Novo Nordisk and Eli Lilly's Combination Therapy Achieves 22.1% Weight Loss Over 72 Weeks with 92.8% Fat Reduction in Phase II Trial

On July 12, 2025, the Phase II clinical trial results jointly announced by Novo Nordisk and Eli Lilly and Company garnered significant attention in the field of obesity treatment. The trial demonstrated that the combination therapy of Bimagrumab and Semaglutide not only achieved a notable 22.1% weight reduction over 72 weeks but also delivered a breakthrough result with 92.8% of the weight loss attributed to fat, while providing muscle protection, establishing a new paradigm for obesity treatment.

This 48-week clinical trial data shows that the combination therapy group demonstrated a significant advantage over monotherapy: subjects receiving Bimagrumab combined with semaglutide intervention,The average weight loss reached 22.1%, with fat tissue accounting for 92.8% of the reduction.In the control group using semaglutide alone, the weight loss was 15.7%, with fat reduction accounting for only 71.8%.

More crucially,The lean body mass (non-fat tissues such as skeletal muscle) preservation in the combination therapy group was significantly higher than that in the monotherapy group.，Effectively addresses the clinical pain point of "concurrent fat and muscle loss" in traditional weight-loss treatments.

Novo Nordisk's semaglutide as a GLP-1 receptor agonist,By suppressing appetite and delaying gastric emptying, it plays a role in weight loss, but long-term use poses a risk of decreased muscle mass.Bimagrumab, developed by Eli Lilly, is aMonoclonal Antibody Targeting Activin Type II Receptor (ActRII), which can block the receptor's negative regulation of muscle growth, maintaining muscle mass during weight loss.

This combination regimen has special clinical value for populations at high risk of sarcopenia (such as middle-aged and elderly obese patients, and those with chronic diseases combined with obesity).As the decline in muscle mass is directly associated with the reduction of physical function and metabolic homeostasis imbalance, combination therapy can ensure muscle function while promoting weight loss.

The breakthrough in this combination therapy lies in the precise targeting of ActRII (activin type II receptor).Studies have confirmed that ActRII plays multiple roles in human physiological regulation: its ligands (such as myostatin, activin A) can inhibit skeletal muscle development, while Bimagrumab, by blocking ActRII signaling, not only reduces fat accumulation but also promotes muscle maintenance, showing greater efficiency compared to strategies solely targeting myostatin.

In addition, ActRII is closely associated with metabolic disorders; for instance, mutations in ActRIIA can lead to pancreatic developmental abnormalities and induce diabetes.Suggesting that drugs targeting ActRII may simultaneously improve obesity and related metabolic complications, providing a new direction for comprehensive treatment.

Notably, Bimagrumab, which initially showed limited efficacy in the treatment of inclusion body myositis, has demonstrated cross-disciplinary potential in the field of obesity, underscoring the feasibility of cross-indication drug development.

Eli Lilly's strategic layout for this target is significant,In July 2023, Eli Lilly acquired Versanis Bio for $1.925 billion to strengthen its ActRII-related drug development capabilities; in the same year, it advanced the combination trial of the dual-target GLP-1/GIP agonist Zepbound with Bimagrumab, expanding application scenarios.

The combination therapy of Bimagrumab and Semaglutide not only brings a medical breakthrough in obesity treatment but also profoundly reshapes the competitive landscape of the global weight-loss drug market. From a market impact perspective, this therapy directly addresses the core pain point of traditional weight-loss drugs — "the inability to achieve both fat reduction and muscle preservation."Its hard data of "22.1% weight loss + 92.8% fat proportion" will significantly enhance patients' trust and acceptance of drug treatment, driving weight-loss medications from a "niche medical option" toward a "mainstream health intervention."

For niche markets, there is a demand for precision treatment targeting special populations such as middle-aged and elderly obesity, and chronic disease combined with obesity.The muscle-protective properties of combination therapy will carve out a differentiated track, squeezing the market space of traditional weight-loss solutions (such as single GLP-1 drugs, diet meal replacements, etc.).

Novo Nordisk and Eli Lilly's collaboration demonstrates a new trend of "complementary strengths and synergistic breakthroughs" among industry giants.Novo NordiskLeveraging the first-mover advantage of semaglutide in the GLP-1 field, Novo Nordisk has consolidated its leading position in the treatment of metabolic diseases.Eli LillyBy deeply exploring the ActRII target through Bimagrumab, they have successfully transformed "cross-border drug development" into a core competitive advantage. The combination of the two not only amplifies their respective technical barriers but also constructs an irreplicable collaborative ecosystem.This model may become an industry benchmark, and in the future, "powerful alliances" around core targets may replace the "closed-door research and development" of single enterprises, accelerating the iteration of weight-loss drugs from "single-target weight loss" to "multi-target metabolic regulation."

Looking ahead, if Phase III clinical trials continue to validate safety and efficacy, this combination therapy is expected to become the "gold standard" for obesity treatment, further boosting Novo Nordisk and Eli Lilly's market share in the global weight-loss market.At the same time, the successful application of the ActRII target will attract more pharmaceutical companies to invest in drug development within this field, driving weight-loss drugs to evolve from "pure weight reduction" towards a comprehensive upgrade of "fat reduction and muscle gain + metabolic improvement." This will ultimately provide more precise and healthier treatment options for over 1 billion obese individuals globally. Novo Nordisk and Eli Lilly and Company will also solidify their leading positions in the metabolic health field through this breakthrough.