Efficacy & Safety Study of KPT-330 in Erythropoietin-Refractory Lower-Risk Myelodysplastic Syndrome Patients

Inclusion Criteria: * Diagnosis of Low risk or Intermediate-1 risk MDS with any cytogenetic abnormalities (according to the IPSS criteria); patients must have bone marrow biopsy/aspiration or tumor tissue available from within 1 month prior to first dose or collected during the Screening period. * Patients \>18 years at Screening who are not candidates for hematopoietic cell transplantation. * Received 1 prior line of treatment; typically erythroid-stimulating agents (ESAs). * Red blood cell (RBC) transfusion-dependent anemia while treated with or after discontinuation of EPO. Transfusion dependence is defined as the requirement for at least 2 units of RBCs transfused during the 8 weeks prior to study initiation. Exclusion Criteria: * Use of recombinant EPO within 8 weeks prior to screening. * Patient has a concurrent active malignancy or prior history of malignancy other than MDS (except basal cell or squamous cell carcinoma of the skin and in situ of the cervix) unless free of disease for at least 1 year. * Unstable cardiovascular function: * Symptomatic ischemia, * Uncontrolled clinically significant conduction abnormalities (i.e., ventricular tachycardia on anti-arrhythmic agents are excluded; 1st degree atrioventricular (AV) block or asymptomatic Left anterior fascicular block/Right bundle branch block (LAFB/RBBB) will not be excluded), or * Congestive heart failure (CHF) New York Heart Association (NYHA) Class ≥3, or myocardial infarction (MI) within 3 months. * Uncontrolled infection requiring parenteral antibiotics, antivirals, or antifungals within 1 week prior to first dose. Infections controlled on concurrent anti-microbial agents are acceptable, and anti-microbial prophylaxis per institutional guidelines is acceptable. * Active bleeding Grade 3-4, in the last 4 weeks prior to enrollment.