Low-Dose Daunorubicin in Relapsed/Refractory Acute Leukemia

Inclusion Criteria: * Ability to understand and the willingness to sign a written informed consent or have parental consent. * Age ≥ 18 years * Pathological confirmation by bone marrow documenting the following: 1. AML which has relapsed after Complete Remission 2. AML which has been refractory to two prior induction attempts 3. ALL which has relapsed after Complete Remission 4. ALL which has been refractory to two prior induction attempts * Disease status allows delay of additional anti-leukemia therapy for the duration of the study (hydroxyurea is allowed for control of WBC throughout study) * Eastern Cooperative Oncology Group (ECOG) performance status score of 0-3 * Able to adhere to the study visit schedule and other protocol requirements * Cardiac ejection fraction ≥45% by ECHO * Serum alanine aminotransferase or aspartate aminotransferase \< 3 times the ULN * Women of child-bearing potential and men with partners of child-bearing potential must agree to use adequate contraception prior to study entry, for the duration of study participation, and for 90 days following completion of therapy. Exclusion Criteria: * Concurrent use of conventional or investigational anticancer agents, except hydroxyurea (Standard prophylactic anti-infectives and medications to prevent/treat tumor lysis syndrome are allowed. Hydroxyurea may be used to keep the WBC\<25,000. Additional anti-leukemia therapy is prohibited during the study.). * Patient has received chemotherapy or radiotherapy within 2 weeks prior to entering the study or has not recovered from adverse events due to agents administered more than 2 weeks earlier, with the exception of hydroxyurea. * Patients with known active uncontrolled central nervous system (CNS) leukemia * History of allergic reactions attributed to compounds of similar chemical or biologic composition to daunorubicin * Patients with a total lifetime anthracycline exposure exceeding the equivalent of 900 mg/m2 of daunorubicin * Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. * Unwilling or unable to undergo serial bone marrow aspirate/biopsy * Pregnant or nursing