Fusion of an EGFR-antagonistic affibody enhances the anti-tumor effect of TRAIL to EGFR positive tumors

Abstract

Tumor necrosis factor-related apoptosis ligand (TRAIL) is a promising antitumor agent candidate for its selective proapoptotic activity to various tumor cells. However, TRAIL showed limited efficacy in clinical trials despite of good tolerability. One important reason might be attributed to the poor tumor-homing ability of TRAIL. Herein, we designed an EGFR-targeting TRAIL (Z-TRAIL) by genetically fusing an EGFR-antagonistic affibody (ZEGFR:1907) to the N-terminus of TRAIL. Z-TRAIL was produced as a soluble protein with high yield in E. coli and it maintained the trimeric state of active TRAIL. Under the EGFR-binding mediated by ZEGFR:1907, Z-TRAIL showed a ∼5 to 20-fold enhancement of cytotoxicity compared to TRAIL on tumor cells in vitro. Furthermore, fusion to ZEGFR:1907 endowed TRAIL with a ∼1.8-fold increase of tumor uptake and a dramatical stronger apoptosis-inducing ability in the mice bearing EGFR-overexpressing A431 tumor xenografts. More importantly, Z-TRAIL exhibited significantly enhanced antitumor efficacy against whether EGFR high-expressing or low-expressing tumors than TRAIL in vivo. In addition, repeated injection of high-dose Z-TRAIL did not show obvious acute toxicity in mice. These results demonstrated that the newly engineered Z-TRAIL might be a promising agent for targeted therapy of EGFR-expressing tumors.