Searching for new TNF-alpha analogs having potential application in cancer therapy

Two new TNF-alpha analogs were prepared and tested for their anti-tumor activity on fibrosarcoma SA-1 tumor model in vivo. In analog LK-801 two histidines (His107His108) were introduced into the surface loop thus enabling efficient purification by metal-affinity chromatography. This analog showed less side effects and can serve as a lead compound to look for other useful mutations. Another analog LK-802 was designed by introduction of additional pair of mutations (Cys95Cys148) into LK-801 in order to prepare disulfide linked TNF trimers. Cytotoxicity on mouse cell line L929 was comparable to TNF-alpha, but effect on tumor growth was quite reduced. Pharmacokinetic study revealed that serum levels of LK-802 were quite low in comparison to native TNF-alpha. This at least partially explains why anti-tumor activity of LK-802 is reduced and also illustrates the problems in designing the analogs with desired in vivo biological properties.