| Trial results
A paper published online on November 9, 2026 in The Lancet reports that efinopegdutide, an investigational once-weekly injection from Merck that activates both the GLP-1 and glucagon receptors, cleared the liver inflammation of MASH in more people than placebo after 52 weeks. MASH is fatty liver disease with inflammation and liver-cell damage. This trial looked at liver biopsies, not weight loss. The Lancet describes efinopegdutide as under development.
The phase 2b trial was randomized, double-blind and placebo-controlled, run at 176 centers in 26 countries. It enrolled 386 adults with biopsy-confirmed MASH and stage 2 or stage 3 liver scarring, called fibrosis. Screening ran from June 2023 to December 2025. People were assigned in equal groups to efinopegdutide 4 mg, 7 mg or 10 mg, to placebo, or to semaglutide 2.4 mg, all as a once-weekly injection under the skin. The semaglutide group was open-label, meaning everyone in it knew what they were getting. In all, 381 people received at least one dose and are in the analysis. Merck Sharp & Dohme, a subsidiary of Merck & Co., funded the trial.
The main question was whether MASH resolved after 52 weeks without the scarring getting worse. Resolved means the inflammation and liver-cell damage seen on biopsy went away. The second question was whether scarring improved by at least one stage without MASH getting worse. In the main analysis, a missing biopsy at the end counted as a failure.
| Measure at week 52 | Efinopegdutide 4 mg | Efinopegdutide 7 mg | Efinopegdutide 10 mg | Placebo | Semaglutide 2.4 mg (open-label) |
|---|---|---|---|---|---|
| MASH resolved, scarring not worse | 56% (31 of 55) | 63% (31 of 49) | 61% (35 of 57) | 13% (7 of 53) | 53% (26 of 49) |
| Scarring improved by at least one stage, MASH not worse | 43% (32 of 75) | 52% (39 of 75) | 34% (26 of 77) | 21% (16 of 77) | 25% (16 of 65) |
Compared with placebo, the gap in MASH resolution was 43.0 percentage points at 4 mg, 49.5 at 7 mg and 47.8 at 10 mg, all statistically significant (p<0.0001). For scarring, the gap was 21.7 points at 4 mg (95% confidence interval 7.1 to 35.7, p=0.0038) and 30.4 at 7 mg (15.4 to 44.3, p<0.0001). At 10 mg the gap was 13.0 points (-1.2 to 26.8, p=0.072), which was not statistically significant. The abstract does not report a test of efinopegdutide against semaglutide, so the semaglutide column is context, not a head-to-head result.
Stomach and gut side effects were the most common, and they were highest at 10 mg. Stopping the medicine because of side effects was more common at 10 mg (9 of 79 people, 11%) than at the other efinopegdutide doses (3% to 4%) or on placebo (1 person, 1%). The authors conclude that 7 mg had the most favorable balance of benefit and risk, with scarring improving in about half of people after one year.
This was a one-year biopsy study. It did not measure liver failure, liver cancer or deaths. The 10 mg dose did no better than 7 mg on scarring and had the most dropouts. The abstract uses different group sizes for the two endpoints and does not say why. The Atlas has read the abstract, not the full paper, which is behind a login. A phase 3 trial would be needed to show whether efinopegdutide changes liver outcomes.
Efinopegdutide acts on the same two receptors as survodutide and pemvidutide, which are also being studied in MASH. The Atlas pipeline lists efinopegdutide under Merck, but there is no medicine page for it yet.
Worth knowing: This is a peer-reviewed paper, funded by the company that makes the medicine. Figures are from the published abstract. In this trial efinopegdutide was studied for liver disease, not as a weight-loss medicine, and nothing here says it is approved or available.
Related: Pemvidutide medicine page | Survodutide medicine page | Semaglutide medicine page | Pipeline | Survodutide heart safety trial
Sources: Lawitz E et al., The Lancet, online first November 9, 2026 (abstract), DOI 10.1016/S0140-6736(26)02043-X; ClinicalTrials.gov, NCT05877547.