A prospective randomized comparison of single‐agent interferon (IFN)‐alpha with the combination of IFN‐alpha and low‐dose IFN‐gamma in chronic myelogenous leukaemia

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Abstract
In patients with previously untreated chronic myelogenous leukaemia (CML) the efficacy of single-agent interferon (IFN)-alpha at an initial dose of 4 x 10(6) U/m2 (arm A) was compared with the combined administration of the identical dose IFN-alpha plus a total dose of 50 micrograms IFN-gamma (arm B). 51 patients entered this study between April 1987 and October 1989; the analysis was performed in March 1991 and was focused on response rates and toxicity. 54% of patients on arm A and 56% of arm B patients attained haematologic remission. 29% of patients on arm A and 24% of arm B patients had partial haematologic remission. A decrease in Philadelphia chromosome (Ph)-positive metaphases of more than 10% was only seen in patients who had achieved complete haematologic normalization. In 21% of patients on arm A and 20% of arm B patients, the percentage of Ph-positive cells declined to less than 35%. Toxicity was different between the two study groups with more pronounced hepatotoxicity observed in patients treated with IFN-alpha alone. Among the patients receiving both IFNs, alpha and gamma, there were 2 fatal infectious complications. This serious toxicity in conjunction with lack of a clinically meaningful difference between the two treatment schedules has led us to terminate the study. In conclusion, the addition of low-dose IFN-gamma failed to improve the efficacy of IFN-alpha in this study.