Pemvidutide delivered statistically significant 48-week improvements on multiple non-invasive fibrosis markers in the Phase 2b IMPACT trial. Mean ELF reductions reached −0.49 at 1.2 mg and −0.58 at 1.8 mg versus +0.16 on placebo, and LSM fell by −3.04 kPa and −3.97 kPa versus −0.03 kPa on placebo. Thirty percent or more reductions in LSM coupled with at least a 0.5 ELF decrease were achieved by 27.8% and 32.4% of patients on 1.2 mg and 1.8 mg, respectively, compared with 3.2% on placebo. Liver fat content fell 45.2% and 54.7% versus 8.2% on placebo; ALT declined by roughly 38 IU/L on both doses versus 10 IU/L on placebo; and cT1 dropped by 124 ms and 140 ms versus 21 ms on placebo. Weight loss reached 4.5% at 1.2 mg and 7.5% at 1.8 mg, with the higher dose showing no plateau at 48 weeks. Discontinuations due to adverse events were 0% and 1.2% for the active arms versus 3.5% for placebo; no serious or severe treatment-related adverse events were reported.
Altimmune combined these data with a regulatory update: an End-of-Phase 2 meeting yielded alignment with FDA on parameters for a registrational Phase 3 in MASH patients with F2–F3 fibrosis, and openness to integrating AIM-MASH AI Assist, an FDA-qualified tool intended to standardize histologic assessment. IMPACT enrolled 212 biopsy-confirmed F2–F3 patients randomized 1:2:2 to weekly subcutaneous pemvidutide 1.2 mg, 1.8 mg, or placebo for 48 weeks. While the original primary endpoints—MASH resolution without worsening of fibrosis, or fibrosis improvement without worsening of MASH—were assessed at week 24, the new readout focuses on 48-week secondary endpoints from non-invasive tests and metabolic measures.
Strategically, Altimmune is positioning a balanced glucagon/GLP-1 agonist to target both hepatic and metabolic components of MASH, leaning into a clean tolerability signal and antifibrotic NIT profile over a 48-week horizon. The company’s embrace of AI-assisted histology reflects a broader pivot toward reducing inter-reader variability and cycle times in liver biopsy assessment, a known bottleneck in MASH development. The tension remains that the strongest new data are non-invasive: compelling for operational feasibility and patient management, but still adjunctive to the histologic outcomes regulators prioritize for approval. Dose selection also looms, as the 1.8 mg arm shows deeper biomarker and weight effects, potentially at the cost of class-typical tolerability tradeoffs that sponsors often navigate during scaling.
For sites and CROs, a Phase 3 that marries histology with NITs and AI support shifts operational complexity upstream. Expect digital pathology workflows, centralized reads, and tighter imaging vendor coordination for MRI-PDFF, elastography, and cT1. Training and infrastructure for digitized slide handling and data integration will be critical to reduce re-reads and maintain timelines. Vendors offering imaging core services and AI-enabled pathology stand to gain, while sponsors will need to standardize acquisition protocols across a broader global site footprint. Patients could benefit from weekly subcutaneous dosing that, to date, appears tolerable with low discontinuation, but adherence and supply logistics will matter at Phase 3 scale.
Next, watch for Phase 3 initiation in 2026 with clarity on co-primary histology endpoints, dose selection, and the operational plan for AIM-MASH integration. Key risks include the degree of concordance between the 48-week NIT gains and biopsy-based outcomes, the durability of effect beyond one year, and the scalability of digital pathology infrastructure across diverse geographies. With metabolic agents converging on MASH, the differentiation bar will rest on reproducible histologic benefit, operational execution at scale, and a safety profile that holds up under longer exposure.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
