Lilly Halts Phase IIb Obesity Study, Shifting Focus in Competitive Weight Loss Market

Eli Lilly has announced the termination of a Phase IIb clinical trial investigating the combination of bimagrumab and Zepbound (tirzepatide) for weight loss. This decision marks a significant shift in the company's obesity treatment strategy and highlights the intense competition in the rapidly evolving weight loss drug market.

Study Termination and Strategic Considerations

The pharmaceutical giant cited "strategic business reasons" for halting the mid-stage study, according to information published in a federal clinical trials database. The trial, which aimed to enroll 180 patients with type 2 diabetes and overweight or obesity, was designed to evaluate the efficacy of bimagrumab alone and in combination with Zepbound over a 36-week period.

Bimagrumab, an antibody that targets activin/myostatin type II receptors, was being investigated for its potential to promote muscle formation and improve the quality of weight loss by preserving lean mass. The primary endpoint of the study was change in body weight, with secondary outcomes focusing on reductions in body fat and visceral adipose tissue.

Muscle Preservation: A Key Focus in Obesity Treatment

Despite the trial's termination, the pursuit of muscle-preserving therapies in conjunction with weight loss remains a priority for several pharmaceutical companies. In June, Lilly released promising Phase IIb data demonstrating bimagrumab's ability to maintain muscle mass when combined with Novo Nordisk's semaglutide. The combination therapy resulted in a 22.1% reduction in body weight after 72 weeks, with 92.8% of the weight loss attributed to fat loss.

Lilly's commitment to this approach 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 could help maintain muscle mass and function during weight loss.

Other companies are also making strides in this area. Regeneron reported Phase II data for its investigational antibody trevogrumab, showing a 51.3% improvement in muscle preservation compared to semaglutide monotherapy. Additionally, Scholar Rock announced that its drug apitegromab, when used alongside tirzepatide, preserves 55% more muscle mass than tirzepatide alone.

As the pharmaceutical industry continues to innovate in the field of obesity treatment, the focus on muscle preservation alongside weight loss represents a significant trend that could shape future therapeutic approaches. While Lilly's decision to terminate the bimagrumab-Zepbound trial may represent a strategic pivot, it underscores the complex and competitive nature of the obesity drug market.