Improved antitumor activity and tumor targeting of NH₂-terminal- specific PEGylated tumor necrosis factor-related apoptosis-inducing ligand

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is considered an attractive anticancer agent due to its tumor cell-specific cytotoxicity. However, its low stability, solubility, unexpected side effects, and weak pharmacokinetic profiles restrict its successful clinical application. To develop efficient TRAIL-based anticancer biotherapeutics, a new version of trimeric TRAIL was constructed by incorporating trimer-forming zipper sequences (HZ-TRAIL), and then NH₂-terminal-specific PEGylation was done to produce PEGylated TRAIL (PEG-HZ-TRAIL). The biological, physicochemical, and pharmaceutical characteristics of PEG-HZ-TRAIL were then investigated using various in vitro and in vivo experiments, including a cell-based cytotoxicity test, a solubility test, pharmacokinetic analysis, and antitumor efficacy evaluations. Although slight activity loss occurred after PEGylation, PEG-HZ-TRAIL showed excellent tumor cell-specific cytotoxic effects via apoptotic pathways with negligible normal cell toxicity. The stability and pharmacokinetic problems of HZ-TRAIL were successfully overcome by PEGylation. Furthermore, in vivo antitumor tests revealed that PEG-HZ-TRAIL treatment enhanced therapeutic potentials compared with HZ-TRAIL in tumor xenograft animal models, and these enhancements were attributed to its better pharmacokinetic properties and tumor-targeting performance. These findings show that PEG-HZ-TRAIL administration provides an effective antitumor treatment, which exhibits superior tumor targeting and better inhibits tumor growth, and suggest that PEG-HZ-TRAIL should be considered a potential candidate for antitumor biotherapy.