Foundational guide
FOXO4-DRI What Is It? Mechanism, Construction, Evidence Tier
A precisely characterised molecule with a structurally resolved binding mechanism and an evidence base that has not left the preclinical tier in nine years.
FOXO4-DRI is a synthetic peptide designed to induce apoptosis selectively in senescent cells by displacing the FOXO4 protein from p53. Its mechanism is unusually well resolved, down to the structural level, and its clinical evidence base is empty.
That combination, mechanistic clarity alongside no human data, is what makes the compound easy to overstate.
Supplier publishing lot-level data
FOXO4-DRI, Ascension Peptides
Two independent laboratories have certified this product, though on different batches. The code below halves the listed price on the vial.
The two published certificates cover different lots and disagree on fill: Kovera Labs assays batch 55-05260628 at 11.41 mg, MZ Biolabs assays lot 55-01260229 at 8.30 mg, both against a 10 mg label, moving the real figure between $5.87/mg and $8.07/mg. Endotoxin and sterility screens appear on the Kovera lot only, so testing scope here is a batch property rather than a product feature. The vendor spells the product FOX04 with a zero, including in the link.
- Kovera Labs and MZ Biolabs certificates, different lots
- Carriage free above $250
- Same-day dispatch before 2pm CST
Laboratory research material only, not for human consumption. FOXO4-DRI holds no marketing authorisation in any market and has never been administered in a registered human trial. Affiliate links: we may earn a commission at no additional cost to you. Figures checked September 2, 2026.
FOXO4-DRI what is it: reference characterisation
Start with what can be independently verified, since it anchors the rest and is frequently misstated in secondary sources.
Note that the fourth character of the name is the letter O, from Forkhead box protein O4. Several vendors render it as a digit zero, including within product URLs, which is a propagated typographical error rather than a distinct substance.
| Property | Value |
|---|---|
| Full name | Forkhead box protein O4, D-Retro-Inverso |
| PubChem CID | 167312269 |
| CAS number | 2460055-10-9 |
| Molecular formula | C228H388N86O64 |
| Class | Senolytic peptide |
| Regulatory status | No approval in any market |
| Registered human trials | None |
| Highest evidence tier reached | Preclinical |
FOXO4 and FOXO4-DRI are distinct entities
The names are separated by three characters and the entities are unrelated in kind, which is a persistent source of confusion in secondary literature.
FOXO4 is an endogenous human transcription factor of the FOXO family, involved in stress resistance, metabolic regulation and cell-cycle control. It is a normal component of human biology.
FOXO4-DRI is a synthetic molecule engineered to interfere with a specific function of that protein within senescent cells. It is not an analogue, supplement or derivative in any therapeutic sense; it is an antagonist of an interaction.
The D-retro-inverso construction
The DRI designation describes synthesis strategy rather than pharmacology, and it explains why the molecule persists long enough to act.
Conventional peptides are chains of L-amino acids, which makes them substrates for the proteases that degrade dietary and endogenous protein. A D-retro-inverso peptide inverts two properties simultaneously: the residues are the D enantiomer, and the sequence order is reversed. The resulting topology places side chains in approximately the original spatial arrangement, preserving the binding interface, while presenting a backbone that proteases recognise poorly.
This has an analytical consequence that bears on certificate interpretation. A D-retro-inverso peptide is compositionally identical to its L-form counterpart and therefore isobaric with it. Mass spectrometry confirms composition and cannot distinguish stereochemistry, so a standard LC-MS identity confirmation is necessary but not sufficient to establish that material is the D-retro-inverso form.
Mechanism, as currently resolved
Cells sustaining sufficient damage may enter senescence, an irreversible exit from the cell cycle. They persist rather than dying, remaining metabolically active and secreting a characteristic profile of inflammatory cytokines and proteases. They accumulate with chronological age.
The question the 2017 work addressed was why these cells resist apoptosis despite their damage burden. The answer was FOXO4: within senescent cells it binds p53 and sequesters it in a configuration that prevents apoptotic signalling.
FOXO4-DRI acts as a competitive decoy, occupying the p53 interface that FOXO4 would engage. Displaced, p53 relocates from the nucleus and apoptosis proceeds. Cells not relying on that interaction for survival are comparatively unaffected, which is the basis of the selectivity.
A 2025 study resolved the target further, identifying the disordered transactivation domain of p53 as the binding region for both FOXO4 and the peptide.
Evidence tier, and why it has not moved
Applying evidence tiers honestly, every efficacy result for this compound sits at preclinical. There is no validated tier entry, because validation requires human trial data and none exists.
The 2021 chondrocyte study is the closest thing to human evidence and is routinely overstated. It applied the peptide to human cells expanded in culture. Those are human cells, and they are also cells in a dish, without circulation, immune involvement, clearance or organism-level consequence.
There is also a finding that runs against the direction of enthusiasm. A 2023 report found that eliminating senescent cells could promote the development and progression of pulmonary hypertension, indicating the intervention is context-dependent rather than uniformly beneficial.
Frequently asked questions
- What does FOXO4-DRI stand for?
- Forkhead box protein O4, D-Retro-Inverso. The first names the protein whose interaction it disrupts; the second describes construction from D-amino acids in reversed sequence.
- What is the difference between FOXO4 and FOXO4-DRI?
- FOXO4 is an endogenous human transcription factor. FOXO4-DRI is a synthetic antagonist of one of its interactions, specifically its binding to p53 in senescent cells.
- Why does the D-retro-inverso construction matter analytically?
- Because it makes the molecule isobaric with its L-form counterpart. Mass spectrometry confirms composition but not stereochemistry, so LC-MS identity confirmation alone cannot establish the D form.
- What evidence tier does FOXO4-DRI reach?
- Preclinical. Every efficacy result comes from mice, rats or cultured cells. No registered interventional human trial exists, so nothing reaches a validated tier.
Limitations of the evidence
Mechanistic characterisation is not efficacy evidence. Every claim about what FOXO4-DRI does in an organism rests on preclinical work in mice, rats or cultured cells. No registered interventional trial in humans exists, so nothing here reaches a validated evidence tier.
References
Citations are annotated with an evidence tier reflecting study design and replication. See Methodology for criteria.
- 1.Baar MP, Brandt RMC, Putavet DA, et al. · Targeted Apoptosis of Senescent Cells Restores Tissue Homeostasis in Response to Chemotoxicity and Aging · Cell · 2017PMID 28340339Preclinical
- 2.Bourgeois B, Spreitzer E, Platero-Rochart D, et al. · The disordered p53 transactivation domain is the target of FOXO4 and the senolytic compound FOXO4-DRI · Nature Communications · 2025PMID 40593617Preclinical
- 3.Frontiers in Bioengineering and Biotechnology · Senolytic Peptide FOXO4-DRI Selectively Removes Senescent Cells From in vitro Expanded Human Chondrocytes · Frontiers in Bioengineering and Biotechnology · 2021PMID 33996787Preclinical
- 4.Circulation · Eliminating Senescent Cells Can Promote Pulmonary Hypertension Development and Progression · Circulation · 2023PMID 36515093Preclinical