Molecular design of conjugated tumor necrosis factor-alpha: Synthesis and characteristics of polyvinyl pyrrolidone modified tumor necrosis factor-alpha

We conjugated tumor necrosis factor-alpha (TNF-alpha) with the synthetic po lymeric modifier polyvinyl pyrrolidone (PVP) to facilitate its clinical use for anti-tumor therapy. TNF-alpha was chemically conjugated with the termi nal carboxyl-bearing PVP at one end of its main chain, which was radically polymerized via the formation of an amide bond between the lysine amino gro ups of TNF-alpha and carboxyl group of PVP, In vitro specific bioactivity o f PVP-conjugated TNF-alpha (PVP-TNF-alpha) relative to that of native TNF-a lpha gradually decreased with increases in the degree of PVP attachment. In contrast, PVP-TNF-alpha in which 40% of TNF-alpha lysine residues were cou pled with PVP (MPVP-TNF-alpha) exhibited the highest anti-tumor activity am ong the conjugated derivatives examined. MPVP-TNF-alpha had more than 200-f old higher anti-tumor efficacy than native TNF-alpha, and the anti-tumor ac tivity of MPVP-TNF-alpha was more than 5-fold stronger than that MPEG-TNF-a lpha. which had the highest anti-tumor activity among PEG-conjugated TNF-al pha s examined. Additionally, a high dose of native TNF-alpha induced toxic side-effects such as body weight reduction, piloerection and tissue inflam mation, while no side effects were observed following i.v. administration o f MPVP-TNF-alpha. The plasma half-life of MPVP-TNF-alpha (360 min) was abou t 80 and S-fold longer than those of native TNF-alpha (4.6 min) and MPEG-TN F-alpha (122 min), respectively. These results suggested that PVP is a usef ul polymeric modifier for increasing the anti-tumor activity of PVP. (C) 19 99 Academic Press.