Pemvidutide: The GLP-1/Glucagon Dual Agonist With 15.6% Weight Loss

Most of the obesity pipeline is a race to the highest number on the scale. Pemvidutide (ALT-801), Altimmune's once-weekly subcutaneous peptide, is making a different argument: that the quality of weight loss matters as much as the quantity. Pemvidutide is a balanced 1:1 dual agonist of the GLP-1 receptor and the glucagon receptor, and in its Phase 2 MOMENTUM trial it delivered 15.6% mean weight loss at 48 weeks while preserving an unusually high fraction of lean mass. It has since collected an FDA Breakthrough Therapy designation in metabolic dysfunction-associated steatohepatitis (MASH) and a Fast Track designation in alcohol use disorder — a breadth that reflects how directly the glucagon arm acts on the liver.

Evidence: "At week 48, subjects receiving pemvidutide achieved mean weight losses of 10.3%, 11.2%, and 15.6% at the 1.2 mg, 1.8 mg, and 2.4 mg doses, compared with 2.2% for placebo, with over 30% of subjects on 2.4 mg achieving 20% or greater weight loss. Body composition analysis showed 21.9% of weight loss attributable to lean mass and 78.1% to fat." — Altimmune MOMENTUM Phase 2 topline results, presented at the ADA Scientific Sessions, 2024.

The molecule sits in the same mechanistic family as Boehringer Ingelheim's survodutide — both engage GLP-1 plus glucagon and skip GIP — but pemvidutide is differentiated by a flat dosing schedule that requires no titration and by a body-composition profile its developer markets as class-leading.

Why Pairing Glucagon With GLP-1 Changes the Math

If you came to obesity pharmacology through semaglutide, adding glucagon to a weight-loss drug sounds backwards. Glucagon is the hormone that raises blood sugar by driving hepatic glucose output during a fast. But glucagon has a second job that the obesity field underused for years: it increases resting energy expenditure and pushes the liver to oxidize fat.

Evidence: "Glucagon receptor agonism increases energy expenditure and stimulates hepatic lipid oxidation; when combined with GLP-1 receptor agonism, which suppresses appetite and protects against glucagon's hyperglycaemic effect, the two signals act in complementary directions to reduce body weight and hepatic fat content." — Winther JB, Holst JJ. Diabetes, Obesity and Metabolism. 2024. DOI: 10.1111/dom.15693

The logic of dual agonism is that GLP-1 lowers calories in while glucagon raises calories out — and because GLP-1's incretin effect on insulin secretion offsets glucagon's tendency to raise blood sugar, the combination stays glycemically neutral. Pemvidutide's peptide is engineered with a proprietary lipid moiety (the EuPort domain) that slows absorption and extends its half-life to support once-weekly dosing without the gradual dose escalation that semaglutide and tirzepatide require.

How pemvidutide compares mechanistically

Drug	Receptor activity	Best reported weight loss	Status
Semaglutide 2.4 mg (Wegovy)	GLP-1	~14.9% at 68 wks	Approved
Tirzepatide 15 mg (Zepbound)	GLP-1 + GIP	~20.9% at 72 wks	Approved
Retatrutide 12 mg	GLP-1 + GIP + glucagon	~24.2% at 48 wks (Ph 2)	Phase 3
Survodutide 6.0 mg	GLP-1 + glucagon	16.6% at 76 wks (Ph 3)	Phase 3 readout
Pemvidutide 2.4 mg	GLP-1 + glucagon (1:1)	15.6% at 48 wks (Ph 2)	Phase 2 complete

Pemvidutide and survodutide test nearly the same hypothesis — GLP-1 plus glucagon, no GIP — but pemvidutide's deliberately balanced 1:1 receptor ratio is its signature design choice, intended to maximize the glucagon-driven metabolic and hepatic effects without overshooting into hyperglycemia.

MOMENTUM: 15.6% Weight Loss Without Dose Titration

MOMENTUM enrolled 391 adults with obesity, or overweight with at least one weight-related comorbidity, and without diabetes. Participants were randomized 1:1:1:1 to weekly subcutaneous pemvidutide at 1.2 mg, 1.8 mg, or 2.4 mg, or placebo, for 48 weeks alongside diet and exercise. Unlike incretin drugs that climb through months of escalating doses, pemvidutide was started at or near its target dose.

The 15.6% mean loss at the top dose corresponded to roughly 32 pounds, and the curve had not plateaued at week 48 — meaning the ceiling was not yet visible when the trial ended. Beyond weight, MOMENTUM reported reductions in serum lipids and improvements in blood pressure, with no imbalance in cardiac events or arrhythmias and no clinically meaningful rise in heart rate, an outcome that matters given that glucagon agonism can nudge heart rate upward.

The lean-mass headline

The number Altimmune leans on hardest is not 15.6% — it is 78.1%. That is the share of total weight loss that came from fat rather than lean tissue.

Rapid weight loss from any cause strips away some muscle along with fat, and the incretin class is no exception; we cover the stakes in detail in our guide to preserving muscle on GLP-1 medications. In MOMENTUM, only 21.9% of the weight lost was lean mass — a ratio that compares favorably with the roughly one-quarter to one-third lean-mass fraction often reported with GLP-1 monotherapy. The mechanistic explanation tracks with the pharmacology: glucagon receptor activation preferentially mobilizes hepatic and visceral fat for oxidation, biasing the body toward burning fat rather than catabolizing muscle. The caveat is that MOMENTUM had no active comparator, so this is a favorable within-trial signal rather than a head-to-head win over tirzepatide or semaglutide.

IMPACT: One of the Strongest MASH Data Sets in the Field

Because the glucagon arm acts directly on hepatocytes, MASH was always the indication where pemvidutide's mechanism had the most to prove — and it delivered. The Phase 2b IMPACT trial randomized 212 adults with biopsy-confirmed MASH and fibrosis stage F2 or F3, with and without diabetes, in a 1:2:2 ratio to weekly pemvidutide 1.2 mg, 1.8 mg, or placebo for 24 weeks. It became the first drug to show significant MASH resolution and weight loss at the 24-week mark.

Evidence: "MASH resolution without worsening of fibrosis was achieved in 58.1% of patients in the 1.2 mg group and 52.1% in the 1.8 mg group, versus 19.6% with placebo. Fibrosis improvement of at least one stage without worsening of MASH occurred in up to 34.5% of pemvidutide-treated patients, with consistent improvements across non-invasive markers of fibrosis and inflammation." — Noureddin M, Harrison SA, et al. The Lancet. 2025. DOI: 10.1016/S0140-6736(25)02114-2

A 24-week MASH resolution rate near 58% is among the highest reported for any obesity-adjacent agent, and it arrived with only 24 weeks of treatment. At the 48-week analysis reported in December 2025, pemvidutide produced statistically significant improvements over placebo across blood-based and imaging non-invasive tests — including the Enhanced Liver Fibrosis (ELF) score and liver stiffness measured by FibroScan — while preserving its favorable tolerability profile with a low rate of treatment-related discontinuation. An End-of-Phase 2 meeting with the FDA cleared the path to a registrational Phase 3 program. For the broader context of how incretin and dual-agonist drugs treat fatty liver, see our overview of GLP-1 medications and fatty liver disease.

The Phase 1 Foundation: 68% Liver-Fat Reduction in 12 Weeks

The MASH program was built on an earlier randomized, placebo-controlled MASLD study that established pemvidutide's signature effect on liver fat in just three months.

Evidence: "Relative reductions in liver fat content at week 12 were 46.6%, 68.5%, and 57.1% with pemvidutide 1.2 mg, 1.8 mg, and 2.4 mg respectively, versus 4.4% with placebo (p < 0.001 for all comparisons). At the 1.8 mg dose, 94.4% of patients achieved at least a 30% reduction and 55.6% achieved liver-fat normalization." — Harrison SA, Browne SK, et al. Journal of Hepatology. 2025. DOI: 10.1016/j.jhep.2024.07.006

The depth and speed of that liver-fat response — nearly two-thirds of liver fat gone in 12 weeks — is the clearest demonstration that the glucagon receptor is doing real metabolic work, not just adding noise to a GLP-1 backbone.

How Pemvidutide Stacks Up Against Approved Drugs

Placed against the approved benchmarks, pemvidutide's 15.6% sits between Wegovy and Zepbound on raw magnitude, while its differentiation lives in body composition, hepatic effect, and dosing convenience rather than peak number.

Evidence: "Once-weekly subcutaneous semaglutide at a dose of 2.4 mg plus lifestyle intervention was associated with a mean change in body weight of −14.9% at 68 weeks." — Wilding JPH, et al. New England Journal of Medicine. 2021. DOI: 10.1056/NEJMoa2032183

Evidence: "In adults with obesity, once-weekly tirzepatide at a dose of 15 mg produced a mean change in body weight of −20.9% at 72 weeks." — Jastreboff AM, et al. New England Journal of Medicine. 2022. DOI: 10.1056/NEJMoa2206038

A direct comparison carries an important asterisk: MOMENTUM ran 48 weeks against trials of 68 and 72 weeks, and pemvidutide's curve had not yet flattened. Whether the no-titration schedule and lean-mass advantage translate into a commercial edge will hinge on longer trials and, eventually, head-to-head data the obesity field still lacks for this drug. For how the leading approved options compare on weight loss directly, see tirzepatide vs. semaglutide.

Safety: GI-Dominant, With Glucagon-Specific Watch-Outs

Pemvidutide's adverse-event profile is the familiar incretin pattern — predominantly gastrointestinal, dose-dependent, and concentrated early in treatment. In MOMENTUM, most nausea and vomiting was mild to moderate, but discontinuations driven by adverse events were higher on pemvidutide (5.1% to 19.6% across doses) than on placebo (6.2%), and most occurred within the first 16 weeks. The absence of a slow titration schedule is a convenience, but it also concentrates early tolerability challenges, and dose optimization is an explicit focus of the next development stage.

Two glucagon-specific considerations warrant ongoing surveillance:

Heart rate: glucagon agonism can raise resting heart rate, though MOMENTUM reported no clinically meaningful increase and no arrhythmia imbalance
Glycemia: GLP-1 co-agonism is designed to neutralize glucagon's hyperglycemic effect, and trials to date support glycemic neutrality, but vigilance remains appropriate in patients with diabetes

The class-level cautions that apply across GLP-1 drugs — the rodent medullary thyroid carcinoma signal, pancreatitis and gallbladder surveillance — are expected to carry over to pemvidutide as the program advances.

Regulatory Path: Breakthrough in MASH, Fast Track in Addiction

Pemvidutide's regulatory momentum in early 2026 is concentrated on the liver. In January 2026 the FDA granted Breakthrough Therapy designation for pemvidutide in MASH with moderate-to-advanced fibrosis — a status reserved for drugs showing substantial improvement over available therapy on a clinically significant endpoint, and one that unlocks more intensive FDA guidance. Altimmune has aligned with the FDA on a registrational Phase 3 MASH trial with biopsy-based endpoints intended to support accelerated approval.

Separately, pemvidutide received Fast Track designation for alcohol use disorder, reflecting the growing interest in whether the GLP-1 axis can blunt reward-driven consumption — an emerging research area we examine in our piece on GLP-1 medications and alcohol.

What This Means for Patients and Clinicians

Pemvidutide is unlikely to claim the weight-loss crown — tirzepatide and the triple agonist retatrutide post higher peak numbers. Its case rests on three things the scale alone does not capture: a high fat-to-lean loss ratio, a deep and fast effect on liver fat, and a flat once-weekly dose with no titration. The likely positioning, assuming Phase 3 confirms the Phase 2 signals:

Patients with obesity plus MASH or significant hepatic steatosis, where the glucagon mechanism offers a metabolic rationale beyond weight loss alone
Patients prioritizing lean-mass preservation, particularly older adults and those at risk of sarcopenia
Patients who want a simpler regimen without months of dose escalation

The nearest-term approval opportunity is MASH, not obesity — that is where Breakthrough designation and an aligned Phase 3 plan put pemvidutide on the clearest regulatory runway. An obesity registrational program would follow on a longer timeline. As always, pemvidutide remains investigational and is not yet approved or available by prescription.

Key Takeaways

Pemvidutide (ALT-801) is a once-weekly subcutaneous, balanced 1:1 GLP-1/glucagon dual receptor agonist developed by Altimmune
Phase 2 MOMENTUM showed 15.6% mean weight loss at 48 weeks with no dose titration, and weight loss had not plateaued
Body composition was a standout: 78.1% of weight lost came from fat and only 21.9% from lean mass
Phase 2b IMPACT achieved up to 58% MASH resolution at 24 weeks, with significant non-invasive fibrosis improvements maintained at 48 weeks
A Phase 1 MASLD study showed up to 68.5% relative liver-fat reduction in just 12 weeks
Pemvidutide holds FDA Breakthrough Therapy designation in MASH and Fast Track designation in alcohol use disorder, with a registrational Phase 3 MASH trial planned

References

Noureddin M, Harrison SA, Loomba R, Alkhouri N, Chalasani N, Sheikh MY, et al. Safety and efficacy of weekly pemvidutide versus placebo for metabolic dysfunction-associated steatohepatitis (IMPACT): 24-week results from a multicentre, randomised, double-blind, phase 2b study. Lancet. 2025;406(10520):2644-2655. DOI: 10.1016/S0140-6736(25)02114-2 · PubMed
Harrison SA, Browne SK, Suschak JJ, Tomah S, Gutierrez JA, Yang J, et al. Effect of pemvidutide, a GLP-1/glucagon dual receptor agonist, on MASLD: A randomized, double-blind, placebo-controlled study. J Hepatol. 2025;82(1):7-17. DOI: 10.1016/j.jhep.2024.07.006 · PubMed
Winther JB, Holst JJ. Glucagon agonism in the treatment of metabolic diseases including type 2 diabetes mellitus and obesity. Diabetes Obes Metab. 2024;26(9):3501-3512. DOI: 10.1111/dom.15693 · PubMed
Wilding JPH, Batterham RL, Calanna S, Davies M, Van Gaal LF, Lingvay I, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2021;384(11):989-1002. DOI: 10.1056/NEJMoa2032183 · PubMed
Jastreboff AM, Aronne LJ, Ahmad NN, Wharton S, Connery L, Alves B, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387(3):205-216. DOI: 10.1056/NEJMoa2206038 · PubMed

Last updated: 2026-06-12 Medical review: Dr. James Chen, MD, PhD, FACE