Altimmune’s investigational drug pemvidutide receives FDA Breakthrough Therapy Designation for MASH, supported by Phase 2b IMPACT trial data and advancing toward Phase 3.
Written By: Pharmacally Medical News Desk
Altimmune, Inc. today announced that the U.S. Food and Drug Administration has granted Breakthrough Therapy Designation (BTD) to its investigational therapy pemvidutide for the treatment of metabolic dysfunction-associated steatohepatitis (MASH). The designation applies specifically to pemvidutide’s development in MASH following promising clinical data from the ongoing Phase 2b IMPACT trial.
Jerry Durso, President and CEO of Altimmune, said the Breakthrough Therapy Designation highlights the strength of pemvidutide’s clinical data and validates its potential role in MASH and other serious liver diseases. He noted that, as the company moves toward Phase 3 with FDA alignment, Altimmune is focused on advancing pemvidutide through late-stage development while building the company’s foundation and delivering value to patients and stakeholders.
Basis for Grant
The breakthrough designation for pemvidutide in MASH was based on 24-week data from the IMPACT Phase 2b study (NCT05989711) demonstrating statistically significant MASH resolution without worsening fibrosis, along with notable early improvements in liver fat and measures of fibrosis and hepatic inflammation.
In addition to the 24-week outcomes, Altimmune recently reported 48-week topline data showing continued improvements in non-invasive tests including Enhanced Liver Fibrosis (ELF) and Liver Stiffness Measurement (LSM), additional reductions in liver fat, and a favourable tolerability profile with sustained weight loss at the higher dose level.
Safety Profile
Pemvidutide was generally well tolerated in the Phase 2b IMPACT trial, with low rates of adverse events leading to treatment discontinuation and no treatment-related serious adverse events reported in topline results. The favorable tolerability profile was maintained through 48 weeks, consistent with prior observations for the program.
Regulatory and Development Plans
Altimmune has completed a productive end-of-Phase 2 meeting with the FDA, resulting in alignment on key parameters for a registrational Phase 3 trial in MASH patients, anticipated to evaluate multiple doses of pemvidutide over a 52-week treatment period with biopsy-based efficacy endpoints. The Phase 3 design, informed by FDA guidance and IMPACT data, aims to support a potential accelerated approval pathway. The trial is expected to incorporate advanced histopathology tools and is being finalized with input from regulatory authorities. In parallel with U.S. plans, Altimmune intends to seek scientific advice from European regulators to inform global development strategy.
About Pemvidutide
Pemvidutide is designed to exert balanced activation of glucagon and GLP-1 receptors. This dual mechanism aims to target metabolic and liver-specific pathways relevant to MASH. Activation of glucagon receptors may directly influence liver fat metabolism and fibrosis, while GLP-1 receptor activity supports metabolic effects such as appetite regulation and weight loss. The FDA has also granted Fast Track designation to pemvidutide for MASH and for alcohol use disorder, reflecting ongoing regulatory support for its clinical development in multiple liver-related indications
Pemvidutide Clinical Development Program
Altimmune is also evaluating the Pemvidutide in other indications, including alcohol use disorder (AUD) and alcohol-associated liver disease (ALD), with respective Phase 2 trials underway.
RECLAIM Phase 2 AUD Trial: Initiated in mid-2025 to assess pemvidutide’s effects in alcohol use disorder patients.
RESTORE Phase 2 ALD Trial: Also started in 2025 to evaluate pemvidutide in alcohol-associated liver disease.
References
Altimmune Receives FDA Breakthrough Therapy Designation for Pemvidutide in MASH, 05 January 2026, https://ir.altimmune.com/news-releases/news-release-details/altimmune-receives-fda-breakthrough-therapy-designation
Altimmune Announces Positive Topline Results from the IMPACT Phase 2b Trial of Pemvidutide in the Treatment of MASH, 26 June 2025, https://ir.altimmune.com/news-releases/news-release-details/altimmune-announces-positive-topline-results-impact-phase-2b
IMPACT TRIAL: Efficacy and Safety of Pemvidutide in Subjects with Nonalcoholic Steatohepatitis (NASH) (IMPACT), ClinicalTrials.gov ID NCT05989711, https://clinicaltrials.gov/study/NCT05989711
Noureddin M et al, 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. Lancet. 2025 Dec 6;406(10520):2644-2655. doi: 10.1016/S0140-6736(25)02114-2. Epub 2025 Nov 11. PMID: 41237796. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(25)02114-2/abstract