This protocol targets patients aged 60 years or younger with essential thrombocythemia who have no history of thrombosis, test JAK2 wild-type, and present with cardiovascular risk factors, a CALR-1 mutation, or an MPL mutation — in whom once-daily low-dose aspirin has not adequately alleviated vasomotor (microvascular) disturbances.
ET thrombosis risk is stratified into four tiers — very low, low, intermediate, and high — based on age, thrombosis history, and driver mutation status. Patients aged ≤60 years with no thrombosis history and JAK2 wild-type status occupy the very low-risk tier. Within this group, the presence of cardiovascular risk factors, a CALR-1 mutation, or an MPL mutation identifies those in whom antiplatelet therapy is warranted.
The preceding step for this population is once-daily low-dose aspirin. This protocol is indicated when that approach has not met its primary goal: alleviation of vasomotor (microvascular) disturbances. The structured options below represent the next clinical step after once-daily aspirin has proven insufficient.
DOI: 10.1002/ajh.27216
Figure 5 outlines our general treatment approach in ET, which starts with thrombosis risk stratification: very low (age ≤60 years, no thrombosis history, JAK2 wild-type), low (same as very low but JAK2 mutation present), intermediate (age >60 years, no thrombosis history, JAK2 wild-type), and high (thrombosis history present or age >60 years with JAK2 mutation).
Thrombosis risk in very low risk patients with triple-negative driver mutational status is too low to warrant the need for any form of therapy, but once-daily aspirin therapy is advised in the presence of either CV risk factors or CALR-1/MPL mutations.
In the presence of aspirin-resistant symptoms, it is reasonable to utilize a twice-daily rather than once-daily regimen of low-dose aspirin or alternative antiplatelet agents such as clopidogrel (75 mg/day) alone or in combination with aspirin, as long as patients are monitored closely for drug side effects.
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