Pemvidutide (code name ALT-801) is an investigational once-weekly injectable peptide that activates two hormone receptors: the glucagon-like peptide-1 (GLP-1) receptor and the glucagon receptor. It is developed by Altimmune, a US biotech company. It was first studied for obesity, and the company now develops it for metabolic dysfunction-associated steatohepatitis (MASH, the inflammatory form of fatty liver disease formerly called NASH), alcohol use disorder (AUD) and alcohol-associated liver disease (ALD) (Altimmune Q2 2026 release).
The single most important fact: pemvidutide is not approved anywhere. As of the newest company update we could verify (August 12, 2026), a phase 3 MASH trial called PERFORMA started in July 2026, with its 52-week readout expected in 2029. The FDA has granted it Breakthrough Therapy designation for MASH and Fast Track designations for MASH and AUD, but these designations speed up review; they are not approvals.
This page summarizes what the published trials, trial registrations and company disclosures report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Drug class | Dual GLP-1 and glucagon receptor agonist; peptide with a glycolipid (“EuPort”) modification |
| Developer / code | Altimmune (ALT-801; earlier SP-1373 at Spitfire Pharma) |
| Approval status | Investigational; not approved by the FDA, EMA or any other regulator |
| Route | Subcutaneous injection once weekly |
| Doses studied | 1.2, 1.8 and 2.4 mg/week in phase 2; 1.8 and 2.4 mg/week in phase 3 |
| Half-life | Designed for weekly dosing; a human half-life value is not reported in the peer-reviewed publications we could access |
| Receptor balance | Described by the developer as a balanced 1:1 GLP-1:glucagon agonist |
| US regulatory designations | Breakthrough Therapy (MASH); Fast Track (MASH and AUD) |
| Current trials | PERFORMA phase 3 (MASH), RESTORE phase 2 (ALD); RECLAIM phase 2 (AUD) completed |
| WADA status | Not named on the 2026 List; as an unapproved drug it falls under S0 (non-approved substances) |
What it is
Pemvidutide is a stabilized peptide that combines sequence elements of GLP-1 and glucagon. It carries a proprietary glycolipid side chain that Altimmune calls EuPort (Nestor et al., Sci Rep 2022). The developers describe two effects of that side chain:
- it binds serum albumin transiently but almost completely (estimated at over 99%), which protects the peptide from breakdown and from filtering by the kidneys;
- its surfactant-like (detergent-like) structure forms micelles under the skin, which slows release into the blood.
The same paper reports that the compound was originally developed as SP-1373 by Spitfire Pharma. A full chemical formula is not listed in PubChem.
The design goal was balanced activity at the two receptors. Many other dual agonists lean more toward the GLP-1 receptor. The rationale is shared with the rest of the class:
- the GLP-1 receptor mainly reduces appetite and food intake;
- the glucagon receptor acts directly on the liver, where it increases fat burning (fatty acid oxidation) and reduces new fat production (Harrison et al., J Hepatol 2025).
That liver-directed effect is why Altimmune focuses on liver disease rather than weight loss alone.
Animal data
In mice with diet-induced obesity and biopsy-confirmed steatohepatitis, 12 weeks of daily pemvidutide reduced body weight by about 25% and lowered liver fat, liver enzymes and markers of inflammation (galectin-3) and fibrosis (collagen type 1) compared with vehicle (Nestor et al., Sci Rep 2022). These are mouse results and do not predict effect sizes in people.
How it compares with related drugs
| Drug | Receptors activated | Status | Library page |
|---|---|---|---|
| Semaglutide | GLP-1 | Approved | Semaglutide |
| Tirzepatide | GIP and GLP-1 | Approved | Tirzepatide |
| Pemvidutide | GLP-1 and glucagon | Phase 3 (MASH) | This page |
| Survodutide | GLP-1 and glucagon | Investigational | Survodutide |
| Mazdutide | GLP-1 and glucagon | Approved in China | Mazdutide |
| Retatrutide | GIP, GLP-1 and glucagon | Investigational | Retatrutide |
Survodutide and mazdutide are the closest relatives. All three are once-weekly GLP-1/glucagon dual agonists; they differ in structure, receptor balance, the doses studied and how far each has progressed.
Pharmacokinetics
Human pharmacokinetic data for pemvidutide have not been published in a peer-reviewed journal that we could locate. A phase 1 trial in healthy volunteers with overweight or obesity (NCT04561245) and a drug-interaction study (NCT04972396) are completed, but their results are not posted on ClinicalTrials.gov.
In mice, a single injection gave a later and lower peak level than semaglutide at the same molar dose, with similar total exposure. The authors concluded this was consistent with once-weekly dosing (Nestor et al., Sci Rep 2022). In human trials, the 1.2 and 1.8 mg doses were given without dose titration (gradual dose increases), while the 2.4 mg dose used a short titration.
Regulatory status
- Not approved. No regulator has approved pemvidutide for any use.
- Phase 3. The PERFORMA trial (NCT07795164) started on July 30, 2026. It plans to enroll about 1,800 adults with F2–F3 (moderate to advanced) MASH fibrosis, randomized to 1.8 mg, 2.4 mg or placebo weekly. Its primary endpoints are MASH resolution and fibrosis improvement at week 52, plus a clinical-outcome endpoint (progression to cirrhosis, liver events, transplant or death) over about 60 months. Estimated primary completion is December 2028.
- FDA designations. The FDA granted Breakthrough Therapy designation for MASH based on the 24-week phase 2b data (Altimmune Q4 2025 release). Altimmune also reports Fast Track designations for MASH and AUD (Altimmune Q2 2026 release).
- Obesity. A 48-week phase 2 obesity trial was completed in 2023, but the company’s 2026 releases list only MASH, AUD and ALD as indications in development.
- Controlled substances. Pemvidutide is not listed in DEA Schedule III (21 CFR 1308.13).
- Sport. It is not named on the WADA 2026 Prohibited List. Section S0 prohibits at all times any pharmacological substance with no current approval by a governmental health authority for human therapeutic use, including drugs in clinical development.
What the research shows
Liver fat in MASLD (phase 1, 12 and 24 weeks)
The first liver trial randomized 94 adults with a BMI of at least 28 and at least 10% liver fat (measured by MRI-PDFF, an MRI method that quantifies liver fat) to pemvidutide 1.2, 1.8 or 2.4 mg or placebo weekly for 12 weeks (Harrison et al., J Hepatol 2025). Completers could continue on the same dose for 12 more weeks; 64 entered this extension (Browne et al., JHEP Rep 2025).
| Relative reduction in liver fat | Placebo | 1.2 mg | 1.8 mg | 2.4 mg |
|---|---|---|---|---|
| Week 12 (n = 94) | 4.4% | 46.6% | 68.5% | 57.1% |
| Week 24 (n = 64) | 14.0% | 56.3% | 75.2% | 76.4% |
All doses differed from placebo (p under 0.001). At 1.8 mg, 55.6% of participants reached normal liver fat (≤5%) at week 12 and 53.8% at week 24. Weight loss at 1.8 mg was 4.3% at 12 weeks. At 24 weeks it was 5.1%, 6.2% and 5.2% on 1.2, 1.8 and 2.4 mg vs 1.4% on placebo. The 12-week trial reported no severe or serious adverse events.
MASH with fibrosis (IMPACT, phase 2b)
IMPACT (NCT05989711) randomized 212 adults with biopsy-confirmed MASH and F2 or F3 fibrosis at 83 sites in the US and Australia. Participants received pemvidutide 1.2 mg, 1.8 mg or placebo weekly without titration, in a 1:2:2 ratio. The 24-week results were published in The Lancet (Noureddin et al., Lancet 2025):
| Primary endpoint at 24 weeks | Placebo (n = 86) | 1.2 mg (n = 41) | 1.8 mg (n = 85) |
|---|---|---|---|
| MASH resolution without fibrosis worsening | 20% | 58% | 52% |
| Difference vs placebo (95% CI) | — | 38% (21–56); p under 0.0001 | 32% (19–46); p under 0.0001 |
| Fibrosis improvement without MASH worsening | 28% | 33% | 36% |
| Difference vs placebo (95% CI) | — | 5% (−13 to 22); p = 0.59 | 8% (−6 to 22); p = 0.27 |
The trial therefore met one of its two primary endpoints (MASH resolution) but not the fibrosis endpoint at 24 weeks. The authors noted that longer trials are planned. In the company’s topline report, weight loss at 24 weeks was 5.0% and 6.2% on 1.2 and 1.8 mg vs 1.0% on placebo (Altimmune IMPACT 24-week release).
The 48-week IMPACT data have so far been reported by the company (December 2025) and were scheduled for presentation at the EASL Congress in May 2026 (Altimmune Q1 2026 release); we did not find a peer-reviewed publication (Altimmune IMPACT 48-week release). No biopsy was reported at week 48; the results are non-invasive tests:
| Change from baseline at 48 weeks | Placebo | 1.2 mg | 1.8 mg |
|---|---|---|---|
| ELF score (blood fibrosis score) | +0.16 | −0.49 | −0.58 |
| Liver stiffness (LSM, kPa) | −0.03 | −3.04 | −3.97 |
| Liver fat (relative) | −8.2% | −45.2% | −54.7% |
| ALT (liver enzyme, IU/L) | −10.3 | −37.8 | −37.4 |
| Body weight | −0.2% | −4.5% | −7.5% |
| Stopped treatment for adverse events | 3.5% | 0% | 1.2% |
These markers are associated with fibrosis but are not the same as biopsy-proven fibrosis improvement, which is what the phase 3 trial will test.
Obesity (MOMENTUM, phase 2)
MOMENTUM (NCT05295875) randomized 391 adults with obesity, or overweight with at least one related condition, and without diabetes, to pemvidutide 1.2, 1.8 or 2.4 mg or placebo weekly for 48 weeks with diet and exercise. Results are from the company’s topline release; we did not find a peer-reviewed publication (Altimmune MOMENTUM release, November 2023).
| Outcome at 48 weeks | Placebo | 1.2 mg | 1.8 mg | 2.4 mg |
|---|---|---|---|---|
| Mean weight change | −2.2% | −10.3% | −11.2% | −15.6% |
| ≥15% weight loss (responder analysis) | 2.0% | 21.4% | 28.6% | 51.8% |
| ≥20% weight loss (responder analysis) | 2.0% | 10.0% | 9.5% | 32.1% |
| Triglycerides | +7.3% | −21.7% | −22.3% | −34.9% |
The responder analyses included fewer participants than the full trial (51–70 per group). Fasting glucose and HbA1c did not change meaningfully in this population without diabetes. The company reported that weight loss on 2.4 mg had not plateaued at week 48.
Lean mass
Because glucagon receptor activation raises energy expenditure, there is interest in whether these drugs spare muscle. Altimmune reported that in a MOMENTUM body-composition analysis, 25.5% of the weight lost was lean mass and 74.5% was fat (Altimmune Q4 2023 release). The release did not state how many participants were in this analysis, and the full data have not been published in a peer-reviewed journal we could find. Lean mass measured this way includes water, organs and other non-fat tissue, not only skeletal muscle. No trial has tested pemvidutide for building muscle or strength.
Alcohol use disorder (RECLAIM, phase 2)
RECLAIM (NCT06987513) randomized 100 adults with moderate to severe AUD and a BMI over 25 to pemvidutide 2.4 mg or placebo weekly for 24 weeks. Topline results, reported by the company in July 2026 and not yet peer reviewed (Altimmune RECLAIM release):
| Outcome at 24 weeks | Placebo | Pemvidutide 2.4 mg | p |
|---|---|---|---|
| Change in heavy drinking days per week (primary) | −2.75 | −4.20 | 0.0014 |
| 2-level drop in WHO risk drinking level | 34.8% (16/46) | 64.4% (29/45) | 0.0049 |
| Zero heavy drinking days, weeks 21–24 | 17.4% (8/46) | 42.2% (19/45) | 0.0066 |
| Change in PEth (blood alcohol-use marker) | +22.0 | −153.4 | under 0.0001 |
Placebo-adjusted weight loss was 9.1% at 24 weeks. Altimmune plans to request an End-of-Phase 2 meeting with the FDA for AUD.
Alcohol-associated liver disease (RESTORE, phase 2)
RESTORE (NCT07009860) is a 48-week placebo-controlled trial in about 120 people with ALD. Enrollment finished in July 2026. Its primary endpoint is change in liver stiffness, and topline data are expected in the second half of 2027 (Altimmune Q2 2026 release).
Side effects and risks
Gastrointestinal effects
As with other GLP-1-based drugs, nausea, vomiting, diarrhea and constipation are the most common side effects. They were dose-related and highest at the higher doses in the 48-week obesity trial (Altimmune MOMENTUM release):
| Adverse event | Placebo (n = 97) | 1.2 mg (n = 98) | 1.8 mg (n = 99) | 2.4 mg (n = 97) |
|---|---|---|---|---|
| Nausea | 11.3% | 25.5% | 59.6% | 51.5% |
| Vomiting | 3.1% | 6.1% | 27.3% | 27.8% |
| Diarrhea | 5.2% | 8.2% | 10.1% | 18.6% |
| Constipation | 8.2% | 17.3% | 13.1% | 22.7% |
| Stopped for any adverse event | 6.2% | 5.1% | 19.2% | 19.6% |
Most discontinuations happened in the first 16 weeks. In the RECLAIM AUD trial, which used a newer two-step titration to 2.4 mg, nausea occurred in 44% vs 24% on placebo, vomiting in 18% vs 6%, and constipation in 26% vs 6%; 10% stopped because of drug-related adverse events vs 0% on placebo (Altimmune RECLAIM release).
In the liver trials at 1.2–1.8 mg, discontinuations for adverse events were lower. In IMPACT, adverse events of any kind occurred in 78% (1.2 mg) and 81% (1.8 mg) vs 67% on placebo, mostly mild or moderate, and 0–1% stopped treatment because of them (Noureddin et al., Lancet 2025).
Heart rate and cardiovascular measures
Glucagon receptor agonists can raise heart rate. In MOMENTUM (Altimmune MOMENTUM release), mean heart rate changes were small (−1.4 bpm on placebo; +0.1 to +3.1 bpm on pemvidutide), with no major adverse cardiac events and similar rates of cardiac adverse events, including arrhythmias, across groups (3.1–4.1%). The 24-week MASLD extension found no significant change in heart rate (Browne et al., JHEP Rep 2025). These trials were too small and short to rule out rare cardiovascular harms.
Serious adverse events
Serious drug-related events were uncommon in the reported trials. MOMENTUM reported one drug-related serious event (vomiting at 2.4 mg). RECLAIM reported serious adverse events in 4% on pemvidutide vs 2% on placebo, including one case of hyponatremia (low blood sodium) judged possibly related to the drug.
Gaps in the safety data
- The completed trials are small (the largest enrolled 391 people) and lasted at most 48 weeks.
- Much of the efficacy and safety data are company-reported toplines that have not been peer reviewed.
- Class risks seen with approved GLP-1 drugs, such as gallbladder disease, pancreatitis and loss of muscle with rapid weight loss, cannot yet be ruled in or out for pemvidutide.
- Effects in pregnancy, in people with cirrhosis and in long-term use are unknown. The phase 3 trial excludes people with cirrhosis.
Unapproved products
Because pemvidutide is not approved, any product sold outside a clinical trial is not an FDA-regulated medicine. Its identity, purity, dose and sterility cannot be assumed.
Key takeaways
- Investigational dual agonist. Pemvidutide activates GLP-1 and glucagon receptors in a roughly balanced ratio and is not approved anywhere; a phase 3 MASH trial began in July 2026.
- Liver is the main target. In the IMPACT phase 2b trial, 52–58% reached MASH resolution at 24 weeks vs 20% on placebo, but fibrosis improvement was not significantly better than placebo at that point.
- Moderate weight loss at liver doses, more at 2.4 mg. About 6–7.5% at 1.8 mg in liver trials, and 15.6% at 2.4 mg after 48 weeks in the obesity trial (company-reported).
- New signal in alcohol use disorder. The RECLAIM phase 2 trial reported fewer heavy drinking days on 2.4 mg vs placebo; the data are not yet peer reviewed.
- GI side effects are dose-related. Nausea affected more than half of participants at 1.8–2.4 mg in the obesity trial, and nearly 1 in 5 stopped treatment at those doses.
- Lean-mass claims are preliminary. The “25.5% lean mass” figure comes from an unpublished company analysis and is not evidence of muscle building.
Sources
- 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. PubMed; PMC.
- Harrison SA, Browne SK, Suschak JJ, 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. PubMed.
- Browne SK, Suschak JJ, Tomah S, 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. PubMed.
- Noureddin M, Harrison SA, Loomba R, 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. PubMed.
- Altimmune. Altimmune announces positive topline results from MOMENTUM 48-week phase 2 obesity trial of pemvidutide. Press release (Form 8-K, Exhibit 99.1), November 30, 2023. SEC.
- Altimmune. Altimmune announces positive lean mass preservation data for pemvidutide and reports fourth quarter and full year 2023 financial results. Press release (Form 8-K, Exhibit 99.1), March 27, 2024. SEC.
- Altimmune. Altimmune announces positive topline results from the IMPACT phase 2b trial of pemvidutide in the treatment of MASH. Press release (Form 8-K, Exhibit 99.1), June 26, 2025. SEC.
- Altimmune. Altimmune announces that pemvidutide achieved key measures of success at 48 weeks in IMPACT phase 2b MASH trial. Press release (Form 8-K, Exhibit 99.1), December 19, 2025. SEC.
- Altimmune. Altimmune announces fourth quarter and full-year 2025 financial results and business updates. Press release (Form 8-K, Exhibit 99.1), March 5, 2026. SEC.
- Altimmune. Altimmune announces first quarter 2026 financial results and business update. Press release (Form 8-K, Exhibit 99.1), May 13, 2026. SEC.
- Altimmune. Altimmune announces positive topline results from RECLAIM phase 2 trial of pemvidutide in alcohol use disorder. Press release (Form 8-K, Exhibit 99.1), July 28, 2026. SEC.
- Altimmune. Altimmune announces second quarter 2026 financial results and business update. Press release (Form 8-K, Exhibit 99.1), August 12, 2026. SEC.
- ClinicalTrials.gov. Phase 3 study of the efficacy, safety, and clinical outcomes of pemvidutide in MASH (PERFORMA). NCT07795164. ClinicalTrials.gov.
- ClinicalTrials.gov. IMPACT trial: efficacy and safety of pemvidutide in subjects with nonalcoholic steatohepatitis (NASH). NCT05989711. ClinicalTrials.gov.
- ClinicalTrials.gov. Efficacy and safety of ALT-801 in the treatment of obesity (MOMENTUM). NCT05295875. ClinicalTrials.gov.
- ClinicalTrials.gov. RECLAIM study: phase 2 study of the efficacy and safety of pemvidutide in the treatment of alcohol use disorder (AUD) in subjects with obesity or overweight. NCT06987513. ClinicalTrials.gov.
- ClinicalTrials.gov. RESTORE trial: study of the efficacy and safety of pemvidutide in the treatment of alcohol-associated liver disease (ALD). NCT07009860. ClinicalTrials.gov.
- ClinicalTrials.gov. ALT-801 (pemvidutide) in healthy overweight and obese volunteers to study safety and tolerability. NCT04561245. ClinicalTrials.gov; Pemvidutide (ALT-801) DDI study in healthy volunteers. NCT04972396. ClinicalTrials.gov.
- World Anti-Doping Agency. The 2026 Prohibited List. WADA 2026 Prohibited List.
- US Code of Federal Regulations. 21 CFR 1308.13, Schedule III. 21 CFR 1308.13.