Anagrelide Retard in Essential Thrombocythemia

Inclusion Criteria:

• willing and able to give written informed consent prior to any study specificprocedures and able to comply with the trial protocol

• confirmed diagnosis of ET according to 2008 WHO diagnostic criteria* (Swerdlow et al, 2008), defined as meeting all four criteria

• at high risk of experiencing ET-related events, indicated for Thromboreductin®treatment as defined by one or more of the following criteria: age ≥ 60 years,platelet counts ≥ 1000 G/L, increase of platelet count ≥ 300 G/L within 3 months,severe thrombohemorrhagic or ischemic symptoms in anamnesis

• either currently treated with anagrelide

• or ET treatment naive

• or anagrelide naive

Exclusion Criteria:

• Diagnosis of any myeloproliferative disorder other than ET

• Any known cause for a secondary thrombocytosis

• ET currently well controlled by another cytoreductive treatment than Anagrelide andthe opportunity to continue to receive this treatment

• ET currently treated with combination of any two of the following agents: anagrelide,hydroxyurea, interferons, busulfan

• Hypersensitivity to either active or non-active ingredients of anagrelide or to anyother excipients of the investigational products

• Known hereditary problems of galactose intolerance, the Lapp lactase deficiency orglucose-galactose malabsorption

• Cardiovascular disease grade 3 with a negative benefit/risk assessment or grade 4 (South West Oncology Group; Green and Weiss, 1992)

• Clinically significant abnormal laboratory values (excluding markers for ET) ininvestigator's opinion

• Severe renal insufficiency (creatinine clearance <30 ml/min)

• Moderate to severe hepatic insufficiency (ALT or AST > 5 times upper normal limit [UNL])

• White blood count (WBC) ≥ 15 G/L at screening

• Diagnosis of any malignancy, other than ET (except basal cell and squamous cellcarcinomas of the skin and carcinoma in situ of the cervix that have been completelyexcised and are considered cured), within the last 3 years, or coexisting malignant,systemic disease

• Poorly controlled diabetes mellitus

• Known infection with hepatitis B, hepatitis C or HIV

• Pregnant or lactating women

• Women of childbearing potential or male patients, who have sexual intercourse withfemales of childbearing potential, not willing to use an effective method ofcontraception during the study.

• History of drug/alcohol abuse within the previous 2 years

• Participation in another investigational study within 4 weeks prior to informedconsent signed or for a longer duration if specified in local regulations

• Any significant psychiatric disorder that, in the opinion of the investigator, mightprohibit the understanding and giving of informed consent, or that might prevent thepatient from completing the trial.