AstraZeneca has finalized the acquisition of Swiss biotech SixPeaks Bio in a deal valued at up to $300 million, reinforcing its push into next-generation obesity treatments that emphasize muscle preservation. The agreement includes a $170 million upfront payment, an additional $30 million in two years, and up to $100 million tied to regulatory milestones. The acquisition, completed in late October, marks a key step in AstraZeneca’s broader effort to redefine obesity care as a metabolic and medical challenge rather than a cosmetic issue.
Targeting Fat Loss Without Sacrificing Muscle
SixPeaks Bio, launched by Versant Ventures in 2024 through its Ridgeline Discovery Engine in Basel, is developing bispecific antibodies that block activin type IIA and IIB receptors. This mechanism is designed to help patients shed fat while maintaining muscle mass, addressing a limitation seen in current obesity drugs such as Novo Nordisk’s Wegovy and Eli Lilly’s Zepbound. AstraZeneca’s CEO Pascal Soriot explained that the acquisition is part of the company’s strategy to pursue “new mechanisms that help patients lose fat but not so much muscle,” highlighting a shift toward treatments that sustain metabolic health rather than merely reduce weight.
A Medical, Not Aesthetic, Approach
Soriot underscored AstraZeneca’s intent to distinguish itself in the increasingly crowded obesity market by focusing on medical outcomes. During the company’s third-quarter earnings call, he described obesity as a disease affecting organ health, pointing specifically to visceral fat accumulation around the liver and heart. “This is what we need to drive down,” Soriot said, adding that muscle preservation is a “fundamental aspect of keeping people healthy.” This focus aligns with AstraZeneca’s broader therapeutic philosophy of improving long-term health outcomes rather than promoting superficial weight loss.
SixPeaks’ Scientific Edge
Founded in 2022, SixPeaks Bio has made rapid progress in developing biologics that address muscle loss linked to weight reduction. Its lead program involves an activin IIA/B receptor antibody designed to preserve skeletal muscle mass in humans while promoting fat reduction. Preclinical studies have shown promising results, with SixPeaks’ molecules outperforming competing antibodies in maintaining muscle integrity in both lean and obese mouse models. The company is also advancing combination therapies that pair its activin-targeting antibody with GLP-1 peptides to enhance fat loss without the adverse muscle depletion associated with current GLP-1-based drugs.
Bolstering AstraZeneca’s Obesity Pipeline
The deal builds on AstraZeneca’s growing portfolio in metabolic disease. The company already has three obesity drug candidates in Phase 2 trials and has been broadening its obesity pipeline through strategic partnerships. Notably, AstraZeneca signed a $185 million agreement in November 2023 with Chinese biotech Eccogene for its oral GLP-1 therapy ECC5004, a deal that could reach $1.83 billion with milestones. AstraZeneca has also collaborated with Regeneron Pharmaceuticals on metabolic research, complementing its existing GLP-1 product, Bydureon.
Versant Ventures’ Build-to-Buy Success
The SixPeaks acquisition also validates Versant Ventures’ build-to-buy model, which allows larger pharmaceutical partners to acquire startups they helped incubate once development milestones are met. Alex Mayweg, Managing Director at Versant and chair of SixPeaks’ board, said AstraZeneca’s “drive, interest, capability, and motivation to win in this race was extremely strong.” The transaction reflects AstraZeneca’s strategic use of external innovation to accelerate entry into fast-moving therapeutic categories.
AstraZeneca’s Growth Momentum
The acquisition coincides with strong financial results for AstraZeneca. In the third quarter, the company reported product revenues of nearly $15.2 billion, marking a 10% year-on-year increase at constant exchange rates and surpassing analyst expectations by around 2%. Its oncology division led the growth, generating $6.6 billion in revenue with an 18% rise. AstraZeneca maintained its full-year outlook, expecting high single-digit revenue growth and low double-digit increases in core earnings per share.
By acquiring SixPeaks Bio, AstraZeneca is positioning itself at the forefront of a new generation of obesity treatments focused on metabolic health and muscle preservation. As the pharmaceutical industry pivots from viewing obesity as a lifestyle condition to treating it as a chronic disease, this deal underscores AstraZeneca’s intent to deliver therapies that improve quality of life while addressing the biological complexities of fat and muscle balance. The move not only strengthens its metabolic portfolio but also signals a shift in how major drugmakers approach one of the world’s most pressing health challenges.