| dc.description.abstract | OBJECTIVE: Rheumatoid Arthritis (RA) is a systemic autoimmune disease with a prevalence of 0.5-1% worldwide. In the last two decades we observed the rapid evolution of RA therapeutics, and currently, a wide range of anti-rheumatic drugs is available. In particular, the discovery of anti-Tumor Necrosis Factor-α (TNF-α) antibodies has significantly improved disease management. However, the lack of therapeutic efficacy in a significant proportion of patients and the potential systemic implications (e.g. risk of serious infections) still represent an unmet need in RA therapy. Developing novel agents with synovial targeting specificity might increase the therapeutic index while reducing systemic side effects of RA therapeutics. This project aims to design, construct and evaluate in vitro and ex vivo the targeting and anti-inflammatory capability of a novel bispecific tandem single-chain variable fragment (scFv)-Fc antibody combining synovium specificity with anti-TNFα activity. The potential advantage of this construct, called F7-TNF scFv-Fc, is a reduced systemic TNF-binding activity and increased delivery and activation of TNF-neutralizing capacity at the inflamed joints. METHODS: The first part of this work focuses on the optimisation of synovium specific scFv domains previously identified by in vivo phage display using a SCID mouse model transplanted with human synovium, A7 scFv and F7 scFv. The second part of this project moves to the generation and evaluation of a tandem bispecific scFv-Fc antibody comprising F7 scFv external arms with synovium specific targeting ability linked through a metalloproteinase (MMP) cleavable linker to the anti-TNFα variable regions of Adalimumab fused to Fc domain of human IgG1. RESULTS: F7 scFv-Fc and the tandem bispecific F7/TNF scFv-Fc antibodies proved to satisfy the essential properties as joint-targeted agents showing specific reactivity to human arthritic synovium and no reactivity to normal tissues and other chronic diseases. In addition, F7/TNF scFv-Fc demonstrated ex vivo specific synovium targeting ability and intended reduced anti-TNFα activity in its intact form prior to reaching the joint tested by ELISA and NF-Kb reporter cell assay. Human synovial fluid and recombinant human MMP-1 showed efficient cleavage of the external arms of the antibody, releasing anti-TNF scFv-Fc with same TNF inhibitory capacity/potency as Adalimumab. CONCLUSION: Overall, F7-TNF scFv-Fc has the potential of decreasing the anti-TNFα off-site activity and consequently, reduce systemic toxicity while maintaining high on-site activity. Also, the presence of a synovium targeting domain has the advantage of increasing the delivery and retention within the inflamed synovium and possibly increase the therapeutic index of anti-TNF therapeutics. | en_US |
