Pemvidutide: What the Evidence Actually Shows

Pemvidutide shows up in peptide forums and vendor catalogs as the next big weight-loss compound, usually shelved next to retatrutide. Its own published trials point somewhere else entirely, and the gap between the two is the reason this page exists.

What pemvidutide actually is

Pemvidutide (Altimmune's development code ALT-801) is a dual agonist: it activates the GLP-1 receptor and the glucagon receptor at once. That second target is what makes it different from semaglutide. GLP-1 agonists produce weight loss mainly by acting on appetite; glucagon-receptor agonists act directly on the liver, driving fatty-acid oxidation and suppressing the manufacture of new fat. The drug's own trial authors describe this as "a more potent mechanism for reducing liver fat content than weight loss alone³."

Hold onto that sentence. It is the key to everything below.

The weight-loss numbers, stated plainly

Here is what pemvidutide has actually produced on the scale in published, peer-reviewed, placebo-controlled trials.

In a randomized, double-blind, placebo-controlled trial of 94 patients with fatty liver disease and a median BMI of 36.2, twelve weeks of weekly pemvidutide produced a maximum weight loss of −4.3% — at the 1.8 mg dose, the dose that performed best on every measure in that trial². A 12-week extension carried 64 of those patients to 24 weeks total; body weight fell 6.2% from baseline³.

For the comparison that matters: semaglutide's STEP 1 trial reported roughly 15% body-weight loss at 68 weeks, and tirzepatide's SURMOUNT-1 reported up to 22.5%. Those are longer trials in different populations, so this is not a head-to-head — no head-to-head exists. But nobody looking at 4-6% and 15-21% needs a statistician to see which column they are in.

If your goal is weight loss, pemvidutide's own data does not put it in the conversation. The two compounds that are in it are the ones this site actually ranks providers for.

Where the drug is genuinely impressive

Now the other half, because dismissing pemvidutide on the weight number alone would miss what it does.

In that same 12-week trial, liver fat content fell 68.5% at the 1.8 mg dose, against 4.4% on placebo. At that dose, 94.4% of patients hit a 30% reduction, 72.2% hit 50%, and 55.6% saw their liver fat normalize outright — dropping to 5% or less². By 24 weeks the reduction reached 75.2%, with 53.8% normalized³.

Those are not incremental numbers. That is the glucagon half of the molecule doing exactly what the mechanism predicts, and it is why Altimmune has aimed this drug at the liver.

The Phase 2b result: one endpoint met, one missed

The largest trial of pemvidutide to date is IMPACT, a 212-patient, 83-site, randomized, double-blind, placebo-controlled Phase 2b study in patients with biopsy-confirmed MASH and stage F2 or F3 fibrosis. It carried two primary endpoints, and it split them.

It met the first. MASH resolution without worsening of fibrosis reached 58% at 1.2 mg and 52% at 1.8 mg, against 20% on placebo — differences of 38 and 32 percentage points, both at p<0.0001¹.

It missed the second. Fibrosis improvement without worsening of MASH reached 33% and 36% against 28% on placebo — differences of 5 and 8 points, at p=0.59 and p=0.27. Neither came close to significance¹.

The trial's own published interpretation says both halves out loud: pemvidutide "met the primary endpoint of MASH resolution without worsening of fibrosis at 24 weeks but did not meet the other primary endpoint of fibrosis improvement without worsening of MASH at this timepoint. Additional trials of longer duration are planned¹." A 2026 GRADE-assessed meta-analysis pooling the randomized pemvidutide evidence reports the same shape: real reductions in liver fat, ALT, AST, body weight and blood pressure⁴.

Read a summary that quotes only the 58% and you would think this drug cleared its Phase 2b. It cleared half of it.

There is no Phase 3 — anywhere

This is the fact most likely to be missing wherever else you read about pemvidutide, and it is checkable in about a minute.

A live query of ClinicalTrials.gov returns seven pemvidutide studies, every one sponsored by Altimmune, and every one of them is Phase 1 or Phase 2. There is no Phase 3 program for obesity, for MASH, or for anything else. Compare that with the other investigational GLP-1s this site covers — retatrutide, survodutide and mazdutide all have real Phase 3 work behind them, and mazdutide is already approved in China. Pemvidutide is at an earlier stage than the company it gets listed alongside.

A direct query against FDA's Drugs@FDA database returns nothing for pemvidutide. It is not approved in the United States, for any indication, at any dose.

Where its sponsor is actually taking it

The trial registry tells you what a company believes about its own drug better than any press release does. Altimmune's two active or recently completed Phase 2 programs are RESTORE, in alcohol-related liver disease, and RECLAIM, in alcohol use disorder. The obesity work sits back in Phase 1.

A GLP-1/glucagon agonist being pointed at alcohol use disorder is not a strange detour — the whole GLP-1 class is under serious investigation for addiction. But it does tell you where the sponsor sees this molecule winning, and it is not on the scale.

★ The ALT-801 trap

One specific hazard, worth more than anything else on this page if you are researching the development code rather than the drug name.

There are two entirely unrelated drugs called ALT-801. Altimmune's is pemvidutide. The other is an interleukin-2/T-cell-receptor fusion protein developed for advanced cancers, which has its own published Phase 1 trial reporting dose-limiting toxicities including a grade 4 thrombocytopenia and a myocardial infarction, and a maximum tolerated dose of 0.04 mg/kg⁵.

None of that has anything to do with pemvidutide. Different molecule, different mechanism, different disease, different decade. But a search for "ALT-801 side effects" surfaces the oncology trial, and a vendor page or forum post that borrows those numbers would be describing a cancer immunotherapy while selling you a GLP-1. If you see ALT-801 safety data attached to a weight-loss product, check which ALT-801 it came from.

What to do with all this

If you came here because you are choosing something to take for weight loss, the honest answer is that pemvidutide is not that, on its own trial data, and it is not legally purchasable in the United States regardless. The compounds with real weight-loss trial evidence behind them are tirzepatide and semaglutide, and this site tracks what providers actually charge for both.

If you came here because of the liver-fat numbers, they are real, they are large, and they are also from Phase 2 trials in patients with diagnosed liver disease — not from healthy people using it off-label. The drug that produced them is not available outside a trial.