Study to Evaluate Imetelstat (GRN163L) in Subjects with IPSS Low or Intermediate-1 Risk Myelodysplastic Syndrome (MDS)

Prior treatment

• Subject has received an experimental or investigational drug or used an invasive investigational medical device within 30 days prior to C1D1 (Part 1) or Randomization (Part 2) or is currently enrolled in an investigational study.
• Prior treatment with imetelstat.
• Have received corticosteroids >30 mg/day prednisone or equivalent, or growth factor treatment within 4 weeks prior to C1D1 (Part 1) or Randomization (Part 2).
• Prior treatment with a hypomethylating agent (eg, azacitidine, decitabine); b) Prior treatment with lenalidomide, thalidomide, or other thalidomide analogues; c) Has received an ESA or any anti-MDS therapy, chemotherapy, immunomodulatory, or immunosuppressive therapy within 4 weeks prior to C1D1 (Part 1) or Randomization (Part 2) (8 weeks for long-acting ESAs).

Other illness

• Subject has known allergies, hypersensitivity, or intolerance to imetelstat or its excipients.

• Man or woman ≥18 years of age (or the legal age of consent in the jurisdiction in which the study is taking place)
• In Part 1, diagnosis of myelodysplastic syndromes (MDS) according to WHO criteria confirmed by bone marrow aspirate and biopsy within 12 weeks prior to C1D1. A local laboratory report from this diagnostic bone marrow aspirate and biopsy must be reviewed and approved by the sponsor. In Part 2, diagnosis of MDS according to WHO criteria confirmed by bone marrow aspirate and biopsy within 12 weeks prior to Randomization. A sample of the baseline bone marrow aspirate and biopsy must be submitted to the Independent Central Pathology Reviewer for diagnostic confirmation. Central laboratory review is required to confirm diagnosis prior to Randomization.
• International Prognostic Scoring System (IPSS) low or intermediate-1 risk MDS.
• Red blood cell (RBC) transfusion dependent, defined as requiring at least 4 RBC units transfused over an 8-week period during the 16 weeks prior to C1D1 (Part 1) or Randomization (Part 2); pre-transfusion Hb should be ≤9.0 g/dL to count towards the 4 units total.
• Has MDS that is relapsed/refractory to ESA treatment; as defined by meeting any one of the criteria below: - Received at least 8 weeks of treatment with a minimum weekly dose of epoetin alfa 40,000 U, epoetin beta 30,000 U or darbepoetin alfa 150 mcg (or equivalent agent/dose), without having achieved a Hb rise ≥1.5 g/dL or decreased RBC transfusion requirement by at least 4 units over 8 weeks - Transfusion dependence or reduction in Hb by ≥1.5 g/dL after hematologic improvement from at least 8 weeks of treatment with therapies outlined in the above inclusion criteria, in the absence of another explanation. - Endogenous serum EPO level >500 mU/mL
• Eastern Cooperative Oncology Group (ECOG) performance status 0, 1 or 2.