A Phase II Trial of CD24Fc for the Prevention of Acute GVHD Following Myeloablative Allogeneic HSCT

Inclusion Criteria:

- A prospective patient for allogeneic HCT for a malignant hematologic disorder

- The donor and recipient must have an HLA-8/8 allelic match at the HLA-A, -B, -C, and -
DRB1 loci. High-resolution typing is required for all alleles. Only matched unrelated
donors are acceptable for this trial.

- The following diagnoses are to be included:

1. Acute Myeloid Leukemia (AML) or Acute Lymphoblastic Leukemia (ALL) in first or
second remission. Remission is defined as the absence of blasts in the peripheral
circulation at the time of enrollment, < 5% blasts in the bone marrow and absence
of extramedullary disease including CNS involvement.

2. Chronic Myelogenous Leukemia (CML) in first or subsequent chronic phase failing
to respond (or intolerant) to at least two different tyrosine kinase inhibitors.
CML in accelerated or blast phase (CML-AP/BP) are eligible without requirement to
fail tyrosine kinase inhibitor therapy, but must be in remission at time of
enrollment. Remission is defined as the absence of blasts in the peripheral
circulation at the time of enrollment, < 5% blasts in the bone marrow and absence
of extramedullary disease including CNS involvement.

3. Myelodysplastic syndrome (MDS) with intermediate or high-risk IPSS or equivalent
IPSS-R score with < 10% blasts in the bone marrow

4. Chronic Myelomonocytic Leukemia (CMML) with < 10% blasts in the bone marrow

- Males or non-pregnant, non-lactating females, ≥ 18 years of age

- Karnofsky >70% (an attempt to quantify cancer patients' general well-being and
activities of daily life. The score ranges from 0 to 100 where 100 is "perfect" health
and 0 is death.)

- Patients must have normal or near normal organ function as defined by their treating
institutions BMT program clinical practice guidelines.

- Ability to understand and the willingness to sign a written informed consent document

- Women of child bearing potential and men must agree to use contraception prior to
study entry and through day 100 post HCT.

Exclusion Criteria:

- Subjects may not have presence of active CNS disease or extramedullary disease.

- Prior cytotoxic chemotherapy within 21 days from the initiation of HCT conditioning.
Note, certain low intensity treatments not intended to induce remission but rather
stabilize disease are acceptable up to 7 days prior to initiation of HCT conditioning

- Matched sibling, cord blood and haploidentical donors are not eligible.

- HLA-mismatch at the HLA-A, -B, -C, and - DRB1 loci. Note, HLA-DQ mismatches are
permissible

- Pregnant and nursing mothers are excluded from this study.

- Any physical or psychological condition that, in the opinion of the investigator,
would pose unacceptable risk to the patient or raise concern that the patient would
not comply with protocol procedures

- Uncontrolled infections

- Patients seropositive or PCR positive for the human immunodeficiency virus (HIV).
Patients with evidence of Hepatitis B or Hepatitis C PCR positivity

- Prior HCT (allograft or prior autograft)

- Use of T cell depletion either ex vivo or in vivo (i.e. ATG, alemtuzumab) is
prohibited.

4.2.11 Current or prior diagnosis of antecedent Myelofibrosis is excluded