Anagre Cap. in Patients With High-Risk Essential Thrombocythemia

• Anagre Cap. (Drug): from 0.5mg twice a day to maximally increase total10mg in 8 weeks and maintain maximal tolerable dose to 104 weeks

Primary outcomes

• response rate for less than 60 X 10^4/ul in platelet count [at week 8]

Secondary outcomes

• response rate for less than 60 X 10^4/ul in platelet count [at week 52]
• changes from baseline in 50% reduction rate in platelet count [up to 52 weeks]
• response rate for less than 40 X 10^4/ul in platelet count [up to 52 weeks]
• cumulative incidence of essential thrombocythemia related events (e.g thromboembolic or hemorrhagic events) [at 52 week]
• incidence of adverse events [up to 52 weeks]

Other outcomes

• expression of MPN-oncogene(JAK2/CALR/MPL) [at 52 week]: association of known MPN-oncogene(JAK2/CALR/MPL) with epigenetic modifiers, mRNA splicing, oncogene and other minor somatic mutations
• genomic biomarker search for prediction of side effects of anagrelide [at 52 week]

Sex: All, ages: 19 Years to any

Inclusion Criteria:

* Patients with essential thrombocythemia according to WHO 2008
* Any of the following as high-risk patient

  * Over 60 years old
  * >100 X 10\^4/ul of platelet count
  * increased more than 300K of platelet count in 3 months
  * Hypertension, diabetes, past history of thromboembolic bleeding

Exclusion Criteria:

* Patients with an adverse drug reaction or intolerability to anagrelide
* Any of the following cardiac abnormalities;

  * Complete left bundle branch block on ECG
  * Patients using a pacemaker
  * Patients with a family history of congenital QT prolongation syndrome or known QT prolongation syndrome
  * Currently, there is no clinically uncontrolled ventricular or atrial tachycardia
  * Clinically significant bradycardia (<less than 50 per minute)
  * History of clinically proven myocardial infarction and unstable angina within 3 months
* Pregnant women, nursing mothers