Pemvidutide

An experimental weekly injection made by Altimmune that switches on two receptors at once — the GLP-1 receptor, which is the one semaglutide uses to make people feel full, and the receptor for glucagon, a hormone that tells the liver to release stored fuel and burn its own fat. It is not approved as a medicine anywhere in the world. Note that the development code ALT-801 is ambiguous: Altor BioScience used the same code from 2007 for an interleukin-2 fusion protein tested in cancer, which is a completely different molecule.

Sold as

Injection under the skin, once a week (only within clinical trials).

Legal status in the EU

No marketing authorisation in the EU, the US or anywhere else. Available only within clinical trials. The US regulator has granted Fast Track and, in early 2026, Breakthrough Therapy status for liver disease — both are promises of a faster review, not decisions that it works or is safe. In Europe the company had, as of March 2026, only reached the stage of requesting scientific advice from regulators.

It acts on the GLP-1 and glucagon receptors together, in what the maker describes as a balanced one-to-one ratio. The GLP-1 side is the one that reduces appetite in this family of drugs; the glucagon side acts directly on the liver, which is where this compound's distinctive results are. The claim that the glucagon side also makes the body burn more energy has never been measured in a person given pemvidutide. The sequence field is deliberately left empty: pemvidutide is a lipidated peptide carrying a stearic-acid chain (Advanced Healthcare Materials 2026), no public chemical database holds an entry for it, and no source we could open prints a verified one-letter code — writing one would describe a different molecule.

Part of the bodyWhat happensHow it is knownKind of evidence

The liver

This is what pemvidutide is now being developed for, and it is where the strongest evidence sits. Fat collects inside liver cells in people with weight and blood-sugar problems; when inflammation and swollen, dying liver cells join the fat, the condition is called MASH — metabolic dysfunction-associated steatohepatitis. On pemvidutide the fat drains out of the liver quickly, the blood test that rises when liver cells are being damaged comes down, and on a second biopsy the inflammation has often settled. The scarring, which is the part that decides whether someone ends up with liver failure, moved much less.

Measured in 212 adults with MASH confirmed by biopsy, over 24 weeks, with a second biopsy at the end. Measured again in 94 adults with fatty liver over 12 weeks and in 64 of them over 24 weeks, using a scan rather than a biopsy: liver fat fell 56.3%, 75.2% and 76.4% across the three amounts against 14.0% on dummy injections at 24 weeks.

Measured in people

Source [01]Source [02]Source [03]

Stomach and gut

Feeling sick is the commonest thing that happens, and vomiting follows it. Constipation and loose stools both turn up, and in the obesity trial constipation was the more common of the two. The trouble arrives early, in the first weeks, and it is the main reason people stopped taking it. How bad it is depends heavily on the amount and on how fast it was reached: in the liver trial, where the amounts were lower and given without stepping up, almost nobody left because of side effects, while in the obesity trial one person in five on the two higher amounts stopped.

Measured in 391 adults over 48 weeks: feeling sick in 25.5%, 59.6% and 51.5% across the three amounts against 11.3% on dummy injections; vomiting in 6.1%, 27.3% and 27.8% against 3.1%; constipation in 17.3%, 13.1% and 22.7% against 8.2%; loose stools in 8.2%, 10.1% and 18.6% against 5.2%. Those figures come from the company's own press release, not from a journal. Measured again in 212 adults with MASH over 24 weeks and published in a journal: any side effect at all in 78% and 81% on the two amounts against 67% on dummy injections, and stopping because of a side effect in 0% and 1% against 2% on dummy injections.

Measured in people

Source [01]Source [04]

Blood sugar

The worry with any compound that switches on the glucagon receptor is that glucagon is the hormone that pushes blood sugar up, so it could in principle make diabetes worse. In the published trials it did not — but neither did it make blood sugar better, which is what separates pemvidutide from most of the drugs it is compared with. In 54 adults who had type 2 diabetes, long-term blood sugar stayed roughly where it started on pemvidutide, at 6.5% to 7.0%, while the dummy-injection group drifted up from 6.6% to 7.0%. That was a 12-week safety trial of 54 people, not a trial designed to show a benefit, and the big obesity trial excluded anyone with diabetes.

Measured in 54 adults with type 2 diabetes over 12 weeks: no meaningful change in fasting glucose or long-term blood sugar in any group, and no episode of high blood sugar reported as a side effect in any group. Measured again in 391 adults without diabetes over 48 weeks: long-term blood sugar 5.5–5.6% at the start and 5.5–5.6% at 48 weeks in every group including dummy injections.

Measured in people

Source [04]Source [13]Source [14]

Heart and blood vessels

The resting heart runs slightly faster on the two higher amounts. This matters more here than it would for an ordinary weight drug, because a faster heart is the effect that ended the development of several earlier glucagon-based compounds. Blood pressure came down. What is missing is the thing that would settle it: no trial has ever been run to find out whether pemvidutide causes or prevents heart attacks and strokes, and none is registered.

Measured in 391 adults over 48 weeks: resting heart rate changed by +0.1, +3.1 and +2.5 beats a minute across the three amounts against −1.4 on dummy injections. The top blood pressure number fell 2.3, 1.6 and 4.6 mmHg against a rise of 3.5 on dummy injections. No major heart events occurred in any group, and heart side effects including irregular heartbeats were reported by 3.1%, 4.0% and 3.1% against 4.1% on dummy injections. All of these come from the company's press release, not from a journal. In the 24-week liver extension trial, published in a journal, the authors report no significant change in heart rate.

Measured in people

Source [02]Source [04]

Fat and muscle

The claim made most often about this compound is that it takes off fat while leaving muscle alone. What was actually measured was a scan of 67 people inside the 391-person trial, 50 of whom were on pemvidutide. In those 50, lean tissue — muscle and everything else that is not fat — made up 21.9% of the weight they lost. The fat around the organs inside the belly, which is the kind most closely tied to heart disease, came off faster than the fat under the skin: down 28.3% against 19.5% on the largest amount. No figure for the placebo group's lean tissue has ever been published, and nobody measured whether anyone was stronger, could walk further or fell over less often.

An MRI substudy of 67 people out of 391, over 48 weeks, presented at a conference in September 2024 and reported in a company press release. It has never appeared in a peer-reviewed journal, and no comparison group figure was given for the lean tissue result.

One small study

Source [06]Source [12]

Appetite, and how much people eat

People lose weight, and a lot of it. What nobody has published is why. No pemvidutide trial has reported a measurement of hunger, of fullness, of how much food people actually ate, or of any questionnaire about eating — not in the obesity trial, not in either liver trial. The explanation offered is that the GLP-1 half of the molecule reduces appetite, which is what GLP-1 medicines do, but for this compound that step has never been measured in a person and published.

Weight was measured in 391 adults over 48 weeks and fell 15.6% on the largest amount against 2.2% on dummy injections. No published pemvidutide trial reports an appetite, hunger or food-intake measurement of any kind.

Claimed, never tested

Source [04]Source [11]

How much energy the body burns

This is the compound's central claim and nobody has tested it. The argument for switching on the glucagon receptor is that it makes the body burn more fuel and pushes the liver to burn its own fat, so that weight comes off by two routes rather than one — the company describes it as mimicking the effects of diet and exercise together. No published trial of pemvidutide has measured how much energy a person burns, and no registered trial is set up to.

The claim appears in the company's own description of the compound in every press release. Searching the published record turns up no measurement of energy expenditure, metabolic rate or fat burning in a person given pemvidutide, and no animal study of pemvidutide itself that separates the two receptors.

Claimed, never tested

Source [06]Source [12]

The largest published trial, IMPACT (The Lancet, 6 December 2025, 212 adults with liver disease confirmed by biopsy, 24 weeks), had two main targets and hit one: the liver inflammation cleared without the scarring worsening in 52% of people on the higher amount against 20% on dummy injections, but the scarring itself improved in only 36% against 28% — a gap whose range of possibilities included no effect at all (p=0.27), and the paper states that endpoint was not met. Liver fat fell far and fast in two smaller published trials: down 56.3% to 76.4% across three amounts against 14.0% on dummy injections at 24 weeks in 64 adults. The obesity evidence is weaker in an unusual way: the 391-person, 48-week MOMENTUM trial reported 15.6% weight loss on the largest amount against 2.2% on dummy injections, but it finished in September 2023 and has never been published in a peer-reviewed journal or posted results on the registry — every obesity figure in circulation comes from company press releases and conference talks. The widely repeated claim that it preserves muscle better than other weight drugs rests on a scan of 67 people, 50 of them on pemvidutide, whose placebo comparison was never published. A phase 3 trial in liver disease, PERFORMA, was announced as starting on 3 August 2026 with a 52-week reading expected in 2029; it was not yet registered on ClinicalTrials.gov when this entry was written, and the tier here rests on the phase 2 trials still recruiting, not on it.

Fast to get on, and nothing at all is known about getting off. Unlike most drugs in this family, the lower amounts were given at full strength from the very first injection, with no weeks of stepping up; only the largest amount used a build-up, and that was four weeks rather than the twenty to thirty-two weeks other compounds use. The sickness follows that schedule: it turns up in the first weeks, and in the obesity trial almost all the people who stopped had stopped within 16 weeks. Weight came off steadily and had not levelled off at 48 weeks on the largest amount, which is as far as any obesity measurement goes. Liver fat falls fastest of anything measured — a large drop was already there at 12 weeks and it continued to 24. The liver biopsy result was read at 24 weeks and the blood and scan markers at 48; nothing has been published beyond 48 weeks for any outcome. And there is no published follow-up whatsoever after stopping: no trial has reported what happens to weight, liver fat or heart rate in the weeks or months after the last injection.

What was measuredWhat happenedIn whomHow it is known

Liver inflammation clearing up without the scarring getting worse

The compound's best result, and it is published. Everyone had a piece of liver taken at the start and again at 24 weeks, and it was read by a pathologist who did not know who had received what. The inflammation cleared without the scarring worsening in 24 of 41 people on the lower amount (58%) and 45 of 85 on the higher amount (52%), against 18 of 86 on dummy injections (20%). The differences were 38 percentage points (95% CI 21 to 56) and 32 points (95% CI 19 to 46), both with p below 0.0001.

212 adults aged 18 to 75 with MASH confirmed by biopsy and scarring at stage 2 or 3 of 4, with and without type 2 diabetes, at 83 sites in the United States and Australia; 1,557 people were screened to find them

Measured in people

Source [01]

The scarring in the liver itself getting better

Missed. This was the trial's second main target and it was not reached: the scarring improved by at least one stage without the inflammation worsening in 13 of 41 people on the lower amount (33%) and 30 of 85 on the higher amount (36%), against 24 of 86 on dummy injections (28%). The differences were 5 percentage points (95% CI −13 to 22, p=0.59) and 8 points (95% CI −6 to 22, p=0.27) — ranges that include no effect at all. The trial's own authors state that the endpoint was not met at this timepoint. The company's press release about the same result was headlined "Positive Topline Results".

The same 212 adults, all with paired biopsies at 24 weeks

Measured in people

Source [01]Source [15]

Blood and scan markers of liver scarring, at 48 weeks

Better on the drug, but measured a weaker way and reported only by the company. A blood score for liver scarring fell 0.49 and 0.58 points on the two amounts against a rise of 0.16 on dummy injections. A scan that measures how stiff the liver is fell 3.04 and 3.97 units against 0.03. Meeting both of those targets at once happened in 27.8% and 32.4% of people on the drug against 3.2% on dummy injections. None of this is a biopsy: these are stand-ins for scarring, not scarring itself, and the trial took no second biopsy at 48 weeks. The 48-week results have not been published in a journal.

The same 212 adults with biopsy-confirmed MASH, followed to 48 weeks

Measured in people

Source [16]Source [17]

Fat draining out of the liver, measured by scan

The largest and most consistent effect in the whole record, and this part is published. Over 12 weeks, liver fat fell 46.6%, 68.5% and 57.1% across the three amounts against 4.4% on dummy injections. Over 24 weeks in the people who carried on, it fell 56.3%, 75.2% and 76.4% against 14.0%. On the middle amount, 84.6% of people lost at least half their liver fat and 53.8% ended with a liver back under 5% fat, which is the normal range — against nobody at all on dummy injections on either count. In the MASH trial at 48 weeks, liver fat fell 45.2% and 54.7% against 8.2% on dummy injections. A scan measures fat only; it says nothing directly about the inflammation or the scarring.

94 adults with a BMI of 28 or more and at least 10% liver fat, over 12 weeks; 64 of them over 24 weeks; separately the 212 adults with MASH over 48 weeks

Measured in people

Source [02]Source [03]Source [16]

Body weight in adults with obesity and no diabetes, over 48 weeks

The number everyone quotes, and it has never been through a journal. Weight fell 10.3%, 11.2% and 15.6% across the three amounts against 2.2% on dummy injections. Counting the people who reached particular thresholds: at least 5% of body weight gone in 68.6%, 76.2% and 83.9% against 17.6%; at least 10% in 42.9%, 49.2% and 71.4% against 3.9%; at least 15% in 21.4%, 28.6% and 51.8% against 2.0%; at least 20% in 10.0%, 9.5% and 32.1% against 2.0%. All of it comes from a company press release and a conference presentation. There is no published paper to check the analysis against, and the trial has posted no results on the registry either.

391 adults with a BMI of 30 or more, or 27 or more with an obesity-related problem, and no diabetes; mean age about 50, mean BMI about 37, mean weight about 104 kg, roughly 75% women; 30 sites in the United States, 48 weeks alongside diet and exercise

Measured in people

Source [04]Source [05]Source [11]

Body weight in people who had MASH

Smaller than in the obesity trial, because the amounts used were lower. Weight fell 4.5% and 7.5% on the two amounts against 0.2% on dummy injections over 48 weeks. Reported by the company only. Over 24 weeks in the earlier liver trials, weight fell 4.3% at the middle amount against dummy injections at 12 weeks, and 6.2% against 1.4% on dummy injections at 24 weeks.

212 adults with biopsy-confirmed MASH over 48 weeks; separately 94 and 64 adults with fatty liver over 12 and 24 weeks

Measured in people

Source [02]Source [16]

Cholesterol, triglycerides and blood pressure

Total cholesterol fell 11.6%, 13.1% and 15.1% across the three amounts against 2.8% on dummy injections. Triglycerides fell 21.7%, 22.3% and 34.9% against a rise of 7.3%. LDL cholesterol fell 6.2%, 11.2% and 9.9% against 2.8%, and none of those three reached statistical significance. The top blood pressure number fell 2.3, 1.6 and 4.6 mmHg against a rise of 3.5. All from a company press release.

The same 391 adults, 48 weeks

Measured in people

Source [04]

Long-term blood sugar

A null result, and it is the one that stops this being a diabetes drug. In 391 adults without diabetes, long-term blood sugar was 5.5% to 5.6% at the start and 5.5% to 5.6% at 48 weeks in every group, dummy injections included. In 54 adults who did have type 2 diabetes, it went from 6.5% to 6.5% and from 6.6% to 6.7% on the two lower amounts and stayed at 6.9–7.0% on the highest, while the dummy-injection group went from 6.6% to 7.0%. Nobody in any group had an episode of high blood sugar reported as a side effect. Fifty-four people over twelve weeks cannot settle whether it helps diabetes; what it does show is that it did not make it worse.

391 adults without diabetes over 48 weeks, and 54 adults with type 2 diabetes over 12 weeks

Measured in people

Source [04]Source [13]

Liver measurements pooled across the trials

An independent group pooled the randomised trials against dummy injections and found the same directions: at 12 weeks, liver fat down 52.90 percentage points more than on dummy injections, weight down 3.50% more; at 24 weeks, the liver blood test ALT down 18.09 units more, AST down 13.02 units more, liver fat down 45.51 points more and the blood scarring score down 0.44 points more. The authors' own conclusion is that larger, longer trials are needed to confirm any effect on scarring — the same gap the biopsy result left open.

Pooled randomised trials of pemvidutide against dummy injections in adults with fatty liver disease

Measured in people

Source [20]

How much of the weight lost was muscle and other lean tissue

The claim that made this compound's name, and it has no comparison group. In a scan substudy of 67 people, 50 of them on pemvidutide, lean tissue made up 21.9% of the weight lost over 48 weeks. The placebo group's equivalent figure was never published, so there is nothing in this trial to compare 21.9% against. The comparisons that are made instead — roughly 40% for semaglutide, roughly 25% for diet and exercise — come from entirely separate trials in different people, measured in different ways. Nobody measured strength, walking speed, or falls in any pemvidutide trial, and the expert workshop where this was presented noted in its own summary that more lean tissue does not automatically mean more strength.

67 of the 391 adults in the obesity trial, 50 of them on pemvidutide, scanned by MRI at the start and at 48 weeks

One small study

Source [06]Source [12]

Heavy drinking, in people with alcohol use disorder

A newer and separate use, reported so far only by the company. Over 24 weeks, heavy drinking days per week fell by 4.20 on pemvidutide against 2.75 on dummy injections — a difference of 1.45 days a week, p=0.0014. Dropping two levels on the World Health Organization's drinking-risk scale happened in 29 of 45 people on the drug (64.4%) against 16 of 46 on dummy injections (34.8%). Having no heavy drinking day at all in the last four weeks happened in 19 of 45 (42.2%) against 8 of 46 (17.4%). A blood marker of alcohol use fell 153.4 units on the drug against a rise of 22.0 on dummy injections. Weight fell 9.1% more than on dummy injections. None of this has been published in a journal; the trial finished on 30 July 2026 and has posted no results.

100 adults with moderate to severe alcohol use disorder and obesity or overweight, 24 weeks, half on pemvidutide 2.4 mg and half on dummy injections

One small study

Source [18]Source [19]

Feeling sick is the main problem and it tracks the amount given. In the 391-person obesity trial it was reported by 59.6% and 51.5% of people on the two higher amounts against 11.3% on dummy injections, vomiting by about 27% against 3.1%, and constipation by up to 22.7% against 8.2%; about one person in five on those amounts stopped taking it because of a side effect, against 6.2% on dummy injections. At the lower amounts used in the liver trial, fewer people stopped because of a side effect on the drug (0% and 1%) than on dummy injections (2%). One person out of 97 on the largest amount had nausea and vomiting that needed rehydration. The resting heart rate rose by 2.5 to 3.1 beats a minute on the two higher amounts, against a fall of 1.4 beats a minute on dummy injections. No trial has published a rate of low blood sugar; no heart-outcomes trial exists; nothing has been published beyond 48 weeks or after stopping.

EffectWhat it feels likeHow often

Vomiting bad enough to need rehydrationSerious

The only side effect in the obesity trial that the company classed as both serious and caused by the drug. The company's earlier report of the same trial describes it as nausea and vomiting requiring rehydration; nothing published says whether the person was admitted to hospital. It happened at the 2.4 mg amount, the one that produced the 15.6% weight loss. One event in 97 people is not a rate and cannot be turned into one.

One person out of 97 on the largest amount in the 48-week obesity trial — 1.0% — against nobody on dummy injections and nobody on the two lower amounts.

Source [04]Source [13]

Salt levels in the blood dropping too lowSerious

Low blood sodium causes confusion, headache and, if it goes far enough, seizures. It is a single event in a single trial of people who were drinking heavily, which is itself a cause of the same problem, so nothing about it is settled. It is here because it is the only serious event anywhere in this record that a trial investigator linked to the drug.

One person out of 50 on pemvidutide in the alcohol trial — 2% — and nobody on dummy injections. The trial's lead doctor judged it possibly caused by the drug.

Source [18]

Blood sugar dropping too lowSerious

The absence is worth naming rather than reading as reassurance. The obesity trial excluded everyone with diabetes, and the 54-person diabetes trial only enrolled people on diet and exercise, metformin or an SGLT-2 medicine — not on insulin or on the tablets that push insulin out, which are the medicines that make low blood sugar likely in the first place. The group most at risk was never tested.

Not reported in any published pemvidutide trial. No trial has published a rate of low blood sugar, in people with or without diabetes.

Source [05]Source [13]

Feeling sick

The defining side effect and the main reason people left the obesity trial. It arrives early. The two lower amounts were given straight away with no stepping up at all, which is unusual for this class of drug and is what the company puts forward as the reason the liver trials were tolerated so much better.

Very common, and strongly dependent on the amount. In 391 adults over 48 weeks: 25.5%, 59.6% and 51.5% across the three amounts against 11.3% on dummy injections. In the alcohol trial: 44% against 24%. In the 212-person liver trial, where the amounts were lower, the published abstract gives no separate figure for it, but stopping because of any side effect happened less often on the drug than on dummy injections.

Source [04]Source [18]

Vomiting

Roughly nine times as common as on a dummy injection at the two higher amounts. It is the route by which people become dried out, and it was the reason the single drug-related serious event in the obesity trial happened.

Common — 6.1%, 27.3% and 27.8% across the three amounts against 3.1% on dummy injections in 391 adults over 48 weeks. In the alcohol trial, 18% against 6%.

Source [04]Source [18]

Constipation

More common than loose stools on this compound, which is the opposite way round from some others in the family. In the alcohol trial it was one of the five reasons given by the five people who stopped taking it because of a side effect.

Common — 17.3%, 13.1% and 22.7% across the three amounts against 8.2% on dummy injections. In the alcohol trial, 26% against 6%.

Source [04]Source [18]

Loose stools

The most inconsistent of the gut effects across trials, and in the smallest trial the dummy injections produced as much of it as the drug. That is a reminder of how much bowel trouble people report regardless of what they are given.

Common — 8.2%, 10.1% and 18.6% across the three amounts against 5.2% on dummy injections. In the alcohol trial, 20% against 10%. In the 24-week liver extension, 18.8%, 33.3% and 7.1% against 21.1% — where the dummy group had more of it than two of the three drug groups.

Source [02]Source [04]

Stopping the drug because of a side effect

This is the single number that best describes what taking it is like, because it counts people who decided it was not worth it. At the amount that produced the headline 15.6% weight loss, one person in five left. At the amounts used for the liver, fewer people left than on dummy injections. Almost all the leaving happened in the first 16 weeks, and the obesity trial's rules did not allow anyone to drop to a lower amount instead of stopping.

Depends almost entirely on the amount and how fast it was reached. In the obesity trial: 5.1%, 19.2% and 19.6% across the three amounts against 6.2% on dummy injections. In the 212-person liver trial at 24 weeks, at the two lower amounts: 0% and 1% against 2% on dummy injections. In the alcohol trial, with a new two-step build-up: 10% against 0%.

Source [01]Source [04]Source [13]

A faster resting heart

Small, and most people would not notice it. It is listed because a rise in heart rate is the effect that ended the development of several earlier glucagon-based compounds, so it is the number to watch on this one. No major heart event occurred in any group of the obesity trial, and heart side effects including irregular heartbeats were no more common on the drug than on dummy injections. What a small permanent rise does over years is unknown for this compound, and the trial that could answer it does not exist.

An average change of +0.1, +3.1 and +2.5 beats a minute across the three amounts at 48 weeks, against −1.4 on dummy injections. In the 24-week liver extension, the authors report no significant change in heart rate at any amount.

Source [02]Source [04]

These are the amounts the studies below gave their participants, and they are here as facts about those studies. They are not a recommendation, not a starting point and not a range to pick from. What a person should take, if anything, is a question for a doctor who knows them.

MOMENTUM, weight loss in 391 adults with obesity or overweight and no diabetes

1.2 mg, 1.8 mg or 2.4 mg once a week under the skin, alongside diet and exercise. The two lower amounts were given at full strength from the first injection with no stepping up; the highest used a four-week build-up

48 weeks

Source [04]Source [05]

IMPACT, 212 adults with MASH confirmed by biopsy and scarring at stage 2 or 3

1.2 mg or 1.8 mg once a week under the skin, given without any stepping up

48 weeks, with the main results read at 24 weeks

Source [01]

The earlier liver trial and its extension, in 94 adults with fatty liver disease

1.2 mg, 1.8 mg or 2.4 mg once a week under the skin

12 weeks, then a further 12 weeks at the same amount for the 64 people who continued

Source [02]Source [03]

The safety trial in 54 adults with overweight or obesity and type 2 diabetes

1.2 mg, 1.8 mg or 2.4 mg once a week under the skin, with no diet or exercise programme attached

12 weeks

Source [13]

RECLAIM, 100 adults with moderate to severe alcohol use disorder and obesity or overweight

2.4 mg once a week under the skin, reached through a new two-step build-up

24 weeks

Source [18]

What people report

• Whether it stops anyone with liver disease actually becoming ill — no trial has yet measured liver failure, transplant or death, and the phase 3 trial that will began the day this record was written
• Whether it improves the scarring in the liver at all — the one biopsy measurement of that missed its target, with a range that included no effect
• Whether the weight-loss results are sound — the 391-person trial that produced them has never been published in a peer-reviewed journal and has posted no results on the registry, more than two and a half years after it finished
• Whether it preserves muscle better than anything else — the placebo group's lean-tissue figure from the same substudy has never been published, and no head-to-head comparison exists
• Whether anyone on it is stronger, walks further or falls over less — no pemvidutide trial has measured any physical function at all
• Whether it makes a person burn more energy, which is the entire argument for the glucagon half — no trial has measured it and none is registered to
• Why people eat less on it — no trial has published a measurement of hunger, fullness or food intake
• Whether it causes or prevents heart attacks and strokes — no heart-outcomes trial exists or is registered
• What a permanent rise of two to three heartbeats a minute does over years
• What happens after stopping — not one trial has published weight, liver fat or heart rate in the weeks or months after the last injection
• Whether it is safe or keeps working beyond 48 weeks — nothing published goes further for any outcome
• How often blood sugar drops too low — no trial has published a rate, and the people most at risk, those on insulin or on tablets that push insulin out, were excluded from the only trial in people with diabetes
• Whether it helps or harms people who have both obesity and type 2 diabetes — the only trial in them lasted 12 weeks and enrolled 54 people
• What the alcohol results mean — the trial finished on 30 July 2026, has posted no results and has not been through a journal
• What it does in anyone under 18, over 75, in pregnancy or while breastfeeding — none of them has been studied
• What it does in people with untreated depression, a history of suicidal thoughts, schizophrenia or bipolar disorder, a previous inflamed pancreas, or previous stomach or bowel surgery — all were excluded from the trials
• What its exact chemical structure is, as published — no public chemical database holds an entry for it, and no admissible source prints a verified amino-acid sequence

Does pemvidutide work?

For weight, and for the fat in a liver, the trials show a clear effect against dummy injections: 15.6% of body weight gone at 48 weeks on the largest amount against 2.2%, and liver fat down by half to three-quarters against almost nothing. For the thing that actually decides whether someone with liver disease gets ill — the scarring — it has not been shown to work: that was one of the two main targets of the biggest liver trial and it was missed, with results that included no effect at all. And the weight-loss numbers have a separate problem: the trial that produced them finished in 2023 and has never been published in a medical journal, so there is no paper anyone can check them against.

Source [01]Source [04]Source [11]

Is pemvidutide legal, and can you buy it?

It is not approved as a medicine anywhere in the world, so no doctor can prescribe it and no pharmacy can dispense it. The only lawful way to receive it is to be enrolled in one of the trials. The US regulator has given it Fast Track and Breakthrough Therapy status for liver disease, but both of those are promises of a faster review, not decisions that it works or is safe; in Europe the company had reached only the stage of asking regulators for scientific advice as of March 2026. It is also banned in sport at all times, because anything still in clinical development and approved by no health authority falls under the anti-doping list's first category.

Source [07]Source [08]

What are the side effects of pemvidutide?

Feeling sick is the main one, and how bad it gets depends on the amount. In the 48-week obesity trial it was reported by 59.6% and 51.5% of people on the two higher amounts against 11.3% on dummy injections, vomiting by about 27% against 3.1%, and constipation by up to 22.7% against 8.2%. About one person in five on those higher amounts stopped taking it because of a side effect, against about one in sixteen on dummy injections. At the lower amounts used in the liver trial, fewer people stopped because of side effects on the drug than on dummy injections. The resting heart rate rose by about two to three beats a minute on the two higher amounts, against a fall of about one beat a minute on dummy injections.

Source [01]Source [04]

Pemvidutide vs semaglutide — which is better?

Nobody has run the trial that would answer that. Pemvidutide has never been compared head-to-head against semaglutide, tirzepatide or anything else; every comparison you will read is between separate trials in different people, which is not evidence. For orientation only: pemvidutide's 15.6% at 48 weeks sits near semaglutide's published weight figures and below tirzepatide's, and unlike both of them it has not been shown to lower long-term blood sugar. Where it is genuinely different is the liver, and there it has never been compared against the drug already approved for that disease.

Source [01]Source [04]Source [13]

Does pemvidutide preserve muscle better than other weight drugs?

That has not been measured against a comparator, and it is the compound's most repeated claim. What exists is a scan of 67 people inside the 391-person trial, 50 of them on pemvidutide, in which lean tissue made up 21.9% of the weight lost. The figure for the people on dummy injections in that same substudy has never been published, so there is nothing in the trial to compare it against. The roughly 40% attributed to semaglutide comes from completely different trials in different people, measured in different ways. And nobody measured whether anyone on pemvidutide was stronger, could walk further, or fell over less — which is what preserving muscle is supposed to be for.

Source [06]Source [12]

What is MASH, and what did the liver trial actually show?

Fat collects inside the cells of the liver in people with weight and blood-sugar problems. When inflammation and swollen, dying liver cells join the fat, the condition is called MASH. The dying and repairing lays down scar tissue, and it is the scarring — not the fat — that eventually stops the liver working. The trial had two targets. It hit the first: the inflammation cleared up without the scarring worsening in 52% of people on the higher amount against 20% on dummy injections. It missed the second: the scarring itself improved in 36% against 28%, a gap small enough that no effect at all is within the range of possibilities. Whether any of this stops people going on to liver failure is what the new phase 3 trial is meant to find out, and its main reading is not due until 2029.

Source [01]Source [10]

Is pemvidutide approved, and when could it be?

No, not anywhere. As of 3 August 2026 the phase 3 trial in liver disease had just been announced as starting, with its main 52-week result expected in 2029 and follow-up for liver events running about five years. The obesity programme has not gone past phase 2 at all: that trial finished in September 2023 and no later-stage obesity trial has been registered since. Most drugs at this stage never reach approval.

Source [10]Source [21]

Does pemvidutide help people drink less?

One trial says so, and it has not been published. In 100 adults with moderate to severe alcohol use disorder, heavy drinking days per week fell by 4.20 on pemvidutide against 2.75 on dummy injections over 24 weeks, and 64% of people on the drug dropped two levels on the World Health Organization's drinking-risk scale against 35% on dummy injections. Those are the company's own figures from a stock-market announcement; the trial finished on 30 July 2026, has posted no results on the registry and has not been through a journal. A separate 100-person trial in alcohol-related liver disease is still recruiting and runs to 2027.

Source [18]Source [22]

Why do some sources say ALT-801 is a cancer drug?

Because two different companies used the same code. Altimmune's ALT-801 is pemvidutide. Altor BioScience's ALT-801 was an interleukin-2 fusion protein tested in melanoma, bladder cancer, leukaemia and myeloma from 2007 onwards. Six of the twelve trials on ClinicalTrials.gov that mention ALT-801 are that other molecule and have nothing whatsoever to do with this one. If a search result about ALT-801 talks about tumours, it is not about pemvidutide.

Source [23]Source [24]

1. [01]Noureddin M 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)
2. [02]Browne SK et al. Safety and efficacy of 24 weeks of pemvidutide in metabolic dysfunction-associated steatotic liver disease: a randomized, controlled clinical trial. JHEP Rep (64 participants) (2025)
3. [03]Harrison SA et al. Effect of pemvidutide, a GLP-1/glucagon dual receptor agonist, on MASLD: a randomized, double-blind, placebo-controlled study. J Hepatol (94 participants, 12 weeks) (2025)
4. [04]Altimmune announces positive topline results from MOMENTUM 48-week phase 2 obesity trial of pemvidutide — the only source for the 48-week obesity figures (company press release, 30 November 2023) (2023)
5. [05]ClinicalTrials.gov NCT05295875 — MOMENTUM, 391 participants, phase 2, completed 28 September 2023, no results posted (2023)
6. [06]von Haehling S et al. Muscle Loss in Obesity Therapy as a Therapeutic Target: Trial Design and Endpoints for Regulatory Discussions. J Cachexia Sarcopenia Muscle — section 3.2, the body-composition substudy in 67 subjects (2025)
7. [07]Altimmune fourth quarter and full-year 2025 results — Breakthrough Therapy designation, End-of-Phase 2 meeting, scientific advice requested from European regulators (SEC Form 8-K exhibit 99.1, 5 March 2026) (2026)
8. [08]WADA Prohibited List 2026, S0 non-approved substances: any pharmacological substance with no current approval by any governmental regulatory health authority for human therapeutic use, including drugs under clinical development, is prohibited at all times (official publication, Austrian BGBl. III no. 219/2025) (2025)
9. [09]Strategies to Improve the Lipophilicity of Hydrophilic Macromolecular Drugs, Adv Healthc Mater 2026, Table 2 — pemvidutide listed as a GLP-1/glucagon peptide lipidated with stearic acid (C18); a review, not the primary chemistry (2026)
10. [10]Altimmune announcement, 3 August 2026 — the PERFORMA phase 3 trial of pemvidutide in MASH has begun enrolling; 52-week readout anticipated in 2029 (2026)
11. [11]PubMed, all 13 indexed records for "pemvidutide" — none reports an appetite or food-intake outcome (search reproducible at this URL) (2026)
12. [12]Altimmune, "About Pemvidutide" — "Activation of the GLP-1 and glucagon receptors is believed to mimic the complementary effects of diet and exercise on weight loss, with GLP-1 suppressing appetite and glucagon increasing energy expenditure" (company press release, 10 September 2024) (2024)
13. [13]Altimmune announces results from week 24 interim analysis of MOMENTUM and the 12-week phase 1b type 2 diabetes safety trial — company press release with full glycaemic table, 21 March 2023 (2023)
14. [14]ClinicalTrials.gov NCT05134662 — pemvidutide in 55 overweight and obese subjects with type 2 diabetes, phase 1, completed March 2023, no results posted (2023)
15. [15]Altimmune announces positive topline results from the IMPACT phase 2b trial of pemvidutide in the treatment of MASH (company press release, 26 June 2025) (2025)
16. [16]Altimmune announces that pemvidutide achieved key measures of success at 48 weeks in the IMPACT phase 2b MASH trial (company press release, 19 December 2025) (2025)
17. [17]ClinicalTrials.gov NCT05989711 — IMPACT, 212 participants, completed 25 November 2025, no results posted (2025)
18. [18]Altimmune announces positive topline results from the RECLAIM phase 2 trial of pemvidutide in alcohol use disorder — full efficacy and safety tables, SEC Form 8-K exhibit 99.1, 28 July 2026 (2026)
19. [19]ClinicalTrials.gov NCT06987513 — RECLAIM, 100 participants, phase 2, completed 30 July 2026, no results posted (2026)
20. [20]Rajab I et al. Efficacy and safety of pemvidutide in metabolic dysfunction-associated steatohepatitis: a GRADE-assessed meta-analysis of randomized controlled trials. Naunyn Schmiedebergs Arch Pharmacol (2026)
21. [21]ClinicalTrials.gov, all registered pemvidutide trials — four phase 1, three phase 2, no phase 3 registered as of 3 August 2026 (2026)
22. [22]ClinicalTrials.gov NCT07009860 — RESTORE, pemvidutide in alcohol-associated liver disease, 100 participants, recruiting, completion August 2027 (2026)
23. [23]ClinicalTrials.gov, all studies with the intervention ALT-801 — six sponsored by Altimmune (pemvidutide) and six by Altor BioScience (an interleukin-2 fusion protein in cancer) (2026)
24. [24]ClinicalTrials.gov NCT00496860 — safety and efficacy study of ALT-801 to treat progressive metastatic malignancies, Altor BioScience, 26 participants (2008)