Introducing NanoProTEN, a novel approach for anticoagulation in patients with prothrombotic autoantibodies - Project summary This project aims to investigate a novel approach to mitigate the risk of vascular thromboses, which imposes a significant economic burden in the US. Our strategy is to develop a technology that, by specifically targeting the lipid-binding domains of factor X (read factor ten) and prothrombin, two essential coagulation factors, regulates the rate at which factor Xa and thrombin are produced and, consequently, controls the formation of blood clots. This approach is unique compared to current pharmacologic methods that either directly (DOACs) or indirectly (heparins) target the active site of clotting proteases or impair the proper synthesis of a family of proteins to which multiple coagulation factors belong (warfarin). We propose this approach will offer potential benefits for patients with prothrombotic antiphospholipid antibodies who experience limited effectiveness with existing medications. Antiphospholipid antibodies are a defining feature of antiphospholipid syndrome (APS), which is an acquired autoimmune disorder. Additionally, there is evidence of their involvement in infectious diseases, including COVID-19. By using an in vitro selection process, our preliminary studies identified a nanobody suitable for testing this hypothesis, which we called NanoProTEN. Aim 1 of this project aims to investigate the biochemical characteristics of NanoProTEN, including its affinity and specificity towards coagulation factors and plasma proteins involved in the blood clotting cascade. We will then assess its anticoagulant potential in human plasma and with purified coagulation factors, and its ability to interfere with antiphospholipid antibodies. These studies will define the molecular interactions of NanoProTEN, evaluate its potential off-target effects, and establish its anticoagulant potential compared to existing therapies. Studies in Aim 2 will define the unique mechanism of action of NanoProTEN through structural studies using cryo-electron microscopy. By determining the structures of NanoProTEN bound to prothrombin and factor X, we will uncover the structural elements contributing to its dual selectivity. These studies will determine how NanoProTEN interacts with these factors, offering mechanistic insights into its mode of action and providing essential information for enhancing its activity. In conclusion, the primary outcome of this research project is the development of an innovative technology represented by NanoProTEN. This technology holds promise as a versatile research tool and a potential candidate for a new class of anticoagulants for improving outcomes in patients with prothrombotic autoantibodies and potentially other thrombotic disorders.
