An oral drug that can increase muscle mass and reduce fat without exercise has entered human clinical trials for the first time.
Researchers at the University of Copenhagen, Denmark, and biotech company Atrogi announced that they have begun an eight-week clinical trial in which a drug named ‘ATR-258’ will be administered to 10 overweight men once a day.
This study is in the early clinical stage to evaluate muscle mass, strength, and metabolic changes in actual patients, and the results are scheduled to be released later this year.
This clinical trial is based on the results of existing preclinical and early human studies. The mechanism of action of the drug was first presented in a paper (GRK-biased adrenergic agonists for the treatment of type 2 diabetes and obesity) published in the international journal Cell in 2025.
The research was conducted jointly by multi-institutions including the Karolinska Institutet in Sweden, the University of Copenhagen in Denmark, and Monasae in Australia, and participants including Thore Bengtsson, Roger Summers, and Morten Hostrup.
According to the researchers, ATR-258 acts as a ‘biased agonist’ that selectively stimulates the beta-2 adrenergic receptor present in skeletal muscle.
In this process, it was shown that muscle glucose uptake increased, energy metabolism was activated, and insulin sensitivity improved. In animal experiments, the effect of maintaining or increasing muscle mass along with reducing fat mass was observed, raising the possibility of compensating for the problem of muscle loss that has been pointed out in existing GLP-1 type obesity treatments.
The key to clinical trials currently underway is to verify whether these mechanisms are reproduced in actual humans. The researchers plan to comprehensively evaluate metabolic indicators such as changes in muscle mass, strength, blood sugar control, and blood pressure. Developer Artology expects that this drug will be able to produce an exercise effect of about 30 minutes by mimicking some of the physiological responses that occur during exercise.
Experts believe that if this drug is commercialized, it could become a new treatment option for obese patients, elderly people who have difficulty exercising, and patients with muscle wasting diseases such as muscular dystrophy. However, the size of the effect in actual clinical trials, long-term safety, and whether it can completely replace exercise must be confirmed through additional research.
Meanwhile, in the field of obesity treatment, the use of GLP-1 drugs such as Wigobi and Maunjaro is expanding, but the fact that muscle mass can also decrease during the weight loss process has been pointed out as a limitation. Drugs such as ATR-258 may be used as a complement to these treatments or as a muscle maintenance strategy after weight loss.
The researchers plan to verify the long-term effects through large-scale clinical trials in the future, and are expected to take about 5 years to commercialize.