From the Guidelines
The management of essential thrombocythemia (ET) should focus on preventing thrombotic complications while minimizing bleeding risks, with hydroxyurea as the first-line cytoreductive therapy for high-risk patients, as recommended by the European LeukemiaNet guidelines 1. The approach to managing ET involves assessing the patient's risk category, with low-risk patients (age <60 years, no history of thrombosis, platelet count <1,500,000/μL) often requiring only observation with aspirin 81-100 mg daily, while high-risk patients (age ≥60 years, history of thrombosis, or extreme thrombocytosis) necessitate cytoreductive therapy. Key considerations in the management of ET include:
- Monitoring for new thrombosis, acquired von Willebrand disease, and/or disease-related major bleeding, as outlined in the NCCN guidelines 1
- Managing cardiovascular risk factors, such as hypertension, diabetes, and hyperlipidemia
- Using aspirin (81–100 mg/d) for vascular symptoms, as recommended by the NCCN guidelines 1
- Initiating cytoreductive therapy with hydroxyurea, which has been shown to be effective in reducing the risk of thrombotic complications, as demonstrated in the UK-PT1 trial 1
- Considering alternative cytoreductive agents, such as anagrelide or interferon-alpha, for patients who are intolerant to hydroxyurea or have contraindications to its use, as recommended by the European LeukemiaNet guidelines 1
- Regular monitoring of complete blood counts, platelet counts, and cardiovascular risk factors to assess treatment efficacy and adjust therapy as needed. The goal of treatment is to balance thrombosis prevention with minimizing treatment-related complications, as ET is a chronic condition with generally good prognosis but requires lifelong management, as emphasized by the European LeukemiaNet guidelines 1.
From the FDA Drug Label
Patients were treated with anagrelide starting at doses of 0.5 mg to 2.0 mg every 6 hours. The dose was increased if the platelet count was still high, but to no more than 12 mg each day. Efficacy was defined as reduction of platelet count to or near physiologic levels (150,000/μL to 400,000/μL). The criteria for defining subjects as “responders” were reduction in platelets for at least 4 weeks to ≤600,000/μL, or by at least 50% from baseline value Anagrelide was effective in phlebotomized patients as well as in patients treated with other concomitant therapies including hydroxyurea, aspirin, interferon, radioactive phosphorus, and alkylating agents
The management of essential thrombocythemia includes:
- Platelet reduction: using anagrelide to reduce platelet count to or near physiologic levels (150,000/μL to 400,000/μL) 2
- Dosing: starting at 0.5 mg to 2.0 mg every 6 hours, increasing as needed to a maximum of 12 mg per day
- Concomitant therapies: anagrelide can be used with other therapies such as hydroxyurea, aspirin, interferon, radioactive phosphorus, and alkylating agents 2
- Response criteria: reduction in platelets for at least 4 weeks to ≤600,000/μL, or by at least 50% from baseline value 2
From the Research
Management of Essential Thrombocythemia
The management of essential thrombocythemia (ET) involves a comprehensive plan to prevent thrombosis and bleeding, while minimizing the risk of disease transformation.
- The use of low-dose aspirin (81-100 mg/day) is recommended for most patients with ET to lower the risk of thrombosis 3, 4.
- Aspirin therapy should be individualized based on the patient's risk factors, with twice daily administration considered for patients with high platelet counts or those who do not respond to once daily therapy 3.
- Cytoreductive therapy, such as hydroxyurea, is recommended for high-risk patients, including those with a history of thrombosis, age older than 60 years, or cardiovascular risk factors 4, 5, 6.
- Interferon alpha or anagrelide may be considered as alternative or second-line therapies for patients who are resistant or intolerant to hydroxyurea 5, 6.
- Strict control of coexistent cardiovascular risk factors is mandatory for all patients with ET 6.
Risk Stratification
Patients with ET should be stratified according to their risk of thrombosis and bleeding, with the following factors considered:
- Age older than 60 years 4, 5, 6
- History of thrombosis 4, 5, 6
- Cardiovascular risk factors (e.g., hypertension, diabetes mellitus, hyperlipidemias, tobacco use) 4
- JAK2 gene variant 4
- Platelet count > 1500 × 10(9)/L 6
- Leukocytosis 5
Special Considerations
- Pregnancy: low-risk women should receive low-dose aspirin throughout pregnancy and prophylactic low-molecular-weight heparin postpartum, while high-risk cases may require low-molecular-weight heparin throughout pregnancy and/or interferon alpha 5.
- Disease transformation: patients with ET are at risk of transforming to myelofibrosis or acute leukemia, particularly with certain therapies 7, 6.