Patients who meet all of the following criteria are eligible for enrollment in the study:

          1. Histologically or cytologically diagnosed as myelodysplastic syndrome (MDS) according
             to WHO criteria or FAB classification. For patients with RAEB in transformation
             (RAEB-t), peripheral WBC is ≦25,000 /mm3 and the disease is stable for at least 4
             weeks.

          2. Classified as Intermediate-1, Intermediate-2 or High-risk, according to IPSS
             classification.

          3. Patients with a history of previous treatment of the target disease (e.g.,
             immunosuppressive therapy, protein anabolic steroids, and chemotherapy including
             azacitidine and lenalidomide) and meet one of the followings:

               -  Patients who failed to achieve complete remission, partial remission, or
                  hematologic improvement*

               -  Patients experienced with recurrence/relapse after achieving complete remission,
                  partial remission, or hematologic improvement*

               -  Patients who were intolerable to the previous therapy *: The most recent
                  assessment of the therapeutic effect based on "Clinical application and proposal
                  for modification of the International Working Group (IWG) response criteria in
                  myelodysplasia" (IWG2006 criteria)

          4. Off all other treatment (including erythropoiesis stimulating agents) for MDS, for at
             least 4 weeks prior to enrollment and no carry-over (of antitumor effect) from
             previous treatment is expected as judged by Investigator. Transfusion is allowed, as
             clinically indicated.

          5. Patients with expected survival of ≥3 months.

          6. Patients aged 20 years or older (at the time of informed consent).

          7. ECOG Performance Status (PS) of 0, 1 or 2

          8. Patients with adequate major organ functions (including the heart, lungs, liver, and
             kidneys).

               -  AST (GOT): ≤2.5 -fold the upper limit of normal range at each institution

               -  ALT (GPT) : ≤2.5 -fold the upper limit of normal range at each institution

               -  Total bilirubin: <2.0 mg/dL (except patients with Gilbert's disease or hemolysis)

               -  Serum creatinine: <2.0 mg/dL

               -  ECG: Absence of abnormal findings that require treatment

               -  Echocardiography: Absence of abnormal findings that require treatment

          9. The patient must sign an informed consent form indicating that s/he understands the
             purpose of and procedure required for the study and is willing to participate in the
             study.