ALPHA-INTERFERON AS INITIAL TREATMENT OF ESSENTIAL THROMBOCYTHEMIA - ANALYSIS AFTER 2 YEARS OF FOLLOW-UP

Aims and background: Recombinant alpha-interferon has been shown to be effective in essential thrombocythemia and in thrombocytosis associat ed with other myeloproliferative disorders, Patients and methods: Twen ty-five untreated patients were enrolled in our study from May 1989 to April 1992. Recombinant alpha interferon-ab was administered at an in itial dose of 2 megaunits (MU)/m(2) three times a week at escalating d oses to 5 MU/m(2) or the maximum tolerated dose. The mean follow-up fo r patients still in treatment at the time of this report was 35.9 mont hs (range, 24-63). Results: Fourteen patients (56%) had achieved a com plete remission by a mean time of 152 days; 6 patients (24%) had achie ved a good partial remission by a mean of 180 days, In addition to the favorable effect on platelet count, a marked improvement in clinical symptoms was observed. Treatment had to be discontinued in 9 patients (36%), 5 for toxicity (3 neurologic, 1 anemia and 1 severe hypertrigly ceridemia) at a median of 155 days from the beginning of therapy (rang e, 39-400). Four patients refused to continue therapy because of low t olerance (flu-like syndrome) at mean of 160 days from the beginning of therapy (range, 34-301). Conclusions: In our study, lower doses were administered compared with previous short-time trials. The present dat a show that interferon is an effective alternative to cytostatic agent s In long-term treatment of patients with essential thrombocythemia, e ven when used at lower dosages.