[Alfa-2b interferon in the treatment of thrombocytosis associated to chronic non leukemic myeloproliferative syndromes].
BACKGROUND
The effect of interferons in the correction of thrombocytosis in chronic myeloproliferative syndromes is well known. In this study the efficacy of alpha-2b interferon in a regimen of induction followed by a phase of sequential maintenance to progressively decreasing doses was evaluated with the aim of knowing the minimum doses necessary to maintain response.


METHODS
The response to treatment with alpha-2b interferon was prospectively studied in a group of 37 patients with chronic myeloproliferative syndromes with associated thrombocytosis (excluding chronic myeloid leukemia). Likewise, the toxicity of the treatment was analyzed.


RESULTS
Sixty-seven percent of the patients responded (platelets lower than 600 x 10(9)/1) to the daily administration of 3 or 5 MU of interferon. Forty percent of the patients who responded to the daily schedule of administration maintained the response upon receiving 3 doses weekly for 4 months. Half of the 8 patients who received 2 weekly doses of interferon for 4 months continued maintaining the responses. Only two of the 4 patients who received one sole weekly dose during the following 4 months maintained the response. Only one of the 37 patients who initiated treatment underwent progression of the symptoms present at the beginning of the study. Toxicity was high and was the cause of 12 discontinuations of treatment (32% of the patients) during the daily treatment phase (9 patients) or during maintenance of 3 weekly doses (3 patients). No toxicity was observed in the schedule of one or two weekly doses.


CONCLUSIONS
Alpha-2b interferon is effective in the treatment of thrombocytosis of the chronic myeloproliferative syndromes (excluding chronic myeloid leukemia) when administered daily and is ever less so when the doses are spaced at 3, 2 or 1 week. The toxicity of interferon treatment is high when administered at affective doses.
Petit
J
J
Servicio de Hematología Clínica, Ciutat Sanitària, Universitària de Bellvitge-Hospital Duran i Reynals L'Hospitalet de Llobregat, Barcelona.
Callís
M
M
Domingo Albós
A
A
Fernández de Sevilla
A
A
Besses
C
C
Martí
J M
JM
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009196:Myeloproliferative Disorders / Q000150:complications / Q000628:therapy*; D011446:Prospective Studies; D011994:Recombinant Proteins; D013922:Thrombocytosis / Q000209:etiology / Q000628:therapy*
D000077190:Interferon alpha-2; D016898:Interferon-alpha; D011994:Recombinant Proteins
Interferón alfa-2b en el tratamiento de la trombocitosis asociada a síndromes mieloproliferativos crónicos no leucémicos.