HEC88473
HEC88473, dual GLP-1 and FGF21 receptor agonist
Written by Aaron CuhaReviewed Sep 2026
Also known as: GLP-1/FGF21 dual agonist
The only GLP-1 pairing on this site that is not with another incretin. Combining GLP-1 with FGF21 targets appetite and liver metabolism through genuinely separate pathways.
Overview
Almost every dual agonist documented here pairs GLP-1 with GIP, glucagon or amylin, all of which are gut or pancreatic hormones acting on related receptors. This one pairs it with FGF21, which is a different kind of signal entirely.
FGF21 is a hormone released largely by the liver under metabolic stress, acting on adipose tissue and the brain to increase energy expenditure, improve insulin sensitivity and reduce liver fat. FGF21 analogues have been developed principally for metabolic liver disease, and the site already covers three of them separately.
Combining the two means addressing appetite and hepatic metabolism through mechanisms that barely overlap, which is a stronger case for combination than stacking two appetite pathways, a strategy that has repeatedly run into shared side effects on this site.
The evidence is a first-in-human single ascending dose study. That is the beginning of a programme, not a result.
Mechanism of action
A single molecule with agonist activity at both the GLP-1 receptor and the FGF21 receptor complex. GLP-1 receptor agonism reduces food intake and improves glycaemic control conventionally. FGF21 signals through FGF receptor 1c paired with the co-receptor beta-klotho, which is why beta-klotho expression determines which tissues respond: adipose tissue, liver and specific brain regions. Downstream effects include increased energy expenditure, improved insulin sensitivity and reduced hepatic fat, which is a substantially different set of actions from appetite suppression. Note that beta-klotho is a distinct gene from alpha-klotho, the longevity-associated protein covered separately on this site, and the two are routinely conflated.
Human evidence
One first-in-human single ascending dose study. No efficacy trial and no repeat-dose data published.
- First-in-human, single escalating doses, reporting tolerability, pharmacokinetics and pharmacodynamics.
- No phase 2 result, no weight or liver fat outcome, and no repeat-dose data located.
- The mechanistic case rests on FGF21 analogues developed separately for metabolic liver disease, which are covered on their own pages here.
What this does not tell you: A single ascending dose study is the earliest human step there is. It tells you a molecule can be administered and how it behaves in blood, and nothing about whether it helps anyone. The interesting claim, that pairing GLP-1 with FGF21 does more than either alone, has not been tested in people. It is also worth knowing that FGF21 analogues as a class have a mixed clinical record on hard endpoints despite consistently improving liver fat.
Reading the research record
This compound is worth a page for the pairing rather than the data, because the pairing is the interesting part of an argument this site has been making across several entries.
The combination era in obesity pharmacology has mostly meant stacking appetite pathways: GLP-1 with GIP, with glucagon, with amylin, with peptide YY. Where those have disappointed, the reason has frequently been that the pathways share side effects even when they do not share mechanisms, so nausea and gastric slowing accumulate and the dose ceiling arrives before the benefit does.
FGF21 is a genuinely different kind of partner. It is a metabolic stress signal acting on fat, liver and brain to change energy expenditure and hepatic fat rather than to suppress appetite, so the combination has a better theoretical case for adding benefit without adding the same toxicity. Whether that survives contact with a phase 2 is unknown, and a single ascending dose study is not evidence that it will.
The evidence, charted
Fig. 1 · evidence composition
1of 1 citation (100%) is in people
Every citation cited here is Human work; no other study type is cited on this page. This count is of our own citation list and understates any literature larger than the sources we cite.
Fig. 2 · evidence over time
Every citation here was published in 2025.
Too few distinct publication years on this page to plot as a timeline.
Fig. 3 · legal status at a glance
US
Not approved
UK
Approved
AU
Approved
CA
Not approved
Approved in 2 of 4, prescription route in 0, not approved in 2. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Fig. 4 · dose response
No human dose response curve exists
We draw this figure where the data supports it. For this compound in humans it does not, so the panel stays empty rather than borrowing an animal curve and implying it transfers.
Key studies & citations
- Human2025
First-in-human study on tolerability, pharmacokinetics, and pharmacodynamics of single escalating doses of HEC88473, a novel dual GLP-1 and FGF21 receptor agonist
The entire human record for this compound: a first-in-human single ascending dose study reporting tolerability, pharmacokinetics and pharmacodynamics. Phase 1 single-dose work establishes that a molecule can be given to people and what it does to measurable parameters. It does not establish that it treats anything.
BioDrugs
Frequently asked questions
What makes this different from tirzepatide?
Tirzepatide pairs GLP-1 with GIP, another gut incretin acting on a related receptor. This pairs GLP-1 with FGF21, a liver-derived metabolic stress hormone acting on fat, liver and brain through a different receptor complex. The actions barely overlap, which is a better theoretical case for combining than stacking two appetite signals.
Does it work?
Unknown. The entire human record is a first-in-human single ascending dose study, which establishes that it can be given to people and how it behaves in blood. There is no efficacy trial.
Is FGF21 related to klotho?
To beta-klotho, which is the co-receptor FGF21 needs in order to act, and which determines which tissues respond to it. That is a different gene from alpha-klotho, the longevity-associated protein, and the two are frequently conflated. This site keeps them apart on their own pages.