Studies on the anti-tumor efficacy of systemically administered recombinant tumor necrosis factor against several murine tumors in vivo

The anti-tumor activity of recombinant human tumor necrosis factor (rHTNF) was examined against four newly induced murine sarcomas (MCA-101, -102, -105, and -106) and a murine adenocarcinoma (MCA-38) transplanted s.c. into C57BL/6 mice. The serum half-life after a single i.v. injection of rHTNF was determined to be 30 ± 2 min. Tumor-bearing mice were more susceptible to the toxic side effects of rHTNF than were normal mice. Forty-eight percent (41/86) of the tumor bearing animals that received 10 μg rHTNF died within 48 hr after treatment compared with no deaths in 28 normal animals receiving this dose. Treatment of mice bearing either the MCA-101, -102, -105, or -106 sarcoma or the MCA-38 adenocarcinoma with rHTNF resulted in a marked necrosis of the central portion of each tumor within 24 hr. Animals bearing the weakly immunogenic tumors MCA-105, -106, and -38 experienced a reduction in average tumor area of 47% ± 5, 46% ± 6, and 37% ± 11, respectively, by 3 to 4 days after treatment with rHTNF compared with pre-treatment values (p < 0.001); increases of 79% ± 11, 74% ± 10, and 41% ± 6 were seen in excipient-treated control animals over the same period. In contrast, animals bearing the non-immunogenic tumors MCA-101 and -102 experienced little if any decrease in tumor area at the doses of rHTNF used. rHTNF failed to mediate cures in animals bearing MCA-38, -101, or -102. In contrast, 67 and 28% of animals bearing MCA-105 and -106, respectively, which received 6 to 10 μg rHTNF were cured. Likewise, animals bearing MCA-105 and -106 sarcomas treated with 6 to 10 μg rHTNF had significantly increased survival compared with excipient-treated control animals. In contrast, no significant difference in mean survival was observed between excipient and rHTNF treated animals bearing MCA-38, -101, or -102. Histologically, the necrotic response of immunogenic MCA-106 and non-immunogenic MCA-102 tumors to systemically administered rHTNF was very similar. These two tumors differed morphologically, however, by the greater degree of chronic inflammation that was present at the periphery of the MCA-106 tumor in comparison with the MCA-102. By 72 hr after rHTNF administration, the sites of regressed MCA-106 tumors were replaced by a heterogeneous population of inflammatory cells and tumor cell 'ghosts'. In contrast, MCA-102 tumors observed at 72 hr after rHTNF administration exhibited a crescentic rim of peripheral viable sarcoma around the central area of tumor necrosis. Our results show that rHTNF has greater toxicity in tumor bearing vs non-tumor bearing animals; despite its brief serum half-life, rHTNF at single i.v. doses is capable of causing necrosis and size reduction in several s.c. murine tumors; and there appears to be a differential tumor sensitivity to rHTNF that may be related to the relative immunogenicity of these tumors.