Pemvidutide

What is Pemvidutide?

Pemvidutide (development code ALT-801) is Altimmune's investigational once-weekly subcutaneous peptide unimolecular dual agonist at the GLP-1 receptor and the glucagon receptor (GCGR). The molecule is engineered for a balanced 1:1 GLP-1R:GCGR potency ratio — the most glucagon-weighted of the named clinical-stage dual agonists, in contrast to survodutide (~8–10:1), mazdutide (~6:1), cotadutide (~5:1, discontinued), and DA-1726 (3:1). The molecular formula is C182H275N39O54 with a molecular weight of approximately 3,873 g/mol. Pemvidutide does not require dose titration, a differentiator versus the lengthy titration regimens of competitor incretin therapies. It is being developed primarily for metabolic dysfunction-associated steatohepatitis (MASH), with secondary indications in obesity and alcohol use disorder. The FDA has granted Fast Track and Breakthrough Therapy designations for MASH and a separate Fast Track designation for alcohol use disorder. The Phase 2b IMPACT trial (NCT05989711) is the asset-defining program: a 212-patient biopsy-confirmed MASH study in F2 or F3 fibrosis with or without diabetes, randomized 1:2:2 to placebo, 1.2 mg, or 1.8 mg pemvidutide weekly for 48 weeks across 83 sites in the US and Australia. The 24-week primary endpoint analysis was published in The Lancet on December 6, 2025 (Noureddin et al., PMID 41237796): MASH resolution without worsening fibrosis was achieved in 58% of the 1.2 mg arm and 52% of the 1.8 mg arm versus 20% on placebo, with both doses significantly superior to placebo. Fibrosis improvement without worsening MASH (the second primary endpoint) trended in favor of pemvidutide (28%, 33%, 36% across placebo, 1.2 mg, 1.8 mg respectively) but did not reach independent statistical significance at 24 weeks. The 48-week non-invasive readout was presented at EASL 2026 (Barcelona, May 27–30, 2026) and showed continued separation: ELF (Enhanced Liver Fibrosis test) declined 0.58 from baseline at 1.8 mg versus +0.16 on placebo (p<0.0001); liver stiffness on FibroScan dropped 3.97 kPa at 1.8 mg vs −0.03 kPa placebo; MRI-derived liver fat content reduced 54.7% at 1.8 mg vs 8.2% placebo (p<0.0001); ALT dropped 37.4 IU/L at 1.8 mg vs 10.3 IU/L placebo; and dual responders for ELF + liver-stiffness improvement reached 32.4% at 1.8 mg vs 3.2% on placebo. Weight loss as a secondary endpoint reached 7.5% at 48 weeks on 1.8 mg (no plateau yet observed) versus 0.2% on placebo. Treatment discontinuation due to adverse events was 1.2% at 1.8 mg, 0% at 1.2 mg, and 3.5% on placebo — a notable tolerability profile for a dual incretin/glucagon agonist. The Phase 3 MASH program is planned to initiate in 2026 following the FDA end-of-Phase-2 alignment.

What Pemvidutide Is Investigated For

Pemvidutide is one of the most clinically advanced MASH-focused dual GLP-1/glucagon agonists, with the IMPACT Phase 2b readout representing the asset's defining moment as of mid-2026. The Lancet publication (December 2025, PMID 41237796) reported 24-week MASH resolution rates of 58% (1.2 mg) and 52% (1.8 mg) versus 20% on placebo in biopsy-confirmed F2/F3 MASH patients — among the strongest histologic resolution numbers reported in MASH trials, comparable to survodutide's Phase 2 NEJM signal. The 48-week EASL 2026 readout extended the picture: ELF and liver stiffness improvements at 1.8 mg substantially exceeded placebo (ELF −0.58 vs +0.16; liver stiffness −3.97 vs −0.03 kPa; both p<0.0001), MRI liver fat content fell 54.7%, and 32.4% of patients achieved dual ELF + liver-stiffness response versus 3.2% on placebo. Weight loss as a secondary endpoint reached 7.5% at 48 weeks. Pemvidutide's distinguishing pharmacology is the 1:1 GLP-1R:GCGR balanced ratio — the most glucagon-weighted of the clinical-stage dual agonists — which Altimmune positions as the source of stronger hepatic effects relative to GLP-1-dominant incretin therapy. The tolerability profile in IMPACT was notable: zero treatment-related discontinuations on 1.2 mg and only 1.2% on 1.8 mg, versus 3.5% on placebo. Honest caveats remain: fibrosis improvement (the second primary endpoint at 24 weeks) did not reach independent significance, the 48-week readout is non-invasive only (no biopsy endpoint at 48 weeks per protocol), and Phase 3 will need to demonstrate the histologic durability and clinical event reduction required for MASH regulatory approval. The competitive landscape is intense — resmetirom (Rezdiffra) is the only FDA-approved MASH therapy (March 2024), survodutide is in Phase 3 with positive obesity readout, and efinopegdutide (Merck) remains active in Phase 3 MASH cirrhosis through 2026. Pemvidutide's Phase 3 program is expected to start in 2026.

History & Discovery

Pemvidutide (development code ALT-801) emerged from Altimmune's metabolic-disease platform as a unimolecular peptide engineered for balanced dual agonism at the GLP-1 and glucagon receptors — a deliberate departure from the GLP-1-dominant receptor ratios of contemporaneous programs at Boehringer/Zealand (survodutide), Innovent (mazdutide), AstraZeneca (cotadutide), and Dong-A ST / MetaVia (DA-1726). The 1:1 receptor balance was conceived to maximize the glucagon-mediated hepatic fat-clearing effect while retaining the appetite-suppressing GLP-1 mechanism, positioning the molecule MASH-first rather than obesity-first. Preclinical proof-of-concept in DIO-NASH mouse models (Nestor et al., Scientific Reports 2022, PMID 35461369) demonstrated greater liver fat reduction than head-to-head semaglutide and elafibranor comparators. Phase 1 first-in-human dose-escalation studies established the absence of meaningful dose-titration requirements — a tolerability differentiator from competitor incretin therapies that require lengthy escalation regimens. Phase 1b MASLD (Harrison et al., J Hepatology 2025, PMID 39002641, n=94, 12 weeks) reported 68.5% relative liver fat reduction at 1.8 mg, the first translational signal supporting MASH-specific development. The Phase 2 MASLD 24-week trial (Browne et al., JHEP Reports November 2025, PMID 41113119) extended the liver-fat signal to 75.2% (1.2 mg) and 76.4% (1.8 mg) reduction at 24 weeks with 84.6% achieving ≥50% reduction on 1.8 mg. The FDA granted Fast Track designation for MASH followed by Breakthrough Therapy designation in 2024, reflecting the unmet need in MASH where resmetirom (Madrigal's THR-β agonist, FDA-approved March 2024) was the first MASH-specific therapy and remains the only one approved. A separate FDA Fast Track designation for alcohol use disorder reflects pemvidutide's exploration in AUD via the RECLAIM Phase 2 trial. The Phase 2b IMPACT trial (NCT05989711) was the asset-defining program: 212 patients with biopsy-confirmed F2/F3 MASH (with or without diabetes), randomized 1:2:2 to placebo, 1.2 mg, or 1.8 mg pemvidutide weekly for 48 weeks across 83 sites in the US and Australia. The 24-week primary endpoint analysis was published in The Lancet on December 6, 2025 (Noureddin et al., PMID 41237796) reporting MASH resolution without worsening fibrosis in 58% (1.2 mg) and 52% (1.8 mg) of patients versus 20% on placebo — both doses significantly superior. The second primary endpoint (fibrosis improvement without worsening MASH) trended positive but did not reach independent statistical significance at 24 weeks. The 48-week non-invasive readout was presented at EASL 2026 (May 27–30, 2026, Barcelona) with continued separation on ELF, liver stiffness, MRI liver fat, ALT, and weight loss endpoints, plus 32.4% of 1.8 mg patients achieving dual ELF + liver-stiffness response versus 3.2% on placebo. Treatment discontinuation due to adverse events was 1.2% on 1.8 mg vs 3.5% on placebo — a notable tolerability profile. Between January and April 2026, Altimmune completed a $75 million direct offering (January 2026, with Alyeska) followed by a $225 million oversubscribed public offering (April 2026) to fund the planned Phase 3 MASH program. FDA end-of-Phase-2 alignment was achieved, supporting Phase 3 design with approximately 1,000 patients, 52-week biopsy endpoints, dose-escalation up to 2.4 mg with titration, and AIM-MASH AI-assisted histology read. Phase 3 initiation is expected in 2026.

How It Works

Pemvidutide activates two metabolism-regulating receptors at once — GLP-1 (the target of Ozempic) and glucagon. The GLP-1 side reduces appetite and slows stomach emptying. The glucagon side tells the liver to burn fat and increase energy expenditure. Pemvidutide has equal activity at both receptors (a 1:1 ratio), making it the most balanced of the dual agonists. This pushes hepatic fat metabolism harder than GLP-1-dominant drugs, which is why pemvidutide is positioned primarily for fatty liver disease (MASH) rather than obesity.

Pemvidutide is a synthetic unimolecular peptide with balanced dual agonist activity at the GLP-1 receptor (GLP-1R) and the glucagon receptor (GCGR), engineered for a 1:1 potency ratio. This receptor balance distinguishes pemvidutide from other clinical-stage dual agonists, which tilt toward GLP-1: survodutide (~8–10:1 GLP-1R:GCGR), mazdutide (~6:1), cotadutide (~5:1, discontinued), DA-1726 (3:1). Mechanistically, GLP-1R activation suppresses appetite via hypothalamic and brainstem circuits, enhances glucose-dependent insulin secretion, suppresses glucagon postprandially, and delays gastric emptying — the same anorectic and incretin axis exploited by semaglutide and tirzepatide. GCGR activation in the liver increases hepatic fatty acid oxidation, energy expenditure, and thermogenesis, and directly reduces hepatic steatosis. The combination of GLP-1-mediated caloric restriction and glucagon-mediated hepatic fat clearance underlies the MASH thesis: reduce hepatic substrate input via appetite suppression, simultaneously drive hepatic fat utilization via glucagon. The 1:1 receptor balance is the key differentiator. More GCGR activity relative to GLP-1 should theoretically produce stronger hepatic effects — lower liver fat, lower liver stiffness, lower fibrosis markers — at the cost of needing to balance the glucagon-receptor's effect on hepatic glucose output. Altimmune's preclinical work in diet-induced obesity NASH mouse models (Nestor et al., Scientific Reports 2022, PMID 35461369) supported this mechanism with direct comparisons against semaglutide and elafibranor showing greater liver fat reduction. The Phase 1b 12-week MASLD trial (Harrison et al., J Hepatol 2025, PMID 39002641, n=94 at 1.8 mg) reported 68.5% relative liver fat reduction at 12 weeks. The Phase 2 MASLD 24-week readout (Browne et al., JHEP Reports November 2025, PMID 41113119) reported liver fat reductions of 75.2% (1.2 mg) and 76.4% (1.8 mg) with 84.6% of patients on 1.8 mg achieving at least 50% reduction. The Phase 2b IMPACT MASH readouts confirm the dual mechanism's translation: at 48 weeks on 1.8 mg, MRI-derived liver fat content fell 54.7%, ALT fell 37.4 IU/L, ELF declined 0.58, and FibroScan liver stiffness fell 3.97 kPa. The fibrosis improvement on biopsy (the 24-week second primary endpoint) trended positive but did not reach independent significance, suggesting longer treatment exposure may be required to confirm fibrosis benefit — consistent with the general MASH treatment principle that MASH resolution precedes fibrosis improvement.

Evidence Snapshot

Research Gaps & Open Questions

What the current literature has not yet settled about Pemvidutide:

• 01Phase 3 fibrosis improvement and MASH resolution at the 52-week biopsy endpoint — IMPACT 24-week fibrosis improvement did not reach independent statistical significance; Phase 3 will need to demonstrate durable histologic benefit.
• 02Head-to-head comparisons versus survodutide, resmetirom, and other MASH candidates — entirely cross-trial.
• 03Long-term outcomes (cirrhosis prevention, hepatocellular carcinoma, hepatic decompensation, transplant) — no completed clinical event-driven trial; Phase 3 and post-approval studies will be required.
• 04Cardiovascular outcomes — no dedicated CVOT yet; needed for broader regulatory acceptance.
• 05T2D populations — IMPACT included with/without diabetes, but T2D-specific analyses and the interaction with glucagon-mediated hepatic glucose output need Phase 3 dedicated characterization.
• 06Pediatric efficacy and safety — not studied.
• 07Post-discontinuation durability — no off-treatment data published; expected weight regain by class analogy.
• 08RECLAIM (alcohol use disorder) Phase 2 readout (primary completion May 2026) and RESTORE (alcohol-associated liver disease) Phase 2.

Forms & Administration

Once-weekly subcutaneous injection. IMPACT Phase 2b tested 1.2 mg and 1.8 mg. MOMENTUM Phase 2 obesity tested up to 2.4 mg. No dose titration required (differentiator from other incretin therapies). Phase 3 MASH program plans to include up to 2.4 mg with titration. Investigational — not commercially available. All injectable peptides should only be administered under qualified clinical supervision; do not self-administer research-chemical material.

Dosing & Protocols

The ranges below reflect protocols commonly discussed in the literature and by clinicians — not a prescription. Actual dosing for any individual should be determined by a qualified healthcare provider who knows the patient.

Pemvidutide is not FDA-approved for any indication. Doses and schedules above reflect published Phase 1/2b trial protocols and are not prescriptions. Legitimate access is limited to enrollment in registered Altimmune clinical trials.

Timeline of Effects

Common Questions

Who Pemvidutide Is NOT For

Drug & Supplement Interactions

No FDA-labeled drug interaction profile exists because pemvidutide is not approved. The expected interaction framework is inherited from the GLP-1 and glucagon receptor classes: (1) hypoglycemia risk when combined with insulin or sulfonylureas (would require downward titration of the concomitant agent if approved); (2) altered oral drug absorption secondary to delayed gastric emptying, particularly for narrow-therapeutic-index agents (warfarin, levothyroxine, oral contraceptives, antiepileptics); (3) potential interactions with concomitant antidiabetic regimens given glucagon-mediated hepatic glucose output effects distinct from semaglutide or tirzepatide. The dedicated drug-drug interaction study (NCT04972396) characterized specific interactions.

Safety Profile

Legal Status

Regulatory status changes over time. Verify current local rules with a qualified professional.

Myths & Misconceptions