Clinical studies of natural interferon alpha (HLBI) in chronic myelogenous leukemia--a multi-institutional cooperative study in Japan]

Clinical trials of natural interferon-alpha (HLBI) in the treatment of Philadelphia chromosome (Ph1) positive chronic myelogenous leukemia (CML) were carried out in a cooperative study of 22 institutions in Japan. Patients with CML in chronic and accelerated phase were given intramuscular or subcutaneous injections of HLBI at the dose of 6 X 10(6) U/body on consecutive days. Of the 47 patients in this study, forty-one were evaluable for clinical effects, and 42 could be assessed for adverse effects. Among 30 evaluable patients in the chronic phase, 9 (30.0%) achieved complete remission (CR) and 20 (66.7%) partial remission (PR). Only one patient had no response (NR), and the response rate (CR + PR) in chronic phase was 96.7% (29/30). Among 11 patients in the accelerated phase, 3 (27.3%) achieved CR and 4 (36.4%) PR. The response rate in the accelerated phase was 63.6% (7/11). In all 41 evaluable patients, the response rate was 87.8% (36/41). In 5 of 13 responding patients treated for more than 6 months, cytogenetic investigation showed the decline of Ph1 positive bone marrow cells from 100% to 92-0% (mean 46%). Adverse effects such as fever (52.4%), general fatigue (35.7%), and liver dysfunction (21.4%), were observed, but they were usually mild and reversible. No patient was taken off this study because of these toxicities. The results confirm the clinical efficacy of HLBI in patients with CML in the chronic and accelerated phase.