A novel bispecific antibody targeting tumor necrosis factor α and ED-B fibronectin effectively inhibits the progression of established collagen-induce arthritis

Specific delivery of TNF-alpha antagonist to the inflamed site can increase its efficacy and reduce the side-effects. In this study, we constructed a bispecific diabody (BsDb) that targets TNF-alpha and ED-B-containing fibronectin (B-FN), a fibronectin isoform specifically expressed in the pannus of the inflamed joint in rheumatoid arthritis. BsDb was produced in Escherichia coli as inclusion bodies, purified to homogeneity, and refolded to the functional form. Our data demonstrate that BsDb could simultaneously bind to human TNF-alpha and B-FN and neutralize TNF-alpha action. In the collagen-induced arthritis mouse model, we compared the biodistrubtion and therapeutic efficacy of BsDb with those of the anti-TNF-alpha scFv (TNF-scFv). Similar to TNF-scFv, BsDb penetrated into the synovial tissue quickly, showing a rapid clearance from blood and normal organs. In contrast, BsDb could selectively accumulate and retain in arthritic joints of mice for a long period time, resulting in a much stronger inhibition of arthritis progression in mice than TNF-scFv. The findings described herein indicate that BsDb has a good specificity to the inflamed joint, with low toxicity to normal organs and seems to be an ideal biological agent for the treatment of RA and other chronic inflammatory disease. (C) 2014 Elsevier B.V. All rights reserved.