Eli Lilly halts bima diabetes combination trial, Laekna "named" and shares surge

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On September 25, according to the U.S. clinical trial registry, Eli Lilly withdrew the Phase IIb clinical trial of ActRIIA/B monoclonal antibody bimagrumab in combination with the core component of semaglutide, tirzepatide, for the treatment of patients with type 2 diabetes, citing "strategic business reasons."

This trial was originally planned to randomly assign 180 overweight or obese participants with diabetes to receive bimagrumab, tirzepatide, or the combination of both, monitoring weight loss and fat/muscle distribution over 70 weeks. The trial was scheduled to run from October 21, 2024, to January 2027. Lilly emphasized that routine assessments are conducted on all programs to optimize resources and did not disclose specific reasons for the trial's termination. The general interpretation is that the company needs to focus resources on more promising research in the obesity indication.

This decision does not mean Lilly is abandoning the bimagrumab track. The company is still conducting a Phase II trial for non-diabetic obese adults, which also evaluates the combination effect of bimagrumab and tirzepatide. A company spokesperson stated that the results will be read out in 2026.

In terms of timeline, compared to the diabetes trial originally planned to end in 2027, the readout for the obesity indication comes a year earlier, and Lilly is focusing efforts on the field of obesity, which is more likely to be approved first.

"High-Quality Weight Loss" Remains Important

Bimagrumab, developed by VersanisBio, can block Activin II-type receptor (ActRII), thereby inhibiting muscle degradation and promoting muscle growth. In the BELIEVE 2b Phase II trial, the combination of bimagrumab and GLP‑1 drug semaglutide resulted in an average weight loss of 22.1% over 72 weeks, of which 92.8% of the weight loss came from fat, with lean body mass almost unchanged; semaglutide monotherapy resulted in a weight loss of 15.7%, of which only 71.8% came from fat.

Even more impressive, bimagrumab monotherapy not only led to a 10.8% weight loss, but all of this weight loss came from fat, and lean mass even increased by 2.5%. This result proves that blocking ActRII signaling can address the problem of muscle loss caused by GLP‑1 drugs, achieving "fat loss without muscle loss."

However, "high-quality weight loss" is still at a preliminary validation stage. The clinical community generally believes that future combination therapies must not only show superiority over GLP‑1 monotherapy in weight control but also provide comprehensive benefits such as improvement of muscle function or metabolic indicators.

Therefore, Lilly's termination of recruitment for the yet-to-start diabetes trial is likely based on comprehensive consideration of commercial priorities and resource allocation.

As of now, Lilly's official website shows that the Phase II trial for the obesity indication is still recruiting. The age range is 18–75 years, and it is expected to enroll 240 obese or overweight adults to compare the safety and efficacy of various combinations of bimagrumab, tirzepatide, and placebo over 70 weeks. According to the publicly disclosed timetable, the trial period is October 21, 2024–January 2027, but the company says primary results will be available as early as 2026. This means that if efficacy is favorable, Lilly could apply for the obesity indication of this combination therapy as early as 2027.

By comparison, trials for the diabetes indication have not yet formally started, the evaluation criteria are more complex, and the approval pathway is also more difficult; against the background that GLP‑1 drugs have already proven very effective in treating diabetes, whether adding an antibody drug can show clear advantages is still uncertain. This may be the fundamental reason why Lilly chose to drop this indication.

An Opportunity for Laekna?

After the news that Lilly halted the trial, Laekna Therapeutics (02105.HK) shares surged against the trend. At one point, Laekna's share price rose over 15%. This is partly because bimagrumab's withdrawal from the diabetes trial reduced potential competition, and partly because it highlighted the value of Laekna's LAE102 pipeline in collaboration with Lilly.

LAE102 is a self-developed ActRIIA monoclonal antibody from Laekna. In November 2024, the company reached a global collaboration with Lilly, where Lilly is responsible for clinical development and commercialization in the U.S. market, while Laekna retains global rights. The company expects to announce preliminary results of LAE102 multiple ascending dose (MAD) studies in China and initial results of U.S. Phase I trials in the "second half of 2025."

Previously, in June 2025, at the American Diabetes Association (ADA) scientific meeting, Laekna released its first human research data:

Design: Healthy subjects received a single intravenous or subcutaneous injection of LAE102 at four dosage levels; overweight and obese populations were also recruited for exploration.
Safety: After a single administration, no serious adverse events were observed, and most adverse events were Grade 1 injection site reactions; no laboratory abnormalities.
Pharmacokinetics/Pharmacodynamics: Single dosing resulted in a short-term increase in Activin A in the body, with this hormone remaining elevated for about 28 days in the high-dose group, suggesting LAE102 has a long half-life and can continuously suppress the target; pharmacokinetic/pharmacodynamic data suggests LAE102 has potential efficacy in overweight and obese populations, supporting further clinical development.

The clinical obesity research team at Zhongshan Hospital affiliated to Fudan University believes that this first-in-class antibody, LAE102, is expected to further reduce fat while maintaining lean body mass, providing new tools for high-quality weight loss.

Laekna's management also emphasized that, based on the efficacy of GLP‑1 drugs, the company will work with Lilly to advance combination therapies, aiming to develop the next generation of high-quality weight loss drugs under the concept of "losing fat and gaining muscle."

Market and Competitive Landscape

Following the weight loss wave driven by GLP‑1 drugs, more and more companies are aiming at the "fat loss without muscle loss" 2.0 era. The ActRII antibody collaborations between Lilly & Versanis and Laekna are just some among many; Regeneron/ScholarRock’s bispecific combinations, Veru’s oral selective androgen receptor modulator enobosarm, and Biohaven’s myostatin inhibitor have all released early muscle-protection data.

Most companies plan to add muscle-regulating factors on top of GLP‑1 drugs to demonstrate additional clinical benefit. Industry forecasts suggest that the market size for muscle-protective weight loss drugs could reach tens of billions of dollars by 2035.

For Lilly, although it has suspended bimagrumab for the diabetes indication, the company’s obesity pipeline remains strong:

tirzepatide (Zepbound) has been approved for weight loss, and is a star product on the market;
retatrutide (GIP/GLP-1/glucagon triple agonist) is undergoing the Phase III TRIUMPH program;
orforglipron (oral small-molecule GLP‑1 agonist) and other new-generation products are also under development;
The collaboration with Camurus is developing long-acting injectable formulations, and the collaboration with Juvena Therapeutics is focused on muscle health factors.

This clinical adjustment by Lilly for bimagrumab signals to the market that obesity indications have greater commercial priority, the data readout timetable is accelerating, and it further highlights the potential of the new track combining muscle gain and fat loss. At the same time, partners such as Laekna may also benefit from it.

Within the next year, early results are expected from the bimagrumab and tirzepatide obesity trial, and the LAE102 multiple dose trial is also set to commence. Will "fat loss without muscle loss" truly enter the mainstream or be a flash in the pan? The data will soon provide the answer.

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