An Evaluation of Safety and Efficacy of Escalating Doses of AMD3100 to Mobilize CD34+ Cells in Healthy Volunteers

Peripheral blood progenitor cells (PBPC) have become the preferred source of hematopoietic
stem cells for allogeneic transplantation because of technical ease of collection and shorter
time required for engraftment. Traditionally, granulocyte-colony stimulating factor (G-CSF)
has been used to procure the PBPC graft. Although regimens using G-CSF usually succeed in
collecting adequate numbers of PBPC from healthy donors, 5%-10% of subjects will mobilize
progenitor cells poorly and may require multiple large volume apheresis or bone marrow
harvesting.

AMD3100 is a bicyclam compound that inhibits the binding of stromal cell derived factor-1
(SDF-1) to its cognate receptor CXCR4. CXCR4 is present on CD34+ hematopoietic progenitor
cells and its interaction with SDF-1 plays a pivotal role in the homing of CD34+ cells in the
bone marrow. Inhibition of the CXCR4-SDF-1 axis by AMD3100 releases CD34+ cells into the
circulation, which can then be collected easily by apheresis. Recently, several reports have
demonstrated that large numbers of progenitor CD34+ cells are rapidly mobilized in healthy
volunteers following a single subcutaneous injection of AMD3100. The ability to collect a
large quantity of PBPC's with a single injection of this drug makes this an attractive agent
for mobilizing both autologous and allogeneic donors for hematopoietic stem cell
transplantation.

A phase one dose escalating trial of AMD3100 in healthy donors done outside the NHLBI
suggested the peak CD34+ mobilizing effects of this agent occurred at the 240 microgram/kg
dose. Of note, no dose limiting toxicities were observed at the highest dose level of 320
mcg/kg. In two current trials at the NHLBI, AMD3100 has also proven to be well tolerated at
the 240 mcg/kg dose, however, the progenitor CD34+ cell yield following a matched volume
apheresis was lower compared to G-CSF mobilizations collected from the same healthy
volunteers. More importantly, the number of CD34+ cells collected following one dose of
AMD3100 has frequently been less than 3 x 10(6) CD34+ cells/kg, the previously defined
minimal dose of progenitor cells required to optimize allogeneic hematopoietic stem cell
transplantation outcomes. In addition, preliminary data from non-human primate studies
suggest that higher doses of AMD3100 may improve CD34+ cell yield in an apheresis collection.

Based on these data, it is possible that inter-subject variability in CD34+ cell mobilization
may have led investigators (in the prior phase I study) to prematurely terminate AMD3100 dose
escalation based on the perception that CD34+ doses had peaked. We therefore propose this
dose escalating study, designed to evaluate the safety and activity of AMD3100 when
administered in escalating higher doses (240 microgram/kg dose, 320 microgram/kg dose 400
microgram/kg dose 480 microgram/kg dose). Activity will be evaluated by measuring the most
effective dose of AMD3100 in mobilizing progenitor CD34 + cells into the circulation in
healthy donors. To minimize inter-subject variability, we will administer two different doses
of AMD3100 to each subject, evaluating the peak CD34+ cell count achieved after each dose.
Separate cohorts of healthy volunteers will be evaluated for each dose escalation. The short
half life and rapid wash-out of AMD3100 allows for this method of study.

- INCLUSION CRITERIA:

Ages greater than or equal to18 years and less than or equal to 50 years

Normal renal function: creatinine less than 1.5 mg/dl

Normal liver function: total bilirubin less than 1.5mg/dl, ALT and AST levels must be below
the laboratory's high normal value.

Normal blood count:

WBC 3000-10000/mm(3)

Granulocytes greater than 1500/mm(3)

Platelets greater than 150,000/mm(3), and

Hemoglobin (females greater than 11.1 g/dl, males greater than 12.7 g/dl)

Antecubital veins must be adequate for peripheral access for phlebotomy (subject must be
eligible for normal blood donation)

Ability to comprehend the investigational nature of the study and provide informed consent

EXCLUSION CRITERIA: ANY OF THE FOLLOWING:

Active infection or history of recurrent infection, hepatitis B and C (HBsAg, Anti-HCV),
HIV and/or HTLV-1

History of autoimmune disease such as rheumatoid arthritis, systemic lupus erythematous

History of cancer within the past 5 years excluding basal cell or squamous cell carcinoma
of the skin

History of any hematologic disorders including thromboembolic disease

History of cardiac disease such as uncontrolled hypertension, peripheral vascular disease,
myocardial infarction, cardiac arrhythmias or related symptoms such as tachycardia, chest
pain, shortness of breath which have required medical intervention or treatment or a
Framingham coronary disease risk prediction score of greater than 10% 10 year CHD risk

History of cerebrovascular disease, transient ischemic attack, or stroke

Pregnant or lactating