Atrogi has announced positive human data for ATR‑258, its first‑in‑class oral GRK2‑biased β2‑adrenergic modulator designed to improve muscle function and body composition.
In an 8‑week investigator‑initiated study in 13 overweight or obese adults, the therapy was well tolerated and associated with an approximately 13% mean improvement in lower‑extremity muscle power. Participants also saw statistically significant reductions in fat mass and increases in lean mass.
The open‑label, single‑arm trial, led by Professor Morten Hostrup, evaluated three ascending dose levels of ATR‑258. Treatment resulted in a mean 1.1 kg reduction in fat mass and a 0.8 kg increase in lean mass. Atrogi said the profile highlights the therapy’s potential in metabolic and muscle‑related diseases with high unmet need.
Professor Tore Bengtsson, Chief Scientific Officer and Founder of Atrogi, said: “These first clinical data give us important confidence that our approach is translating. To see fat loss alongside an increase in lean muscle mass and improvement in muscle function represents a truly differentiated profile, and is highly encouraging.”
He added: “Beyond muscle-sparing weight loss, we believe this mechanism also warrants investigation in sarcopenia and rare diseases marked by substantial muscle loss and weakness.”
The findings build on a landmark Cell publication from 2025, which established Atrogi’s GRK2‑biased signalling approach and detailed first‑in‑human safety data from a 69‑subject phase 1 trial. The new results provide first human proof‑of‑mechanism and support plans to begin a phase 2 trial in 2027.
Professor Morten Hostrup, Principal Investigator, commented: “As a researcher who has long studied β2-adrenergic receptor signalling in skeletal muscle, I was curious whether a biased, highly selective GRK2 modulator could harness this pathway differently – driving beneficial changes in muscle mass and function without the trade-offs seen with classical β2-agonists.”
He continued: “What struck me most was the magnitude of the signal in lower-extremity power.”
Paul Little, Chief Executive Officer at Atrogi, said: “These results are a major step forward for Atrogi and we thank everyone involved. We are a phase 2‑ready biotech with a first‑in‑class, next‑generation oral GRK2‑biased β2‑adrenergic modulator.”
He added: “We now have human data pointing to a unique profile in metabolic health in a broad context where muscle becomes medicine.”
