Why Roche is excited about Hanmi’s muscle-sparing obesity drug

Roche’s Genentech agreed to pay Hanmi Pharmaceutical $190 million upfront, with the deal potentially worth about $2.3 billion, for rights outside South Korea to HM17321.

HM17321 is a long-acting urocortin-2 (UCN2) analog that selectively activates the CRF2 receptor. Unlike GLP-1 drugs, it uses a non-incretin mechanism aimed at reducing fat while preserving—or potentially increasing—lean muscle.

Roche is particularly interested because preclinical studies suggested weight loss was driven largely by fat reduction, with preserved lean mass and improved muscle function. In animal studies, the drug also appeared promising both alone and alongside GLP-1-based treatments.

Reported preclinical findings included substantial fat-mass reductions in obese animals, increases in lean mass, and improvements in measures such as grip strength. However, these results have not yet been demonstrated in humans.

Hanmi is conducting the Phase 1 study, which is assessing safety, tolerability, pharmacokinetics and pharmacodynamics in healthy volunteers and people with obesity. Genentech is expected to assume development from Phase 2 onward.

Roche executives emphasized that they are excited but cautious:
many apparently strong animal results fail to translate clinically, so the key test will be the upcoming human data.