Evaluating the Safety of Zileuton (Zyflo®) in Combination With Dasatinib (Sprycel®) in Chronic Myelogenous Leukemia

The standard treatment for chronic myelogenous leukemia is therapy with tyrosine kinase
inhibitors (TKIs). This treatment can diminish the amount of disease to very low levels that
only very sensitive and specialized techniques can measure; it does not, however, provide a
cure.

Dr. Shaoguang Li and colleagues at University of Massachusetts have published a unique
discovery that the arachidonate 5-lipoxygenase (5-LO) gene (Alox5) is a critical regulator
for LSCs in BCR-ABL-induced CML (Chen Y et al. Loss of the Alox5 gene impairs leukemia stem
cells and prevents chronic myeloid leukemia. Nature Genetics 41:783-792, 2009). In the
absence of Alox5, BCR-ABL failed to induce CML in preclinical studies. While deficiency in
Alox5 had no effect on normal hematopoiesis, impairment of the LSCs function through
differentiation and cell division of CML LSCs was observed. This defect led to a depletion
of LSCs and a failure of CML development. Treatment with a 5-LO inhibitor (zileuton) also
impaired the function of LSCs and prolonged survival. These results demonstrate that a
specific target gene can be found in cancer stem cells and its inhibition can completely
inhibit the function of these stem cells. These findings provide an exciting opportunity to
develop the first anti-cancer stem cell therapy for treating CML.

Patients who did not respond or did not tolerate two TKIs will be considered for this study.

Inclusion Criteria:

Target Population:

1. Patients with CML with known inadequate response (as appropriate for their CML status)
to TKIs or known resistance will be considered for this study

- Patients who are resistant or not responding adequately to dasatinib as a first line
therapy, but are not able or eligible to receive other effective second line
treatment can be considered for participation in the study.

- Age > 18 years

- ECOG performance status ≤ 2

- Total bilirubin < 2.0 times the institutional Upper Limit of Normal (ULN)

- Hepatic enzymes (AST, ALT ) ≤ 1.5 times the institutional ULN

- Serum Na, K+, Mg2+, Phosphate and Ca2+>= Lower Limit of Normal (LLN)

- Serum Creatinine < 2.3 mg/dL

- PT, PTT all Grade 0-1 3) Ability to take oral medication 4) Concomitant Medications

- Patient agrees to discontinue St. Johns Wort while receiving dasatinib therapy 5) Age
and Sex

- Women of childbearing potential and men of fathering potential must use an adequate
method of contraception to avoid pregnancy throughout the study to minimize the risk
of pregnancy

Exclusion Criteria:

1. Sex and Reproductive Status

- Women of childbearing potential and men of fathering potential unable or
unwilling to use an adequate method of contraception to avoid pregnancy
throughout the study to minimize the risk of pregnancy

2. Target Population

- Patients intolerant of dasatinib.

3. Medical History and Concurrent Diseases

- History of active malignancy during the past 5 years with the exception of
nonmetastatic treated skin cancer (e.g. basal or squamous cell carcinoma ) or
stage 0 cervical carcinoma

- Patients known to be HIV-positive

- Patients with active, uncontrolled infections

- Concurrent medical condition which may increase the risk of toxicity, including:

- Pleural or pericardial effusion of any grade

- Cardiac Conditions:

- Uncontrolled angina, congestive heart failure or MI within (6 months)

- Diagnosed congenital long QT syndrome

- Any history of clinically significant ventricular arrhythmias (such as
ventricular tachycardia, ventricular fibrillation, or Torsades de pointes)

- Prolonged QTc interval on pre-entry electrocardiogram (> 450 msec)

- Severe cardiac dysfunction (NYHA classification III-IV)

- Severe pulmonary disease

- History of significant bleeding disorder unrelated to cancer

4. Physical and Laboratory Test Findings

- Hepatic dysfunction (serum bilirubin ≥ 2 x ULN, and/or ALT ≥ 3 x ULN, and/or AST
≥ 3 x ULN)

- Renal dysfunction (creatinine ≥ 200 μmol/l or 2.3 mg/dl)

- Subjects with hypokalemia or hypomagnesemia that cannot be corrected prior to
dasatinib administration

5. Allergies and Adverse Drug Reactions

- Patients with known allergic reaction or intolerance to either dasatinib or
zileuton

6. Prohibited Treatments and/or Therapies

- Category I drugs that are generally accepted to have a risk of causing Torsades
de Pointes including:

- quinidine, procainamide, disopyramide

- amiodarone, sotalol, ibutilide, dofetilide

- erythromycin, clarithromycin

- chlorpromazine, haloperidol, mesoridazine, thioridazine, pimozide

- cisapride, bepridil, droperidol, methadone, arsenic, chloroquine, domperidone,
halofantrine, levomethadyl, pentamidine, sparfloxacin, lidoflazine.

- Patients requiring anticoagulation with Coumadin

7. Other Exclusion Criteria

- Prisoners or subjects who are involuntarily incarcerated.

- Subjects who are compulsorily detained for treatment of either a psychiatric or
physical (e.g. infectious disease) illness.