Refractory ET Cytoreduction — RACP Adult Medicine MCQ

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ModerateHaematologyRefractory ET CytoreductionRACP Adult Medicine

A 60-year-old man with known essential thrombocythaemia (JAK2 V617F positive) on hydroxyurea develops a platelet count of 1,500 × 10⁹/L despite maximal tolerated hydroxyurea dose. He is at high risk of thrombosis (age >60). What additional cytoreductive agent should be considered?

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Correct answer: C — Anagrelide (added to hydroxyurea or as alternative)

For ET patients with inadequate response to hydroxyurea (persistent thrombocytosis, intolerance, or toxicity), anagrelide is the standard second-line cytoreductive agent. It specifically inhibits megakaryocyte maturation and platelet release. The PT-1 trial compared anagrelide + aspirin vs hydroxyurea + aspirin for high-risk ET. Anagrelide can be added to hydroxyurea or used as a substitute. Interferon-alpha (pegylated) is an alternative, particularly for younger patients or those planning pregnancy. Ruxolitinib is used primarily for PV and MF, not ET (though data are emerging). Low-dose aspirin should continue.

Reference: eTG – 2025 – Haematology; EHA – 2022 – MPN Guidelines