Efficacy trial of pipobroman in essential thrombocythemia: A study of 24 patients

Pipobroman (PB) was tested in a prospective efficacy trial in 24 previously untreated patients with essential thrombocythemia and followed up for a median of 47 months (range, 12-120). Plateletpheresis was not done. Hematologic complete response (platelet count <450 x 10⁹/L for 3 consecutive months) was achieved in 92% of the cases, in a median time of 12 weeks (range, 2-22). However, continuous low-dose maintenance therapy with PB was necessary to avoid recurrences of the disease. Major thrombocythemia-related complications were observed in 20% of the cases; the 5-year overall and complication-free survival rates were 92% and 75%, respectively. No acute or chronic toxicity was observed; no drug-induced amenorrhea and subsequent acute leukemia occurred. PB does appear to be efficacious in essential thrombocythemia; however, the evaluation of its leukemogenic risk will await further experience.