GAITHERSBURG, Md. — November 11, 2025 — Leads & Copy — Altimmune, Inc. (Nasdaq: ALT) has announced the publication of 24-week efficacy and safety data from its ongoing IMPACT Phase 2b trial of pemvidutide in patients with metabolic dysfunction-associated steatohepatitis (MASH) in The Lancet.
The paper, titled “Safety and efficacy of weekly pemvidutide versus placebo for metabolic dysfunction-associated steatohepatitis (IMPACT): 24-week results from a multicentre, randomised, double-blind, phase 2b study”, presents data demonstrating significant MASH resolution, weight loss, and strong evidence of anti-fibrotic activity with a favorable tolerability profile.
Dr. Mazen Noureddin, M.D., the IMPACT trial’s principal investigator, will present the data in a late-breaking oral presentation at The Liver Meeting® 2025, hosted by the American Association for the Study of Liver Diseases (AASLD) in Washington, D.C.
Topline 24-week data from the IMPACT Phase 2b trial, previously announced in June 2025, demonstrated that pemvidutide, Altimmune’s 1:1 glucagon/GLP-1 agonist, achieved statistically significant MASH resolution without worsening of fibrosis, meaningful reductions in fibrosis and liver fat, and clinically relevant weight loss with favorable tolerability.
The Lancet publication describes changes across key non-invasive tests (NITs) from blood-based biomarkers (ELF, PRO-C3, and AST), imaging modalities (MRI-PDFF, FibroScan®, and cT1), and combined measures such as FAST score, all markers that offer consistent evidence of fibrosis reduction and improvement in liver inflammation.
Dr. Noureddin said the totality of the 24-week clinical data from the IMPACT trial is very encouraging. He also stated that given the significant resolution of MASH that occurred after only 24 weeks of treatment, along with strong evidence of anti-fibrotic activity and weight loss, the profile of pemvidutide suggests it has the potential to meaningfully alter the course of this disease.
Key highlights from the published IMPACT 24-Week results include:
Primary Endpoint (Histology ITT Analysis):
- MASH resolution without worsening of fibrosis: 58% (1.2 mg) and 52% (1.8 mg) of patients achieved MASH resolution compared to 20% in the placebo group (p < 0.0001).
- Fibrosis improvement without worsening of MASH: 33% (1.2 mg) and 36% (1.8 mg) experienced fibrosis improvement compared to 28% in the placebo group.
Secondary Endpoints:
- Significant changes in liver stiffness measurement (kPa): -3.7 (1.2 mg, p < 0.001) and -2.2 (1.8 mg, p < 0.05) compared to -0.7 in the placebo group.
- Significant changes in Enhanced Liver Fibrosis score: -0.6 (1.2 mg, p < 0.001) and -0.5 (1.8 mg, p < 0.001) compared to 0.03 in the placebo group.
- Significant changes in corrected T1 relaxation time (ms): -124.6 (1.2 mg, p < 0.001) and -134.7 (1.8 mg, p < 0.001) compared to -14.7 in the placebo group.
- Normalization of liver fat content (≤ 5%): 31% (1.2 mg) and 44% (1.8 mg) compared to 4% in the placebo group (p < 0.0001).
- Body weight relative reduction: -4.8% (1.2 mg, p < 0.001) and -5.8% (1.8 mg, p < 0.001) compared to -0.5% in the placebo group.
No serious adverse events related to assigned treatment were reported.
Christophe Arbet-Engels, M.D., Ph.D., Chief Medical Officer of Altimmune, said that the dual glucagon and GLP-1 receptor agonism of pemvidutide was intentionally designed to target both the hepatic and metabolic drivers of MASH. He added that the strength of these IMPACT 24-week results, particularly the rapid resolution of MASH, reinforces their belief in the differentiated mechanism of pemvidutide and its potential to become an important treatment for patients with MASH.
The IMPACT Phase 2b trial enrolled 212 participants with biopsy-confirmed MASH and fibrosis stages F2 or F3, with and without diabetes. Participants were randomized to receive weekly subcutaneous pemvidutide doses at either 1.2 mg, 1.8 mg or placebo for 48 weeks. The primary efficacy endpoints, measured at 24 weeks, were MASH resolution without worsening of fibrosis, or fibrosis improvement without worsening of MASH.
Pemvidutide is a novel, investigational peptide with balanced 1:1 glucagon/GLP-1 dual receptor agonist activity, in development for the treatment of MASH, alcohol use disorder (AUD) and alcohol-associated liver disease (ALD). The FDA has granted Fast Track designation to pemvidutide for the treatment of MASH and AUD.
Lee Roth
Burns McClellan
Phone: 646-382-3403
lroth@burnsmc.com
Savannah Valade
Real Chemistry
altimmune@realchemistry.com
Source: Altimmune, Inc.
