Pegozafermin
Pegylated FGF21 analog with the second major MASH program in late-stage development.
Investigational compounds — read carefully
This section covers peptides at the frontier of research. Most entries are preclinical, in early or mid-stage clinical trials, or theoretical. Evidence levels are explicitly marked on every entry.
Nothing on these pages constitutes medical advice, dosing recommendations, or instructions for use. Many of these compounds are not commercially available; some are not legal for human use. Decisions about treatment require a qualified clinician.
At a glance
89bio's pegylated FGF21 analog. Together with efruxifermin, the two define the FGF21-class race in MASH.
- Class
- FGF21 analog (PEGylated)
- Sponsor
- 89bio
- Stage
- Phase 3
- Lead use case
- MASH with fibrosis
What it is
Pegozafermin is a pegylated FGF21 analog designed for weekly dosing in MASH and severe hypertriglyceridemia. Like efruxifermin, it is a long-acting engineered version of native FGF21, but with PEGylation as the half-life-extension strategy rather than Fc-fusion.
Current research status
The ENLIVEN Phase 2b trial showed pegozafermin produced statistically significant improvements in fibrosis and MASH resolution. The Phase 3 ENLIGHTEN program is underway. A separate program targets severe hypertriglyceridemia, a population with limited current treatment options.
Mechanistic rationale
Same FGF21 receptor pharmacology as efruxifermin — FGFR1c / β-Klotho activation in adipose tissue, liver, and pancreas, producing improvements in insulin sensitivity, hepatic lipid handling, and inflammatory signaling. The two compounds differ in their half-life-extension strategies and their dosing-regimen optimization.
Available evidence
ENLIVEN Phase 2b (Loomba et al., NEJM 2023) — In patients with biopsy-confirmed MASH and stage F2-F3 fibrosis, pegozafermin produced fibrosis improvement in 22-27% vs 7% with placebo at week 24.[1]
ENTRIGUE Phase 2 (severe hypertriglyceridemia) — Reductions in triglycerides of 43-57% supporting the metabolic-health applications of the molecule.
Why it's interesting
The two-horse race between efruxifermin and pegozafermin will partially determine which FGF21-engineering strategy (Fc-fusion vs PEGylation) is the better commercial path forward. The class effect (FGF21 receptor activation) is consistent across the molecules; the molecular-engineering differences are what each company is betting on.
Limitations & risks
Same class-level considerations as efruxifermin — bone-density monitoring, GI side effects, and the evolving regulatory framework for MASH endpoints. PEGylation has its own historical safety considerations (anti-PEG antibody development, pegylation-related kidney effects in some agents) that are part of the long-term safety conversation.
Community discussion notes
Less broadly discussed than incretin candidates but tracked closely in MASH and lipid-metabolism communities. The metabolic-flexibility framing of FGF21 means longevity and biohacker communities have some interest, but the disease-focused development pathway has kept the core conversation in clinical hepatology.
The takeaway
Together with efruxifermin, pegozafermin defines the lead FGF21-analog candidates in MASH. The Phase 3 readouts in 2025-2026 will determine whether one or both become approved MASH therapies and how they position relative to the GLP-1 / GLP-1+glucagon dual agonists also pursuing this indication.
References
- Loomba R, et al. Randomized, Controlled Trial of the FGF21 Analogue Pegozafermin in NASH (ENLIVEN). N Engl J Med. 2023;389(11):998-1008. https://pubmed.ncbi.nlm.nih.gov/37356073/
- Bhatt DL, et al. The FGF21 analogue pegozafermin in severe hypertriglyceridemia (ENTRIGUE). Nat Med. 2023;29(7):1782-1792. https://pubmed.ncbi.nlm.nih.gov/37291213/