Antitumor effect of human fibroblast interferon on the growth of human melanoma cells implanted in nude mice.

The antitumor effect of human fibroblast interferon (HuIFN-beta) on the growth of human melanoma cells (HMV-1) in vitro and in vivo was examined. In in vitro experiments, HMV-1 cells were highly sensitive to HuIFN-beta compared to other human cells. The cell growth in nude mice was also suppressed by daily administration of HuIFN-beta, depending on the dosage and administration route. The most prominent effect was obtained by intratumoral injection and a lesser therapeutic effect was achieved by subcutaneous injection around the inoculated tumor. Intraperitoneal injection of HuIFN-beta was unsuccessful. Pharmacokinetic studies of HuIFN-beta in nude mouse indicated that the three administration routes gave similar blood plasma levels and decline curves, suggesting that there is no correlation between the plasma HuIFN-beta level and the therapeutic efficacy. However, a relatively high interferon titer was detected for a long time after intratumoral injection of HuIFN-beta. Because of the species specificity of interferon and the use of the nude mouse system lacking T-cell function, the antitumor effect observed in the present study might reflect an anticellular activity of HuIFN-beta retained in the tumor region.