Recombinant α-2a interferon (α-IFN) in the treatment of essential thrombocythaemia. Preliminary report

In a pilot study, recombinant α-2a interferon (α-IFN: Roferon A -Roche), administered s.c. at a daily dose of 3 x 106IU, was found to be remarkably effective in the treatment of essential thrombocythaemia (ET). In 6 patients eligible for evaluation (α-IFN induction therapy of 8-13 weeks) the platelet count (967 ± 171 x 109/1) fell to 50% of baseline value after 2.8 ± 0.3 weeks of treatment: the complete response (platelets ≤ 400 x 109/1) and the nadir value (platelets 246 ± 41 x 109/1) were reached after 3.9 ± 1.7 and 6.2 ± 2.6 weeks, respectively. The WBC count showed a similar decrease while the Hb level remained almost unchanged. In another patient with ET in blastic transformation, α-IFN, increased to 6 and 9 x 106 IU after 4 and 8 weeks respectively, was able to induce a complete response after 9 weeks α-IFN, given on alternate days at the dose utilized at the end of induction, appeared to be able to maintain a complete response in these patients.