Interferon α therapy for patients with essential thrombocythemia

• Published in: Cancer 2005-06, Vol.103 (12), p.2551-2557
• Main Authors: Saba, Rashid, Jabbour, Elias, Giles, Francis, Cortes, Jorge, Talpaz, Moshe, O'Brien, Susan, Freireich, Emil J., Garcia‐Manero, Guillermo, Kantarjian, Hagop, Verstovsek, Srdan
• Format: Article
• Language: English
• Subjects: anagrelide; complete hematologic response; essential thrombocythemia; hydroxyurea; pegylated interferon α; response duration
• ISSN: 0008-543X; 1097-0142
• DOI: 10.1002/cncr.21086

BACKGROUND In 1986, a Phase II trial of recombinant interferon‐α (IFN‐α) was initiated as therapy for patients with essential thrombocythemia (ET). METHODS Patients were treated with subcutaneous IFN‐α at a dose of 5 × 106 units/m2 daily. In responding patients, the therapy lasted at least 3 years. RESULTS Twenty‐three patients (14 females and 9 males; median age, 41 years; age range, 20–63 years) with a median platelet count of 1350 × 109/L were treated. After a median follow‐up of 174 months (14.5 years), 15 of 20 evaluable patients (75%) responded, including 14 patients who achieved a complete hematologic response (CHR) (6 of them with bone marrow remission) and 1 patient who demonstrated a partial response. The median time to response was 6 months (range, 0.5–36 months), and the median response duration was 48 months (range, 5–114 months). Seven patients who achieved a CHR and were taken off therapy after they completed 3 years of maintenance therapy sustained their response for a median of 28 months. No symptoms or signs of thrombosis or hemorrhage were observed in responding patients. Eleven of 14 patients (78%) who achieved a CHR developed a recurrence, and 2 of 5 patients with recurrences who were rechallenged with IFN‐α achieved a second response. The treatment was tolerated relatively well. CONCLUSIONS IFN‐α was safe and effective therapy for patients with ET, and the ability of IFN‐α to reverse disease pathology and possibly modify the clinical course of patients with ET warrants its investigation in larger, prospective trials. Cancer 2005. © 2005 American Cancer Society. The results of this Phase II study reinforced the findings of other investigations who evaluated the role of interferon‐α (IFN‐α) for the treatment of essential thrombocythemia (ET). The apparent ability of IFN‐α to reverse disease pathology and possibly modify the clinical course of patients with ET warrants its investigation in larger, prospective trials.