Pemvidutide

Pemvidutide is Altimmune’s investigational once-weekly GLP-1/glucagon peptide for MASH and related metabolic disease. Human randomized trials show real MASH-resolution and weight-loss signals, but the pivotal fibrosis endpoint missed statistical significance. Pemvidutide is not FDA-approved in the United States; a Phase 3 MASH trial is planned, not completed.

Key facts

• Evidence: Human randomized controlled trials; mixed for MASH because one dual primary endpoint hit and one missed
• U.S. status (July 2026): Investigational, with no approved indication
• Research use: Once-weekly subcutaneous injection in trials; not a validated personal protocol
• Main risks: Gastrointestinal side effects and an unfinished long-term safety record
• Sport: Prohibited at all times under WADA S0 as a non-approved substance

What is pemvidutide?

Pemvidutide, formerly called ALT-801, is a synthetic 29-amino-acid peptide developed by Altimmune. It activates two metabolic receptors and is being studied most closely for metabolic dysfunction-associated steatohepatitis (MASH), a fatty-liver disease involving inflammation and scarring. Obesity, alcohol use disorder and alcohol-associated liver disease are also investigational uses. The FDA identity record confirms CAS 2538014-94-5 and UNII A35F525WBG, but an identity record is not an approval.

Pemvidutide belongs on the GLP-1 and metabolic peptide hub, though calling it simply another GLP-1 drug misses half the design. The glucagon side is the reason liver researchers are watching it.

How does pemvidutide work?

Pemvidutide presses two hormone buttons at once. GLP-1 turns down appetite and slows stomach emptying. Glucagon encourages the body to spend stored fuel and acts directly on how the liver handles fat. Picture one hand lowering the food coming in while the other helps clear fuel already sitting in storage. That pairing aims at body weight and liver fat together.

The glucagon arm is not free bonus horsepower. Glucagon can raise blood sugar, while GLP-1 pushes glucose control in the other direction. Trials must show that the balance works in people rather than merely looking tidy on a pathway diagram.

What did the pemvidutide IMPACT trial show?

The pemvidutide IMPACT trial produced one clear win and one clear miss. This was a randomized, double-blind, placebo-controlled Phase 2b trial of 212 adults with biopsy-confirmed MASH and F2 or F3 fibrosis. At week 24, MASH resolved without worsening fibrosis in 59.1% on 1.2 mg and 52.1% on 1.8 mg, versus 19.1% on placebo in the prespecified analysis. Both comparisons were statistically significant.

The other primary endpoint did not clear that bar. Fibrosis improved without worsening MASH in 31.8% and 34.5% on pemvidutide versus 25.9% on placebo; the differences were not statistically significant. The peer-reviewed Lancet report later reported raw responder proportions of 33%, 36% and 28%, respectively, and reached the same conclusion: MASH resolution hit, fibrosis improvement missed.

That distinction matters more than a cheerful press-release adjective. IMPACT ran for 48 weeks, but the biopsy endpoints above were measured at week 24. The EASL 2026 week-48 presentation reported better liver-fat, stiffness and blood-marker results with pemvidutide, plus 4.5% and 7.5% mean weight loss at the two doses versus 0.2% with placebo. No liver biopsy was performed at week 48, so those later markers do not retroactively turn the missed fibrosis endpoint into a hit.

What do pemvidutide weight-loss results mean?

Pemvidutide weight loss is supported by human randomized trials, but the number depends on dose, population and study. In the 391-person MOMENTUM obesity trial, the 2.4 mg group lost an average of 15.6% of body weight at week 48. In IMPACT, which enrolled people with biopsy-confirmed MASH and used 1.2 mg or 1.8 mg, weight loss was smaller. Those are separate trials, not a head-to-head ranking.

The MOMENTUM result makes pemvidutide relevant to weight-loss research, while IMPACT asks the harder liver question. Retatrutide adds a GIP receptor to GLP-1 and glucagon; survodutide uses the same two receptor families as pemvidutide but is a different molecule with its own trials. Cross-trial percentages are useful landmarks, not a winners’ podium.

Is pemvidutide safe? What are the risks?

Pemvidutide has meaningful short-term human safety data, but no approval-sized long-term safety record. In the peer-reviewed IMPACT analysis, adverse events occurred in 78% of the 1.2 mg group, 81% of the 1.8 mg group and 67% of the placebo group. Most were mild or moderate, and adverse-event discontinuations were zero, 1% and 2%, respectively.

Across Phase 2 work, nausea, vomiting, diarrhea and constipation were the recurring problems. MOMENTUM also recorded more drug-related discontinuations at its higher doses. The current evidence can describe months of monitored trial use; it cannot settle rare harms, multi-year use or the contents of an online vial claiming to contain pemvidutide. Trial material and gray-market powder are not interchangeable.

Is pemvidutide FDA-approved or available in 2026?

Pemvidutide is not FDA-approved or a marketed prescription drug as of July 16, 2026. Altimmune describes it as investigational, and the FDA’s 2026 novel-approval list does not include it. Breakthrough Therapy and Fast Track designations can speed development conversations; neither permits pharmacy sales or proves effectiveness.

Altimmune says the global PERFORMA Phase 3 MASH trial is planned for the second half of 2026, with its protocol submitted to FDA and 52-week data anticipated in 2029. “Planned” is doing real work in that sentence. Until the study begins and reports, Phase 3 pemvidutide results do not exist. The dated regulatory-status reference explains why trial status and approval are different lanes.

How was pemvidutide dosed in studies?

Pemvidutide was given by once-weekly subcutaneous injection in the cited trials. IMPACT tested 1.2 mg and 1.8 mg without dose titration; MOMENTUM studied 1.2 mg, 1.8 mg and 2.4 mg, with rapid titration for the higher groups. These are doses reported in controlled research, not instructions for reconstituting a vial or choosing a personal dose.

The evidence grade is therefore Human RCT, mixed for MASH. Pemvidutide cleared the disease-resolution endpoint, missed the fibrosis-improvement endpoint, and produced supportive weight and liver-marker changes. That is a better story than “nothing works,” and a more honest one than “the trial was positive.” The next useful answer belongs to PERFORMA, assuming the planned trial starts and reads out.