Eli Lilly’s bimagrumab led to weight loss that was due almost entirely to fat reduction when combined with semaglutide, marketed by rival Novo Nordisk as Wegovy. BMO Capital Markets called the data “impressive” while raising concerns about the antibody’s safety profile.
Eli Lilly’s antibody bimagrumab, when used alongside Novo Nordisk’s semaglutide, marketed as Wegovy, helps patients lose weight while also preserving their muscle mass.
These results come from the placebo-controlled Phase IIb BELIEVE study, which enrolled more than 500 patients who were given subcutaneous semaglutide weekly and intravenous bimagrumab at weeks 4, 16, 28 and 40. Data presented Monday at the American Diabetes Association annual meeting showed that the combo regimen cut weight by 22.1% at 72 weeks. The vast majority of that weight reduction (92.8%) was attributable to fat loss.
Over this same time span, patients given semaglutide alone saw a 15.7% drop in weight, 71.8% of which was due to fat loss. Patients who got just bimagrumab saw a 10.8% drop, all of which was fat.
Writing to investors on Monday afternoon, analysts at BMO Capital Markets called these bimagrumab data “robust” and “impressive,” noting that its weight-loss figures are a “clear positive for building a regulatory approval case for body composition assets.”
Still, BMO raised concerns about the antibody’s safety profile. “Transient increases in ALT [alanine aminotransferase, a liver enzyme] and more permanent elevations in lipases give us some pause,” the analysts wrote, noting that Lilly will have to resolve such tolerability questions in future trials.
Bimagrumab is an investigational monoclonal antibody that binds to the activin/myostatin type II receptors, in turn helping boost muscle production. Lilly gained access to biologic when it bought Versanis Bio for nearly $2 billion in July 2023. BELIEVE was originally sponsored by Versanis.
Bimagrumab’s promising showing at ADA 2025 continues what has been a winning streak for the muscle preservation space in recent weeks.
Earlier this month, for instance, Regeneron released results from its Phase II COURAGE study, demonstrating that own investigational antibody trevogrumab boosted muscle preservation by 51.3% in patients with obesity when used alongside semaglutide. Adding the company’s other muscle-preserving asset, garetosmab, on top of the doublet further improved preservation to 80.9%.
Then, earlier this week, Scholar Rock announced that its experimental biologic apitegromab, when used with Lilly’s tirzepatide (marketed as Zepbound for weight loss), spares 55% more lean muscle mass than tirzepatide alone.
According to the BMO note on Monday, Lilly comes out ahead with its latest readout. While cautioning that cross-asset comparisons are complicated by different study designs, the analysts noted that in BELIEVE, patients taking bimagrumab with semaglutide had lost 2.6% of their lean muscle at 48 weeks, whereas those on semaglutide alone lost 7.9%. This comes out to a 67% increase in preserved muscle, according to the analysts, noting that this “outperforms” the results presented by Regeneron and Scholar Rock.
