Hanmi Pharm, which recently drew attention by signing a technology export (license-out) agreement with US pharmaceutical company Eli Lilly worth up to approximately KRW 2 trillion, has now unveiled a candidate for a so‑called “miracle obesity treatment” that reduces fat while increasing muscle, attracting intense interest.

Hanmi Pharm announced on the 16th that it had disclosed for the first time the research results for its muscle-increasing obesity drug candidate “LA-MSTN (development code HM500197)” at the American Diabetes Association (ADA) 2026 meeting, held in New Orleans, US, from the 5th to the 8th (local time). It is the company’s second muscle-increasing obesity treatment, following “LA-UCN2 (HM17321),” regarded as the world’s most promising first muscle-increasing obesity drug. The presentation on the 7th reportedly drew so many participants seeking to review the obesity drug data firsthand that it was difficult to find an empty seat. The company presented eight research results on the two new drugs at this conference.

A Hanmi Pharm representative said, “There was significant interest in the development strategy for next-generation obesity treatments, key differentiation points, and preclinical research results,” adding, “Questions continued regarding the development roadmap and commercialization strategy, and some global companies even requested separate meetings.”

According to Hanmi Pharm, in the field of obesity and metabolism, there is growing interest in “high-quality weight loss,” which focuses on effectively reducing body fat while preserving or enhancing muscle. This has emerged as a core theme in next-generation treatment strategies.

Current glucagon-like peptide-1 (GLP-1) class obesity drugs achieve about 15–20% weight reduction through an appetite-suppressing mechanism, but up to 40% of the weight loss is due to muscle loss, which is a major limitation. In addition, because of a decline in basal metabolic rate, side effects such as fat regain (yo-yo effect) after drug discontinuation are reported to occur. ● New mechanism that controls and regulates muscle growth… “A step closer to high-quality weight loss”

Against this backdrop, combination research that modulates myostatin or activin pathways, both involved in muscle growth, is drawing attention. Myostatin is a protein in the body that suppresses muscle growth. Individuals who are genetically deficient in myostatin tend to have a relatively higher muscle mass and a “Hulk-like” body type even without exercise. In line with this characteristic, mechanisms that inhibit myostatin production to increase muscle mass are gaining interest in the obesity treatment field. Activin is a protein hormone involved in various physiological functions, including cell growth and differentiation and hormone regulation. Mechanisms that regulate activin are receiving attention alongside myostatin. However, most candidate substances under development are limited to antibody- and Fc fusion protein-based approaches. Fc fusion protein technology primarily serves as a platform to extend the duration of drug action in the body, and similar technologies are applied in products such as Wegovy and Zepbound.

Hanmi Pharm’s HM500197 can be regarded as the world’s first peptide-based obesity treatment. It is essentially a drug created by synthesizing peptide fragments—protein segments that regulate metabolism in the human body. HM500197 is designed to selectively inhibit only myostatin, thereby increasing lean mass (components other than fat) primarily in skeletal muscle. In effect, it functions as a muscle-enhancing agent. Unlike other antibody-based drugs, it can be more easily developed in combination or as a fixed-dose combination with incretin-class therapies of the same modality, which is expected to improve patient convenience going forward, according to a Hanmi representative.

According to the presentation at the conference, in in vitro studies of this candidate, Hanmi Pharm confirmed myostatin inhibition activity at a level comparable to “bimagrumab,” an antibody-based muscle-preserving drug. In addition, no inhibitory activity was observed against non-target cytokines, indicating excellent selectivity for myostatin. In in vivo studies, HM500197 demonstrated a superior effect in selectively increasing lean mass in skeletal muscle compared with bimagrumab. By minimizing off-target effects, the candidate also showed differentiated outcomes in terms of safety, the company explained.

In particular, HM500197 showed dose-dependent increases in lean mass and selective increases in skeletal muscle mass in a high-fat diet-induced obese mouse model. When co-administered with a GLP-1 class drug, it effectively suppressed muscle loss while inducing body weight reduction centered on body fat, thereby providing scientific evidence supporting its therapeutic potential for “high-quality weight loss.” Together with the HM500197 data, Hanmi Pharm also disclosed eight new studies on HM17321, a candidate regarded as the world’s first muscle-increasing obesity drug. According to the company, a Phase 1 clinical trial of HM17321 is currently progressing smoothly in the United States. The studies presented at this conference focused on thoroughly elucidating the potential for combination with drugs of various mechanisms, the drug’s mechanism of action in the body, and its therapeutic potential related to musculoskeletal, cardiovascular, and renal protection.

Hanmi emphasized that HM17321 is fundamentally differentiated from other obesity drugs as a treatment targeting integrated efficacy, with a focus on fat reduction, muscle increase, and improvement of exercise and metabolic functions.

Choi In-young, Executive Vice President and Head of Hanmi Pharm’s Future Growth Division, said, “Starting with ‘efpeglenatide,’ Korea’s first independently developed obesity treatment, and continuing with our next-generation triple agonist (LA-GLP/GIP/GCG, HM15275, Phase 2), HM17321 (Phase 1), and HM500197, we have further solidified Hanmi’s differentiated, customized obesity treatment portfolio through the ‘H.O.P (Hanmi Obesity Pipeline) project’,” adding, “In particular, our two muscle-increasing obesity drug pipelines will serve as game changers that reshape the global market landscape, overcome the limitations of currently marketed drugs, and present a new treatment paradigm.”

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