A new investigational drug called apitegromab is being explored to preserve muscle mass in adults receiving glucagon-like peptide‑1 (GLP‑1) receptor agonists for obesity.
The BBC has reported on a Nature Medicine study describing a US phase II trial in which 102 adult participants received the glucagon-like peptide‑1 (GLP‑1)/glucose-dependent insulinotropic polypeptide (GIP) agonist tirzepatide for obesity. Those given the monoclonal antibody apitegromab in addition to tirzepatide preserved around 1.9kg, or 55%, more lean mass than the placebo group, while still losing fat. Lean mass accounted for 14.6% of total weight loss in the apitegromab group compared to 30.2% in the placebo arm.
Developed by biotechnology company Scholar Rock, apitegromab is administered by intravenous infusion and is currently available only within clinical trials. It targets a protein involved in muscle breakdown and is also being studied in other muscle-wasting conditions.
Dr Marie Spreckley, an obesity medicine specialist at the University of Cambridge who was not involved in the research, described the data as “encouraging early evidence,” but emphasised that they do not yet amount to proof of clinical benefit. She highlighted the need for larger and longer studies to determine whether preserving lean mass translates into improvements in functional strength, quality of life and long‑term cardiometabolic outcomes.
Dr Brendan Gabriel, a nutrition and metabolic health specialist at the University of Aberdeen, suggested that, if confirmed, such an approach might be most relevant for selected patients at higher risk of muscle loss, rather than for all individuals using GLP‑1 receptor agonists. He also noted that any future role for apitegromab would need to be considered alongside non-pharmacological strategies, such as resistance training and optimised dietary protein intake.