Effects of human fibroblast interferon on human tumors transplanted into nude mice: sensitivity of human tumors to interferon.

The antitumor effect of human fibroblast interferon (HuIFN-beta) was examined using a nude mouse-human tumor xenograft group. Eight subcutaneously transplanted tumors--one line each of ovarian carcinoma, laryngeal carcinoma, carcinoma of the nasopharynx and hepatoma, and two lines each of lung carcinoma and melanoma--were used. HuIFN-beta at 1 X 10(5) IU/mouse was injected subcutaneously around the tumor or into the tumor itself. In the former case, statistically significant growth-suppressive effects were observed in one lung carcinoma (PC-12) and both melanomas (AM-1 and SK-14), but no effect was seen on the other five tumors. Further studies were made to ascertain the effects of intratumoral injections. Increased growth inhibition was observed in both melanomas (AM-1 and SK-14), but not in lung cancer (PC-12). Complete regression was seen in 3 of 8 mice carrying SK-14. The sensitivity of tumors to HuIFN-beta was correlated to the inhibitory effect of HuIFN-beta on cell division detected by histological observation.