UBT251 vs Retatrutide: The Next Chapter in Triple-Agonist Obesity Research

The development of obesity medicines is moving rapidly beyond conventional GLP-1 receptor agonists. After single-receptor treatments such as semaglutide and dual GLP-1/GIP agonists such as tirzepatide, researchers are now focusing on molecules that activate three metabolic pathways at the same time.

Two of the most closely watched candidates are retatrutide, developed by Eli Lilly, and UBT251, originally developed by United Biotechnology and now being developed internationally with Novo Nordisk.

Retatrutide remains further ahead in clinical development, but UBT251 attracted significant attention after producing up to 19.7% mean body-weight reduction after only 24 weeks in a Chinese Phase 2 obesity trial. The result has positioned UBT251 as one of the most promising new competitors in the emerging triple-agonist category.

What Is UBT251?

UBT251 is a long-acting synthetic peptide designed for once-weekly administration. It activates three hormone receptors involved in appetite, glucose regulation and energy metabolism:

• GLP-1 receptor
• GIP receptor
• Glucagon receptor

United Biotechnology initially developed the molecule. In March 2025, Novo Nordisk obtained exclusive development and commercialization rights outside mainland China, Hong Kong, Macau and Taiwan. The agreement included an upfront payment and potential milestone payments that could bring its total value to approximately $2 billion.

The licensing agreement reflects the growing strategic importance of triple-agonist medicines. Rather than depending on a single appetite-control pathway, these molecules are designed to coordinate several metabolic signals within one peptide.

Why Target Three Receptors?

GLP-1, GIP and glucagon each have different physiological functions. A triple agonist attempts to combine their complementary effects while maintaining an acceptable safety profile.

GLP-1

GLP-1 receptor activation supports glucose-dependent insulin secretion, reduces appetite and can delay gastric emptying. It forms the foundation of many modern medicines used in obesity and type 2 diabetes.

GIP

GIP also participates in glucose-dependent insulin secretion. When combined with GLP-1 activity, it may strengthen the overall effect on appetite, glucose control and body weight.

Glucagon

Glucagon receptor activation has a more complicated role. Glucagon can raise blood glucose, but it may also increase energy expenditure and influence lipid and liver metabolism. In a carefully balanced triple agonist, GLP-1 and GIP activity may help counter glucagon-related glucose elevation while preserving some of its potential metabolic benefits.

The clinical behavior of a triple agonist therefore depends not only on which receptors it activates, but also on the relative strength and duration of activity at each receptor. Two medicines targeting the same three receptors may still produce different efficacy, safety and tolerability profiles.

UBT251 Phase 2 Obesity Results

The UBT251 Phase 2 trial enrolled 205 Chinese adults with obesity or overweight accompanied by at least one weight-related condition. Participants had a mean starting body weight of 92.2 kilograms and a mean BMI of 33.1 kg/m².

Participants received weekly UBT251 injections at different dose and dose-escalation schedules or placebo for 24 weeks. The mean body-weight reductions recorded across the UBT251 groups ranged from:

• 13.6% to 19.7% with UBT251
• 2.0% with placebo

The highest-performing treatment group lost an average of approximately 17.5 kilograms. Researchers also reported that participants had not reached a clear weight-loss plateau when the 24-week treatment period ended.

The categorical results were also notable. Depending on the treatment group:

• Up to 98.1% of participants lost at least 5% of their starting weight.
• Up to 89.8% lost at least 10%.
• Up to 48.4% lost at least 20%.

The reported safety profile was generally consistent with the established GLP-1 receptor agonist class. The investigators did not identify an obvious dose-dependent increase in overall treatment-emergent adverse events during the 24-week study. However, the trial was relatively small and short, so larger and longer studies will be needed to characterize uncommon or delayed safety risks.

UBT251 and Type 2 Diabetes

UBT251 is also being investigated in people with type 2 diabetes. In another 24-week Chinese Phase 2 trial, the candidate produced mean HbA1c reductions of up to 2.16 percentage points and mean body-weight reduction of up to 9.8%.

The diabetes study evaluated weekly doses of 2 mg, 4 mg and 6 mg, alongside placebo and semaglutide 1 mg. These early results suggest that UBT251 may have potential across both obesity and glucose-management indications, although confirmation in larger international studies remains necessary.

How Does UBT251 Compare With Retatrutide?

Retatrutide is also a once-weekly peptide activating the GLP-1, GIP and glucagon receptors. Its clinical program is considerably more advanced than that of UBT251.

In retatrutide’s Phase 2 obesity trial, the highest dose produced:

• 17.5% mean weight reduction after 24 weeks
• 24.2% mean weight reduction after 48 weeks

These results established retatrutide as an important proof of concept for triple-receptor agonism in obesity treatment.

Later Phase 3 results strengthened that position. In the TRIUMPH-1 study, participants receiving 12 mg retatrutide lost an average of 28.3% of their body weight after 80 weeks. Among participants with a starting BMI of at least 35 who continued into a prespecified extension, average weight loss reached 30.3% at 104 weeks.

Retatrutide has also completed Phase 3 studies involving type 2 diabetes, knee osteoarthritis and obstructive sleep apnea. Eli Lilly reported meaningful improvements in body weight, HbA1c, cardiometabolic markers and several obesity-related complications, although regulatory review is still required before the medicine can become commercially available.

Is UBT251 Already Better Than Retatrutide?

It would be premature to reach that conclusion.

At first glance, UBT251’s 19.7% weight reduction at 24 weeks appears higher than the 17.5% reported with retatrutide at the same time point in its Phase 2 study. However, the numbers came from separate trials with different participants, baseline body weights, BMI ranges, dose-escalation methods, statistical assumptions and geographic populations.

UBT251 participants had a mean baseline weight of 92.2 kilograms and a mean BMI of 33.1 kg/m². By comparison, participants in retatrutide’s later TRIUMPH-1 Phase 3 study had a mean baseline weight of 112.7 kilograms and a mean BMI of 40.0 kg/m². Results across such different studies cannot be treated as a direct head-to-head comparison.

The amount of available safety information is also very different. UBT251’s published obesity result currently comes from 205 participants treated for 24 weeks. Retatrutide has been evaluated across several longer Phase 3 trials and a much larger participant population.

Therefore, the most accurate interpretation is not that UBT251 has defeated retatrutide, but that it has demonstrated an early efficacy signal strong enough to justify serious global development.

Where UBT251 Could Differentiate Itself

The future value of UBT251 will depend on more than its highest weight-loss percentage. Several areas may determine whether it can compete successfully:

Tolerability

Gastrointestinal effects remain common across incretin-based medicines. A candidate that provides substantial weight loss with fewer discontinuations, easier dose escalation or less nausea and vomiting could offer an important practical advantage.

Glucose Control

UBT251’s early type 2 diabetes results suggest meaningful HbA1c lowering. Future studies will clarify whether its receptor balance provides advantages for people who require both weight reduction and stronger glycemic control.

Body Composition

Large reductions in body weight can involve both fat mass and lean tissue. Future research will need to examine how much of the weight reduction comes from visceral fat, subcutaneous fat and lean mass.

Cardiovascular, Liver and Kidney Outcomes

Triple agonists may influence triglycerides, cholesterol, liver fat, inflammation and blood pressure in addition to body weight. Long-term outcomes studies will be needed to determine whether these changes translate into fewer cardiovascular, renal or liver-related events.

Durability

The UBT251 Phase 2 participants had not reached a weight plateau at week 24. Longer treatment could produce additional loss, but the eventual plateau, weight maintenance after discontinuation and long-term adherence remain unknown.

What Happens Next?

United Laboratories has stated that it is advancing UBT251 toward Phase 3 development in China. Novo Nordisk is also conducting global clinical development, including an international obesity study, with further data expected in 2027. Novo’s pipeline currently lists UBT251 as an active triple-agonist obesity program.

Important future questions include:

• Will the Chinese Phase 2 efficacy be reproduced in broader international populations?
• How will UBT251 perform over 52, 68 or 80 weeks?
• Will its tolerability remain favorable in larger trials?
• How does its receptor-activation profile differ from retatrutide?
• Can it improve obesity-related complications beyond weight loss?
• Will a direct comparison with another advanced obesity medicine eventually be conducted?

Until those questions are answered, UBT251 should be viewed as a promising investigational candidate rather than an established replacement for existing or late-stage medicines.

Final Perspective

UBT251 represents an important development in the next generation of metabolic peptide research. Achieving up to 19.7% mean weight loss in 24 weeks is an encouraging Phase 2 result, particularly because participants had not yet reached a clear plateau.

Retatrutide, however, remains the clinical-development leader. It has produced weight reductions exceeding 28% in Phase 3 obesity studies and has accumulated substantially more long-term efficacy and safety data.

The emerging picture is therefore not “goodbye retatrutide.” Instead, UBT251 shows that the triple-agonist field may soon contain several scientifically distinct competitors.

The next phase of obesity-drug development will not be decided by a single headline weight-loss number. Long-term safety, tolerability, metabolic outcomes, accessibility and performance in diverse patient populations will ultimately determine which triple agonists become successful treatments.

Medical and Research Disclaimer:
UBT251 and retatrutide are investigational drug candidates. Neither should be presented as an approved medicine or used outside properly authorized clinical research. This article is provided for scientific and industry information only and is not medical advice. Retatrutide is not currently approved by the FDA or another regulatory agency for public use.