Pemvidutide MASH responder data show combined liver test gains at 48 weeks

DENVER. New pemvidutide MASH data show that up to 42.9% of patients on the drug met liver fat, liver enzyme and liver stiffness targets at the same time after 48 weeks, against 3.3% on placebo. The responder analyses from the IMPACT Phase 2b trial were shown as a poster at The Liver Meeting 2026 on Nov. 7, according to Altimmune's event listing and a report by HCPLive. The results rest on blood tests and imaging, not a second liver biopsy. Pemvidutide is not approved for any use.

What the 48 week responder analyses found

Altimmune's IMPACT study enrolled 212 adults with MASH confirmed by liver biopsy and fibrosis stage F2 or F3, which means moderate to advanced scarring. Patients were randomly assigned to placebo or to one of two fixed weekly doses of pemvidutide, injected under the skin with no step up period, HCPLive reported. At baseline the average patient was 53 years old with a body mass index of 39, according to the poster. Women made up 58% of the group, and 43% had type 2 diabetes. The new analyses asked how many people improved on several markers at once, rather than on a single marker. Liver fat, the liver enzyme ALT, the ELF blood score and liver stiffness were all secondary endpoints in the trial. Naim Alkhouri presented the poster, the company's listing shows.

The broadest composite required liver fat and liver stiffness to fall by at least 30% each and ALT to fall by at least 17 U/L. On that measure, 42.9% of the higher dose group and 34.3% of the lower dose group responded, against 3.3% on placebo. A fibrosis composite, needing an ELF drop of at least 0.5 plus a stiffness drop of at least 30%, was met by 32.4% and 27.8% on the drug, against 3.2% on placebo. In the strictest analysis, 25.8% of patients on the higher dose met all three thresholds at once, against none of the patients on placebo. That test raised the liver fat bar to a cut of at least 50%, and 17.1% of the lower dose group passed it. Every drug arm beat placebo with a P value of .0018 or lower.

Why noninvasive liver tests were combined

The investigators built the composites from noninvasive liver tests because each cutoff has been tied to changes seen on biopsy in earlier research. In their account, a liver fat drop of at least 30% tracks with MASH improvement, and an ALT drop of at least 17 U/L predicts a response on tissue. An ELF fall of at least 0.5 or a stiffness fall of at least 30% has been linked to fibrosis regression. Requiring several tests to move together, the team argued, makes the assessment stricter and more accurate. The approach also lets researchers follow patients without a second biopsy at 48 weeks. The December 2025 topline report from Altimmune had already shown ELF and stiffness still improving between week 24 and week 48 at both doses.

In the strictest analysis, 25.8% of patients on the higher dose met all three thresholds at once, against none of the patients on placebo.

The analyses have clear limits. The abstract did not say how many patients had usable data for each composite, and it gave no safety figures through 48 weeks, HCPLive noted. Composite responses on these tests are not accepted as surrogate endpoints for drug approval, so they cannot replace biopsy or outcome data with regulators. The data come from a conference poster, not a peer reviewed paper. Earlier safety reporting from IMPACT showed that no patients on the lower dose and 1.2% on the higher dose stopped treatment for side effects, against 3.5% on placebo. That reporting found no serious or severe adverse events judged to be caused by treatment. Full 48 week safety data have not been published.

Where pemvidutide stands with regulators

Pemvidutide is a weekly peptide that acts on the glucagon and GLP 1 receptors in a balanced 1:1 ratio. Lilly's experimental retatrutide, which posted the largest average weight loss in a Phase 3 trial, targets the glucagon receptor as well, though it adds GIP receptors. The IMPACT primary results came at 24 weeks and were based on biopsy. MASH resolution without worse fibrosis occurred in 59.1% and 52.1% of the two dose groups, against 19.1% on placebo. Fibrosis improvement without worse MASH reached 31.8% and 34.5%, against 25.9% on placebo, a gap that was not statistically significant. Mean weight loss was 5.0% and 6.2%, against 1.0% on placebo. Investigator Mazen Noureddin of Houston Methodist Hospital called the mix of MASH resolution and weight loss at 24 weeks "unique" in a statement at the time.

The FDA granted pemvidutide breakthrough therapy designation for MASH in January 2026, and the company said the decision was based on the 24 week IMPACT data. Altimmune also holds Fast Track designations for MASH and for alcohol use disorder, according to the company. Two drugs now have FDA accelerated approval for MASH with moderate to advanced fibrosis. Resmetirom, sold as Rezdiffra, was cleared in March 2024, and semaglutide followed when Wegovy won accelerated approval for fatty liver disease in August 2025. Any pemvidutide MASH filing would therefore enter a market with two approved options. A designation speeds contact with the agency, but it does not mean the drug works or will be approved. The FDA has not reviewed the 48 week responder data.

What PERFORMA Phase 3 must still show

Altimmune said in August 2026 that it had begun enrolling the PERFORMA Phase 3 trial, a global, randomized, double blind, placebo controlled study in adults with MASH and F2 or F3 fibrosis. According to the company release summarized by HCPLive, the event driven trial plans to enroll about 990 patients in a cohort selected by biopsy. That cohort has a primary endpoint of MASH resolution, fibrosis improvement or both at 52 weeks. A second cohort of about 800 patients will be identified by noninvasive tests instead. Unlike IMPACT, patients will start low and step up to one of two higher trial doses. Altimmune expects the 52 week data readout in 2029, which remains a company forecast.

Full approval would rest on liver related clinical events measured at about 60 months, HCPLive reported. That means the 48 week composite results are an early signal, not proof that pemvidutide prevents liver failure or death. Until PERFORMA reports, pemvidutide MASH treatment is available only inside clinical trials. Experimental peptides sold online outside trials carry real risk, as shown by a woman who said she developed liver failure after injecting a vial labelled retatrutide. Patients with MASH who want access to pemvidutide should ask their liver specialist about enrolling in a registered study. This report is for research context and is not medical advice. Readers can check the full HCPLive conference report for the abstract details.

Conclusion

The pemvidutide MASH responder data add a 48 week signal that liver fat, enzyme and stiffness markers moved together far more often on the drug than on placebo. The findings come from noninvasive tests, lack published 48 week safety data and cannot support approval alone. The answer will come from PERFORMA, with company guidance pointing to 52 week biopsy results in 2029 and outcome data years later.