Dose Escalation Study in Acute Myeloid or B-Cell Acute Lymphoblastic Leukemia

Inclusion Criteria: * At least 18 years of age * Pathologic confirmation of AML or B-ALL * Must have relapsed or refractory AML or B-ALL with no alternate therapy of proven benefit * ECOG status of 0 or 1 * Adequate renal function \[creatinine less than or equal to 1.5x ULN\] or GFR of at least 60mL/min * Adequate hepatic function via total bilirubin, AST, and ALT * Corrected QT interval of less than 470 ms (via Fridericia correction formula) * Negative pregnancy test for women of child bearing potential * Willingness to use adequate birth control throughout participation for both men and women Exclusion Criteria: * Diagnosis of acute promyelocytic leukemia * Active grade 2 or higher acute GVHD at time of study entry or active chronic GVHD (moderate or severe) * Gastrointestinal conditions which could interfere with the swallowing or absorption of study medication * Diagnosis of currently active CNS leukemia * Known infection with HIV or AIDS (testing not required) * Known active Hepatitis A, B or C (testing not required) * Patients being actively treated for a secondary malignancy * Cancer-directed therapy within 14 days of the first dose of study drug or 5 half-lives, whichever is longer * Major surgery within 28 days prior to the first dose of study drug * Use of an investigational drug within 28 days or 5 half-lives whichever is longer * Women who are pregnant or breastfeeding * Evidence of uncontrolled infections requiring antibiotic therapy; potential subjects with known or suspected infections on stable antibiotic therapy for 72 hours may be enrolled * Uncontrolled intercurrent illness including symptomatic congestive heart failure, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements