Different antitumor mechanisms of interferon‐alpha in the treatment of hairy cell leukemia and renal cell cancer

Abstract

There is increasing evidence for the therapeutic effectiveness of Interferon‐α (IFN‐α) in malignant diseases. However, the antitumor mechanisms of IFN‐α are not known. Using two examples, hairy Cell leukemia (HCL) and renal cell cancer (RCC), it is shown that the requirements for successful IFN‐α therapy of HCL and RCC are different. In HCL low doses of IFN‐α are sufficient to treat the disease. The reduction of hairy cells in peripheral blood is detectable within the first week of treatment. The endogenous IFN‐α production in these patients is impaired as demonstrated by the lack of IFN‐α induction and by low levels of 2–5 oligoadenylate synthetase in peripheral blood mononuclear cells. A possible reason for deficient endogenous IFN‐α production is the lack of monocytes in HCL patients. It is likely that therapy with low doses of IFN‐α substitutes for the endogenous IFN‐α deficiency. In RCC comparatively high doses of IFN‐α are necessary for a clinical response. There may be differences between the effectiveness of natural and recombinant alpha interferons. High doses given within a week seem to be more important than high single doses, which therefore suggests the need of daily treatment. Responses of RCC to IFN‐α therapy are usually seen several months after the beginning of therapy. These differences in the effectiveness of IFN‐α therapy for HCL and RCC suggest that IFN‐α acts differently in the treatment of each disease. Copyright © 1988 American Cancer Society