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Investigational peptide drugHuman trialsIn clinical trials

Pemvidutide

Pemvidutide

Last reviewed October 27, 2026 · 14 sources · Written for general readers · Compare with another compound →

The bottom line

Pemvidutide is an experimental weekly shot that acts on both GLP-1 and glucagon receptors. Placebo controlled trials showed real weight loss, big drops in liver fat, MASH clearing on biopsy in about half of patients, and fewer heavy drinking days in alcohol use disorder, but liver scarring did not improve more than placebo at 24 weeks and nausea is common. It is not approved, and its final phase 3 trial only started in 2026.

Where the evidence stands

What it is

Pemvidutide is an experimental drug made by the US company Altimmune. It is still investigational, which means it is being tested and is not approved for sale.[1]

It is a modified peptide, a chain of 29 amino acids with some chemically changed building blocks. FDA's substance registry lists it under CAS number 2538014-94-5.[2]

In trials it is given as a shot under the skin once a week.[3]

Altimmune is testing it for MASH, a serious fatty liver disease where fat buildup causes liver inflammation and scarring. It is also being tested for alcohol use disorder and for liver disease caused by heavy drinking.[1]

Early lab papers called it ALT-801.[4] An unrelated cancer drug once used the same code, so older ALT-801 cancer papers are not about this compound.

Name
Pemvidutide (Pemvidutide)
Other names
ALT-801 (early code name)
Type
Investigational peptide drug
CAS number
2538014-94-5

What it does in the body

Pemvidutide is a lab made peptide that copies parts of two natural gut and pancreas hormones. It switches on the GLP-1 receptor, which lowers appetite, and the glucagon receptor, which acts mainly on the liver, in an even balance.[1]

This is the biology, area by area. A change measured in the body, like a higher blood level, does not always mean a person feels a benefit. The claims check below covers that.

Fat and appetite

Measured in people

In a 48 week placebo controlled trial of 391 adults with obesity, average weight loss was about 10 to 16 percent depending on dose, versus about 2 percent on placebo.[5] In a small first in human trial, 34 adults lost up to about 10 percent of body weight in 12 weeks without any diet program.[6]

Liver

Measured in people

Liver fat fell by about 47 to 69 percent in 12 weeks on the drug versus about 4 percent on placebo, and by up to about 76 percent after 24 weeks.[3][7] In people with biopsy confirmed MASH, inflammation cleared in 52 to 58 percent versus 20 percent on placebo, but scarring did not improve more than placebo at 24 weeks.[8] Liver enzymes, blood signs of liver injury, also fell.[9]

Blood fats

Measured in people

In the 48 week obesity trial, triglycerides, a blood fat linked to heart disease, fell about 22 to 35 percent on the drug versus a 7 percent rise on placebo.[10]

Muscle and body makeup

Measured in people

In an MRI substudy of 50 people on the drug in the obesity trial, the company reported that about 22 percent of the weight lost was lean tissue and about 78 percent was fat.[10] This has not been published in a peer reviewed journal, and lean tissue on MRI is not the same as measured strength.

Heart and blood vessels

Measured in people

Heart rate rose slightly at higher doses, by about 3 beats per minute, while blood pressure dipped a little.[5] A pooled analysis of liver trials also found lower blood pressure than on placebo.[9]

Brain and drinking

Measured in people

In a 24 week placebo controlled trial of about 100 adults with alcohol use disorder, heavy drinking days per week fell by about 4.2 on the drug versus 2.75 on placebo. A blood test that tracks recent alcohol use dropped sharply on the drug and not on placebo.[11] This is one company reported trial that is not yet peer reviewed.

How it works

Pemvidutide switches on two hormone receptors, GLP-1 and glucagon, in an even 1 to 1 balance.[1]

  • The GLP-1 side reduces appetite and drives weight loss. Altimmune says it may also affect craving and reward signals in the brain.[1]
  • The glucagon side acts directly on the liver, where it is meant to cut liver fat, inflammation and scarring.[1]
  • In trials, liver fat dropped faster and further than body weight, which fits this liver focused design.[3]

The two receptor design is described by the company. Human trials confirm the drops in liver fat and weight, but long term health outcomes are unknown.

What the research shows

We keep animal and human evidence apart. A result in animals is a reason to study something in people, not proof that it works in people.

Animal and lab studies

Mouse study showed weight and liver improvements

  • In mice with diet induced obesity and biopsy confirmed fatty liver disease, 12 weeks of daily treatment cut body weight by about 25 percent.[4]
  • Liver fat dropped more than with semaglutide or elafibranor, a liver drug used for comparison, and liver enzymes and cholesterol fell.[4]
  • Markers of liver inflammation and scarring dropped, and every treated mouse improved on a standard liver disease activity score.[4]

Limit: This was one company linked mouse study. Human trials now give much better evidence.

Human studies

Strong mid stage results, final trials still running

  • First in human, 2021: 34 adults with overweight or obesity got weekly shots or placebo for 12 weeks with no diet program. Weight fell about 5 to 10 percent on the drug versus about 1.6 percent on placebo, heart rate did not rise, and no one quit because of side effects. Nausea and vomiting were common at the higher doses.[6]
  • Obesity, MOMENTUM: 391 adults with obesity or overweight and no diabetes got weekly shots or placebo for 48 weeks. Average weight loss was about 10 to 16 percent depending on dose, versus about 2 percent on placebo.[5]
  • In MOMENTUM, nausea affected about 26 to 60 percent on the drug versus 11 percent on placebo, and vomiting up to about 28 percent. At the two higher doses, about 1 in 5 quit because of side effects, versus about 6 percent on placebo. Heart rate rose by about 3 beats per minute at the higher doses, while blood pressure dipped a little.[5]
  • In MOMENTUM, triglycerides fell about 22 to 35 percent versus a 7 percent rise on placebo, and an MRI substudy of 50 people reported that about 22 percent of the weight lost was lean tissue.[10]
  • Fatty liver, 12 weeks: in 94 adults with excess weight and fatty liver, liver fat fell by about 47 to 69 percent on the drug versus about 4 percent on placebo. Weight fell up to about 4 percent, and no serious side effects were reported.[3]
  • Fatty liver, 24 weeks: in 64 of those people who continued, liver fat fell by up to about 76 percent and body weight by about 6 percent.[7]
  • MASH, IMPACT: in 212 adults with biopsy confirmed MASH and moderate or advanced scarring, MASH cleared after 24 weeks in 52 to 58 percent on pemvidutide versus 20 percent on placebo. Scarring did not improve more than with placebo. About 8 in 10 people on the drug and about 7 in 10 on placebo had side effects, mostly mild or moderate, and only 1 of 126 people on the drug quit because of them.[8]
  • IMPACT at 48 weeks: Altimmune reported further improvement in noninvasive liver scarring measures, continued weight loss at the highest dose, and fewer dropouts on the drug than on placebo, without giving numbers.[12]
  • Alcohol use disorder, RECLAIM: about 100 adults were randomly given weekly shots or placebo for 24 weeks. Heavy drinking days fell more on the drug, and weight fell about 9 percent more than placebo. Nausea (44 versus 24 percent), vomiting (18 versus 6 percent) and constipation (26 versus 6 percent) were more common on the drug, and serious side effects occurred in 2 people on the drug and 1 on placebo.[11]
  • Pooled analysis: a 2026 meta analysis of the liver trials found lower liver fat, liver enzymes, body weight and blood pressure than placebo, with more mild or moderate nausea as the main safety difference.[9]

Limit: The obesity and alcohol data come from company reports, trials lasted one year or less, and none has yet shown fewer heart attacks, liver failure or deaths.

Claims check

The most common claims about this compound, and what studies actually found. Verdicts rate the evidence, not whether you should use it.

Causes weight loss

Shown in people

In a 48 week placebo controlled trial of 391 adults with obesity or overweight and no diabetes, people on weekly shots lost about 10 to 16 percent of body weight depending on dose, versus about 2 percent on placebo.[5] These results come from a company report, not a journal paper. In peer reviewed liver trials, weight fell up to about 4 percent at 12 weeks and about 6 percent at 24 weeks.[3][7] In the alcohol use disorder trial, weight fell about 9 percent more than placebo over 24 weeks.[11]

Melts liver fat

Shown in people

In a 12 week trial of 94 adults with excess weight and fatty liver, liver fat fell by about 47 to 69 percent on the drug versus about 4 percent on placebo, and over half of those on the middle dose level reached normal liver fat.[3] In 64 people who continued to 24 weeks, liver fat fell by up to about 76 percent versus 14 percent on placebo.[7] A 2026 meta analysis of these trials confirmed large drops in liver fat and liver enzymes.[9]

Reverses fatty liver disease (MASH)

Shown in people

In the IMPACT trial, 212 adults with biopsy confirmed MASH and moderate or advanced scarring got weekly shots or placebo. After 24 weeks, MASH cleared on biopsy in 52 to 58 percent of people on the drug versus 20 percent on placebo.[8] This is a single mid stage trial, and the phase 3 trial is still running.[1]

Heals liver scarring

Mixed results

In IMPACT, scarring on biopsy improved in 33 to 36 percent on the drug versus 28 percent on placebo after 24 weeks, a difference that was not statistically reliable.[8] At 48 weeks, Altimmune reported better blood and scan measures linked to scarring, but it did not publish the numbers or new biopsies.[12]

Curbs drinking and alcohol cravings

Mixed results

In the RECLAIM trial, about 100 adults with alcohol use disorder and excess weight got weekly shots or placebo for 24 weeks. Heavy drinking days per week fell by about 4.2 on the drug versus 2.75 on placebo, 42 percent versus 17 percent had no heavy drinking days in the last month, and alcohol free days were about 39 versus 21 percent.[11] These are company reported results, not yet peer reviewed, from one trial.

Keeps muscle while losing fat

Mixed results

In an MRI substudy of 50 people from the 48 week obesity trial, the company reported that about 22 percent of the weight lost was lean tissue.[10] That is a company presentation, not a peer reviewed paper, and no study has compared muscle loss head to head with other weight loss drugs or measured strength.

Easier to tolerate than other weight loss shots

Not tested

No trial has compared it head to head with semaglutide or tirzepatide. In its own obesity trial, nausea hit about 26 to 60 percent of people on the drug versus 11 percent on placebo, and about 1 in 5 on the higher doses quit because of side effects.[5] In IMPACT, only 1 of 126 people on the drug quit because of side effects.[8] In RECLAIM, 10 percent quit because of side effects versus none on placebo.[11]

Known risks and side effects

  • Nausea and vomiting. Stomach side effects were common and rose with dose, with nausea in up to about 60 percent and vomiting in up to about 28 percent of people in the obesity trial.[5] Constipation affected 26 percent versus 6 percent on placebo in the alcohol trial.[11]
  • Quitting due to side effects. About 1 in 5 people on the higher doses stopped treatment because of side effects in the 48 week obesity trial, versus about 6 percent on placebo.[5] In the alcohol trial, 10 percent stopped for side effects versus none on placebo.[11]
  • Small heart rate rise. Average heart rate went up by about 2 to 3 beats per minute at higher doses. The long term meaning of this is not known.[5]
  • Long term effects unknown. The main phase 3 trial started in 2026, and its 52 week results are not expected until 2029.[1]
  • Unregulated online products. Pemvidutide is not approved and does not appear on FDA's compounding nomination list. Anything sold online under this name has not been checked by FDA for identity, purity or strength.[13]

Regulatory status

Today: Pemvidutide is an investigational drug and is not FDA approved. FDA granted it Breakthrough Therapy designation for MASH, a status that speeds review, and Fast Track status for MASH and alcohol use disorder. A phase 3 trial called PERFORMA began in mid 2026.[12][1] As an unapproved drug in development, it falls under WADA's catch all S0 ban, which applies at all times.[14]

  1. Altimmune reported 12 week results from the first in human trial.[6]
  2. Altimmune reported 48 week results from the MOMENTUM obesity trial, with up to about 16 percent average weight loss.[5]
  3. The 12 week liver fat trial was published in the Journal of Hepatology.[3]
  4. The IMPACT 24 week MASH results were published in The Lancet, and Altimmune announced 48 week topline results.[8][12]
  5. Altimmune reported Breakthrough Therapy designation for MASH and agreement with FDA on its phase 3 design.[12]
  6. Altimmune reported positive RECLAIM results in alcohol use disorder and started the PERFORMA phase 3 MASH trial.[11][1]

Sources

  1. Altimmune, Inc. Altimmune announces second quarter 2026 financial results and business update. Press release, Form 8-K Exhibit 99.1, U.S. Securities and Exchange Commission. August 12, 2026. SEC filing
  2. U.S. FDA and NCATS Global Substance Registration System (GSRS). Pemvidutide, UNII A35F525WBG. FDA GSRS
  3. 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. PMID 39002641
  4. Nestor JJ, Parkes D, Feigh M, et al. Effects of ALT-801, a GLP-1 and glucagon receptor dual agonist, in a translational mouse model of non-alcoholic steatohepatitis. Sci Rep. 2022;12(1):6666. PMID 35461369
  5. Altimmune, Inc. Altimmune announces positive topline results from MOMENTUM 48-week Phase 2 obesity trial of pemvidutide. Press release, Form 8-K Exhibit 99.1, U.S. Securities and Exchange Commission. November 30, 2023. SEC filing
  6. Altimmune, Inc. Altimmune announces positive results from 12 week Phase 1 clinical trial of ALT-801 (pemvidutide) in overweight and obese volunteers. Press release via BioSpace. September 28, 2021. Company release
  7. Browne SK, Suschak JJ, Tomah S, Gutierrez JA, Yang J, Georges B, et al. Safety and efficacy of 24 weeks of pemvidutide in metabolic dysfunction-associated steatotic liver disease: A randomized, controlled clinical trial. JHEP Rep. 2025;7(11):101483. PMID 41113119
  8. 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. PMID 41237796
  9. Rajab I, Emara A, Rakab MS, 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;399(9):14553-14560. PMID 41879841
  10. HCPLive. MOMENTUM: Pemvidutide boasts class-leading lean mass preservation with weight loss. June 23, 2024. News report (ADA 2024)
  11. Altimmune, Inc. Altimmune announces positive topline results from RECLAIM Phase 2 trial of pemvidutide in alcohol use disorder. Press release, Form 8-K Exhibit 99.1, U.S. Securities and Exchange Commission. July 28, 2026. SEC filing
  12. Altimmune, Inc. Altimmune announces fourth quarter and full-year 2025 financial results and business updates. Press release, Form 8-K Exhibit 99.1, U.S. Securities and Exchange Commission. March 5, 2026. SEC filing
  13. U.S. Food and Drug Administration. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the FD&C Act. Updated May 14, 2026. FDA list
  14. World Anti-Doping Agency. The 2026 Prohibited List. In force January 1, 2026. WADA 2026
Medical disclaimer

This page is educational information only. It is not medical advice and does not replace care from a licensed medical provider. Do not use this page to decide whether to take any substance. Talk to a licensed medical provider first.

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