Targeted Cancer Therapy Using Fusion Protein of TNF alpha and Tumor-Associated Fibronectin-Specific Aptide

Abstract

Tumor necrosis factor-alpha has shown potent antitumor effects in preclinical and clinical studies. However, severe side effects at less than therapeutic doses have limited its systemic delivery, prompting the need for a new strategy for targeted delivery of the protein to tumors. Here, we report a fusion protein of mouse tumor necrosis factor (TNF)-alpha (mTNF alpha) and a cancer-targeting, high-affinity aptide and investigate its therapeutic efficacy in tumor-bearing mice. A fusion protein consisting of mTNF alpha, a linker, and an aptide specific to extra domain B (EDB) of fibronectin (APT(EDB)), designated mTNF alpha-APT(EDB), was successfully produced by expression in Escherichia coli. mTNF alpha-APTEDB retained specificity and affinity for its target, EDB. In mice bearing EDB-overexpressing fibrosarcomas, mTNF alpha-APT(EDB) showed greater efficacy in inhibiting tumor growth than mTNF alpha alone or mTNF alpha linked to a nonrelevant aptide, without causing an appreciable loss in body weight. Moreover, in vivo antitumor efficacy was further significantly increased by combination treatment with the chemotherapeutic drug, melphalan, suggesting a synergistic effect attributable to enhanced drug uptake into the tumor as a result of TNF alpha-mediated enhanced vascular permeability. These results suggest that a fusion protein of mTNF alpha with a cancer-targeting peptide could be a new anticancer therapeutic option for ensuring potent antitumor efficacy after systemic delivery.