Pemvidutide is an investigational, once-weekly injectable peptide developed by Altimmune that activates both the GLP-1 receptor and the glucagon receptor in a balanced, roughly 1:1 ratio. It is in phase 2 development for obesity and, separately, for metabolic dysfunction-associated steatohepatitis (MASH), and has not been approved by any regulator. Its phase 2 obesity trial (MOMENTUM) reported up to 15.6 percent weight loss at 48 weeks without a titration period at its lower doses, a notable design choice compared with most other drugs in this class.
Research snapshot
| Category | Current information |
|---|---|
| Peptide category | Balanced GLP-1 / glucagon dual receptor agonist |
| Primary research interest | Obesity/weight loss; separately, MASH (metabolic dysfunction-associated steatohepatitis) |
| Highest available evidence | Tier 2 – placebo-controlled phase 2 human trial (MOMENTUM), topline/conference-reported |
| Human research available | Yes, limited – phase 2 only, in both obesity and MASH programs |
| Development status | Investigational, phase 2 complete; developed by Altimmune |
| Regulatory status | Not approved anywhere |
| Last reviewed | 2026 |
Technical identity
| Technical property | Information |
|---|---|
| Primary name | Pemvidutide |
| Alternative names | ALT-801 (code name), pemvidutide acetate |
| Peptide sequence | Synthetic peptide engineered for balanced, approximately 1:1 potency at the GLP-1 and glucagon receptors; full residue-by-residue sequence not independently verified for this entry |
| Molecular formula | C182H275N39O54 |
| Molecular weight | 3873.42 g/mol |
| CAS Registry Number | 2538014-94-5 |
| UNII | A35F525WBG |
| Chemical modifications | Engineered for balanced dual-receptor agonism (GLP-1 and glucagon), fatty-acid conjugation typical of long-acting injectable peptides in this class |
| Peptide class | Dual GLP-1/glucagon receptor agonist |
| Primary biological target | GLP-1 receptor and glucagon receptor (balanced activation) |
| Developer or originator | Altimmune |
| Development status | Phase 2 complete (obesity and MASH); not approved anywhere |
What it is
Pemvidutide (development code ALT-801) is a synthetic peptide that activates the GLP-1 receptor and the glucagon receptor in balance, in contrast to tirzepatide (GLP-1/GIP) or retatrutide (GLP-1/GIP/glucagon). Altimmune, a clinical-stage biopharmaceutical company, is developing it for two separate indications: obesity, and metabolic dysfunction-associated steatohepatitis (MASH), a progressive liver disease. As of September 2026 it remains investigational, having completed phase 2 trials in both indications, with no marketing application approved anywhere.
How does it work?
Plain-English explanation
Like other drugs in this class, pemvidutide reduces appetite and slows digestion through the GLP-1 receptor. Its glucagon receptor activity is intended to add a modest boost to how many calories the body burns, and separately to help the liver process fat, which is why it is being studied for a liver disease (MASH) as well as for weight loss.
Technical explanation
Pemvidutide is described by its developer as a balanced, roughly 1:1 potency dual agonist at the GLP-1 and glucagon receptors, distinguishing it from unbalanced dual agonists that lean more heavily toward one receptor. Company-presented data describe rapid, marked weight loss without a mandatory titration period at some doses, an unusual feature since most GLP-1 class drugs, including semaglutide and tirzepatide, require a step-up dosing schedule to limit gastrointestinal side effects.
Potential benefits and research applications
Weight loss in obesity and overweight
What is being investigated: weight loss from combined GLP-1 and balanced glucagon receptor activation. How the effect might occur: appetite suppression plus a modest increase in energy expenditure from glucagon receptor activity. Evidence: the phase 2 MOMENTUM trial, 391 adults with obesity or overweight and at least one comorbidity but without diabetes, reported mean weight loss of 10.3, 11.2, and 15.6 percent at 1.2 mg, 1.8 mg, and 2.4 mg once weekly respectively over 48 weeks, against 2.2 percent on placebo, with 32.1 percent of the top-dose group losing 20 percent of body weight or more. Strength: has been shown in a placebo-controlled phase 2 trial with topline results presented at a major diabetes conference. Limitation: this is phase 2 data only; no phase 3 obesity trial had reported results as of September 2026, so the drug is not yet approved for any use.
Liver fat and MASH (metabolic dysfunction-associated steatohepatitis)
What is being investigated: reduction of liver fat and improvement of liver disease markers in MASH, a progressive fatty liver condition that can lead to cirrhosis. How the effect might occur: the glucagon receptor component is believed to directly affect hepatic fat oxidation, in addition to weight loss effects common to the drug class. Evidence: a separate phase 2 MASH trial has been conducted by Altimmune; company reporting described a mixed result on certain histological endpoints alongside a positive effect on liver fat and weight, which was interpreted differently by different observers. Strength: has been studied in a dedicated, controlled phase 2 human trial. Limitation: press coverage described the topline MASH results as mixed rather than uniformly positive, and no phase 3 confirmation of a MASH benefit exists yet.
Lean mass preservation during weight loss
What is being investigated: whether pemvidutide’s glucagon receptor activity helps preserve lean muscle mass relative to fat mass during weight loss, a concern raised across the entire GLP-1 drug class. How the effect might occur: proposed metabolic effects of glucagon receptor agonism on substrate use, though the precise mechanism for any lean-mass-sparing effect is not established. Evidence: company-reported body composition data have been presented at scientific meetings describing favorable fat-to-lean mass loss ratios. Strength: reported in company presentations at a professional conference. Limitation: as of this entry’s research, an independently peer-reviewed, full-length publication with complete body composition statistics was not identified, so specific percentages are not reproduced here.
What dosage information circulates?
Figures in this section summarize amounts and schedules reported in published research or circulating online. Their inclusion documents what is reported and does not establish that a regimen is verified, safe, effective, or appropriate.
Pemvidutide is an investigational, unapproved drug. Every dose figure identified for this entry comes from Altimmune’s own phase 2 trial disclosures; no independent academic dosing trial was identified.
| Reported use or research objective | Route reported | Amount reported | Frequency reported | Reported duration | Evidence or source category |
|---|---|---|---|---|---|
| MOMENTUM phase 2, obesity/overweight | Subcutaneous | 1.2 mg, 1.8 mg, or 2.4 mg | Once weekly (2.4 mg used a 4-week titration) | 48 weeks | Published human clinical trial (phase 2, conference-reported) |
No dose of pemvidutide has been established as safe or effective. It remains investigational, phase 2-stage, with no marketing approval anywhere; every figure above comes from Altimmune’s own phase 2 trial disclosures, not an independent academic dosing study.
Amounts studied in human research
The phase 2 MOMENTUM obesity trial tested pemvidutide 1.2 mg, 1.8 mg, and 2.4 mg once weekly by subcutaneous injection, or placebo, over 48 weeks in 391 adults with obesity or overweight and at least one weight-related comorbidity, without diabetes. The 2.4 mg dose used a 4-week titration period; company materials describe the lower doses as not requiring titration.
Practitioner and community-reported protocols
Not consistently reported. Pemvidutide has not been approved anywhere and this site did not identify an established, sourced community dosing pattern for it distinct from its own phase 2 trial doses; a vendor document referencing this compound and supplied as background for this entry contained only promotional claims about rodent studies and is not used as a source here.
What circulates E5
Not consistently reported. Pemvidutide has not been approved anywhere, and this site did not identify an established, sourced community dosing pattern for it distinct from its own phase 2 trial doses.
Every dose figure identified for this entry comes from Altimmune's own phase 2 trial disclosures (1.2 mg, 1.8 mg, or 2.4 mg once weekly by subcutaneous injection in the MOMENTUM obesity trial); no independent academic or community dosing convention was identified.
Recorded as an observation about what is published elsewhere. No figure here is a dose, a protocol, or a recommendation, and nothing in this section is evidence that any amount is safe or effective.
Side effects, risks, and limitations
In the MOMENTUM trial, gastrointestinal side effects (nausea, vomiting, diarrhea, constipation) were the most common adverse events, with nausea reported in 51.5 percent and vomiting in 27.8 percent of the 2.4 mg group. About 15.5 percent of participants on 2.4 mg discontinued due to drug-related adverse events. One serious adverse event (vomiting) was reported at the top dose. No major adverse cardiac events were reported in the trial. As an unapproved, phase 2-stage molecule, long-term safety data comparable to approved drugs in this class do not yet exist.
Regulatory and developmental status
Pemvidutide is not approved by any regulator. It has completed phase 2 trials in obesity (MOMENTUM) and separately in MASH, both sponsored by Altimmune. No phase 3 trial results, and no marketing application, had been reported as of September 2026.
Frequently asked questions
What is pemvidutide?
An investigational, once-weekly injectable peptide from Altimmune that activates both the GLP-1 and glucagon receptors in balance, being studied for obesity and for a liver disease called MASH. It is not approved anywhere.
How does it work?
It combines GLP-1 receptor activity, which reduces appetite, with balanced glucagon receptor activity, which is believed to modestly increase energy expenditure and affect liver fat processing.
What dosage has been studied?
The phase 2 MOMENTUM trial tested 1.2 mg, 1.8 mg, and 2.4 mg once weekly by subcutaneous injection over 48 weeks; the 2.4 mg dose used a 4-week titration.
How much weight loss has been shown?
Up to 15.6 percent mean weight loss at 2.4 mg over 48 weeks in the phase 2 trial, against 2.2 percent on placebo.
Is it approved?
No. It has completed phase 2 trials only. No phase 3 results or marketing application had been reported as of September 2026.
What side effects have been reported?
Mostly gastrointestinal: nausea (reported by just over half of participants at the top dose), vomiting, diarrhea, and constipation. About 1 in 6 participants at the top dose discontinued due to side effects.
Is it being studied for liver disease?
Yes, separately from the obesity programme, Altimmune has studied pemvidutide in a phase 2 trial for MASH (metabolic dysfunction-associated steatohepatitis); reported results were described in the press as mixed on some histological measures.
What remains unknown?
Phase 3 efficacy and safety, long-term cardiovascular outcomes, and whether the reported lean-mass and liver benefits hold up in larger, independently reviewed trials.
Bottom line
Pemvidutide is a phase 2, investigational GLP-1/glucagon dual agonist from Altimmune with real, company-reported placebo-controlled weight loss data (up to 15.6 percent at 48 weeks) and a separate liver-disease programme with mixed reported results. It is not approved for any use, has not completed phase 3 testing, and the only background document available for this entry was unusable promotional vendor material describing rodent studies as if they applied to people; none of that material is reflected here.