The study will be a prospective open-label single-center study in previously treated patients with Acute Myeloid Leukemia (AML) or Acute Lymphoid Leukemia (ALL). Treatment efficacy and safety of the combination of Oshadi D (DNase in Oshadi carrier) and Oshadi R (RNase in Oshadi carrier) with Salvage Chemotherapy will be evaluated. Oshadi D and Oshadi R were shown to have anti-tumor activity and good safety profile.

Patients will receive Oshadi D and Oshadi R oral treatment combined with salvage chemotherapy. Patient will be evaluated throughout the study for safety and tolerance to multiple dose regimens of Oshadi D and Oshadi R.

Efficacy will be determined by percentage of bone marrow blasts assessment at day 28 post therapy initiation.

Inclusion Criteria:

• Patients is diagnosed as AML or ALL
• Relapse defined as the presence of disease after the achievement of complete remission(CR). Refractory disease is defined as progression from or no response while treated with a previous line chemotherapy regimen, or progression within 30 days of last bone marrow assessment.
• Male or female ≥ 18 years of age
• Minimal performance status (ECOG 0, ≤2)
• Patients must have a measurable disease by bone marrow blast counts of > 5 % of nucleated cells.
• Written informed consent
• Adequate hepatic function (LFTs up to X4 the normal limits), renal function calculated Creatinine clearance (CrCl) for Adverse Effects of >30)
• Ability to swallow the medications.
• Females of childbearing potential and males must be willing to use an effective method of contraception (hormonal or barrier method of birth control; abstinence) from the time consent is signed until 6 weeks after treatment discontinuation.
• Females of childbearing potential must have a negative pregnancy test within 7 days prior to being registered for protocol therapy.

Exclusion Criteria:

• Active infectious disease uncontrolled by antibiotics.
• Partially treated induction patients (i.e. day 14 non responding patients).
• Inability to receive high dose salvage chemotherapy.
• Patient with known positive HIV serology at screening.
• Female patient who are breastfeeding or have a positive pregnancy test at screening or at any time during the study.
• Evidence of ongoing cardiac dysrhythmias of NCI Common Toxicity Criteria for Adverse Effects (CTCAE ) Version 3.0 grade 2.
• Pre-existing mal absorption syndrome, irritable bowel syndrome or other clinical situation which could affect oral absorption.
• Mental disorders.
• Inability to give written informed consent.