A collagen-binding EGFR antibody fragment targeting tumors with a collagen-rich extracellular matrix.

Hui Liang,He Shen,Bing Chen,Yannan Zhao,Yan Zhuang,Zhijun Zhang,Jianwu Dai,Bin Wang,Jiajia Shi,Jie Sun,Xiaoran Li

doi:10.1038/srep18205

Abstract

Many tumors over-express collagen, which constitutes the physical scaffold of tumor microenvironment. Collagen has been considered to be a target for cancer therapy. The collagen-binding domain (CBD) is a short peptide, which could bind to collagen and achieve the sustained release of CBD-fused proteins in collagen scaffold. Here, a collagen-binding EGFR antibody fragment was designed and expressed for targeting the collagen-rich extracellular matrix in tumors. The antibody fragment (Fab) of cetuximab was fused with CBD (CBD-Fab) and expressed in Pichia pastoris. CBD-Fab maintained antigen binding and anti-tumor activity of cetuximab and obtained a collagen-binding ability in vitro. The results also showed CBD-Fab was mainly enriched in tumors and had longer retention time in tumors in A431 s.c. xenografts. Furthermore, CBD-Fab showed a similar therapeutic efficacy as cetuximab in A431 xenografts. Although CBD-Fab hasn’t showed better therapeutic effects than cetuximab, its smaller molecular and special target may be applicable as antibody–drug conjugates (ADC) or immunotoxins.

Highlights

IntroductionFab retains the antigen-binding regions and the therapeutic effect of its parent antibody[18,19]
After the injection of each drug for 96 h, the mean fluorescence intensity (MFI) of tumor cells in the CBD-Fab group was 27.3 but only 1.71 and 19.5 in the NAT-Fab and cetuximab groups, respectively (Fig. 5b,d). These results demonstrated that CBD enhanced the binding of Fab to collagen in tumors and had a longer retention time in tumors compared with NAT-Fab and cetuximab
Many previous studies showed that tumor environment is not just involved in transformed cells, but rather, because of the interactions between mesenchymal and epithelial cells that impose reciprocal influences, the microenvironment acts as an active participant throughout cancer initiation, progression, and metastasis[22,23,24]

Summary

Introduction

Fab retains the antigen-binding regions and the therapeutic effect of its parent antibody[18,19]. This fragment demonstrates faster tissue/tumor penetration than the whole antibody[20]. The rapidly cleared from the body of Fab may reduce its therapeutic effect. We concluded that the recombinant protein of CBD and Fab of cetuximab should show a collagen binding capacity, a more specific target, a faster tumor penetration and demonstrated a similar therapeutic activity as whole antibody cetuximab. We designed and constructed a collagen-binding EGFR antibody fragment for targeting collagen in tumors. CBD-Fab bound to collagen and maintained the antitumor activity of cetuximab both in vitro and in vivo. Treatment with CBD-Fab prevented tumor formation and significantly suppressed the growth of tumors in A431 xenografts

Methods

Results

Conclusion