Inclusion Criteria:

Both female and male patients meeting the mentioned inclusion and exclusion criteria will
be included in this clinical trial. The risk to get PMF or SMF does not depend on a
patient's gender. Patients must meet all of the following inclusion criteria to be
eligible for enrollment into the study:

1. Age ≥50 years at the time of voluntarily signing an IRB/IEC-approved informed consent

2. Diagnosis of Myeloproliferative Neoplasms (MPN) either de novo myelofibrosis
according to WHO criteria (PMF) [20], secondary myelofibrosis (post-PV MF and post-ET
MF according to the IWG-MRT consensus terminology) [21] or unclassifiable MPN with
biopsy proven myelofibrosis

3. Anemia with hemoglobin level of <10 g/dl or transfusion-dependent anemia and/or
thrombocytopenia <50 /nl or transfusion-dependent thrombocytopenia and/or neutropenia
<1.0 /nl

4. Splenomegaly (>11 cm diameter) and/or leukoerythroblastosis

5. Adequate organ function, i.e. ALT and/or AST <3 x upper limit of normal (ULN), total
bilirubin <3 x ULN, and serum creatinine <2 mg/dl

6. Subject must be willing to receive transfusion of blood products

7. ECOG performance status < 3

8. Female subjects with non-childbearing potential:

- Agree to have a pregnancy test at baseline

9. Male subjects:

- Agree to use condoms throughout study drug therapy, during any dose interruption
and for four weeks after cessation of study therapy if their partner is of
childbearing potential and has no contraception.

- Agree not to donate semen during study drug therapy and for four weeks after end
of study drug therapy.

10. All Subjects:

- Will be counseled about potential teratogenic risks of the study medication.

- Agree to abstain from donating blood while taking study drug therapy and for one
week following discontinuation of study drug therapy.

- Agree not to share study medication with another person and to return all unused
study drug to the investigator

- No more than a 12-weeks-supply of study drug will be dispensed at a time.

Exclusion Criteria:

The presence of any of the following will exclude a patient from study enrollment:

1. Females of childbearing potentials°, pregnant or breast feeding females

2. BCR/ABL-positivity

3. Diagnosis of ET (according to WHO 2008 criteria)

4. Diagnosis of PV (according to WHO 2008 criteria)

5. >20% blasts in peripheral blood or bone marrow

6. Known positive status for HIV, HBV or HCV

7. Prior treatment with IMiDs (thalidomide, lenalidomide) or with Interferon-alpha
within a 3 month time period before screening

8. History of thrombosis or pulmonary embolism

9. Peripheral neuropathy >grade 1 CTC

10. No consent for registration, storage and processing of the individual
disease-characteristics and course as well as information of the family physician
about study participation.

11. Presence of any medical/psychiatric condition or laboratory abnormalities which may
limit full compliance with the study, increase the risk associated with study
participation or study drug administration, or may interfere with the interpretation
of study results and, in the judgment of the Investigator, would make the patient
inappropriate for entry into this study

12. Drug or alcohol abuse within the last 6 months

13. Patients with a "currently active" second malignancy other than nonmelanoma skin
cancers. Patients are not considered to have a "currently active" malignancy if they
have completed therapy and are considered by their physician to be at less than 30%
risk of relapse within one year.

Criteria for women of non-childbearing potential:

A female patient or a female partner of a male patient is considered to have childbearing
potential unless she meets at least one of the following criteria:

- Age ≥ 50 years and naturally amenorrhoeic for ≥ 1 year. Amenorrhoea following cancer
therapy does not rule out childbearing potential

- Premature ovarian failure confirmed by a specialist gynecologist

- Previous bilateral salpingo-oophorectomy, or hysterectomy

- XY genotype, Turner syndrome, uterine agenesis