Development of a novel recombinant biotherapeutic with applications in targeted therapy of human arthritis

Abstract

Objective. To isolate recombinant antibodies with specificity for human arthritic synovium and to develop targeting reagents with joint-specific delivery capacity for therapeutic and/or diagnostic applications.Methods. In vivo single-chain Fv (scFv) antibody phage display screening using a human synovial xenograft model was used to isolate antibodies specific to the microvasculature of human arthritic synovium. Singlechain Fv antibody tissue-specific reactivity was assessed by immunostaining of synovial tissues from normal controls and from patients with rheumatoid arthritis and osteoarthritis, normal human tissue arrays, and tissues from other patients with inflammatory diseases displaying neovasculogenesis. In vivo scFv antibody tissue-specific targeting capacity was examined in the human synovial xenograft model using both 125 I-labeled and biotinylated antibody.Results. We isolated a novel recombinant human antibody, scFv A7, with specificity for the microvasculature of human arthritic synovium. We showed that in vivo, this antibody could efficiently target human synovial microvasculature in SCID mice transplanted with human arthritic synovial xenografts. Our results demonstrated that scFv A7 antibody had no reactivity with the microvasculature or with other cellular components found in a comprehensive range of normal human tissues including normal human synovium. Further, we showed that the reactivity of the scFv A7 antibody was not a common feature of neovasculogenesis associated with chronic inflammatory conditions. Conclusion. Here we report for the first time the identification of an scFv antibody, A7, that specifically recognizes an epitope expressed in the microvasculature of human arthritic synovium and that has the potential to be developed as a joint-specific pharmaceutical.

Rational Design of Antirheumatic Prodrugs Specific for Sites of Inflammation

“…The next step in increasing the therapeutic potency and the safety profile would be the development of tissue-specific (not only inflammation-specific) targeting agents (32). With regard to RA synovium, our group of investigators has previously identified peptides and scFv antibody fragments with selective specificity for the synovium (45)(46)(47). The incorporation of the scFv A7 in the aDVD format, as demonstrated herein for ICAM-1, will provide specificity for human arthritic synovium to the molecule, with great potential for tissue-specific drug delivery in RA.…”

Phage Display Identification of CD100 in Human Atherosclerotic Plaque Macrophages and Foam Cells

“…The use of fresh human tissues ( ex vivo ) [28–31]or mouse models ( in vivo ) [7,8,28,32,33]for phage selection enhances the possibility of finding a peptide/antibody that can bind to human tissues in vivo , improving the diagnosis of the associated diseases. Such strategies have been successfully employed for tumors [28], and even for atherosclerosis [32,34].…”

Progress and clinical potential of antibody-targeted therapy for arthritic damage

“…As a follow-up study, the same group developed an antibody specific to human inflamed synovium in xenografted severe combined immunodeficiency mice termed A7 [20]. A7 scFv bound the microvasculature of RA, OA, Crohn's disease, and psoriatic skin sections, but not normal tissues (including normal synovium).…”