Antitumor effect of human recombinant interferon-gamma and -beta against human osteosarcoma transplanted into nude...

The antitumor activity of recombinant human interferon-gamma (ReIFN-gamma) and recombinant human interferon-beta (ReIFN-beta) against human osteosarcoma G-292 cells was compared in vitro and in vivo. Both IFNs inhibited the growth of G-292 cells cultured in vitro and transplanted into nude mice in vivo. In in vivo experiment, both IFNs injected i.t. were more effective at inhibiting the growth of G-292 cells than systemic administration such as i.v., i.p. or s.c. In comparing the various routes of systemic administration of both IFNs, i.v. injection was slightly more effective. Both IFNs exhibited more significant growth inhibition when they were administered every day for 10 d, as compared with a single or intermittent administrations, suggesting that the antitumor activity of both IFNs was time-dependent. Significant difference was not detected in the in vivo antitumor activity between both IFNs when they were compared on the basis of their antiviral units. However, the time dependency for antitumor effect of ReIFN-beta was more significant than that of ReIFN-gamma. ReIFN-gamma and ReIFN-beta used in combination exhibited synergistic antitumor activity both in vitro and in vivo, though the in vivo synergism of both IFNs was not so effective as that of in vitro: These results indicate that both ReIFN-gamma and ReIFN-beta are effective at inhibiting the growth of human osteosarcoma in vivo.