Altimmune Inc. (NASDAQ:ALT) saw its stock tumble by 37% after releasing topline data from its Phase 2b IMPACT trial evaluating pemvidutide for the treatment of metabolic dysfunction-associated steatohepatitis (MASH).
The biopharmaceutical company reported that the trial met its primary goal—up to 59.1% of patients achieved resolution of MASH without worsening fibrosis based on an intent-to-treat analysis. However, investor reaction remained cautious, likely reflecting concerns around the broader dataset.
The 24-week study included 212 participants with biopsy-confirmed MASH and moderate to advanced fibrosis (stages F2/F3). While pemvidutide showed fibrosis improvement in around one-third of patients at 1.2 mg and 1.8 mg doses, the results—31.8% and 34.5%, respectively—did not reach statistical significance when compared to the 25.9% improvement in the placebo group.
Despite this, weight loss outcomes were notable. Participants on pemvidutide lost 5.0% to 6.2% of body weight, a substantial difference versus just 1.0% among those receiving placebo. The treatment also demonstrated a strong safety profile, with less than 1% of participants discontinuing due to adverse events.
Dr. Scott Harris, Altimmune’s Chief Medical Officer, highlighted the significance of the results: “Pemvidutide achieved meaningful MASH resolution and encouraging signs of fibrosis reduction after just 24 weeks.” The company anticipates a productive End-of-Phase 2 meeting with the FDA in the fourth quarter of 2025.
In a supplemental AI-driven analysis, further support for pemvidutide’s antifibrotic potential emerged: 30.6% of patients on the 1.8 mg dose saw fibrosis shrink by 60% or more, compared to 8.2% on placebo, a statistically significant outcome.
Altimmune plans to engage with regulators in the coming months as it moves toward launching Phase 3 trials for pemvidutide.