Atrogi has dosed the first volunteers in a human trial of ATR-258, a muscle-preserving drug designed to help people lose fat without losing muscle.
The eight-week study is examining how ATR-258 affects muscle in overweight male volunteers.
Atrogi describes it as a first-in-class oral therapy designed to mimic some of the metabolic and muscle-related effects of exercise by helping muscle use fuel more efficiently and preserve lean tissue.
The trial begins as the obesity drug market faces a growing concern that not all weight loss is the same.
When body weight falls, some of that loss can come from muscle, and for older adults that may mean less strength, lower resilience and a harder path to healthy ageing.
Muscle is one of the clearest indicators of how well people age, helping support mobility, glucose control, balance, recovery and independence.
Drug developers are now looking not only at whether people lose weight, but also at whether fat loss can be achieved while lean tissue is kept.
The study is being led by associate professor Morten Hostrup of the University of Copenhagen, who will examine how ATR-258 affects human skeletal muscle through daily oral dosing over eight weeks.
The team will also assess whether the drug can activate muscle-building and metabolic pathways in a more targeted way, without causing broader unwanted side effects.
Hostrup said the aim was to understand how the approach could be used “to preserve, or even augment, muscle function in various conditions of muscle wasting, such as immobilisation, ageing and weight loss.”
That could extend the drug’s relevance beyond obesity into areas such as frailty and sarcopenia, the gradual loss of muscle mass and function often seen in later life.
The Stockholm-based company said the trial builds on a June 2025 Cell publication validating its platform, as well as earlier Phase 1 data from 69 subjects, which showed ATR-258 was safe and well tolerated in healthy volunteers and patients with type 2 diabetes.
Professor Tore Bengtsson, founder and chief scientific officer of Atrogi, said the new research builds on findings published in Cell in June 2025 and that Hostrup’s decision to sponsor the study supports the company’s science and technology.
He added that results are expected later this year.
Paul Little, chief executive officer of Atrogi, called the first dosing “an important milestone” and said the resulting muscle physiology data will help support the drug’s development across “metabolic and muscle-wasting conditions.”
The drug remains at an early stage of development.
So-called exercise mimetics, medicines that aim to reproduce the effects of physical activity, have long been one of the pharmaceutical industry’s most attractive but difficult goals.
A promising mechanism is not the same as clinical success, and a carefully designed human study is not the same as proof that patients will see a lasting, meaningful benefit.