Characterisation of scFv A7 reactivity and development of a novel bispecific antibody for targeted therapies in Rheumatoid Arthritis.
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Despite the success of current biological agents, achievement of broader efficacy and improved safety profile remains an unmet need in rheumatoid arthritis therapy. Neovasculogenesis plays a vital role in the progression and perpetuation of rheumatoid arthritis and significant evidence has demonstrated molecular heterogeneity within the endothelium (MVE) of different tissues. The heterogeneity of the synovial MVE can be exploited for the development of organ-specific therapeutic and diagnostic reagents. A novel recombinant antibody fragment, scFv A7, with specificity for human arthritic synovium, was isolated in our laboratory following in vivo phage display. The aim of the project described in this thesis is to characterise the antibody reactivity and develop a novel tissue specific therapeutic. The scFv A7 antibody proved to specifically target the microvasculature of human arthritic synovium with no detectable reactivity in a comprehensive range of normal tissues. Furthermore, the detected reactivity was not a common feature of chronic inflammatory conditions. Hence, the A7 antibody represents a unique and versatile tool with great potential for the development of diagnostic and/or therapeutic agents. The unique properties of A7 were combined with the anti-TNF Adalimumab, forming a bispecific antibody with neutralising activity and synovial homing properties. The new construct was able to retain the synovial specificity and showed comparable TNF binding kinetics and biological activity to the parent Adalimumab antibody in vitro. In conclusion, these results demonstrate that scFv A7 reactivity is specific to the microvasculature of human arthritic synovium, suggesting that the target molecule may have potential as a biomarker in arthritis and applications as an immunotherapeutic target. The bispecific antibody format developed showed unaltered TNF blocking capacity and synovial specificity that may allow reduction in the dosage and/or administration frequency, with the ultimate goal to reduce the systemic exposure, achieve a better therapeutic index and decreasing health care costs.
- Theses