This study will evaluate the safety and tolerability of voreloxin (vosaroxin) injection in combination with cytarabine in patients with relapsed or refractory acute myeloid leukemia.

An open-label, Phase 1b/2 study using a dose-escalation design with expansion at the maximum tolerated dose (MTD) using 2 dosing schedules:

During the Schedule A dose-escalation phase, patients with relapsed or refractory acute myeloid leukemia (AML) enrolled in cohorts of at least 3 patients to identify the MTD. Begin with a starting dosing regimen of vosaroxin of 10 mg/m2 on Days 1 and 4 of each cycle in combination with a 24-hour continuous intravenous (CIV) infusion of cytarabine 400 mg/m2/day × 5 days. If none of the 3 patients or 1 of 6 patients experience a dose-limiting toxicity (DLT) at the vosaroxin starting dose, dose-escalate vosaroxin. If 2 of 6 patients experienced a DLT at the vosaroxin starting dose, reduce the dose of cytarabine to reduced to 200 mg/m2 (only case in which the cytarabine could have been reduced). The vosaroxin dose escalated following a modified Fibonacci schema.

For Schedule B dose-escalation phase, patients with relapsed or refractory AML enrolled in cohorts of at least 3 patients to identify the MTD. Begin with a starting dose regimen of vosaroxin of 70 mg/m2 on Days 1 and 4 in combination with cytarabine as a 2-hour infusion of 1 g/m2/day × 5 days. No reductions of cytarabine allowed in Schedule B. If none of the 3 patients or 1 of 6 patients experienced a DLT in the first cohort of Schedule B, escalate the dose of vosaroxin. If DLTs occurred in 2 of 6 patients during the starting dose, reduce the vosaroxin dose to 50 mg/m2.

For both Schedules, the highest dose at which fewer than 2 of 6 patients experienced a DLT during induction became the MTD and the recommended future dose.

Once the MTD of vosaroxin was determined for Schedule A, first relapse patients were enrolled in the expansion phase at that dose level to obtain additional safety and efficacy information. When the MTD of vosaroxin was determined for Schedule B, first relapse patients and patients with primary refractory disease were enrolled in the expansion phase at that dose level to characterize the safety and efficacy profile in this population.

KEY INCLUSION CRITERIA

1. Relapsed or refractory AML subtypes defined by WHO, except acute promyelocytic leukemia. Relapsed/refractory disease may be de novo AML or secondary AML
2. Treated with one to threee induction/reinduction AML regimens, prior induction or consolidation therapy with cytarabine allowed
3. At least 10% blasts by BM biopsy or aspirate
4. Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0 or 1
5. Clinical laboratory values of a) Serum creatinine ≤1.5 mg/dL and calculated or measured creatinine clearance (CRcl) of ≥50 mL/min, b) Total bilirubin ≤1.5 X upper limit of normal and c) Aspartate aminotransferase (AST) or alkaline phosphatase ≤2.5 X ULN.

KEY EXCLUSION CRITERIA

Patients with:

1. Allogenic bone marrow transplant/stem cell transplant

2. Persistent, clinically significant, chronic toxicities from prior AML therapy that would contraindicate the patient's participation in the clinical study due to safety concerns or compliance with study procedures

3. Acute promyelocytic leukemia

4. Disseminated intravascular coagulation

5. Active infections, unless adequately treated with antibiotic, antiviral, or antifungal agents within in 7 days before Induction Day 1

6. Active central nervous system involvement by AML

7. Other active malignancies or other malignancies within the last 12 months except nonmelanoma skin cancer or cervical intraepithelial neoplasia

8. A requirement for hemodialysis or peritoneal dialysis

9. A history of myocardial infarction within the 3 months before treatment with vosaroxin

10. A history of cerebrovascular accident/transient ischemic attack within the 3 months before treatment with vosaroxin

11. A thromboembolic event (deep vein thrombosis or pulmonary embolus) within 28 days before treatment with vosaroxin

12. Investigational products taken within 28 days before treatment with vosaroxin, and non-investigational cancer therapies or radiation therapy within 14 days before treatment with vosaroxin, with the exception of hydroxyurea.

13. A known intolerance to cytarabine or known allergy to D-sorbitol or methanesulfonic acid (excipients used in vosaroxin)

14. Prior exposure to vosaroxin

15. Any other medical, psychological, or social condition that contraindicates their participation in the clinical study due to safety concerns or compliance with study procedures in the opinion of the Investigator,or Sunesis Medical Monitor

    In addition:

16. Women who are pregnant or breastfeeding

17. Women who are of childbearing potential or male patients who had partners of childbearing potential who were unwilling to use an approved, effective means of contraception according to the study site's standards

Aggregate data of Adverse Events