Rezdiffra and Wegovy are both FDA-approved for certain adults with metabolic dysfunction-associated steatohepatitis, or MASH, and moderate to advanced liver scarring. Now researchers are comparing what happens when patients receive the two medicines in everyday clinical practice.
The comparison is genuinely interesting. Preliminary conference reporting suggests that semaglutide, the active ingredient in Wegovy, was associated with greater improvements in liver enzymes, weight and blood sugar than resmetirom, the active ingredient in Rezdiffra.
But the comparison is not a randomized head-to-head clinical trial. And the difference matters.
Patients starting the two treatments had different clinical characteristics, the analysis relied on electronic medical records, and the most closely watched outcomes were short-term blood tests rather than direct measurements of liver scarring.
For a disease that can take years to progress, six months of encouraging biomarkers cannot settle which medicine better protects the liver.
What Novo Nordisk Is Bringing to the Liver Meeting
The Liver Meeting, the annual congress of the American Association for the Study of Liver Diseases, runs November 5 through 9, 2026, in Denver, Colorado.
Among Novo Nordisk’s presentations is PLATINUM-Truveta, an observational study comparing semaglutide 2.4 mg with resmetirom in people with MASH.
According to Novo’s October 28 announcement, the retrospective analysis used de-identified electronic health records from the Truveta database, covering 30 US health systems.
The study included 2,873 adults who initiated semaglutide 2.4 mg and 2,285 who initiated resmetirom, a total of 5,158 patients.
Researchers assessed changes in alanine aminotransferase (ALT), aspartate aminotransferase (AST), body weight, glycated hemoglobin (HbA1c), platelets and several blood lipid measures.
ALT and AST are enzymes that can rise when liver cells are injured. HbA1c reflects average blood glucose over approximately two to three months.
The principal comparative assessments described in Novo’s release were conducted at three and six months after treatment initiation.
Patients with cirrhosis, other chronic liver diseases or previous exposure to the studied treatments were excluded. Participants also had to remain on treatment to contribute data at each assessment point.
To address differences between the treatment groups, investigators used inverse probability of treatment weighting alongside statistical models accounting for repeated patient measurements.
The study was selected as a Poster of Distinction, a designation assigned to the top 10% of submitted posters at the meeting.
Its scheduled presentation is November 6, from 1 p.m. to 2 p.m. local time.
These are meaningful research credentials. They do not convert an observational study into a randomized trial.
What the Preliminary Results Actually Show
Novo’s October 28 announcement outlined the study without reporting its numerical comparisons.
However, conference coverage published on November 5 by First Report Managed Care described preliminary results from abstract 2461.
According to that report, semaglutide was associated with significantly greater improvements in ALT, AST, body weight and HbA1c than resmetirom after statistical adjustment at three and six months.
At six months, the reported mean weight reduction was 20.2 pounds in the semaglutide group, compared with 3.6 pounds in the resmetirom group.
Mean HbA1c declined by 0.36 percentage points with semaglutide, compared with 0.09 percentage points with resmetirom.
Earlier unadjusted analyses also showed more favorable liver enzyme changes among semaglutide recipients.
During the first month, the report described a mean ALT decline of 6.0 U/L with semaglutide, compared with a 5.4 U/L increase among resmetirom recipients.
AST declined by 4.5 U/L in the semaglutide group, compared with a 4.0 U/L increase in the resmetirom group.
These are associations observed in a particular patient population. They should not be interpreted as proof that one medicine causes better long-term liver outcomes than the other.
The groups were not clinically interchangeable at baseline.
Patients receiving semaglutide were younger on average, approximately 48 versus 59 years, and had a higher mean body mass index, approximately 39 versus 34.
The semaglutide group also had higher average baseline body weight and a different distribution of cardiometabolic risk factors.
Those differences matter because treatment selection in routine clinical practice is influenced by patient characteristics, disease severity, other medical conditions and prescribing decisions.
Statistical weighting can reduce the influence of measured differences. It cannot guarantee that the groups are identical in characteristics that were not recorded or accurately captured.
The most important limitation remains the outcome itself.
Improved liver enzymes can indicate a favorable change in liver injury. They do not establish that scar tissue has regressed, that cirrhosis has been prevented or that future liver-related complications will be reduced.
The reported comparison did not directly measure biopsy-confirmed MASH resolution or fibrosis improvement.
These preliminary figures are drawn from conference reporting and should be checked against the complete poster and eventual peer-reviewed publication.
Two Approved Medicines, Two Different Mechanisms
MASH is the inflammatory form of metabolic dysfunction-associated steatotic liver disease, or MASLD.
It develops in association with metabolic dysfunction and can progress from liver inflammation to fibrosis, cirrhosis and potentially life-threatening complications.
On March 14, 2024, the FDA granted accelerated approval to Rezdiffra, developed by Madrigal Pharmaceuticals, for adults with noncirrhotic MASH and moderate to advanced fibrosis, consistent with stages F2 to F3.
Rezdiffra is an oral thyroid hormone receptor-beta agonist. It acts through a receptor involved in hepatic lipid metabolism and related metabolic processes.
Wegovy received an additional FDA indication for MASH on August 15, 2025, also under accelerated approval and for eligible adults with noncirrhotic disease and stages F2 to F3 fibrosis.
Wegovy contains semaglutide, a GLP-1 receptor agonist that influences appetite, weight regulation and glucose metabolism.
Weight loss is an important mechanism through which semaglutide may improve metabolic liver disease, although other potential effects on liver inflammation and related pathways remain under investigation.
The two therapies therefore approach the disease through different pharmacological pathways.
But different mechanisms do not automatically make the drugs interchangeable competitors for every patient.
Comorbid obesity, diabetes, cardiovascular risk, fibrosis severity, adverse effects, other medications and coverage decisions can all influence treatment selection.
The approved prescribing information also matters. Both MASH indications were granted under the accelerated approval pathway, with longer-term evidence required to verify clinical benefit.
Approval based on improvements in liver tissue is not the same thing as proof that a treatment prevents liver failure, transplantation or death.
One medicine acts primarily through a liver-directed thyroid hormone pathway. The other acts through GLP-1 signaling and broader metabolic effects. The question is which clinical outcomes each can reliably improve.
Why the Real-World Comparison Cannot Prove Which Drug Is Better
The strongest distinction is between the evidence supporting an individual treatment and the evidence required to compare two treatments.
For Wegovy’s MASH approval, the pivotal evidence came from the randomized, placebo-controlled ESSENCE Phase 3 trial.
The interim analysis involved the first 800 participants evaluated at 72 weeks.
According to Novo and FDA documentation, 36.8% of participants receiving semaglutide achieved improvement in liver fibrosis without worsening steatohepatitis, compared with 22.4% receiving placebo.
MASH resolution without worsening fibrosis occurred in 62.9% of semaglutide-treated participants, compared with 34.3% of placebo recipients.
These were histological outcomes assessed using liver biopsy evidence.
Rezdiffra’s accelerated approval was likewise supported by a randomized clinical trial evaluating MASH resolution and fibrosis improvement using liver tissue assessments.
Both studies provide important evidence of benefit against their respective control groups.
Neither trial establishes that one drug is superior to the other because the medicines were not randomized against each other within the same study.
PLATINUM-Truveta brings the drugs into a single observational comparison, but it does not reproduce the protections of randomized allocation.
Patients and clinicians selected treatments for reasons that may be incompletely represented in electronic health records.
The treatment-persistence requirement creates another consideration. Patients who remain on a medicine long enough to contribute follow-up data may differ from those who stop early because of tolerability, access, cost or inadequate response.
Electronic records may also contain incomplete information about actual medication use, underlying disease severity and the timing of clinical assessments.
Even if one group shows stronger improvement in ALT or AST over six months, those changes cannot establish which medicine is better at reducing fibrosis over several years.
Liver enzymes fluctuate for multiple reasons. Fibrosis is a structural process that may require longer follow-up and more direct assessments to evaluate confidently.
Randomized head-to-head trials with clinically relevant outcomes would provide stronger comparative evidence.
Six months of liver enzymes cannot settle a disease that takes years to scar.
Novo’s Other Liver Research at AASLD
PLATINUM-Truveta is only one part of Novo’s liver research program at the meeting.
Another retrospective analysis, RHODIUM-2, evaluates adults with MASH who initiated semaglutide 2.4 mg against a much larger group who did not initiate the treatment.
The study includes 2,479 semaglutide initiators and 70,702 comparators, using electronic medical record data from 30 US health systems.
Researchers are evaluating liver enzymes, weight, HbA1c and other cardiometabolic measures at three, six and twelve months.
Like PLATINUM-Truveta, RHODIUM-2 is observational. Its findings can identify associations, not establish treatment causality.
Novo is also presenting a post hoc ESSENCE analysis involving participants with MASH and a body mass index below 27.
The analysis matters because significant metabolic liver disease can occur in people who do not meet conventional obesity thresholds.
Its results are scheduled for an oral presentation on November 8.
Other presentations include research on investigational efruxifermin in compensated MASH cirrhosis and a Phase 2 study of zalfermin, cagrilintide and semaglutide in alcohol-related liver disease.
These programs address different clinical populations and biological questions. Their outcomes should not be combined into one broad claim that semaglutide has been established as the strongest treatment for every form of liver disease.
Madrigal also entered the meeting with new real-world evidence for Rezdiffra.
On November 5, Madrigal reported several observational analyses examining changes in liver stiffness, liver enzymes and cardiometabolic measures during routine treatment.
In one Truveta analysis involving 150 patients with paired liver-stiffness measurements, 55% achieved at least a 25% improvement at approximately twelve months, according to the company.
Those findings are not directly comparable with the PLATINUM-Truveta results because they involve separate study designs, populations, measurements and follow-up periods.
Liver stiffness measured by elastography is also not identical to biopsy-confirmed fibrosis improvement.
The combined evidence illustrates why individual biomarkers should not become substitutes for a complete assessment of liver disease.
The Commercial Stakes: A Growing Market With Unanswered Questions
The comparison matters commercially because MASH treatment is becoming a significant pharmaceutical market.
Madrigal’s November 3 third-quarter financial announcement reported $431.3 million in Rezdiffra net product sales, representing 50% year-over-year growth.
The company also reported more than 55,850 patients receiving Rezdiffra as of September 30, 2026.
Year-to-date net sales reached approximately $1.1 billion, according to Madrigal.
Those numbers show that an approved treatment directed specifically at MASH can build a substantial commercial business.
For Novo, Wegovy’s expanded indication creates an opportunity to address liver disease in eligible patients, including some who have obesity and other metabolic complications.
But the market is not simply a contest to switch every Rezdiffra patient to Wegovy, or vice versa.
Many people with MASH remain undiagnosed, and identifying patients with clinically significant fibrosis remains a major challenge.
Improved diagnosis, specialist referrals, noninvasive fibrosis testing, treatment access and longer-term outcomes will all influence how the market develops.
There is also the possibility that different treatments could eventually have complementary roles for selected patients, rather than functioning exclusively as substitutes.
However, any combination strategy must be supported by appropriate clinical evidence rather than assumptions derived from separate studies or overlapping patient populations.
The strongest future evidence would address questions that short-term observational studies cannot answer.
Does either therapy reduce progression to cirrhosis, liver-related hospitalizations, transplantation or mortality more effectively?
How durable are the improvements after several years?
Do benefits vary by fibrosis stage, diabetes status, baseline weight or other metabolic conditions?
And how do safety, treatment persistence and cost affect the practical value of each treatment?
For Rezdiffra, Madrigal’s MAESTRO-NASH OUTCOMES program is designed to provide longer-term clinical evidence, with the company expecting data in late 2027.
For Wegovy, the ongoing ESSENCE trial will continue evaluating whether its favorable liver tissue findings translate into reductions in clinically meaningful liver-related events.
The PLATINUM-Truveta results may offer useful insights into real-world metabolic responses. They do not replace those longer-term studies.
As the November 6 poster becomes available, the most important details will be the completeness of follow-up data, the baseline balance achieved after statistical weighting, the analysis of treatment persistence and the full magnitude of the reported differences.
Those details will determine how much confidence readers should place in the comparison.
The broader lesson is not that the two medicines should never be compared.
It is that comparisons should be judged by the strength of their methods and the clinical relevance of their outcomes.
Wegovy and Rezdiffra are now competing for attention in MASH. The more important contest is still being decided by evidence of what happens to patients’ livers over time.
Sources and Further Reading
- Novo Nordisk: Liver Research Presentations at AASLD 2026, October 28, 2026.
- First Report Managed Care: Semaglutide Versus Resmetirom Real-World MASH Findings, November 5, 2026.
- US Food and Drug Administration: Approval of Wegovy for MASH.
- Novo Nordisk: Wegovy Approved in the US for MASH, August 15, 2025.
- US Food and Drug Administration: Rezdiffra Accelerated Approval, March 14, 2024.
- Madrigal Pharmaceuticals: Third-Quarter 2026 Financial Results, November 3, 2026.
- Madrigal Pharmaceuticals: New Rezdiffra Real-World Research at AASLD, November 5, 2026.
