Head to head
FGF21 against Efruxifermin
The hormone and its engineered analogue. Native FGF21 is released by fasting and has a half-life measured in hours, which is why every therapeutic version is a modified protein, and why lifespan results in FGF21 transgenic mice do not transfer to people taking an analogue for liver disease.
Column A
FGF21Fibroblast growth factor 21 (native hormone)
A liver hormone released by fasting, sugar and protein restriction that signals through beta-klotho. Engineered analogues improved liver fibrosis in phase 2b MASH trials of 222 and 128 people; lifespan extension exists only in transgenic mice.
Column B
EfruxiferminEfruxifermin (EFX, AKR-001)
A weekly FGF21 analog that missed its 36-week primary endpoint in compensated MASH cirrhosis but improved fibrosis in 29% of patients by 96 weeks against 11% on placebo, with three Phase 3 SYNCHRONY trials under way.
Side by side, on the facts we can check
| Attribute | FGF21 | Efruxifermin |
|---|---|---|
| Category | Metabolic | Metabolic |
| FDA status | Not FDA-approved. Native FGF21 is not a drug. No FGF21 analogue (efruxifermin, pegozafermin, efimosfermin) had a Drugs@FDA record on 11 September 2026; efruxifermin and pegozafermin are in phase 3. | Investigational; Phase 3 |
| Half-life | Not reported | Weekly subcutaneous dosing |
| Molecular weight | 22,300 Da precursor (209 residues, UniProt Q9NSA1); mature secreted chain residues 29 to 209, 181 amino acids | 92,108 Da (Fc-FGF21 fusion protein) |
| Mechanism | Established in mice: fasting induces hepatic FGF21 through PPAR-alpha; FGF21 induces PGC-1alpha, drives fatty acid oxidation and ketogenesis, improves insulin sensitivity, suppresses growth hormone action, and causes bone loss. FGF21 signals through FGFR1c (and FGFR3c) only in the presence of beta-klotho, which is what restricts its action to fat, liver and specific brain regions. 2025 mouse work reports that FGF21 reverses MASH through coordinated CNS and liver actions and extends lifespan in diet-induced obesity independently of growth suppression. Established in humans: FGF21 rises acutely after sucrose ingestion and a common FGF21 variant associates with sweet and alcohol intake; exercise training raises circulating FGF21. Engineered analogues given weekly reduce liver fat, improve fibrosis histology and lower triglycerides in MASH, with nausea and diarrhoea as the main adverse effects. Whether those are systemic metabolic effects or liver-specific ones is the subject of a 2026 review. | Long-acting FGF21 receptor agonism (FGFR1c/beta-klotho) that lowers liver fat, improves insulin sensitivity and reduces fibrosis. |
| Human studies cited | 4 | 2 |
| Legal status, US | Investigational, not approved | Investigational, not approved |
Frequently asked questions
What is the difference between FGF21 and Efruxifermin?
FGF21: A liver hormone released by fasting, sugar and protein restriction that signals through beta-klotho. Engineered analogues improved liver fibrosis in phase 2b MASH trials of 222 and 128 people; lifespan extension exists only in transgenic mice. Efruxifermin: A weekly FGF21 analog that missed its 36-week primary endpoint in compensated MASH cirrhosis but improved fibrosis in 29% of patients by 96 weeks against 11% on placebo, with three Phase 3 SYNCHRONY trials under way.
Which has stronger research evidence, FGF21 or Efruxifermin?
This database does not grade compounds. It counts what was run in people: 4 of the 10 studies cited on the FGF21 profile were human work, against 2 of 2 for Efruxifermin. Those counts are of our own citation lists and understate any larger literature, and neither is a recommendation.
Are FGF21 and Efruxifermin FDA-approved?
FGF21: Not FDA-approved. Native FGF21 is not a drug. No FGF21 analogue (efruxifermin, pegozafermin, efimosfermin) had a Drugs@FDA record on 11 September 2026; efruxifermin and pegozafermin are in phase 3.. Efruxifermin: Investigational; Phase 3.
Related posts
Blog articles that cover FGF21 or Efruxifermin, newest first.
Reviewed Sep 2026. This page sets two published records side by side. It is educational, it is not medical advice, and it contains no dosing protocols or recommendations for personal use.