Interferon alpha therapy for patients with essential thrombocythemia: final results of a phase II study initiated in 1986.
BACKGROUND
In 1986, a Phase II trial of recombinant interferon-alpha (IFN-alpha) was initiated as therapy for patients with essential thrombocythemia (ET).


METHODS
Patients were treated with subcutaneous IFN-alpha at a dose of 5 x 10(6) units/m(2) 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 x 10(9)/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-alpha achieved a second response. The treatment was tolerated relatively well.


CONCLUSIONS
IFN-alpha was safe and effective therapy for patients with ET, and the ability of IFN-alpha to reverse disease pathology and possibly modify the clinical course of patients with ET warrants its investigation in larger, prospective trials.
Saba
Rashid
R
Department of Leukemia, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Jabbour
Elias
E
Giles
Francis
F
Cortes
Jorge
J
Talpaz
Moshe
M
O'Brien
Susan
S
Freireich
Emil J
EJ
Garcia-Manero
Guillermo
G
Kantarjian
Hagop
H
Verstovsek
Srdan
S
D000328:Adult; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D007370:Interferon Type I / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011994:Recombinant Proteins; D012074:Remission Induction; D013922:Thrombocytosis / Q000188:drug therapy*
D000970:Antineoplastic Agents; D007370:Interferon Type I; D011994:Recombinant Proteins