Abstract
BACKGROUND.
Interferon‐alpha (IFN‐α) has shown significant activity in the treatment of BCR‐ABL–negative myeloproliferative disorders (MPDs), particularly essential thrombocythemia (ET) and polycythemia vera (PV). PEG‐IFN‐α‐2b is a pegylated IFN‐α‐2b with a significant advantage over nonpegylated form in that it is administered once a week.
METHODS.
Thirty‐eight patients with BCR‐ABL–negative MPDs were treated with PEG‐IFN‐α‐2b, given subcutaneously weekly, at the starting dose of 3 μg/kg/wk for the first 14 patients and then 2 μg/kg/wk for the next 24 patients, with intent to treat patients as long as they benefited from the therapy.
RESULTS.
Median age was 54 years. Patient diagnoses were: 13 (34%) ET; 11 (29%) primary myelofibrosis (PMF); 5 (13%) BCR‐ABL–negative chronic myeloid leukemia (CML); 4 (10.5%) hypereosinophilic syndrome (HES); 4 (10.5%) PV; and 1 (3%) unclassified myeloproliferative disease (uMPD). Recorded grade 3–4 toxicities were related to fatigue, myelosuppression, and musculoskeletal pain. Ten (26%) patients stopped treatment because of toxicity. Thirteen (34%) patients achieved a complete remission, and 4 (11%) achieved a partial response. Only 1 patient with PMF responded. Median time to response was 5 months. Median duration of response was 20 months. Three patients had a sustained response for >24 months.
CONCLUSIONS.
PEG‐IFN‐α‐2b, with proper dose modifications, is effective in controlling disease in a significant proportion of BCR‐ABL–negative MPD patients, particularly ET and PV. However, toxicities encountered with PEG‐IFN‐α‐2b therapy are similar to those obtained with conventional IFN‐α, thus limiting the duration of therapy. Cancer 2007. © 2007 American Cancer Society.