Korea’s Hanmi Pharmaceutical has released new preclinical data on its experimental obesity drug HM17321, reporting that the candidate led to fat reduction and lean mass gain in mice -- a dual effect the company says has long been considered biologically unfeasible.

The data were presented at the ISMB/ECCB 2025 conference, held July 20 to 24 in Liverpool, U.K.

HM17321 is a urocortin 2 analog that selectively targets corticotropin-releasing factor 2 (CRF2) receptors, rather than incretin pathways like glucagon-like peptide-1 (GLP-1). It was designed using Hanmi’s internal AI-driven structural modeling platform. 

In studies using diet-induced obese mice, Hanmi said the drug significantly reduced fat mass, increased fat-free mass, and improved muscle function, as measured by wire hang tests and body composition analysis.

Box plots shown in the poster illustrate that animals treated with HM17321 had greater grip strength, leg and arm muscle mass, and lower trunk and whole-body fat mass compared to vehicle-treated controls. In particular, serum proteins linked to fat mass loss and skeletal muscle strength were upregulated after treatment.

To determine whether these effects might translate to humans, Hanmi mapped the mice’s protein profiles against a human proteome–phenome database, a large dataset that links protein expression patterns to physical traits such as body composition and strength.

The analysis predicted similarities between the drug-induced molecular signature in mice and those found in people with low fat mass, high lean mass, and strong grip strength.

The company used a machine learning model to integrate data from more than 10,000 mouse serum proteins with large-scale human multi-omics datasets. According to Hanmi, this approach allows researchers to identify potential clinical outcomes and off-target effects early in the process, reducing the risk of failure in human trials.

“This is scientific validation that HM17321, now preparing to enter phase 1 trials, may replicate its pharmacological effects in humans,” said Choi In-young, head of the R&D Center at Hanmi Pharm. “We are shifting the obesity treatment paradigm from simple weight loss to qualitative loss that improves muscle function and metabolic health, aiming to define a new global standard in obesity care.”

Hanmi plans to initiate a phase 1 trial in the fourth quarter of 2025 to confirm these effects in humans.