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LLY Reports Third Phase III Win for Next-Generation Obesity Drug
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Key Takeaways
LLY's retatrutide met its primary endpoint in TRIUMPH-1, with up to 28.3% weight loss.
Retatrutide improved waist size, BMI thresholds and cardiovascular risk markers in the study.
LLY expects more TRIUMPH data this year from obesity studies in diabetes and heart disease.
Eli Lilly (LLY - Free Report) announced positive top-line results from a late-stage study evaluating its next-generation, experimental once-weekly weight-loss drug, retatrutide, in adults with obesity or overweight and at least one weight-related comorbidity and without diabetes.
This phase III study, called TRIUMPH-1, evaluated the efficacy and safety of three doses (4 mg, 9 mg and 12 mg) of the candidate for 80 weeks against placebo in adults with obesity or overweight. Eli Lilly reported results using two approaches — an efficacy estimand, which reflects outcomes in patients who stayed on treatment throughout the study period and a treatment-regimen estimand, which incorporates data from patients who discontinued treatment.
LLY’s Retatrutide Delivers Superior Weight Loss in Phase III
Per the data readout, Eli Lilly’s retatrutide showed clinically meaningful weight loss compared to placebo in the TRIUMPH-1 obesity study at 80 weeks across all three tested doses. The data also showed dose-dependent benefits, with the higher doses producing the largest reductions in body weight and improvements in obesity-related measures.
Under the efficacy estimand, patients receiving retatrutide 9 mg and 12 mg demonstrated weight loss of 25.9% and 28.3%, respectively, meeting the primary efficacy endpoint. The 4 mg dose, which involved only a single dose-escalation step, led to an average weight loss of 19% compared with 2.2% for placebo. All key secondary endpoints were also met as retatrutide produced sizable waist-circumference reductions and higher rates of patients achieving weight-loss thresholds of at least 25%, 30% and 35%, with the 12 mg dose showing the strongest response.
The efficacy-estimand analysis also showed that 65.3% of patients on retatrutide 12 mg achieved a BMI below 30 at 80 weeks, moving below the obesity threshold, including 37.5% of those who began the study with class 3 obesity. In a pre-specified blinded extension involving participants with baseline BMI of at least 35, those who continued retatrutide 12 mg through 104 weeks experienced even greater weight loss of 30.3%. The drug also improved several cardiovascular risk markers, including waist circumference, non-HDL cholesterol, triglycerides, systolic blood pressure and hsCRP.
Year to date, LLY shares have lost 3.1% compared with the industry’s 0.7% decline.
Image Source: Zacks Investment Research
Under the treatment-regimen estimand, retatrutide also showed improvements across the primary and key secondary endpoints. At 80 weeks, body weight declined 17.6%, 23.7% and 25% with the 4 mg, 9 mg and 12 mg doses, respectively, compared with 3.9% for placebo. In the 104-week extension, body weight declined 25.7% for 4 mg to maximum tolerated dose (MTD), 28.7% for 9 mg to MTD and 29.9% for 12 mg to MTD, while patients switching from placebo to retatrutide MTD lost 18.9%. The most common adverse events observed among patients treated with retatrutide were mild to moderate in severity and generally consistent with studies of other incretin-based therapies.
The TRIUMPH-1 obesity study is part of Eli Lilly’s phase III TRIUMPH clinical development program, which is evaluating the safety and efficacy of retatrutide for the treatment of patients with obesity or overweight, moderate-to-severe obstructive sleep apnea (OSA) and obesity, and knee osteoarthritis pain across four global registrational studies. LLY anticipates reporting additional results later this year, including data from TRIUMPH-2, which is evaluating retatrutide in adults with obesity or overweight and type II diabetes (T2D), and TRIUMPH-3, which is evaluating retatrutide in adults with obesity or overweight and established cardiovascular disease.
Retatrutide’s Past Phase III Wins as Reported by LLY
We remind the investors that the success of the phase III TRIUMPH-1 obesity study marks the third positive phase III data readout for Eli Lilly’s retatrutide.
In late 2025, Eli Lilly reported meeting all primary and key secondary endpoints in the late-stage TRIUMPH-4 study, which evaluated the candidate in adults with obesity or overweight and knee osteoarthritis, without diabetes. Under the efficacy estimand, patients lost 26.4% of body weight on 9 mg and 28.7% on 12 mg, versus 2.1% for placebo, while knee pain fell 74-76% compared with 40.3% for placebo. Under the treatment-regimen estimand, weight loss reached 20% and 23.7% for the 9 mg and 12 mg doses, respectively, versus 4.6% for placebo, with knee pain reductions of 62-67% compared with 35.1%. However, retatrutide was associated with higher adverse-event-related discontinuations, mainly due to gastrointestinal symptoms and dysesthesia.
Additionally, in March 2026, Eli Lilly reported positive top-line results from the late-stage TRANSCEND-T2D-1 study of once-weekly retatrutide in adults with T2D and inadequate glycemic control. The study met its primary endpoint, with retatrutide reducing A1C by 1.7% to 2.0% under the efficacy estimand and 1.7% to 1.9% under the treatment-regimen estimand compared with 0.8% for placebo. The drug also met a key secondary goal, driving body-weight reductions of up to 16.8% under the efficacy estimand and 15.3% under the treatment-regimen estimand, versus about 2.5-2.6% for placebo, with weight loss continuing through 40 weeks.
Across all clinical programs, retatrutide is being evaluated in several phase III studies for obesity and overweight with at least one weight-related medical problem, T2D, knee osteoarthritis pain, moderate-to-severe OSA, chronic low back pain, cardiovascular and renal outcomes and metabolic dysfunction-associated steatotic liver disease.
Retatrutide represents a new generation of “triple-action” therapy targeting three biological pathways — GLP-1, GIP and glucagon — unlike LLY’s approved obesity drug Zepbound, which targets GLP-1 and GIP. In comparison, Novo Nordisk’s (NVO - Free Report) blockbuster obesity drug Wegovy activates only GLP-1.
The obesity market has garnered significant attention over the past few years due to the sizeable and still underpenetrated market opportunity. Currently, Eli Lilly and Novo Nordisk dominate this space with their respective injectable therapies.
Novo Nordisk gained approval for an oral version of its obesity drug, Wegovy, in December 2025 and launched the pill in January 2026, giving it a first-mover advantage over Lilly’s newly approved once-daily oral GLP-1 pill, Foundayo. However, LLY may be able to close the gap quickly now that it has launched Foundayo. Also, Foundayo offers better patient convenience, as it can be taken at any time of day, with or without food. In contrast, NVO’s Wegovy pill must be taken on an empty stomach, followed by a 30-minute wait before eating. However, in terms of side effects, Wegovy has a slight edge, as it appears to have a more stable safety and tolerability profile than Foundayo, whose use is associated with some gastrointestinal side effects.
Smaller biotech firms, like Viking Therapeutics (VKTX - Free Report) and Structure Therapeutics (GPCR - Free Report) , are also advancing GLP-1–based therapies to challenge the incumbents. Viking Therapeutics’ dual GIPR/GLP-1 receptor agonist, VK2735, is being developed both as oral and subcutaneous formulations for the treatment of obesity. Viking Therapeutics plans to advance oral VK2735 into phase III development for obesity in the fourth quarter of 2026.
Structure Therapeutics’ phase II ACCESS study on its orally administered GLP-1 RA, aleniglipron, demonstrated significant weight loss across all doses. Structure Therapeutics expects to initiate the late-stage program of aleniglipron in obesity in the second half of 2026.
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LLY Reports Third Phase III Win for Next-Generation Obesity Drug
Key Takeaways
Eli Lilly (LLY - Free Report) announced positive top-line results from a late-stage study evaluating its next-generation, experimental once-weekly weight-loss drug, retatrutide, in adults with obesity or overweight and at least one weight-related comorbidity and without diabetes.
This phase III study, called TRIUMPH-1, evaluated the efficacy and safety of three doses (4 mg, 9 mg and 12 mg) of the candidate for 80 weeks against placebo in adults with obesity or overweight. Eli Lilly reported results using two approaches — an efficacy estimand, which reflects outcomes in patients who stayed on treatment throughout the study period and a treatment-regimen estimand, which incorporates data from patients who discontinued treatment.
LLY’s Retatrutide Delivers Superior Weight Loss in Phase III
Per the data readout, Eli Lilly’s retatrutide showed clinically meaningful weight loss compared to placebo in the TRIUMPH-1 obesity study at 80 weeks across all three tested doses. The data also showed dose-dependent benefits, with the higher doses producing the largest reductions in body weight and improvements in obesity-related measures.
Under the efficacy estimand, patients receiving retatrutide 9 mg and 12 mg demonstrated weight loss of 25.9% and 28.3%, respectively, meeting the primary efficacy endpoint. The 4 mg dose, which involved only a single dose-escalation step, led to an average weight loss of 19% compared with 2.2% for placebo. All key secondary endpoints were also met as retatrutide produced sizable waist-circumference reductions and higher rates of patients achieving weight-loss thresholds of at least 25%, 30% and 35%, with the 12 mg dose showing the strongest response.
The efficacy-estimand analysis also showed that 65.3% of patients on retatrutide 12 mg achieved a BMI below 30 at 80 weeks, moving below the obesity threshold, including 37.5% of those who began the study with class 3 obesity. In a pre-specified blinded extension involving participants with baseline BMI of at least 35, those who continued retatrutide 12 mg through 104 weeks experienced even greater weight loss of 30.3%. The drug also improved several cardiovascular risk markers, including waist circumference, non-HDL cholesterol, triglycerides, systolic blood pressure and hsCRP.
Year to date, LLY shares have lost 3.1% compared with the industry’s 0.7% decline.
Image Source: Zacks Investment Research
Under the treatment-regimen estimand, retatrutide also showed improvements across the primary and key secondary endpoints. At 80 weeks, body weight declined 17.6%, 23.7% and 25% with the 4 mg, 9 mg and 12 mg doses, respectively, compared with 3.9% for placebo. In the 104-week extension, body weight declined 25.7% for 4 mg to maximum tolerated dose (MTD), 28.7% for 9 mg to MTD and 29.9% for 12 mg to MTD, while patients switching from placebo to retatrutide MTD lost 18.9%. The most common adverse events observed among patients treated with retatrutide were mild to moderate in severity and generally consistent with studies of other incretin-based therapies.
The TRIUMPH-1 obesity study is part of Eli Lilly’s phase III TRIUMPH clinical development program, which is evaluating the safety and efficacy of retatrutide for the treatment of patients with obesity or overweight, moderate-to-severe obstructive sleep apnea (OSA) and obesity, and knee osteoarthritis pain across four global registrational studies. LLY anticipates reporting additional results later this year, including data from TRIUMPH-2, which is evaluating retatrutide in adults with obesity or overweight and type II diabetes (T2D), and TRIUMPH-3, which is evaluating retatrutide in adults with obesity or overweight and established cardiovascular disease.
Retatrutide’s Past Phase III Wins as Reported by LLY
We remind the investors that the success of the phase III TRIUMPH-1 obesity study marks the third positive phase III data readout for Eli Lilly’s retatrutide.
In late 2025, Eli Lilly reported meeting all primary and key secondary endpoints in the late-stage TRIUMPH-4 study, which evaluated the candidate in adults with obesity or overweight and knee osteoarthritis, without diabetes. Under the efficacy estimand, patients lost 26.4% of body weight on 9 mg and 28.7% on 12 mg, versus 2.1% for placebo, while knee pain fell 74-76% compared with 40.3% for placebo. Under the treatment-regimen estimand, weight loss reached 20% and 23.7% for the 9 mg and 12 mg doses, respectively, versus 4.6% for placebo, with knee pain reductions of 62-67% compared with 35.1%. However, retatrutide was associated with higher adverse-event-related discontinuations, mainly due to gastrointestinal symptoms and dysesthesia.
Additionally, in March 2026, Eli Lilly reported positive top-line results from the late-stage TRANSCEND-T2D-1 study of once-weekly retatrutide in adults with T2D and inadequate glycemic control. The study met its primary endpoint, with retatrutide reducing A1C by 1.7% to 2.0% under the efficacy estimand and 1.7% to 1.9% under the treatment-regimen estimand compared with 0.8% for placebo. The drug also met a key secondary goal, driving body-weight reductions of up to 16.8% under the efficacy estimand and 15.3% under the treatment-regimen estimand, versus about 2.5-2.6% for placebo, with weight loss continuing through 40 weeks.
Across all clinical programs, retatrutide is being evaluated in several phase III studies for obesity and overweight with at least one weight-related medical problem, T2D, knee osteoarthritis pain, moderate-to-severe OSA, chronic low back pain, cardiovascular and renal outcomes and metabolic dysfunction-associated steatotic liver disease.
Retatrutide represents a new generation of “triple-action” therapy targeting three biological pathways — GLP-1, GIP and glucagon — unlike LLY’s approved obesity drug Zepbound, which targets GLP-1 and GIP. In comparison, Novo Nordisk’s (NVO - Free Report) blockbuster obesity drug Wegovy activates only GLP-1.
Eli Lilly and Company Price and Consensus
Eli Lilly and Company price-consensus-chart | Eli Lilly and Company Quote
LLY’s Peers in the Obesity Space
The obesity market has garnered significant attention over the past few years due to the sizeable and still underpenetrated market opportunity. Currently, Eli Lilly and Novo Nordisk dominate this space with their respective injectable therapies.
Novo Nordisk gained approval for an oral version of its obesity drug, Wegovy, in December 2025 and launched the pill in January 2026, giving it a first-mover advantage over Lilly’s newly approved once-daily oral GLP-1 pill, Foundayo. However, LLY may be able to close the gap quickly now that it has launched Foundayo. Also, Foundayo offers better patient convenience, as it can be taken at any time of day, with or without food. In contrast, NVO’s Wegovy pill must be taken on an empty stomach, followed by a 30-minute wait before eating. However, in terms of side effects, Wegovy has a slight edge, as it appears to have a more stable safety and tolerability profile than Foundayo, whose use is associated with some gastrointestinal side effects.
Smaller biotech firms, like Viking Therapeutics (VKTX - Free Report) and Structure Therapeutics (GPCR - Free Report) , are also advancing GLP-1–based therapies to challenge the incumbents. Viking Therapeutics’ dual GIPR/GLP-1 receptor agonist, VK2735, is being developed both as oral and subcutaneous formulations for the treatment of obesity. Viking Therapeutics plans to advance oral VK2735 into phase III development for obesity in the fourth quarter of 2026.
Structure Therapeutics’ phase II ACCESS study on its orally administered GLP-1 RA, aleniglipron, demonstrated significant weight loss across all doses. Structure Therapeutics expects to initiate the late-stage program of aleniglipron in obesity in the second half of 2026.
LLY’s Zacks Rank
Eli Lilly currently carries a Zacks Rank #3 (Hold). You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.