Treatment of Essential Thrombocythemia with a Telomerase Inhibitor

Patients with essential thrombocythemia (ET) are at risk for vascular events and transformation to myelofibrosis or leukemia. Cytoreduction in symptomatic patients is usually achieved with hydroxyurea, anagrelide, or interferon, but there are few options for those who are refractory or have unacceptable adverse effects with these agents. Recently, the megakaryocyte telomerase enzyme from patients with ET was found to be more sensitive to inhibition than the enzyme from healthy individuals.

Now, investigators have conducted an industry-funded, phase II, open-label study to examine the clinical activity of the telomerase inhibitor imetelstat in 18 symptomatic patients with poorly controlled ET. The drug was given intravenously once weekly in d…