Interferon alfa-2b in acute- and chronic-phase chronic myelogenous leukaemia: initial response and long-term results in 54 patients.

Fifty-four patients with Ph1-positive chronic myelogenous leukaemia (CML) (48 with chronic-phase and six acute-phase disease) were treated with interferon alfa-2b subcutaneously (s.c.). The starting dose was 4 million units (MU)/m2 body surface area daily. It was reduced in parallel with serially determined leucocyte counts, and minimal effective doses were given as maintenance after achieving remission. Haematological remissions were induced in 22 of the 48 patients (46%) with chronic-phase disease. Thirteen patients (27%) revealed partial haematological remission and another 13 no response to treatment. No complete remission could be induced, although minor or partial cytogenetic responses were seen in 16 patients (33%). Moreover, a bcr-abl reduction was detected on Southern blot analysis in two patients. In chronic-phase disease, results of treatment were influenced by elapsed time after diagnosis, extent of previous treatment and interferon dosage. No beneficial effects of interferon were detected in the six patients with acute-phase disease. Principal acute side effects were fever and flu-like symptoms at the beginning of the therapy, which usually subsided within 3-7 days. Chronic side effects, especially weakness and neuropathy, were less frequent but more severe and necessitated discontinuation of treatment in 10 patients. In summary, interferon alfa-2b seems to be an effective treatment in early chronic-phase CML. Long-term effects on the course of the disease, however, must be determined.