Pemvidutide: The Muscle-Sparing Incretin
Altimmune's investigational weekly injectable (ALT-801) pairs GLP-1 appetite suppression with a glucagon arm that burns liver fat and defends lean mass. Still Phase 2 — here is what the peer-reviewed and company-reported data actually show.
How It Works
The GLP-1 receptor component drives centrally and peripherally mediated appetite suppression and slowed gastric emptying — the same satiety pathway used by semaglutide and the incretin half of tirzepatide.
Unlike pure GLP-1 or GLP-1/GIP drugs, the glucagon receptor agonist arm acts directly on the liver to stimulate fatty-acid oxidation and inhibit lipogenesis, and raises energy expenditure — a mechanism the J Hepatol authors flag as potentially more potent for liver-fat reduction than weight loss alone.
In the MOMENTUM MRI body-composition sub-study, 78.1% of the weight lost was fat and 21.9% was lean mass — a ratio Altimmune reports as lower lean-mass loss than publicly reported for semaglutide or tirzepatide. This is company-reported and not yet peer-reviewed.
Pemvidutide is a once-weekly subcutaneous injection dosed in trials at 1.2, 1.8 and 2.4 mg without the multi-month dose-titration schedule used by approved GLP-1 drugs.
What the Data Shows
Key Takeaways
- Pemvidutide (ALT-801, Altimmune) is a once-weekly GLP-1/glucagon dual receptor agonist in Phase 2 clinical development for obesity and MASH.
- MOMENTUM 48-week obesity topline (company-reported, n=391, no diabetes): mean weight loss of 10.3%, 11.2% and 15.6% at 1.2, 1.8 and 2.4 mg vs 2.2% placebo; over 30% of the 2.4 mg group lost ≥20%.
- MRI body-composition sub-study (company-reported): 78.1% of weight lost was fat and 21.9% lean mass — the "muscle-sparing" differentiator.
- IMPACT Phase 2b MASH trial (Lancet, peer-reviewed): at 24 weeks, MASH resolution without fibrosis worsening reached 58% (1.2 mg) and 52% (1.8 mg) vs 20% placebo (both p<0.0001).
- Earlier 12-week MASLD study (J Hepatol, peer-reviewed): liver-fat content fell 68.5% at 1.8 mg vs 4.4% placebo, with 55.6% of the 1.8 mg group normalising liver fat.
- The glucagon arm targets the liver directly (fatty-acid oxidation, reduced lipogenesis) and raises energy expenditure — a mechanistic distinction from GLP-1-only and GLP-1/GIP drugs.
- Pemvidutide is NOT approved by the FDA or any regulator and is not available for sale or prescription — it is investigational.
- IMPACT met MASH resolution at 24 weeks but did NOT meet its co-primary fibrosis-improvement endpoint at that timepoint; longer-duration data are pending.
- The headline obesity and body-composition numbers (MOMENTUM, MRI sub-study) are company-reported topline, not yet published in a peer-reviewed journal.
- There is no head-to-head randomised trial versus tirzepatide, retatrutide or survodutide — cross-drug comparisons are indirect.
- No long-term or cardiovascular-outcome (CVOT) data exist; safety and durability beyond ~48 weeks are unknown.
- GI adverse events (nausea, vomiting) were the most common tolerability issue and, in the company-reported MOMENTUM topline, drove dose-dependent treatment discontinuations concentrated in the early titration weeks — exact rates await peer-reviewed publication.
Frequently Asked Questions
What is pemvidutide?
Pemvidutide (development code ALT-801) is an investigational once-weekly subcutaneous peptide from Altimmune that activates both the GLP-1 and glucagon receptors. It is in Phase 2 trials for obesity and metabolic dysfunction-associated steatohepatitis (MASH) and is not yet approved or available for sale.
How much weight loss does pemvidutide produce?
In the company-reported MOMENTUM 48-week Phase 2 obesity trial, mean weight loss was 15.6% at the 2.4 mg dose versus 2.2% for placebo, with over 30% of the top-dose group losing at least 20% of body weight. These topline figures have not yet been peer-reviewed.
Why is pemvidutide called muscle-sparing?
In an MRI-based body-composition sub-study, Altimmune reported that 78.1% of the weight lost was fat and only 21.9% was lean mass — a lower lean-mass loss ratio than the company cites for semaglutide or tirzepatide. The glucagon arm and energy-expenditure effect are the proposed reasons. This remains a company-reported claim without a peer-reviewed publication.
How is pemvidutide different from tirzepatide or retatrutide?
Tirzepatide is a GLP-1/GIP dual agonist and retatrutide is a GLP-1/GIP/glucagon triple agonist. Pemvidutide uses GLP-1 plus glucagon (no GIP). The glucagon component acts directly on the liver to oxidise fat and is central to its MASH and lean-mass-preservation profile. No head-to-head trial has compared them.
Is pemvidutide FDA approved or available to buy?
No. As of 2026 pemvidutide is an investigational Phase 2 compound. It is not FDA approved, not prescribable, and not sold by any legitimate vendor. Any site claiming to sell "pemvidutide" is not supplying an approved product.
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Educational purposes only. Not medical advice.
Pemvidutide is an investigational drug that is not FDA approved and not available for sale or prescription. Nothing here is an offer to supply it.
Figures labelled "company-reported" come from Altimmune press releases and conference presentations and have not been peer-reviewed. Consult a licensed physician before making any medical decision.