207-OR: Myostatin Inhibition Synergizes with GLP-1R Agonism to Accelerate Weight Loss in Male, Obese Nonhuman Primates

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have become standard-of-care for the pharmacological treatment of obesity by inducing clinically meaningful weight loss through a reduction in appetite. While these agents potently reduce fat mass, the caloric restriction also reduces skeletal muscle mass. Strategies to preserve skeletal muscle in the presence of caloric restriction are needed to improve weight loss quality in obese patents. Trevogrumab (∝-MSTN) and garetosmab (∝-ActA) are fully human monoclonal antibodies that potently inhibit two mediators of skeletal muscle atrophy: myostatin (MSTN) and activin A (ActA). We first tested the effects of ∝-MSTN, ∝-ActA and GLP-1RA (Semaglutide [Sema]) on body composition of diet-induced obese mice either alone or in combination. Sema (-29.8%) and ∝-MSTN/∝-ActA (-23.4%) produced significant reduction in fat mass after 4 weeks of treatment vs baseline. Adding MTSN and ActA blockade to Sema produced an additive effect on fat mass (-54.2%). This combination also increased lean mass by 9.8% vs a 1.9% loss with Sema alone. To test this in primates, we performed a 20-week study with the combined administration of either Sema + ∝-MSTN or Sema + ∝-MSTN and ∝-ActA in obese male cynomolgus monkeys. The combination of ∝-MSTN + Sema was sufficient to cause an additive effect on fat mass -43.9% vs -25.1% for Sema alone. The addition of ∝-ActA to the combination produced a similar reduction in fat (-49.6%). The Sema control group also lost -2.5% lean mass after 20 weeks; despite the significant reduction in fat mass, the addition of ∝-MSTN to Sema slightly increased lean mass over the same period (0.5%); the addition of ∝-ActA increased lean mass even further (6.2%). These data suggest the blockade of MSTN and ActA to GLP-1RA treatment could greatly improve the quality of weight loss with this class of anti-obesity agents. Disclosure J.Mastaitis: Employee; Regeneron Pharmaceuticals Inc., Stock/Shareholder; Regeneron Pharmaceuticals Inc. D.Gomez: Employee; Regeneron Pharmaceuticals Inc., Stock/Shareholder; Regeneron Pharmaceuticals Inc. V.Le rouzic: Employee; Regeneron Pharmaceuticals Inc., Stock/Shareholder; Regeneron Pharmaceuticals Inc. M.Stec: Employee; Regeneron Pharmaceuticals Inc., Stock/Shareholder; Regeneron Pharmaceuticals Inc. N.Khan: Employee; Regeneron Pharmaceuticals Inc., Stock/Shareholder; Regeneron Pharmaceuticals Inc. E.Na: Employee; Regeneron Pharmaceuticals Inc., Stock/Shareholder; Regeneron Pharmaceuticals Inc. T.Mcwilliams: None. S.Min: Employee; Regeneron Pharmaceuticals Inc., Stock/Shareholder; Regeneron Pharmaceuticals Inc. M.Sleeman: Employee; Regeneron Pharmaceuticals Inc. Funding Regeneron Pharmaceuticals Inc.