MitoRx Therapeutics, a biotechnology company developing mitochondrial-targeted persulfide modifiers, has shared new preclinical data on its lead compound Myo4.
The results were presented at the European Association for the Study of Diabetes (EASD) 2025 Annual Meeting, taking place in Vienna from 15 – 19 September 2025.
The study in a diet-induced obesity mouse model demonstrated that Myo4 increased muscle fiber size and reduced liver fat accumulation over a four-week period. These findings build on earlier MRI evidence of lean mass preservation.
MitoRx is investigating Myo4 as an alternative to current GLP-1–based obesity therapies, which have been associated with muscle loss and weight regain.
Mechanism And Potential Of Myo4
Myo4 works through a novel mitochondrial-targeted mechanism of action, distinct from GLP-1 approaches. According to MitoRx, the compound demonstrated no detectable toxicity in preclinical testing and improved overall tissue quality.
“The clearance of liver fat and preservation of muscle fibers provide strong support for continued development of Myo4,” said Xavier Jacq, Chief Scientific Officer of MitoRx.
The British company’s CEO, Jon Rees, noted that nearly 890 million people worldwide live with obesity and highlighted the importance of alternatives that minimize muscle loss. “Patients need options that deliver durable weight loss and better long-term health outcomes,” he said.
The new findings expand on data presented earlier in 2025. At the European Congress on Obesity (ECO), MitoRx reported that Myo4 preserved both muscle and bone mineral content during fat loss. Additional results at the American Diabetes Association (ADA) Scientific Sessions showed that Myo4 restored insulin sensitivity in obesity models. When combined with semaglutide, Myo4 enhanced fat loss while maintaining muscle mass.
Collectively, the data suggests that Myo4 could improve the quality of weight loss by addressing both fat reduction and tissue preservation.
The company is progressing Myo4 toward clinical candidate nomination while also developing oral follow-up compounds through its Candidate Engine platform.
Obesity Landscape
The obesity treatment landscape is evolving rapidly. Blockbuster drugs like GLP-1 receptor agonists, including Novo Nordisk’s Wegovy (semaglutide) and Eli Lilly’s Zepbound (tirzepatide), are leading the way as weight loss treatment, as pharma giants and investors rush to get a piece of the action in a market expected to be worth hundreds of billions.
This competitive environment has also spurred a wave of deals. In March, Roche entered a $5.3 billion co-development deal with Zealand Pharma for an obesity candidate, and AbbVie licensed Gubra’s obesity drug for $2.2 billion. More recently, Novo Nordisk partnered with Septerna in a $2.2 billion collaboration to develop oral small molecules for obesity and cardiometabolic diseases.
