This is an open label, multicenter Phase 1 dose escalation study evaluating five doses of ezatiostat in combination with lenalidomide in patients with non-del(5q) low to intermediate 1 risk MDS. The HI-E, HI-N, HI-P rates [by International Working Group (IWG) 2006 criteria] and safety of each treatment group will be evaluated to select the optimal dose of ezatiostat in combination with lenalidomide for future studies.

Inclusion Criteria:

• Histologic diagnosis of primary or de novo MDS using WHO classification
• Non-del(5q) low or Intermediate-1risk MDS
• ECOG performance status of 0-1
• Documented significant cytopenia for at least 2 months
• Must have discontinued growth factors (EPO, G-CSF, GM-CSF) for at least 21 days prior to study entry
• All study participants must be registered into the mandatory RevAssist® program and be willing and able to comply with the requirements of RevAssist®
• Females of childbearing potential should have two negative serum pregnancy tests with a sensitivity of at least 50 mIU/mL. The first test should be performed within 10-14 days, and the second test within 24 hours of prescribing lenalidomide (prescriptions must be filled within seven days)

Exclusion Criteria:

• Known hypersensitivity to Telintra™ (intravenous or oral)

• Known prior therapy with or hypersensitivity to thalidomide or lenalidomide

• Prior allogenic bone marrow transplant for MDS

• History or prior malignancy

  • Except for treated carcinoma of uterine cervix, basal cell or squamous cell skin cancer, or other cancers (e.g. breast, prostate) for which patient has been disease-free for at least 3 years.

• MDS evolving from:

  • A pre-existing myeloproliferative disorder
  • An autoimmune disease
  • Secondary to prior treatment with radiation or chemotherapy

• History of MDS IPSS score>1.0

• Pregnant or lactating women

• Leptomeningeal or leukemic meningitis

• Prior treatment with DNA methyltransferase inhibitors (DMTI) [e.g., azacitadine, decitabine, etc.]