Obesity impacts millions of people around the world and increases the risk of health problems like type 2 diabetes and heart disease. For many, diet and exercise alone aren’t enough to lose weight.
Bimagrumab, a new treatment being tested, could help by reducing fat while preserving muscle. As of July 12, 2025, it’s still in clinical trials and doesn’t have a set price yet. This article looks at how Bimagrumab works, what the trials have shown so far, and what it might cost in the future.
Obesity and the Need for New Treatments Treatments
Obesity is when someone has a body mass index (BMI) of 30 or more. It can be caused by genetics, environment, and lifestyle, and it’s linked to serious health problems like diabetes and heart disease.
Most weight loss drugs today cause people to lose both fat and muscle which isn’t great for long-term health. New treatments like Bimagrumab focus on helping people lose fat while keeping their muscle.
What is Bimagrumab?
Bimagrumab, also known as BYM338, is a fully human monoclonal antibody. It targets activin type II receptors (ActRIIA and ActRIIB), which regulate muscle growth and fat metabolism.
By blocking these receptors, Bimagrumab helps increase muscle mass while reducing fat. This sets it apart as a potential obesity treatment that offers an approach beyond appetite suppression.
Mechanism of Action
Bimagrumab helps muscles grow and reduces fat by blocking two proteins, activin and myostatin, which usually slow down muscle growth and promote fat storage.
It stops these proteins from working by attaching to their receptors. This can lead to more muscle, less fat, and better overall health, especially for people with obesity-related issues.
Development History of Bimagrumab
Initially developed by Novartis for muscle-wasting conditions like sporadic inclusion body myositis (sIBM), Bimagrumab received FDA breakthrough therapy designation in 2013 (according to Fierce Biotech).
However, it failed a Phase IIb/III study for sIBM in 2016. Versanis Bio later acquired the rights, focusing on obesity. In July 2023, Eli Lilly bought Versanis Bio for nearly $2 billion, advancing Bimagrumab’s development.
Clinical Trial Results
The Phase 2b BELIEVE trial, presented at the American Diabetes Association’s 85th Scientific Sessions in June 2025, studied Bimagrumab in obese patients without diabetes. Highlights of the results include:
- Combination Therapy (Bimagrumab + Semaglutide): Achieved a 22.1% reduction in baseline body weight over 48 weeks, with 92.8% of the loss coming from fat mass and a 1.2 kg increase in lean muscle mass.
- Semaglutide Alone: Resulted in a 16.2% weight reduction, with 71.8% from fat mass but a 2.1 kg loss in lean muscle mass.
- Bimagrumab Alone: Demonstrated significant fat loss and muscle gain, though less effective than the combination therapy.
These results highlight Bimagrumab’s ability to improve weight loss quality by preserving muscle, a notable advantage compared to current treatments..
Bimagrumab Price
As Bimagrumab is not FDA-approved as of July 2025, no market price exists. Estimates can be drawn from similar drugs:
| Drug | Type | Approximate Monthly Cost |
|---|---|---|
| Wegovy (semaglutide) | GLP-1 receptor agonist | $1,300 |
| Zepbound (tirzepatide) | GLP-1/GIP receptor agonist | $1,060 |
| Keytruda (pembrolizumab) | Monoclonal antibody (cancer) | $12,500+ |
Monoclonal antibodies like Bimagrumab are expensive to make, which makes them costly for patients. If approved, it could cost between $20,000 and $50,000 per year, depending on the dose, how it’s given (monthly IV), and market factors. This is just an estimate as the final price will depend on production costs, competition, and insurance deals..
Cost of Clinical Trial Participation
Clinical trials offer you to try Bimagrumab before it’s fully approved. Companies like Eli Lilly usually pay for the drug and medical care. However, you might have to pay for travel, a place to stay, or time off work. Make sure to check the trial details so you know what costs you may need to cover..
Safety and Side Effects
Clinical trials have reported mild side effects, including:
- Injection site reactions
- Nausea
- Headaches
Some studies observed temporary increases in liver enzymes and lipases, which may raise potential safety concerns. Further trials are needed to better understand these risks.
Patients are advised to consult their healthcare providers for more detailed information.
Comparison with Other Weight Loss Drugs
Unlike drugs like Wegovy and Zepbound that mainly lower appetite, Bimagrumab focuses on improving body composition. It helps keep muscle while reducing fat, solving a common problem with other weight loss drugs that can cause muscle loss.
This makes Bimagrumab a great option for people looking for healthier, long-term weight loss.
Future Outlook and Market Impact
If approved, Bimagrumab could change how obesity is treated by helping people lose fat while keeping their muscle. However, it might be expensive especially without insurance.
The obesity treatment market already has popular drugs like Wegovy and Zepbound, but Bimagrumab’s unique approach could appeal to people who don’t get good results from those options..
Challenges and Considerations
High costs and possible side effects are big challenges. Monoclonal antibodies are expensive to make, which raises prices. New weight loss drugs often aren’t fully covered by insurance at first. Plus, we need more long-term safety information to know if Bimagrumab is a good option..
Conclusion
Bimagrumab shows potential as an innovative obesity treatment, with Phase 2b trials demonstrating notable fat loss and muscle preservation.
However, as of July 2025, it has not received FDA approval, and no official market price has been established. If approved, annual costs are estimated to range between $20,000 and $50,000. Patients and healthcare providers are encouraged to stay informed about its development, availability, and pricing updates..
FAQ
What is Bimagrumab’s current status?
Bimagrumab is currently in Phase 2b clinical trials as of July 2025, focusing on the treatment of obesity.
When might Bimagrumab be available?
If the trials are successful, Bimagrumab could move to Phase 3 and may receive approval by 2027 or later.
What is the price of Bimagrumab?
A price has not been set since it’s not yet approved. Based on similar drugs, it could cost between $20,000 and $50,000 annually.
Will insurance cover Bimagrumab?
Insurance coverage will depend on the drug’s approval and individual insurance policies. New drugs often face challenges with initial coverage.
What are the side effects of Bimagrumab?
Common side effects include nausea, headaches, and injection site reactions. More research is needed to understand any serious risks.
How does Bimagrumab compare to other drugs?
Unlike GLP-1 drugs that may lead to muscle loss, Bimagrumab is unique in reducing fat while preserving muscle mass.
Can I join Bimagrumab trials?
Eligible individuals can participate in trials. Visit ClinicalTrials.gov for details on current studies.