bone marrow transplantation, with allogeneic peripheral blood stem cells from a haploidentical donor using a novel immunosuppressive regimen without myeloablation in an attempt to further decrease the transplant-related morbidity/mortality. The low intensity nonmyeloablative conditioning regimen will consist of a relatively low radiation dose for therapeutic radiation, Alemtuzumab (Campath ), Sirolimus (Rapamune ), and Cyclophosphamide (Cytoxan ) as a strategy to provide adequate immunosuppression to allow sufficient engraftment for clinical remission with a lower risk of GVHD development. T-cell replete, donor-derived, granulocyte colony-stimulating factor (G-CSF)-mobilized PBSC will be used to establish hematopoietic and lymphoid reconstitution.

The primary endpoint of this study is the percentage of patients who have sustained donor type hemoglobin without significant GVHD for patients with SCD, or who are transfusion-independent and without significant GVHD for patients with thalassemia. Other endpoints include degree of donor-host chimerism necessary for long term graft survival and disease amelioration, incidence of acute and chronic GVHD, incidence of graft rejection, transplant-related morbidity, as well as disease-free and overall survival.

• INCLUSION CRITERIA:

Recipients (must fulfill one disease category in 5.1.1 and all of 5.1.2)

5.1.1 Disease specific

5.1.1.1 Patients with sickle cell disease (HB SS, SC, or SBeta(0)-thal) at high risk for disease-related morbidity or mortality, defined by having severe end-organ damage (A, B, C, or D) or potentially modifiable complication(s) not ameliorated by hydroxyurea (E):

A. Stroke defined as a clinically significant neurologic event that is accompanied by an infarct on cerebral MRI or cerebral arteriopathy requiring chronic transfusion therapy; OR

B. Sickle cell-related renal insufficiency defined by a creatinine level greater than or equal to 1.5 times the upper limit of normal and kidney biopsy consistent with sickle cell nephropathy OR nephrotic syndrome OR creatinine clearance less than 50mL/min OR requiring peritoneal or hemodialysis; OR

C. Pulmonary hypertension defined as tricuspid regurgitant jet velocity (TRV) of greater than or equal to 2.5 m/s at baseline (without vaso-occlusive crisis); OR

D. Sickle hepatopathy defined as EITHER ferritin greater than 1000mcg/L OR direct bilirubin greater than 0.4 mg/dL AND platelet count less than 250,000/microL at baseline (without vaso-occlusive crisis)

E. Any one of the below complications:

-Complication: Vaso-occlusive crises;

Eligible for hydroxyurea*: At least 3 hospital admissions in the last year.

Eligible for HSCT: More than 1 hospital admission per year while on maximal tolerated dose of hydroxyurea*

-Complication: Acute chest syndrome

Eligible for hydroxyurea*: 2 prior ACS

Eligible for HSCT: any ACS while on hydroxyurea*

*hydroxyurea at maximum tolerated dose for at least 6 months

5.1.1.2 Patients with thalassemia who have grade 2 or 3 iron overload, determined by the presence of 2 or more of the following:

• portal fibrosis by liver biopsy
• inadequate chelation history (defined as failure to maintain adequate compliance with chelation with deferoxamine initiated within 18 months of the first transfusion and administered subcutaneously for 8-10 hours at least 5 days each week)
• hepatomegaly of greater than 2cm below the costochondral margin

5.1.2 Non-disease specific:

5.1.2.1 Age greater than or equal to 18 years

5.1.2.2 Haploidentical relative donor available

5.1.2.3 Ability to comprehend and willing to sign an informed consent

5.1.2.4 Negative Beta-HCG

Exclusion criteria

Recipient (any of the following would exclude the subject from participating)

5.2.1 6/6 HLA-matched with or without an ABO minor mismatched sibling donor

5.2.2 ECOG performance status of 3 or more

5.2.3 Evidence of uncontrolled bacterial, viral, or fungal infections (currently taking medication and progression of clinical symptoms) within one month prior to starting the conditioning regimen. Patients with fever or suspected minor infection should await resolution of symptoms before starting the conditioning regimen.

5.2.4 Major anticipated illness or organ failure incompatible with survival from PBSC transplant

5.2.5 Pregnant or lactating

5.2.6 Major ABO mismatch

Inclusion criteria

Donor

5.3.1 Haploidentical relative donor

5.3.2 Weight greater than or equal to 20 kg (insofar that the weight difference between recipient and donor does not exceed a reasonable likelihood of being able to obtain an adequate cell dose from the donor within two aphereses)

5.3.3 Fit to receive filgrastim (G-CSF) and to give peripheral blood stem cells (blood counts and blood pressure within DTM standards)

5.3.4 No history of congestive heart failure or unstable angina, and no history of stroke)

5.3.4 Ability to comprehend and willing to sign an informed consent; assent obtained from minors

Exclusion criteria

Donor: (any of the following would exclude the donor from participating)

5.4.1 Pregnant or lactating

5.4.2 HIV positive

5.4.3 Hemoglobin S greater than or equal to 50 percent, or beta

thalassemia intermedia