Optimisation of a novel antibody format targeting ion channels involved in autoimmune diseases

Abstract

Autoimmune diseases affect 3 % to 6 % of the world’s population but current immunotherapies cause detrimental side-effects or cannot be used effectively for the treatment of most patients. There is a huge unmet need of novel therapeutic drugs for the specific treatment of autoimmune diseases. The potassium voltage-gated ion channel Kv1.3 became a prominent target for this cause. Inhibiting Kv1.3 results in the specific suppression of effector memory T-lymphocytes that mediate autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, and type-1-diabetes. However, due to their complexity and high sequence homology, the selective targeting of ion channels is a huge challenge. To provide remedy, the KnotBody technology was created. It combines the high potency of venom peptides with the engineerability and pharmacokinetics of monoclonal antibodies. During the course of this project a panel of anti-Kv1.3 KnotBodies was developed. A significant improvement of the KnotBody biophysical properties was achieved through mammalian display while retaining KnotBody inhibitory activity against Kv1.3. Sequence analysis gave first insights into the interplay between specific amino acid residues of the antibody framework, complementarity determining regions, and the venom peptide. To enable future in vitro selections and screening campaigns for lead candidate optimisation, Kv1.3 and the chimera KcsA1.3 were recombinantly produced using either a traditional detergent approach or through the SMALP technology. Furthermore, the selective binding of an anti-Kv1.3 KnotBody against the chimera was proven through a newly established DELFIA-TRF binding assay.