Moonwalk raises $70M for a muscle-sparing fat drug

Ozempic and drugs like it changed how people lose weight. But they come with a downside: some of what patients lose is muscle, not just fat. Moonwalk Biosciences, a biotech near San Francisco, wants to fix that. This week, it raised $70 million for MW101, an experimental shot that targets fat tissue directly. The company says it spares muscle in the process.

The drug uses something called RNA interference, or RNAi. It works by switching off the specific gene that tells fat cells to store fat. That's different from GLP-1 drugs, which work by suppressing appetite instead. The company says patients would only need a shot twice a year. Compare that with the weekly injections Ozempic and Wegovy require. Backers reportedly include Eli Lilly, already one of the biggest players in weight-loss drugs. That's notable: Lilly's own bestsellers use a completely different mechanism than Moonwalk's. Betting on a rival approach is a sign the industry sees real potential in muscle-sparing drugs.

Keep reading — what to watch

Will it actually work in people? Nobody knows yet — MW101 hasn't been tested in a single human patient. Everything so far comes from lab work, not people. The real test starts when human trials begin, and that's still ahead. Until then, this is a well-funded bet, not a proven treatment.