Efinopegdutide (MK-6024): The GLP-1/Glucagon Dual That Beat Semaglutide on Liver Fat (July 22, 2026)
Table of Contents
A gut hormone the body already uses as a dual agonist
Efinopegdutide starts from oxyntomodulin, a peptide the gut releases after meals that naturally activates both the GLP-1 receptor and the glucagon receptor at once. Where a drug like semaglutide hits only the GLP-1 receptor, oxyntomodulin is a built-in dual agonist - the body's own way of coordinating fullness, blood sugar and energy expenditure. The problem with the natural hormone is that it lasts only minutes. Efinopegdutide is the engineered fix: a modified, protease-resistant GLP-1/glucagon dual-agonist sequence conjugated to a human IgG4 Fc fragment through a roughly 10 kDa PEG linker, using Hanmi Pharmaceutical's LAPSCovery half-life-extension platform. That chemistry turns a minutes-long signal into a once-weekly subcutaneous injection. Most of what makes efinopegdutide a drug rather than a curiosity is this half-life engineering, not new receptor biology.
Why add glucagon when GLP-1 already works?
GLP-1 receptor agonists reduce liver fat, but mostly indirectly - by driving weight loss and improving insulin sensitivity. Glucagon does something more direct. Acting on liver cells, it increases fatty-acid oxidation, raises mitochondrial energy expenditure and suppresses the liver's own fat production (de novo lipogenesis). In other words, a well-balanced glucagon signal can strip triglyceride out of the liver faster than weight loss alone would predict. The historical catch is that unopposed glucagon raises blood sugar, which is exactly why you pair it with a GLP-1 arm that lowers glucose. That balancing act - glucagon for hepatic fat-burning, GLP-1 to keep glycemia in check and add appetite suppression - is the entire rationale of GLP-1/glucagon co-agonism for liver disease, and efinopegdutide is one of its cleanest tests.
The head-to-head number: 72.7% vs 42.3%
Most early metabolic trials use a placebo control, which tells you a drug works but not whether it beats the standard of care. Efinopegdutide's Phase 2a did the harder thing. Published in the Journal of Hepatology in 2023, it randomized 145 adults with NAFLD and MRI-confirmed liver fat to efinopegdutide 10 mg or semaglutide 1 mg, both once weekly for 24 weeks. The least-squares mean relative reduction in liver fat content was 72.7% with efinopegdutide versus 42.3% with semaglutide - a large, statistically significant gap - and about two-thirds of efinopegdutide recipients dropped below the 5% liver-fat threshold that defines a normal liver. The detail that matters most: weight loss was similar in both arms (roughly 8.5% vs 7.1%). Because the two groups lost about the same weight, the extra liver-fat clearance is attributable to the glucagon-driven hepatic mechanism, not to greater appetite suppression. The cost was tolerability - efinopegdutide caused somewhat more nausea and vomiting, in line with the class and an unoptimized dose.
A molecule that changed hands twice
Efinopegdutide has an unusually well-traveled history. Hanmi discovered it as HM12525A and licensed it to Janssen (Johnson & Johnson) in 2015 for $105 million upfront, where it became JNJ-64565111 and was tested in obesity and type 2 diabetes. J&J handed the rights back after those programs underwhelmed. In 2020 Merck picked the compound up, renamed it MK-6024, and - crucially - repositioned it away from weight loss and toward fatty liver disease, where the glucagon arm's direct hepatic effect is the differentiator rather than a liability. That pivot from 'another obesity drug' to 'a liver drug that happens to cause weight loss' is the strategic story of efinopegdutide, and it mirrors how the whole field has come to view the glucagon receptor: less a weight-loss accelerant, more a targeted tool for hepatic metabolism.
What still has to be proven
The strongest human evidence so far is an imaging surrogate - MRI-measured liver fat at 24 weeks. That is genuinely predictive, but it is not the finish line. Regulators approving MASH drugs want biopsy-confirmed outcomes: resolution of steatohepatitis without worsening fibrosis, and improvement in fibrosis without worsening MASH. Merck holds FDA Fast Track designation and is running Phase 2b work on those histological endpoints, plus a dedicated Phase 2 study in compensated (F4) cirrhosis due to steatohepatitis (MK-6024-017, NCT06465186), with primary completion estimated in 2026. Whether the striking liver-fat numbers translate into biopsy benefit is the open question that efinopegdutide shares with the entire MASH field - the surrogate-versus-outcome debate now at the center of steatotic-liver-disease drug development.
Where it sits in the pipeline
As a GLP-1/glucagon dual, efinopegdutide competes directly with pemvidutide, survodutide, cotadutide and mazdutide, and on the MASH battlefield it lines up against the FGF21 analogs (efruxifermin, pegozafermin, efimosfermin) and the triple agonist efocipegtrutide. Its calling card is the benchmark it set - a published, head-to-head win over semaglutide on the imaging endpoint MASH programs are judged by. But it is investigational: not approved, not a supplement, and not a product available for purchase. Any 'efinopegdutide' or 'MK-6024' offered by a research-chemical vendor is unverified and is not the studied drug. For now it is a compound to watch, not to use.
The bottom line
Efinopegdutide is an oxyntomodulin-based, once-weekly GLP-1/glucagon co-agonist that Merck is developing for MASH after two prior owners tried and set it aside for obesity and diabetes. Its Phase 2a head-to-head cut liver fat by 72.7% versus semaglutide's 42.3% at matched weight loss - isolating the glucagon arm's direct hepatic effect as the reason. That makes it one of the more compelling GLP-1/glucagon stories for the liver specifically. The remaining question is the one that governs the whole MASH field: does dramatic liver-fat reduction on MRI become resolution of steatohepatitis and fibrosis improvement on biopsy? The answer is what the current trials are built to find.
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Citations
- [1] A phase IIa active-comparator-controlled study to evaluate the efficacy and safety of efinopegdutide in patients with non-alcoholic fatty liver disease - Journal of Hepatology, 2023 Source
- [2] Merck to Present Data for Efinopegdutide (MK-6024) in Patients with NAFLD at EASL 2023 - Merck.com Source
- [3] A Clinical Study of Efinopegdutide in Compensated Cirrhosis Due to Steatohepatitis (MK-6024-017) - ClinicalTrials.gov NCT06465186 Source
- [4] Efinopegdutide - Wikipedia (identifiers, mechanism, development history) Source
- [5] Merck bags J&J castoff from Hanmi to expand NASH pipeline - Fierce Biotech Source
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