Designing Therapeutic SERPINs: Biotechnological Approaches to Improve Specificity and Potency

Native SERPINs are currently the treatment of choice for diseases driven by excessive serine protease activity. Nonetheless, their lack of specificity and potency as well as the short half-life of their recombinant counterparts hamper their therapeutic application and cost-effectiveness. These limitations can be overcome by designing novel SERPIN variants with increased potency or improved specificity. However, designing novel therapeutic SERPINs is hampered by limited insights into reactive center loop (RCL) sequence-function relationship. This thesis describes several biotechnological improvements to increase SERPIN target specificity and inhibition potency by I) modification of the RCL, II) by targeting SERPINs to their site of action. To enhance the design of novel therapeutic SERPINs, we developed a SERPIN RCL-based prediction platform. It provides primary insights into the SERPIN RCL sequence-function relationship and can assist the selection of RCL sequences for desired specificity and potency. We demonstrated its value by developing novel SERPIN variants with improved therapeutic potential for three different disease models I) thrombosis, II) hemophilia, and III) bradykinin-driven inflammation. With the combined new insights obtained from our SERPIN RCL-based prediction platform and the possibility of developing VHH for desired target sites, we believe that novel SERPINs can be developed for a wide range of therapeutic purposes.