Effectiveness of mouse interferon alpha/beta compared to single-agent chemotherapy in increasing survival time of mice after intravenous inoculation of Friend erythroleukemia cells.

DBA/2 mice received an iv injection of 2 X 10(6) Friend erythroleukemia cells (FLCs; approximately equal to 4 X 10(5) lethal dose50), which multiplied rapidly in the liver and spleen and killed all untreated or control treated mice between 7 and 12 days. Daily interferon (IFN) treatment resulted in a very marked increase in survival time and apparent cure of 4 of 22 tumor-inoculated mice. In contrast, treatment of tumor-injected (iv) mice with cyclophosphamide, 5-fluorouracil, and methotrexate increased survival time by only a few days; and treatment of mice with cisplatin, vincristine, doxorubicin, bleomycin, or etoposide was ineffective. However, when FLCs were injected ip, both cytostatic drugs and IFN exerted an antitumor effect. We conclude that IFN alpha/beta was particularly effective in inhibiting the development of liver and spleen metastases and in increasing mouse survival time after iv inoculation of FLCs.