FOXO4-DRI
From PeptidePlaza, the free peptide reference · Entry #046 · Anti-Aging · Hand-curated entry · Editorial standards
FOXO4-DRI (also known as FOXO4-DRI, Proxofim, FOXO4 p53 interfering peptide) is a anti-aging research peptide. A mirror-image peptide that pries p53 away from FOXO4 inside senescent cells — removing the block that keeps those cells alive instead of apoptotic.
FOXO4-DRI is a designed senolytic peptide built as a D-retro-inverso analogue: the sequence is reversed and all residues are D-amino acids, producing a molecule with a similar side-chain topology to the parent L-peptide but near-complete resistance to proteolysis. Its target is the interaction between FOXO4 and p53. In senescent cells, FOXO4 sequesters p53 in nuclear foci, preventing the p53-driven apoptosis that would normally clear a damaged cell — this is a large part of why senescent cells persist and accumulate. FOXO4-DRI competitively disrupts that interaction, releasing p53 to the mitochondria and triggering apoptosis selectively in senescent cells while sparing healthy ones. The foundational work (Baar et al., Cell, 2017) reported restored fitness, fur density and renal function in aged and progeroid mice. Subsequent structural work published in Nature Communications in 2025 identified the disordered p53 transactivation domain as the binding target, and further work has examined retro-inverso senolytics in brain ageing and cognitive decline. There are no human trials. The safety question is intrinsic rather than incidental: a compound designed to trigger p53-mediated apoptosis operates on the same axis that governs tumour suppression and normal tissue homeostasis.
1 Mechanism of action
Competitively disrupts the FOXO4-p53 interaction by binding the disordered p53 transactivation domain, preventing FOXO4 from sequestering p53 in senescent-cell nuclear foci. Released p53 translocates to the mitochondria and initiates intrinsic apoptosis. Selectivity arises because the FOXO4-p53 interaction is specifically upregulated in senescent cells. The D-retro-inverso configuration confers protease resistance and prolonged intracellular activity.
Primary targets: FOXO4-p53 protein-protein interaction (intracellular target)
2 Reported effects
Effects below are those reported in the published literature cited on this page. They are not claims of clinical benefit and not medical advice.
2.1 Reported benefits
- Selective apoptosis of senescent cells in preclinical models
- Restored fur density, fitness and renal function in aged and progeroid mice
- Protease-resistant D-retro-inverso design gives unusual stability
- Structurally characterised mechanism (Nature Communications, 2025)
- Investigated for chemotherapy-induced senescence and brain ageing models
2.2 Side effects
- No human safety data of any kind
- p53 activation is not confined to senescent cells at higher exposures
- Injection site reactions reported anecdotally
- Theoretical risk to stem and progenitor populations that depend on p53 regulation
- Potential impairment of wound healing and tissue regeneration
3 Chemical and physical properties
| Purity (typical) | >98% |
|---|---|
| Half-life | Prolonged intracellular activity due to D-amino acid protease resistance; plasma kinetics not well characterised |
| Storage | −20 °C, lyophilised powder, desiccated |
| Solubility | Sterile water / bacteriostatic water |
| Receptors / targets | FOXO4-p53 protein-protein interaction (intracellular target) |
3.1 Amino acid sequence
D-retro-inverso analogue of the FOXO4 p53-binding region (all-D amino acids, reversed sequence), typically fused to a cell-penetrating peptide
4 Research dosages
Murine studies used approximately 5 mg/kg intraperitoneally, given in intermittent three-dose cycles rather than continuously. No human protocol exists.
5 Research studies (8)
- Targeted Apoptosis of Senescent Cells Restores Tissue Homeostasis in Response to Chemotoxicity and Aging
Cell (2017) · Preclinical · N/A (murine)Original description of FOXO4-DRI as a senolytic in chemotoxicity, fast-ageing (Xpd) and naturally aged mouse models.Key finding: Selectively induced apoptosis in senescent cells, restoring fur density, fitness and renal function in aged mice without observed toxicity to healthy tissue. - The disordered p53 transactivation domain is the target of FOXO4 and the senolytic compound FOXO4-DRI
Nature Communications (2025) · Preclinical · N/A (structural biology)Structural and biophysical characterisation of the FOXO4-p53 interaction and how FOXO4-DRI disrupts it.Key finding: Defined the disordered p53 transactivation domain as the binding interface, clarifying the molecular basis of the senolytic effect. - Targeting the FOXO4-p53 axis by retro-inverso peptide senolytic agents: a pharmacological strategy to mitigate brain aging and cognitive decline.
Naunyn-Schmiedeberg's archives of pharmacology (2026) · ReviewCellular senescence, driven by the interaction between FOXO4 and p53, is increasingly recognized as a crucial mechanism in brain aging and the development of neurodegenerative disorders. - The disordered p53 transactivation domain is the target of FOXO4 and the senolytic compound FOXO4-DRI.
Nature communications (2025) · PreclinicalA central process contributing to the phenotype of aging is cellular senescence. - Senolytic-sensitive p16Ink4a+ fibroblasts in the tumor stroma rewire lung cancer metabolism and plasticity.
Cell stem cell (2025) · PreclinicalSenescence has been demonstrated to either inhibit or promote tumorigenesis. - Eliminating Senescent Cells Can Promote Pulmonary Hypertension Development and Progression.
Circulation (2023) · PreclinicalElimination of senescent P-ECs by senolytic interventions may worsen pulmonary hemodynamics. - Inflammatory fibroblasts mediate resistance to neoadjuvant therapy in rectal cancer.
Cancer cell (2022) · PreclinicalStandard cancer therapy targets tumor cells without considering possible damage on the tumor microenvironment that could impair therapy response. - Senolytic Peptide FOXO4-DRI Selectively Removes Senescent Cells From in vitro Expanded Human Chondrocytes.
Frontiers in bioengineering and biotechnology (2021) · PreclinicalAutologous chondrocyte implantation (ACI) is a procedure used to treat articular cartilage injuries and prevent the onset of post-traumatic osteoarthritis.
6 Safety and risk profile
6.1 Regulatory status
FOXO4-DRI is currently classified as Investigational. It has no approved human indication in the United States; availability elsewhere does not imply demonstrated safety or efficacy.
Safety score: 38/100 — high concern. Derived from clinical data volume, known risks and regulatory status.
6.2 Contraindications
Conditions and populations in which use is contraindicated:
- Pregnancy or lactation
- Active malignancy or recent chemotherapy (uncharacterised interaction with p53-dependent therapy)
- Wound healing or post-surgical recovery
- Known bone marrow suppression
6.3 Drug interactions
| Drug or class | Interaction | Risk |
|---|---|---|
| Chemotherapeutic agents | Chemotherapy induces senescence and engages p53 pathways; combined effects on apoptosis are unpredictable. | High |
| Other senolytics (dasatinib + quercetin, fisetin) | Additive senescent-cell clearance with additive and uncharacterised risk. | Moderate |
| Immunosuppressants | Senescent cell clearance depends partly on immune function; suppression may reduce efficacy. | Low |
6.4 Long-term risks
- Unknown consequences of repeated p53 pathway activation
- Potential depletion of stem and progenitor cell populations
- Impaired tissue repair capacity with repeated senolytic cycles
- No data on immunogenicity of D-peptides with chronic administration
6.5 Research best practices
- Store lyophilised at −20 °C or below, desiccated and protected from light
- Dissolve in appropriate vehicle immediately before use — cell-penetrating conjugates aggregate readily
- Intermittent cycling, not continuous exposure, is the design of every published protocol
- Verify D-amino acid composition by chiral analysis; L-peptide contamination changes both stability and activity
7 Frequently asked questions
- What does "D-retro-inverso" actually mean?
- The amino acid sequence is written backwards and every residue is the D-enantiomer rather than the natural L form. The combination approximately preserves the spatial arrangement of side chains — so the molecule still binds its target — while making it essentially invisible to proteases, which only recognise L-peptides.
- How does it kill senescent cells but not healthy ones?
- The FOXO4-p53 interaction it disrupts is specifically elevated in senescent cells, where it functions to block apoptosis. In a healthy cell, breaking that interaction does comparatively little because p53 is not being sequestered in the same way.
- Has it been tested in humans?
- No. All data is preclinical — cell culture and mouse models. Given that the mechanism operates directly on p53-mediated apoptosis, the pathway central to tumour suppression, the absence of human safety data is a serious limitation rather than a formality.
8 References
- Targeting the FOXO4-p53 axis by retro-inverso peptide senolytic agents: a pharmacological strategy to mitigate brain aging and cognitive decline. PubMed (2026). Alameen AAM, et al.. View source
- The disordered p53 transactivation domain is the target of FOXO4 and the senolytic compound FOXO4-DRI. PubMed (2025). Bourgeois B, et al.. View source
- Senolytic-sensitive p16Ink4a+ fibroblasts in the tumor stroma rewire lung cancer metabolism and plasticity. PubMed (2025). Lee JY, et al.. View source
- Eliminating Senescent Cells Can Promote Pulmonary Hypertension Development and Progression. PubMed (2023). Born E, et al.. View source
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