Analysis
Moonwalk Biosciences announced the close of an oversubscribed $70 million Series B on September 8 to advance MW101, its lead adipose-targeted RNA interference candidate for obesity, toward first-in-human trials, according to BioSpace. The round was co-led by Alpha Wave and YK Bioventures, with new investor Eli Lilly and Company and Gaorong Ventures joining returning backers ARCH Venture Partners, Khosla Ventures and Future Ventures.
Moonwalk launched in 2024 with backing from Arch Venture Partners and Khosla Ventures, BioPharma Dive reported, to build a treatment based on gene-editing technology licensed from the Broad Institute. Its platform delivers siRNA therapeutics selectively to adipose tissue, aiming to modulate non-incretin pathways involved in energy homeostasis, adipogenesis, lipolysis and thermogenesis while minimizing effects on other organs. The new funding brings total capital raised since launch to roughly $127 million.
The RNAi obesity field now includes several well-capitalized competitors pursuing a similar non-incretin thesis:
“The new funding brings total capital raised since launch to roughly $127 million.”
- Arrowhead Pharmaceuticals -- its ARO-INHBE candidate targets the INHBE pathway and entered a first-in-human Phase I trial in November 2024.
- Alnylam Pharmaceuticals -- the RNAi pioneer behind several approved liver-targeted drugs, now running a Phase I trial of ALN-6222, an investigational siRNA obesity candidate.
- SanegeneBio -- also chasing an adipose-targeted approach with candidate SGB-7342, closing a $110 million Series B last December that likewise included Eli Lilly as a strategic investor.
Eli Lilly backing both Moonwalk and SanegeneBio within nine months looks less like conviction in either specific chemistry and more like Lilly buying optionality across the non-incretin obesity field while its own GLP-1 franchise, alongside Novo Nordisk's, continues to dominate a market some analysts size at roughly $200 billion.
The open question is delivery. RNAi to the liver is proven -- Alnylam has multiple approved drugs built on that route, including Leqvio for cholesterol -- but delivering siRNA selectively to adipose tissue at meaningful concentration is a harder, less-validated problem. Liver-targeted RNAi works because the liver's blood supply and cell structure make it unusually easy to reach with lipid nanoparticles; fat tissue is more diffuse and harder to target without off-tissue effects, which is precisely the engineering problem Moonwalk says its platform solves. Moonwalk won't have human data on whether its chemistry actually does until late 2027 at the earliest, which is a long runway for a Series B to fund on preclinical promise alone.
The commercial logic, if the science holds, is durability rather than magnitude. GLP-1 drugs require ongoing weekly or monthly dosing to maintain weight loss, and patients who stop taking them tend to regain the weight. An RNAi therapy that silences a fat-storage gene for months at a time on a single dose -- Alnylam's own liver-targeted drugs already demonstrate multi-month dosing intervals -- would compete on a completely different axis than incremental improvements to GLP-1 efficacy, which is the bet every company in this cluster, Moonwalk included, is underwriting years before any of them will know if it pays off.
