Molecular design of hybrid tumour necrosis factor-alpha. II: The molecular size of polyethylene glycol-modified tumour necrosis factor-alpha affects its anti-tumour potency

Abstract

Summary To design hybrid tumour necrosis factor-a (TNF-a) applicable to systemic anti-tumour therapeutic use, we assessed the relationships among the molecular size of hybrid TNF-a, in vitro bioactivity and in vivo anti-tumour potency. Natural human TNF-a was covalently modified with polyethylene glycol (PEG) of various number-average molecular weights (Mn = 2000, 5000, 12 000). The in vitro bioactivity of PEGmodified TNF-as decreased with an increase in the degree of PEG modification, irrespective of the molecular weight of PEG. This decrease in the specific bioactivity markedly increased with an increase in the molecular weight of the attached PEG. The in vivo anti-tumour effects of the hybrid TNF-cxs with a molecular size from 100 to 110 kDa, which had more than 50% of specific bioactivity of native TNF-a, were significantly superior to other PEG-TNF-as. These hybrid TNF-as showed over ten times greater anti-tumour effects than native TNF-a. Thus, the molecular size, which was determined by the degree of PEG modification and PEG molecular weight, influences the specific activity and anti-tumour effects of hybrid TNF-a.

Linkage with cathepsin B-sensitive dipeptide promotes the in vitro and in vivo anticancer activity of PEGylated tumor necrosis factor-alpha (TNF-α) against murine fibrosarcoma

“…administration of native TNF-α, PEG-TNF-α or PEG-vcTNF-α are shown in Figure 7. Native TNF-α was rapidly eliminated from the circulation, and its plasma half-life was only 0.31 h (Table 3) which corresponds to that reported previously [32]. In contrast, the plasma clearance of both PEG-TNF-α and PEG-vcTNF-α was markedly decreased relative to that of native TNF-α and their plasma half-lives were 27.23 and 21.22 h, respectively, approximately 85-and 65-fold longer than that of native TNF-α.…”

“…Additionally, it is well known that macromolecules are accumulated and retained in the tumor tissue much more than in normal tissues, a phenomenon termed the "enhanced permeability and retention (EPR)" effect [35,36]. Many macromolecular anticancer agents, such as synthetic polymer-conjugating drugs, polymeric micelle-containing drugs and others, have been reported accordingly [32,37]. The increased tumor growth inhibition seen here with the TNF-α conjugates might also result from the EPR effect of PEGylation.…”

Site-specific chemical modification with polyethylene glycol of recombinant immunotoxin anti-Tac(Fv)-PE38 (LMB-2) improves antitumor activity and reduces animal toxicity and immunogenicity

“…The PEG remains with the Fv whereas most of the toxin (amino acids 280-613) is transported to the endoplasmic reticulum, where it translocates to the cytosol and kills the cell. Usually, the activity of PEGylated proteins decreases with increasing molecular weight of the attached PEG because the steric hindrance caused by the attached PEG increases with the increasing length of the PEG chain (26). However, in this case PEG20K-LMB-2 had almost the same activity as PEG5K-LMB-2.…”

Preparation and evaluation of a new releasable PEGylated tumor necrosis factor-α (TNF-α) conjugate for therapeutic application

“…Recombinant human TNF- (17000 kD, 1×10 7 from Biosea Biotechnology Co., Ltd. (Beijing, China) and cell counting kits-8 (CCK-8) were from Dojindo Laboratories (Kumamoto, Japan). Other reagents and solvents used were of analytical grade.…”

“…One of such strategies is PEGylation with a permanent linkage, resulting in an effective drug delivery platform [4]. Conjugation of cytokines such as TNF- with PEG has been shown to improve their in vivo stability and their therapeutic effects [5][6][7]. However, the target molecules conjugate randomly with PEG, and several active cysteine residues are unavoidably modified, reducing the biological activity of these polypeptides.…”