Roche's Genentech licenses a Korean obesity drug designed to spare muscle in a deal worth up to $2.5 billion

What happened

The announcement is a company communication from the two firms involved, not an independent report or a regulatory decision.

The terms disclosed in the release are $190 million paid up front, as much as $2.3 billion more tied to development, regulatory and commercial milestones, and tiered royalties on any future sales. Several trade outlets described the package as roughly $2.5 billion by adding the upfront payment to the milestone ceiling, which is why the figure appears two different ways in coverage.

What makes the compound unusual is its target. HM17321 is an analog of urocortin 2, a natural hormone, and it works through the CRF2 receptor rather than the incretin pathway that GLP-1 medicines use. Hanmi describes it as potentially first in class, designed to strip fat while holding onto or improving lean body mass and muscle function. According to the release, animal work showed benefits both on its own and alongside GLP-1 based drugs, though no numbers were given. BioPharma Dive reported that Hanmi has run head-to-head animal studies, including in primates, against semaglutide.

The program is early. The FDA cleared Hanmi's application to begin human testing in November 2025, and a Phase 1 study is now measuring safety, tolerability, and how the drug moves through and acts on the body, first in healthy volunteers and then in people with obesity. Hanmi will finish that study, after which Genentech takes over development from Phase 2 onward.

In-Young Choi, Hanmi's senior executive vice president for research and development, framed the deal around body composition rather than weight alone. Boris L. Zaïtra of Roche's corporate business development group said the company looks to develop the medicine against unmet needs. At least one other company, the Danish firm Gubra, is working on a urocortin 2 program of its own.

What it means

This deal is a signal about where obesity drug development is headed. People who lose a lot of weight on GLP-1 medicines lose some muscle along with the fat, and that concern shows up constantly in patient conversations, especially for older adults and anyone worried about strength, balance, or falls. A large drugmaker paying nine figures up front for a muscle-sparing mechanism at Phase 1 tells you how seriously the industry takes the question.

Practically, though, nothing changes for anyone currently on treatment. The things that protect muscle during weight loss today remain unglamorous and available now: adequate protein, resistance training, and a rate of weight loss your care team is comfortable with.

What it does not mean

There is no human efficacy evidence for this drug. Phase 1 studies are built to answer questions about safety and dosing in small groups, not to show weight loss or muscle preservation. The muscle-sparing claim rests on animal models, and animal results in obesity have repeatedly failed to carry over to people. The headline dollar figure is also mostly hypothetical, since milestone payments are only earned if the drug clears hurdles it has not yet reached. Beyond that, it has not been established that keeping more lean mass during weight loss actually translates into better strength, function, or long-term health, so "preserves muscle" should be read as a development goal rather than a proven benefit. A drug at this stage is realistically years away from a pharmacy, and most candidates at this stage never arrive.