A novel human tumor necrosis factor alpha mutant showed potent antitumor activity and reduced toxicity in vivo

AIM: To study the antitumor activity and systemic toxicity of human tumor n ecrosis factor alpha (hTNF alpha) mutant M2 ( R2K-N30S-R32W-L157FhTNF alpha ). METHODS: Mouse sarcoma S180 tumors and hepatoma HAC tumors were implante d into mice, and human urocyst carcinoma CP-3 tumors were implanted into nu de mice. The xenografted mice were injected with wild-type hTNF alpha and i ts mutant M2 at different doses. After 7 d (mice) or 10 d (nude mice) of in jection, the tumor weight was measured to calculate the inhibition rate of hTNF alpha and M2. Systemic toxicity experiments were done on Rhesus monkey s by injecting them with wild-type hTNF alpha and mutant M2 respectively fo r 10 consecutive d. Observations were made on the monkeys both before and a fter the injection. RESULTS: For mice implanted with sarcoma S180 and hepat oma HAC tumors, the inhibition rate of M2 was similar to that of wild-type hTNF alpha at the dose of 0.025 mg/kg, while for nude mice implanted with h uman urocyst carcinoma CP-3, the inhibition rate of M2 (45.5 %) was much hi gher than that of wild-type hTNF alpha (15.5 %). When the dose came to 0.25 and 2.5 mg/kg respectively, however, the inhibition rate of M2 greatly inc reased (the highest was 75.9 %). The tests of systemic toxicity of hTNF alp ha and its mutant M2 in monkeys proved that M2 presented lower toxicity tha n wild-type hTNF alpha did. CONCLUSION: hTNF alpha mutant M2 not only prese nted higher antitumor activity than wild-type hTNF alpha did on mouse tumor (S180 and HAC)and human tumor (CP-3)-implanted mice, but also showed lower systemic toxicity in the Rhesus monkey.