Lilly Halts Mid-Stage Obesity Study, Shifts Focus in Weight Loss Market

Bimagrumab Trial Terminated for Strategic Reasons

Eli Lilly has announced the discontinuation of its Phase IIb trial evaluating bimagrumab, an investigational antibody, in combination with its weight loss drug Zepbound (tirzepatide). The decision, attributed to "strategic business reasons" according to a federal clinical trials database, marks a significant shift in the company's approach to obesity treatment.

The study, which aimed to enroll 180 patients with type 2 diabetes and overweight or obesity, was designed to assess changes in body weight over 36 weeks. Secondary outcomes focused on the loss of body fat and visceral adipose tissue, aligning with bimagrumab's mechanism of action as a muscle-sparing agent.

Muscle Preservation Remains a Key Focus

Despite the termination of the bimagrumab trial, Lilly continues to prioritize muscle preservation during weight loss. In June, the company released Phase IIb data demonstrating bimagrumab's efficacy in maintaining muscle mass when combined with Novo Nordisk's semaglutide. The combination resulted in a 22.1% body weight reduction, with 92.8% attributed to fat loss, compared to semaglutide alone, which led to a 15.7% weight drop with 71.8% fat loss.

Lilly's commitment to this area is further evidenced by its recent $650 million deal with Juvena Therapeutics. This collaboration aims to leverage AI technology for the discovery and development of novel drugs that maintain muscle mass and function during weight loss.

Competitive Landscape in Muscle-Sparing Weight Loss

The race for muscle-preserving weight loss solutions extends beyond Lilly. Regeneron recently reported Phase II data for its antibody trevogrumab, showing a 51.3% improvement in muscle preservation compared to semaglutide monotherapy. When combined with garetosmab, muscle preservation increased to 80.9% relative to semaglutide alone.

Scholar Rock has also entered the arena, announcing that its drug apitegromab, when used alongside tirzepatide, preserves 55% more muscle mass than tirzepatide monotherapy.

As the pharmaceutical industry continues to evolve its approach to obesity treatment, the focus on quality weight loss—emphasizing fat reduction while preserving lean mass—remains a key area of innovation and competition.