8040 Precision-Engineered Activin and GDF Ligand Trap HS235: A Novel Lean Mass-Preserving Treatment for Obesity

Abstract Disclosure: G. Schang: Employee; Self; 35Pharma. M. De Molliens: Employee; Self; 35Pharma. E. Brule: Employee; Self; 35Pharma. C. Chauvet: Employee; Self; 35Pharma. J. Denis: Employee; Self; 35Pharma. A. Sours: Employee; Self; 35Pharma. V. Ganesh: Employee; Self; 35Pharma. G. Tremblay: Employee; Self; 35Pharma. J. Schoelermann: Employee; Self; 35Pharma. M. O'Connor: Employee; Self; 35Pharma. Introduction: Novel anti-obesity medications including incretin mimetics have revolutionized the pharmacotherapy of obesity and type 2 diabetes, leading to unprecedented weight loss and clinically meaningful improvement of glucose metabolism and cardiometabolic health. However, incretins reduce body mass in a non-selective manner; both fat mass and lean mass are lost with incretin treatment. In obese patients treated with incretins, undesirable loss of lean body mass (LBM) can account for up to 40% of overall weight loss. Loss of LBM negatively impacts resting metabolic rate, leading to a weight loss plateau and often unsustainable results. Furthermore, individuals with sarcopenia, characterized by low muscle mass and strength, are at greater risk for heart failure. The preservation, or even increase, of LBM is therefore a desirable treatment goal for obesity pharmacotherapy and overall cardiometabolic health. Activins and growth differentiation factors (GDFs), which are members of the TGF-beta superfamily, are validated targets controlling body composition and metabolism. Specifically, blockade of activins and GDFs has anabolic effects in metabolically active tissues such as skeletal muscle and brown adipose tissue, while reducing white adipose tissue mass. Therefore, specific and selective blockade of activins and GDFs represents a novel anti-obesity treatment strategy which can act orthogonally to current anti-obesity medications. HS235 is an activin receptor ectodomain-based (ActR) Fc-fusion protein that has been rationally designed to attain optimal inhibition of ligands controlling body composition in obesity. Methods: A structure-assisted rational molecular engineering approach coupled with cell-based potency screening was employed to design HS235. To validate the anti-obesogenic potential of HS235, diet-induced obese (DIO) mice were injected with HS235, an incretin mimetic, or a combination of both. Fat mass, LBM, muscle weights, and biomarker readouts were assessed at the end of study. Results: In cell-based assays, HS235 potently and selectively neutralized activins and GDFs implicated in body composition. This translated to complete in vivo target engagement and pharmacodynamic response. In a DIO mouse model, both HS235 and the incretin mimetic significantly improved metabolic parameters and decreased fat mass, but only HS235 increased LBM, while incretin-based treatment led to LBM loss. Importantly, the addition of HS235 to the incretin mimetic lead to a synergistic fat mass loss and prevented loss of LBM. Conclusion: Potent and selective inhibition of activins and GDFs by HS235 represents a novel LBM preserving weight loss strategy orthogonal to incretin mimetics. Collectively, these data support the development of HS235 as a novel anti-obesity agent to complement currently approved incretin-based medications to improve quality of weight loss. Presentation: 6/3/2024