Moonwalk Biosciences closed a $70 million Series B on September 8 to develop obesity medicines that work directly in fat tissue. The California biotechnology company is pursuing treatments for people with obesity and related metabolic diseases, but its drugs are not yet in human trials. Its aim is to change the behavior of fat cells without relying on reduced appetite.
The proposed medicines use small interfering RNA, or siRNA, to reduce the activity of selected genes. Delivery is central to the approach: the molecules must reach fat cells and act on the intended target. Moonwalk is investigating mechanisms involved in storing fat, releasing it and managing energy, rather than treating every change in body weight as the same biological outcome.
To choose those targets, researchers compare genetic and gene-regulation data from different types of human fat tissue, including samples from people with and without obesity. They then test promising targets in human fat cells in the laboratory and in animal disease models. The workflow connects a proposed biological explanation to an experiment that can show whether changing that gene actually changes fat-cell behavior.
That work remains drug development, not an available treatment. Moonwalk's pipeline lists its lead obesity program in studies intended to support an application to begin human testing, with other programs still preclinical. The company reports animal results suggesting fat reduction while preserving lean mass. Whether that combination can be achieved safely in people is still an open question; the results are not a demonstrated clinical benefit.
Alpha Wave and YK Bioventures co-led the financing, joined by Eli Lilly, Gaorong Ventures and existing investors ARCH Venture Partners, Khosla Ventures and Future Ventures. CEO Alex Aravanis told BioXconomy that the capital is intended to advance the lead program into first-in-human studies in late 2027, develop additional candidates and support the discovery platform. Lilly's participation is an investment, not evidence of an approved medicine or a commercial supply contract.
For the business, the next transition is from finding targets to producing a medicine suitable for clinical testing. Aravanis described chemistry, manufacturing and clinical development as a growing focus, with future decisions about advancing programs internally or with partners depending on the data. The meaningful milestone will be a human study that tests the fat-cell approach, rather than another laboratory result being treated as proof of how patients will respond.