Study of Iomab-B Prior to HCT vs. Conventional Care in Older Subjects With Active, Relapsed or Refractory AML

Inclusion Criteria:

- Have active, relapsed or refractory Acute Myeloid Leukemia (AML). Active, relapsed or
refractory AML is defined as either (1) primary induction failure (PIF) after 2 or
more cycles of chemotherapy, (2 first early relapse after a remission duration of
fewer than 6 months, (3) relapse refractory to salvage combination chemotherapy
containing high-dose AraC, and (4) second or subsequent relapse

- Have documented CD45 expression by leukemic cells via flow cytometry (a "blast gate"
on CD45 vs. side scatter analysis consistent with AML)

- Be at least 55 years of age

- Have a circulating blast count of less than 10,000/mm3 (control with hydroxyurea is
allowed)

- Have a calculated creatinine clearance (Cockroft-Gault equation) > 50 mL/min

- Have adequate hepatic function (bilirubin, aspartate aminotransferase (AST), and
alanine aminotransferase (ALT), defined as ≤ 2 times the upper limit of normal [ULN])

- Have a Karnofsky score ≥ 70

- Have an expected survival of > 60 days

- Have a central venous catheter line in place prior to study treatment administration

- Have 8/8 allele-level, related or unrelated, medically cleared HSC donor matching at
human leukocyte antigen (HLA)-A, HLA-B, HLA-C, and DRB-1

- Women of childbearing potential, be surgically sterile or agree to practice abstinence
or utilize acceptable contraception (intrauterine, injectable, transdermal, or
combination oral contraceptive) through 1-year post transplant; Males who are sexually
active with women of childbearing potential must be surgically sterile or using an
acceptable method of contraception (defined as barrier methods in conjunction with
spermicides) from time of screening through 12 weeks after last dose of study drug

- Be able to understand the study procedures, agree to participate in the study program,
and voluntarily provide written Informed Consent

Exclusion Criteria:

- Have circulating HAMA noted on initial screening

- Have received prior radiation to maximally tolerated levels to any critical normal
organ

- Have active leukemic central nervous system (CNS) involvement, as defined by any
leukemic blasts detected in the cerebrospinal fluid (CSF) by morphology or flow
cytometry and/or any chloromas detected by CNS imaging

- Have previously received HCT

- Have clinically significant cardiac disease (NYHA Class III or IV); clinically
significant arrhythmia i.e. ventricular tachycardia, ventricular fibrillation, or
"Torsade de Pointes". Myocardial infarction with uncontrolled angina within 6 months,
congestive heart failure, or clinical significant cardiomyopathy

- Have abnormal QTcF (>450milliseconds) after electrolytes have been corrected (at least
two different ECG readings and at least 15 minutes between readings)

- Have current or prior positive test results for human immunodeficiency virus (HIV) or
hepatitis B (HBV) or C. Subjects who have positive HBV test results due to having been
previously vaccinated against hepatitis B, as evidenced by negative hepatitis B
surface antigen (HBsAg), negative anti- hepatitis B core protein (HBc) and positive
antibody to the HBsAg (anti-HBs) are not excluded

- Have active serious infection uncontrolled by antibiotics or antifungals

- Have acute promyelocytic leukemia and the associated cytogenic translocation t:(15/17)

- Have active malignancy within 2 years of entry. Active malignancy is defined as those
malignancies requiring treatment with anti-cancer therapy or in the event of indolent
malignancies, having measurable disease. Exceptions to this exclusion include:
myelodysplastic syndrome, treated non-melanoma skin cancer, completely resected Stage
0 or 1 melanoma no less than 1 year from resection, carcinoma in situ or cervical
intraepithelial neoplasia, and successfully treated organ-confined prostate cancer
with no evidence of progressive disease based on prostate specific antigen (PSA)
levels and are not on active therapy

- Have received an antibody therapy within 3 weeks

- Have a perceived inability to tolerate diagnostic or therapeutic procedures,
particularly treatment in radiation isolation

- Currently receiving any other active investigational agents