Pemvidutide IMPACT 48-Week MASH Data Lands At EASL 2026 Ahead Of Phase 3

On May 28, 2026, twenty-four hours after MetaVia closed out a late-breaking poster on a 48 mg Phase 1 oxyntomodulin analogue, Altimmune walked an oral session at the EASL Congress in Barcelona with a much harder dataset behind it. The drug is pemvidutide. The trial is IMPACT — NCT05989711 — a 212-patient Phase 2b in biopsy-confirmed F2/F3 MASH. Forty-eight weeks of once-weekly subcutaneous dosing. A 1.8 mg arm, a 1.2 mg arm, and placebo. The 48-week numbers presented Thursday afternoon were the broadest readout the program has put into public view: triglycerides down 23.7 percent at the high dose, total cholesterol down 15.4 percent, body weight down 7.5 percent, blood pressure down on both numerator and denominator, waist circumference down 5.3 centimeters. The Enhanced Liver Fibrosis responder rate at 48 weeks reached 32.4 percent at the high dose against 3.2 percent on placebo. The qFibrosis-measured fibrosis regression at 24 weeks reached 54.5 percent in the 1.8 mg arm against 29.6 percent on placebo. The presentation earned a "Best of EASL 2026" designation, and the company said its Phase 3 program, PERFORMA, will start in the second half of this year.

What Is Actually New In This Readout

Altimmune already disclosed top-line IMPACT 48-week data in December 2025. That release named the headline numbers: liver-fat content down 45 percent at 1.2 mg and 55 percent at 1.8 mg by MRI-PDFF; ALT down by roughly 37 IU/L on both active arms; cT1 down 124 ms and 140 ms; ELF down 0.49 and 0.58 against +0.16 on placebo; LSM down 3.04 and 3.97 kPa against −0.03 on placebo. What was missing in December was the cardiometabolic detail — what was happening to lipids, blood pressure, body composition, and waist over the same 48 weeks — and the fibrosis regression analysis using the AI-quantified qFibrosis tool that operates on biopsy slides rather than serum panels.

That is what Thursday's oral session, delivered by Dr. Mazen Noureddin of Houston Methodist and Summit Clinical Research, added. The 1.8 mg arm at week 48 produced a 23.7 percent drop in triglycerides, a 15.4 percent drop in total cholesterol, a weight reduction of 7.5 percent, a BMI reduction of 3.0 kg/m², a waist-circumference reduction of 5.3 centimeters, a 4.0 mmHg drop in systolic blood pressure, and a 2.2 mmHg drop in diastolic blood pressure. ELF responder rates — defined as a reduction of at least 0.5 in ELF combined with a reduction of at least 30 percent in liver stiffness on VCTE — came in at 27.8 percent in the 1.2 mg arm and 32.4 percent in the 1.8 mg arm, both highly significant against placebo's 3.2 percent.

The qFibrosis analysis is the part that hepatologists are paying the closest attention to. Run on liver biopsies obtained at week 24, the AI-quantified scoring system found that 54.5 percent of patients on the 1.8 mg dose and 68.6 percent of patients on the 1.2 mg dose achieved at least a one-stage regression in fibrosis, against 29.6 percent on placebo (p=0.002 and p<0.001, respectively). That the 1.2 mg arm posted a higher fibrosis regression rate than the 1.8 mg arm at this timepoint is one of the trial's open questions; the company has framed it as consistent with non-monotonic dose-response patterns sometimes seen with incretin agents and within the bounds of statistical noise at n≈85 per arm. A larger, longer dataset — the kind PERFORMA is designed to produce — will resolve it.

Why The Cardiometabolic Detail Matters

MASH, formerly NASH, is a liver disease, but it is rarely the only thing wrong with a MASH patient. Cardiovascular disease is the leading cause of death in people with MASH, not cirrhosis. That epidemiological fact is the reason the FDA's resolution-of-steatohepatitis and improvement-of-fibrosis endpoints exist alongside what regulators have been signaling will eventually become an outcomes endpoint — major adverse cardiovascular events, or MACE, in the MASH population. A drug that resolves steatohepatitis but does nothing to lipids or blood pressure leaves the patient walking out of the office with their primary mortality risk unaddressed.

The pemvidutide cardiometabolic profile speaks to that question. A 23.7 percent drop in triglycerides is in the range that statins on top of dietary change deliver. A 4.0 mmHg systolic blood pressure reduction is the kind of number antihypertensive medications produce as a primary endpoint. The weight loss — 7.5 percent at the high dose — is not class-leading by GLP-1 standards (semaglutide in obesity trials hits 15 percent and tirzepatide hits 21 percent), but pemvidutide's MASH program was not designed to prove dominance on the obesity axis. It was designed to prove that a balanced GLP-1/glucagon dual agonist can address MASH and the cardiometabolic comorbidities that drive its mortality, in the same molecule, at the same dose, over the same trial.

The lipid-lowering signal in particular is what distinguishes pemvidutide's mechanism from a pure GLP-1 approach. The glucagon receptor on hepatocytes drives β-oxidation of fatty acids and hepatic lipid export; the GLP-1 receptor in the central nervous system and on pancreatic beta cells drives appetite suppression and insulinotropic effect. The two together act on the lipid pool from both ends — input via reduced food intake and weight loss, output via direct hepatic lipid metabolism. That is the design hypothesis. The week-48 IMPACT lipid panel is the first time the hypothesis has been tested at trial scale.

The GLP-1/Glucagon Design Problem

The reason GLP-1/glucagon dual agonism took fifteen years longer to reach trials than GLP-1 monotherapy is that the glucagon receptor does two things at once. It drives hepatic fat oxidation and basal energy expenditure — the upside. It also drives hepatic glucose production — the downside, especially in patients who already have impaired glucose tolerance or type 2 diabetes. The peptide-engineering challenge for the field has been to build a molecule whose GLP-1 component suppresses the glucagon-driven glucose elevation hard enough that the net effect is glycemic-neutral or glycemic-positive, while preserving enough glucagon agonism to drive the liver and energy-expenditure effects.

Pemvidutide's reported balance is roughly 1:1 GLP-1 to glucagon receptor activity. Survodutide, Boehringer Ingelheim and Zealand Pharma's competing dual agonist now in Phase 3 for MASH and obesity, sits at a more GLP-1-weighted ratio. DA-1726, MetaVia's earlier-stage Phase 1 oxyntomodulin analogue presented the day before in the same EASL session, also runs a balanced GLP-1/glucagon design. Retatrutide, the Lilly triple agonist, adds GIP to the mix and is the highest-weight-loss compound in late-stage development. Each of those programs is making a different bet on what the right balance of receptor agonism is for MASH, for obesity, and for the cardiometabolic outcomes that flow from both.

The IMPACT data lets the field begin to compare those bets. Pemvidutide at 1.8 mg over 48 weeks produced 7.5 percent weight loss with 32.4 percent ELF responder rate and 23.7 percent triglyceride reduction. Survodutide's published 48-week MASH data from 2024 reported 83 percent of patients on the high dose achieving the FDA's primary MASH-resolution endpoint at week 48, with weight loss in the 15–18 percent range. The two trials had different inclusion criteria, different fibrosis-stage cutoffs, and different secondary endpoints, so direct numerical comparison is hazardous. What is comparable is the design question each is answering: how much weight loss the field is willing to trade for how much liver and lipid benefit, in a single molecule.

The Safety Picture

For an incretin-class drug, pemvidutide's safety profile in IMPACT looks unremarkable, which is the most one can hope for at this point in development. Treatment-related discontinuations were approximately 1 percent across the active arms — under that 1.2 percent at 1.8 mg and zero at 1.2 mg — against 3.5 percent on placebo. The discontinuation imbalance favoring drug over placebo is not an outcome anyone predicted; the company's read is that the placebo arm self-selected toward dropouts because patients knew their week-48 biopsy was coming and some preferred to leave the trial rather than undergo it. Adverse events were predominantly mild-to-moderate gastrointestinal complaints — nausea, decreased appetite, diarrhea — concentrated in the first eight weeks of dosing and resolving thereafter, the same profile every weekly GLP-1-class drug has shown.

The cardiac safety question that hangs over all glucagon-receptor agonists — is there a heart-rate signal, is there a QTcF signal, is there an atrial fibrillation signal — was answered cleanly. No clinically meaningful heart-rate increase. No QTcF prolongation. No imbalance in atrial events. That is a meaningful negative finding, because the historical concern with glucagon agonism has been precisely that the same hepatic energy-expenditure effect that produces the upside might run through cardiac tissue at higher exposures. At 1.8 mg over 48 weeks in 85 patients, it did not.

What IMPACT does not yet test is what happens at exposures higher than 1.8 mg, or in patients with more advanced fibrosis (F4 cirrhotic patients were excluded), or over time horizons longer than 48 weeks. Those are PERFORMA's questions to answer.

What PERFORMA Will Have To Prove

Phase 3 MASH trials run on FDA-defined biopsy endpoints. The primary endpoints, by guidance, are resolution of steatohepatitis without worsening of fibrosis, and improvement of fibrosis by at least one stage without worsening of steatohepatitis. A drug must hit at least one to qualify for accelerated approval; demonstrating both is the path to a full label. Rezdiffra (Madrigal's resmetirom, the only fully FDA-approved MASH drug as of 2024) cleared the bar by hitting both. Pemvidutide's IMPACT program tested resolution and fibrosis improvement at 48 weeks but at a sample size and fibrosis-stage range that the FDA will require Phase 3 to confirm in larger numbers.

PERFORMA is the program designed to do that confirmation. Altimmune said on Thursday that the trial will start in the second half of 2026; the company has not publicly disclosed sample size, treatment duration, or whether the trial will use the 1.2 mg dose, the 1.8 mg dose, or both. The MASH Phase 3 standard at this point is roughly 1,500 to 2,000 patients followed for 18–24 months on biopsy endpoints, with adaptive readouts at the resolution-and-fibrosis stage and longer-term follow-up for outcomes.

Outside MASH, pemvidutide is also in Phase 2 in alcohol use disorder — the RECLAIM trial, with topline expected in the third quarter of 2026 — and in Phase 2 in alcohol-associated liver disease, the RESTORE trial, currently enrolling. Both of those programs are betting that the drug's mechanism of action against hepatic fat handling and cardiometabolic dysfunction translates beyond pure MASH into the alcohol-driven liver-disease population, which is roughly the same size as the MASH population in the United States and which has substantially fewer late-stage drug candidates.

The Investor And Prescriber Read

Altimmune is a Gaithersburg, Maryland clinical-stage biotech with a market capitalization that has tracked the pemvidutide readouts closely. Vipin Garg leads the company; Christophe Arbet-Engels is chief medical officer. The FDA granted pemvidutide Breakthrough Therapy Designation in MASH earlier in 2026 and Fast Track designations in both MASH and alcohol use disorder in prior cycles. A breakthrough designation does not change the standard of evidence for approval, but it accelerates the FDA's interaction cadence with the sponsor and signals that the agency views the unmet need as substantial and the available data as suggestive of meaningful benefit.

The investor question now is partnership versus solo Phase 3. Phase 3 MASH programs cost north of $300 million and run for two to three years. Altimmune at its current scale can begin PERFORMA, but the conventional pattern for a clinical-stage biotech with a positive Phase 2b in a high-prevalence indication is to seek a development-and-commercialization partnership with a large-cap pharma — the same pattern Madrigal followed before Rezdiffra and the same pattern most MASH-stage biotechs have followed. Whether Altimmune chooses that path or runs PERFORMA alone is the financial signal the next twelve months will produce.

For prescribers, the practical question — when can I write a script for this drug — is straightforward: not for several years, even in the best case. PERFORMA starts in the second half of 2026. Two-year primary endpoints would read out in 2028 or 2029. FDA review and label negotiation add another year. A realistic earliest-approval date is 2030 or later, contingent on Phase 3 success. The drug is not available through compounding pharmacies and will not become available through them; novel patented peptides not derived from FDA-approved products are not eligible for 503A or 503B compounding. Patients who encounter "research-grade" pemvidutide marketing — and the field's history with semaglutide and tirzepatide knockoffs suggests this will happen — should treat such offerings the same way the Alabama Board of Medical Examiners advised patients to treat research-grade peptides generally: as unverified, illegal for human administration, and unsafe.

Where This Fits In The Field

The Phase 2b MASH peptide pipeline at the start of summer 2026 has roughly five active assets at meaningful stages. Pemvidutide is the most advanced biopsy-endpoint Phase 2b dual GLP-1/glucagon agonist. Survodutide is in Phase 3. Resmetirom is approved. Semaglutide cleared its MASH Phase 3 in the ESSENCE trial in 2024. Tirzepatide's Phase 3 in MASH is enrolling. Retatrutide is testing MASH in late-stage trials as a secondary indication on top of obesity. Beyond these, a long tail of earlier-stage assets — DA-1726 at Phase 1, EB618 oral oxyntomodulin at Phase 1, several FGF21 analogues, PNPLA3 silencers, and multiple receptor-agonist combinations — is moving through development.

What pemvidutide's IMPACT readout adds to that field is a data point on a specific question: can a balanced GLP-1/glucagon dual agonist achieve meaningful MASH fibrosis regression alongside cardiometabolic improvement at a moderate weight-loss profile, in a 48-week trial in F2/F3 patients. The IMPACT answer is yes, with caveats about the dose-response oddity in the qFibrosis data and the open question of how 48-week findings will scale to 18-month or 24-month outcomes. PERFORMA is the trial that will turn that yes into either a label or a setback.

Frequently Asked Questions

What is pemvidutide?

Pemvidutide is a once-weekly subcutaneous peptide that activates two receptors at the same time — the GLP-1 receptor, the same one targeted by Wegovy and Ozempic, and the glucagon receptor, which sits primarily on liver cells and drives the burning of fat stored in those cells. The molecule was designed by Altimmune, a Gaithersburg-based biotech, with the goal of producing both the appetite-suppressing weight-loss effect of a GLP-1 drug and the direct liver-fat-burning effect of a glucagon drug, in a single peptide, at a balanced ratio. It is in Phase 2b for metabolic dysfunction-associated steatohepatitis (MASH) and Phase 2 for alcohol use disorder and alcohol-associated liver disease.

What did the EASL 2026 IMPACT presentation actually show?

The 48-week data from the IMPACT Phase 2b trial showed that the 1.8 mg dose of pemvidutide reduced triglycerides by 23.7 percent, total cholesterol by 15.4 percent, body weight by 7.5 percent, BMI by 3.0 kg/m², waist circumference by 5.3 cm, systolic blood pressure by 4.0 mmHg, and diastolic blood pressure by 2.2 mmHg, while producing an ELF responder rate of 32.4 percent and a 24-week qFibrosis fibrosis-regression rate of 54.5 percent at the same dose. The placebo arm posted small or no changes on those endpoints.

How does this compare to Rezdiffra?

Rezdiffra (resmetirom) is the only fully FDA-approved MASH drug. It works through a different mechanism — selective activation of the thyroid hormone receptor-β in the liver — and is given as a daily oral tablet. The two drugs are not in head-to-head comparison; they target the same disease through different molecular routes. Rezdiffra has the labeling and the market lead. Pemvidutide, if it succeeds in Phase 3, would offer a different mechanism with cardiometabolic effects Rezdiffra does not produce, particularly on weight, blood pressure, and lipids.

Is pemvidutide available now?

No. Pemvidutide is investigational. It is available only through participation in Altimmune-sponsored clinical trials. There is no FDA-approved pemvidutide. There is no compounded pemvidutide that is legally available through 503A or 503B pharmacies; the drug does not meet the eligibility criteria for either pathway. Anyone marketing "research-grade pemvidutide" is selling an unverified product that is not legal for human use.

When could pemvidutide reach the market?

The Phase 3 PERFORMA trial begins in the second half of 2026. Phase 3 MASH trials typically run 18–24 months on biopsy endpoints. Adding FDA review time, the earliest realistic approval is 2030. That timeline assumes Phase 3 succeeds at the primary endpoints — a substantial assumption, since attrition rates in Phase 3 MASH programs have been historically high.

What happens if the qFibrosis dose-response anomaly persists?

The IMPACT 24-week qFibrosis analysis showed 68.6 percent fibrosis regression on the 1.2 mg dose against 54.5 percent on the 1.8 mg dose. Non-monotonic dose-response is occasionally seen in incretin biology, particularly in tissue-level rather than systemic readouts, but the more common explanation in trials of this size is statistical noise. PERFORMA at much larger sample sizes will resolve which dose to take forward, or whether both should be carried as label options.

How does this read for the broader GLP-1 field?

The pemvidutide data adds incremental evidence that adding glucagon-receptor activity to a GLP-1 backbone produces benefits a pure GLP-1 drug does not — particularly on lipid and liver biomarkers — without bringing the diabetogenic or cardiac safety problems that historically blocked glucagon-only agonists. That mechanism-level conclusion was not obvious before the IMPACT and parallel survodutide datasets emerged. Whether the dual-agonist class becomes a category alongside or downstream of single-receptor GLP-1 monotherapy depends on Phase 3 outcomes, label differentiation, and payer decisions — none of which are yet settled.

Sources

• Altimmune, Inc. "New IMPACT Phase 2b Data Highlight Concurrent Improvements Across Multiple Non-Invasive Markers and qFibrosis-Measured Fibrosis Regression with Pemvidutide in MASH at EASL 2026." BioSpace press release, May 28, 2026.
• Altimmune, Inc. "Pemvidutide Demonstrates Significant Metabolic Improvements in IMPACT Phase 2b MASH Trial at EASL 2026." Stocktitan summary, May 28, 2026.
• Altimmune, Inc. "Altimmune Announces that Pemvidutide Achieved Key Measures of Success at 48 Weeks in IMPACT Phase 2b MASH Trial." GlobeNewswire, December 19, 2025.
• Altimmune, Inc. "Altimmune to Present Results of Pemvidutide in MASH in Oral Presentation and Multiple Poster Presentations at EASL Congress 2026." BioSpace, May 13, 2026.
• European Association for the Study of the Liver. "EASL Congress 2026." Barcelona, May 27–31, 2026.
• U.S. Food and Drug Administration. "FDA Approves First Treatment for Patients with Liver Scarring Due to Fatty Liver Disease (Rezdiffra/resmetirom)." March 14, 2024.
• Newsome PN et al. "Semaglutide in Adults with Steatohepatitis (ESSENCE trial)." New England Journal of Medicine, 2024.
• ClinicalTrials.gov. "A Study of Pemvidutide for the Treatment of Subjects with Metabolic Dysfunction-Associated Steatohepatitis (MASH) — IMPACT." NCT05989711.