Clinical Trial of Aplidin® in Patients With Primary Myelofibrosis

Inclusion Criteria: 1. Diagnosis of Primary Myelofibrosis (PMF) or Post Polycythemia Vera/Essential Thrombocythemia Myelofibrosis(post-ET/PV MF) as per revised World Health Organization (WHO) criteria. 2. High-risk or intermediate-2 risk Myelofibrosis (MF) as defined by the International Prognostic Scoring System (IPSS); or intermediate-I risk MF associated with symptomatic splenomegaly/hepatomegaly and/or unresponsive to available therapy. 3. At least 18 years of age, with life expectancy of ≥12 weeks. 4. Able to provide informed consent and being willing to sign an informed consent form (ICF). 5. Eastern Cooperative Oncology Group (ECOG) performance status ≤2. 6. Evidence of acceptable organ function within seven days of initiating study drug Exclusion Criteria: 1. Previous treatment with plitidepsin. 2. Any of the following therapies within two weeks prior to initiation of study drug: * chemotherapy (e.g., hydroxyurea), * immunomodulatory drug therapy (e.g., thalidomide), * immunosuppressive therapy, * corticosteroids \>10 mg/day prednisone or equivalent, or * erythropoietin. 3. Incomplete recovery from major surgery within four weeks of study entry. 4. Radiation therapy within four weeks of study entry. 5. Women of childbearing potential 6. Women who are pregnant or are currently breastfeeding. 7. Myopathy grade \> 2 8. Known positive status for human immunodeficiency virus (HIV). 9. Active hepatitis B or C virus (HBV or HCV) infection 10. Diagnosis of another invasive malignancy 11. Any acute active infection. 12. Known hypersensitivity to the study drug or any of its formulation components (e.g., Cremophor®). 13. Treatment with any investigational product in the 30 days before inclusion in the study.