Antitumor effect of systemic administration of novel recombinant tumor necrosis factor (rTNF-S) with less toxicity than conventional rTNF-alpha in vivo.

This study reported that acute toxicity (expressed as the LD50 value) of rTNF-SAM1 and rTNF-SAM2 which we constructed was considerably lower than that of rTNF-alpha (1). Following this finding, the antitumor effects of systemic administration of these novel recombinant tumor necrosis factors (TNF-S) (named rTNF-SAM1 and rTNF-SAM2) were examined in vivo on murine tumors (Meth A fibrosarcoma, MH134 hepatoma, and B16 melanoma). Both rTNF-SAM1 and rTNF-SAM2 could be administered systemically to tumor-bearing mice at doses up to 3 X 10(4) to 10(5) U. Growth of all tumors was significantly inhibited by systemic administration of rTNF-SAM1 or rTNF-SAM2 at a dose of greater than 3 X 10(4) U; at this dosage conventional rTNF-alpha could not be administered systemically to any of the mice strains due to its toxicity. These results confirm our previous finding that the rTNF-SAM group can be administered with safety at higher doses than rTNF-alpha, and revealed that these novel rTNF-S could be more promising antitumor drugs than rTNF-alpha in view of their lower toxicity compared with antitumor effect.