Lilly Halts Key Obesity Drug Trial
Eli Lilly has halted one of its two Phase 2 clinical trials of the experimental obesity drug bimagrumab, citing “strategic business reasons,” according to a U.S. registry of clinical trials.
The discontinued study was evaluating bimagrumab alone and in combination with tirzepatide, the active ingredient in Lilly’s marketed medicine Zepbound, in patients who were overweight or obese and had Type 2 diabetes.
The trial was expected to track 180 adult participants for more than a year, with weight reduction as the primary measure and fat versus muscle loss as a key secondary outcome. It was scheduled to conclude in late 2026 but was terminated on June 10, less than a month after initiation.
Company Cites Strategy, Continues Parallel Study
A Lilly spokesperson said, “We routinely evaluate our clinical development programs to optimize the potential for each product.” The company also stated that a parallel trial in obese patients without diabetes remains ongoing, with results expected in 2026. That study is testing patients receiving a placebo or various dosing regimens of bimagrumab with or without Zepbound, focusing on both weight loss and muscle preservation.
The Challenge of Muscle Preservation in Weight Loss
Bimagrumab is among a class of drugs designed to address concerns about muscle loss associated with GLP-1-based weight loss medicines such as Zepbound and Novo Nordisk’s Wegovy. These treatments, while effective at reducing body weight, have also been linked to decreases in lean muscle mass, partly due to appetite suppression and reduced protein intake.
The Food and Drug Administration has indicated that drugs like bimagrumab may need to show more than muscle preservation. Veru, another company developing a similar therapy, stated this week that the agency “now guides that incremental weight loss” over a GLP-1 drug alone “is an acceptable primary endpoint to support approval.” Following that announcement, Veru reported a 3% drop in its shares on Tuesday and another 3% decline on Thursday.
Bimagrumab’s Journey to Lilly
Bimagrumab was first developed by Novartis and tested for rare muscle-wasting conditions such as sarcopenia and inclusion body myositis. Novartis later licensed the drug to Versanis Bio, which launched in 2021 with plans to incorporate it into obesity treatment regimens. In 2023, Lilly acquired Versanis for up to $1.9 billion, obtaining the rights to bimagrumab.
Alongside Lilly, other companies, including Regeneron Pharmaceuticals, Biohaven, Scholar Rock, and Veru, are advancing obesity drugs intended to preserve muscle.
According to company updates, Lilly’s ongoing non-diabetic obesity study is expected to provide initial results in April 2026.
