Experimental studies on the combined effects of alpha and gamma interferons against human tumor xenografts transplanted into nude mice.

The antitumor activities, resulting from the combined treatment of leukocyte interferon (IFN-alpha), with recombinant human immune interferon (IFN-gamma), against human tumor xenografts in nude mice, were studied. Nine human tumor xenografts, (7 from gastric carcinoma, 1 from gallbladder carcinoma and 1 from breast carcinoma), were serially transplanted into nude mice for the purpose of this experiment. Each human tumor xenograft was inoculated subcutaneously into BALB/c nu/nu nude mice and treatment was started after the estimated tumor had reached 100-300 mg. IFN was administered intramuscularly at a schedule of qd X 14. Treatment with either IFN-alpha or IFN-gamma alone, did not produce any antitumor effect against the various human tumor xenografts, however the combination of IFN-alpha with IFN-gamma resulted in achieving significant antitumor effects against the various human tumors. Inhibition of tumor growth was observed in 7 of the 9 tumors (77.8 per cent), and regression of the tumor was noted in 5 of the 9 tumors (55.6 per cent).