HM17321: Hanmi Pharm's muscle-sparing obesity drug poised to reshape $97.6b market

HM17321, a next-generation obesity drug candidate that Hanmi Pharm licensed to Genentech — a subsidiary of global pharmaceutical giant Roche — in a deal worth up to $2.3 billion, is widely regarded as a potential game-changer in the global obesity treatment market, projected to reach $97.6 billion.

The compound belongs to the non-incretin class and can overcome the most-cited shortcoming of the dominant glucagon-like peptide-1 (GLP-1) drugs: muscle loss and associated side effects.

HM17321 is an analogue that acts on urocortin-2 (UCN2) receptors, which regulate energy metabolism, appetite and cardiovascular function. Unlike existing incretin-based treatments — such as Novo Nordisk's Wegovy, a single agonist, or Eli Lilly's Mounjaro, a dual agonist — that suppress appetite and stimulate insulin secretion to reduce body weight, HM17321 works through a distinct next-generation mechanism. It boosts the body's own metabolic activity to selectively reduce fat while preserving or even increasing muscle mass.

Despite their strong weight-loss results, existing GLP-1 treatments carry a well-known limitation: a significant portion of the weight lost comes from lean mass, including muscle, which lowers basal metabolic rate and can trigger rebound weight gain after patients stop the drug. Nausea, vomiting and other gastrointestinal side effects, along with the inconvenience of frequent injections, have also been cited as major factors undermining long-term patient adherence.

HM17321, by contrast, demonstrated meaningful weight reduction alongside preserved muscle mass in preclinical studies even when administered alone. Combined with existing GLP-1 agents, it showed a synergistic effect — amplifying weight loss while optimizing body composition. As a peptide-based compound, it also offers broad potential for expansion into combination strategies, including fixed-dose combinations with incretin-class agents.

According to IQVIA, the global obesity treatment market is forecast to reach $97.8 billion by 2034. Against that backdrop, competition among global pharmaceutical companies is rapidly moving beyond a simple race for higher weight-loss percentages. The field is shifting toward multi-agonists incorporating glucagon or gastrin, amylin analogues, oral formulations, microneedle patches and once-monthly long-acting injectables — all aimed at improving patient convenience and the quality of weight loss.

That context explains why Roche and Genentech placed a large upfront payment of 285 billion won on HM17321, which is still in Phase 1 trials. While Novo Nordisk and Eli Lilly have moved to secure next-generation mechanisms through amylin analogues and activin receptor-based compounds designed to preserve muscle, Roche has moved first to lock in what analysts consider the most differentiated non-incretin drug pipeline available.

The emergence of HM17321 carries broader significance. At an inflection point where the obesity treatment market is evolving from simple appetite suppression toward a precise metabolic-therapy paradigm that manages muscle and body composition together, it demonstrates that Korean biotech's independent research and development capabilities have earned recognition as a global standard.

As domestic companies accelerate the search for new targets beyond the limitations of existing GLP-1 drugs and develop differentiated formulation technologies, competition for leadership in the global obesity treatment market is expected to intensify further.