From the Guidelines
Hydroxyurea is the first-line cytoreductive therapy for essential thrombocytosis (ET) patients who are at high risk for thrombotic complications. The typical starting dose is 500-1000 mg daily, with dose adjustments made to achieve a target platelet count below 400,000/μL while maintaining white blood cell counts above 2,500/μL and without causing significant anemia, as recommended by the European LeukemiaNet guidelines 1.
Key Considerations
- Treatment is typically long-term or indefinite for high-risk patients, with regular monitoring of complete blood counts every 2-4 weeks initially, then every 3-6 months once stable 1.
- High-risk features that warrant hydroxyurea treatment include age over 60, history of thrombosis, platelet count over 1,500,000/μL, and cardiovascular risk factors.
- For patients who fail hydroxyurea or experience intolerable side effects, alternatives include interferon-alpha, anagrelide, or busulfan, with pegylated interferon alpha-2a showing promise in inducing durable hematological and molecular responses in patients with ET 1.
- Regular monitoring for potential transformation to myelofibrosis or acute leukemia is also important during follow-up, as the presence of additional mutations (TET2, ASXL1, IDH2, and TP53) can be associated with poorer molecular response 1.
Side Effects and Monitoring
- Common side effects of hydroxyurea include cytopenias, gastrointestinal symptoms, skin ulcers, and hyperpigmentation.
- Patients should be closely monitored for these side effects, and dose adjustments made as necessary to minimize their impact.
- The use of low-dose acetyl salicylic acid in combination with cytoreductive therapy may also be beneficial in preventing vascular events in ET patients, particularly those with cardiovascular risk factors or a history of thrombosis 1.
From the Research
Hydroxyurea for Essential Thrombocytosis
- Hydroxyurea is a commonly used treatment for essential thrombocytosis, a Philadelphia chromosome-negative chronic myeloproliferative neoplasia characterized by a risk of bleeding and thromboembolic complications 2.
- The treatment aims to lower the incidence of bleeding/thrombotic episodes in patients with essential thrombocythemia, and hydroxyurea is often used as a first-line treatment 3, 4, 5.
- Studies have shown that hydroxyurea can reduce the risk of thrombotic events and improve overall survival in patients with essential thrombocythemia 3, 4.
- However, some patients may develop resistance or intolerance to hydroxyurea, and alternative treatments such as anagrelide or interferon-alpha may be used 2, 5, 6.
- The choice of treatment depends on the patient's risk category, with high-risk patients typically requiring more aggressive treatment 5.
- Hydroxyurea has been shown to be effective in reducing platelet counts and preventing thrombotic events, but its use must be carefully monitored due to potential side effects 2, 3, 4.
Treatment Outcomes
- Complete hematological response (CHR) to hydroxyurea has been associated with better outcomes, including reduced risk of arterial thrombosis and improved survival 3.
- Resistance or intolerance to hydroxyurea has been linked to a higher risk of myelofibrosis, but its impact on survival and thrombotic risk is less clear 3, 6.
- Anagrelide, a second-line treatment option, has been shown to be effective in reducing platelet counts and preventing thrombotic events in patients who are intolerant or resistant to hydroxyurea 2, 6.
Patient Management
- Patients with essential thrombocythemia should be carefully monitored and managed to minimize the risk of thrombotic events and bleeding complications 5.
- Treatment decisions should be based on individual patient risk factors, including age, prior thrombosis, and cardiovascular risk factors 5.
- Hydroxyurea remains a key treatment option for patients with essential thrombocythemia, but alternative treatments may be necessary for patients who develop resistance or intolerance 6.