SYNERGY-NASH

SYNERGY-NASH tested tirzepatide in people whose fat-related liver disease had progressed to inflammation and scarring — metabolic dysfunction-associated steatohepatitis, or MASH, the condition formerly called NASH. It is a phase 2 dose-finding trial: 190 adults with biopsy-confirmed MASH and moderate or severe fibrosis were randomized to tirzepatide at 5, 10 or 15 mg weekly or to placebo for 52 weeks. Loomba and colleagues published it in the New England Journal of Medicine in 2024.

What makes the trial demanding is the endpoint. Instead of a blood marker or a scan, researchers required a repeat liver biopsy at week 52, read by pathologists blinded to treatment, to determine whether the steatohepatitis had resolved without the fibrosis getting worse. That is a hard bar, and it is the standard regulators have used in this disease.

The results: MASH resolved without worsening fibrosis in 10% on placebo, 44% at 5 mg, 56% at 10 mg and 62% at 15 mg. A separate measure — improvement of at least one fibrosis stage without worsening MASH — reached 30% on placebo versus 51% to 55% across the tirzepatide doses. Adverse events were the usual gastrointestinal ones, mostly mild or moderate.

Two things are worth keeping straight. First, this is phase 2, not phase 3 — 190 participants is small, only 157 had evaluable week-52 biopsies, and missing results were imputed conservatively. Second, resolving inflammation is not the same as reversing scarring; the fibrosis-improvement numbers were real but more modest, and confidence intervals were wide. Zepbound is not approved for MASH on the strength of this trial.

Worth asking your clinician: whether you have been screened for fatty liver disease at all, what your FIB-4 score or elastography result shows, and whether liver disease changes which GLP-1 makes sense for you. Our SYNERGY-NASH deep dive covers the design, and the MASH and MASLD study roundup tracks the rest of the field.