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FOXO4-DRI

Tier 3 · Reported use
Also known as FOXO4 D-Retro-Inverso · FOXO4-DRI peptide · Proxofim

The strongest evidence is Tier 2 — animal (in vivo mouse) and in vitro mechanistic studies, anchored by the 2017 Cell paper (Baar et al.). There are zero completed or registered human clinical trials and no human pharmacokinetic data; all efficacy and safety evidence is animal or in vitro. Many physical-description, dosing, and side-effect specifics come from Tier-3 vendor pages, some of which are mutually contradictory. One human-observational claim concerns fisetin (a FOXO4-axis modulator), not FOXO4-DRI itself.

Half-life
~48 h
Routes
Intraperitoneal (used in animal studies) · Subcutaneous (reported in some preclinical work and unvalidated human protocols) · Intravenous (reported in subsequent preclinical work) · Intramuscular (unvalidated human regimen)
Goals
Longevity / anti-aging · Senolytic / senescent-cell clearance · Tissue repair / regeneration · Anti-fibrotic · Cognitive (reported in review only)
Cost / mg
Not recorded

How it works

Vendor and educational guides describe FOXO4-DRI as a synthetic peptide designed to selectively kill senescent ('zombie') cells(vendor claim) — cells that have stopped dividing but remain metabolically active and secrete inflammatory signals. According to these sources, senescent cells survive by using a protein called FOXO4 to hold the tumor-suppressor protein p53 captive in the nucleus, blocking p53's ability to trigger cell death. A vendor guide explains that FOXO4-DRI mimics the part of FOXO4 that binds p53, competitively displacing the real FOXO4 so that p53 is released and can move to the mitochondria to switch on the cell's self-destruct (apoptosis) program, specifically in senescent cells(vendor claim). The peptide is built from D-amino acids in a retro-inverso arrangement, which sources say roughly preserves its shape while making it resistant to the enzymes that would normally break peptides down.

Overview

Overview

FOXO4-DRI (also marketed as FOXO4 D-Retro-Inverso and Proxofim) is described by vendor and educational guides as a synthetic D-retro-inverso peptide designed to selectively kill senescent cells by disrupting the FOXO4-p53 binding interaction inside the cell17. An anti-aging peptide guide states that its landmark characterization was published in Cell in 2017 (Baar et al.), developed at Erasmus University Medical Center by de Keizer and colleagues, establishing it as one of the first mechanistically targeted senolytic peptides(vendor claim). Vendor sources cite the founding paper's PubMed ID inconsistently as PMID 28340339 and PMID 2834034716, creating some ambiguity about the exact reference.

How It Is Described to Work

A vendor guide explains that in senescent cells FOXO4 protein is upregulated and sequesters p53 in the nucleus, preventing p53 from executing its pro-apoptotic function, and that FOXO4-DRI mimics the FOXO4 domain binding the p53 transactivation domain, competitively displacing endogenous FOXO4 from p53(vendor claim). Vendor and mechanistic sources state that this releases p53 to translocate to mitochondria and activate the intrinsic apoptosis pathway specifically in senescent cells6. An educational guide notes that FOXO4 is a member of the FOXO transcription factor family with roles in stress response, metabolism, cellular longevity and homeostasis, and that senescent cells remain metabolically active and secrete pro-inflammatory cytokines, proteases, growth factors and ECM-modifying signals(vendor claim).

An in vitro study reported that FOXO4 expression was markedly increased in senescent fibroblasts compared with other FOXOs, that FOXO4-DRI dose-dependently competed with FOXO4 for p53 binding with higher affinity, reduced viability only in senescent (not normal) fibroblasts, and that its apoptotic activity is caspase-dependent1. A structural in vitro study reported that FOXO4-DRI binds p53 forming a transiently folded complex, with both the FOXO4-derived region and the cationic cell-permeability peptide contributing to the interaction, and that p53 phosphorylation enhances affinity for both FOXO4 and FOXO4-DRI7. An animal study characterized the mechanism as activating the p53/BCL-2/Caspase-3 pathway, facilitating phosphorylated p53 nuclear exclusion and triggering BAX and cleaved caspase-3 to promote selective apoptosis of senescent endothelial cells6. An educational guide notes that the widely repeated 10:1 selectivity figure — that FOXO4-DRI kills senescent cells ten times more readily than healthy cells — traces to Dr. de Keizer's public commentary rather than a peer-reviewed measurement(vendor claim).

Physical Identity (Contested)

Sources give wildly inconsistent basic physical descriptions. Vendor sources list the CAS number as 2460055-10-9 and molecular formula as C228H388N86O64(vendor claim). Molecular weight is reported variously as ~5,358 Da / ~5.4 kDa, ~5,382 Da, and ~1,738 Da; amino-acid length is given as 34, 29, 46, 48, or 16 residues. One vendor guide describes it as a 34-amino-acid stapled peptide built entirely from D-amino acids in a retro-inverso configuration(vendor claim). These figures are mutually incompatible and mostly from tier-3 vendor pages, so the true identity/size of the marketed compound cannot be established from these sources.

Animal & In Vitro Evidence

The landmark 2017 Cell paper (Baar et al.) reported that FOXO4-DRI treatment of naturally aged mice restored fur density, improved renal function, and increased physical fitness including grip strength and treadmill performance, and, per one vendor source, extended median lifespan by 24.8%(vendor claim) — but this specific lifespan figure is uncorroborated by higher-tier sources and closely matches the ~25% median-lifespan extension reported by Baker et al. for genetic clearance of p16-positive senescent cells in INK-ATTAC transgenic mice, a different intervention entirely, so the figure has likely been misattributed to the FOXO4-DRI peptide (whose landmark paper primarily reported healthspan rather than a defined lifespan-extension percentage). A vendor guide reports Baar et al. found reduced p21-positive senescent cell burden, restored running distance, improved fur density and renal function versus vehicle controls, with senescent cell clearance confirmed by p21 and p16 immunostaining in liver and kidney, and that running-wheel distance improved roughly 2-fold with hair regrowth in chemotherapy-induced alopecia models within two weeks(vendor claim). A summary of the Baar work reported that doxorubicin increased FOXO4 expression in senescent fibroblasts and hepatocytes, and that FOXO4-DRI reversed doxorubicin-induced effects including hepatic IL-6 increase and plasma AST elevation, and increased apoptosis of senescent renal tubular cells restoring kidney function, with similar effects in naturally aging and fast-aging mice1. A tier-2 review of the original work reported that the cell-penetrating peptide induced forced apoptosis, reducing age-associated damage across multiple organs (particularly the kidney) and increasing performance and lifespan15,16.

Subsequent tissue-specific studies have been reported: an in vitro study found FOXO4-DRI removed more than half of highly-expanded PDL9 chondrocytes but did not significantly affect minimally-expanded PDL3 chondrocytes, though it did not enhance chondrogenic potential3,13. Studies reported reduction of bleomycin-induced pulmonary fibrosis with downregulated SASP and reset p53 distribution11,12, keloid fibroblast apoptosis via p53-serine15 phosphorylation5, suppression of aortic aging and improved vascular function6, apoptosis of senescent Leydig cells with improved spermatogenesis and testosterone secretion in aged mice9,14, and in a bronchopulmonary dysplasia rat pup model decreased senescence and improved alveolar complexity8. A review of retro-inverso senolytic peptides for brain aging4 reported that in aged mammalian models FOXO4-DRI restored cerebral blood flow and blood-brain barrier integrity, reversed hippocampal atrophy, and improved cognition, including in Alzheimer's and tauopathy models4. Importantly, a peer-reviewed study reported a potential harm signal — that eliminating senescent pulmonary endothelial cells with FOXO4-DRI in SM22-5-HTT mice may worsen pulmonary hemodynamics10.

Human Status

Multiple sources state there are zero published or registered human clinical trials of FOXO4-DRI, with none in ClinicalTrials.gov as of January 2025 and the compound remaining entirely preclinical as of 202617. An educational guide notes the keystone evidence is a single 2017 mouse paper extended by a handful of independent in vitro and in vivo replications(vendor claim). A longevity source notes Dr. de Keizer has publicly discouraged human self-experimentation and stated mouse data does not translate to humans, and that Cleara Biotech has moved its clinical program to two optimized next-generation candidates rather than the original peptide. A 2024 biorxiv preprint (not peer-reviewed) reported a next-generation inhibitor, CPP-CAND, with improved cell permeability, selectivity and cost-effectiveness2. A review of retro-inverso senolytic peptides for brain aging4 noted preliminary human studies of a different FOXO4-axis modulator, high-dose fisetin, showed SASP reductions and cognitive/physical improvements in older adults4 — this concerns fisetin, not FOXO4-DRI.

What the research shows

140 findings extracted from the 20 sources cited below, strongest evidence first within each group. Every one links to the source it came from.

What human studies found

Based on 2 human study findings, 29 animal findings, 16 in vitro findings and 2 expert opinion findings.

  • human studyPreliminary human studies involving FOXO4-axis modulators, such as high-dose fisetin, show a reduction in the senescence-associated secretory phenotype (SASP)4

  • human studyPreliminary human studies involving FOXO4-axis modulators, such as high-dose fisetin, show enhancements in cognitive and physical measures among older adults4

  • animalFOXO4-DRI restored tissue function in tissues affected by chemotherapy and aging1

  • animalIn aged mammalian models, administering FOXO4-DRI decreases the accumulation of senescent cells4

  • animalIn aged mammalian models, administering FOXO4-DRI restores cerebral blood flow and the integrity of the blood-brain barrier (BBB)4

  • animalIn aged mammalian models, administering FOXO4-DRI reverses hippocampal atrophy4

  • animalIn aged mammalian models, administering FOXO4-DRI enhances cognitive function4

  • animalIn models of Alzheimer's disease (AD) and tauopathy, FOXO4-DRI eliminates amyloid-β and pathological tau4

Show 41 more findings

  • animalIn models of Alzheimer's disease (AD) and tauopathy, FOXO4-DRI leads to improved memory performance4

  • animalFOXO4-DRI significantly improves vascular function and delays vascular aging6

  • animalInjection of FOXO4-DRI in both naturally aged and induced aging mice effectively suppressed aortic aging and improved aortic function6

  • animalFOXO4-DRI alleviates endothelial cell senescence induced by OGD, thereby enhancing endothelial cell function6

  • animalFoxo4 dri administered at P4, P6, P8, and P10 led to outcomes similar to TUDCA and KYC8

  • animalFoxo4 dri administration resulted in decreased cellular senescence, improved alveolar complexity, and partially maintained the numbers of type 2 alveolar cells8

  • animalFOXO4-DRI induced apoptosis in senescent Leydig cells9

  • animalFOXO4-DRI reduced the secretion of certain Senescence-Associated Secretory Phenotype9

  • animalFOXO4-DRI improved the proliferation of cocultured GC-1 SPG cells9

  • animalSM22-5-HTT mice given FOXO4-DRI showed pulmonary hemodynamic alterations and lung pulmonary endothelial cell loss compared with relevant controls10

  • animalIn bleomycin-induced pulmonary fibrosis mouse model, FOXO4-DRI therapeutic administration shows milder pathologic change and less collagen deposition compared with BLM-induced group11

  • animalFOXO4-DRI decreased senescent cells in bleomycin-induced pulmonary fibrosis mouse model12

  • animalFOXO4-DRI attenuated BLM-induced morphological changes and collagen deposition12

  • animalFOXO4-DRI decreased myofibroblasts in bleomycin-induced PF mouse model12

  • animalFOXO4-DRI ameliorates BLM-induced pulmonary fibrosis in mouse12

  • animalFOXO4-DRI improved the testicular microenvironment in naturally aged mice14

  • animalFOXO4-DRI alleviated age-related testosterone secretion insufficiency in naturally aged mice14

  • animalFOXO4-DRI peptide-induced senescent cell depletion reduced age-associated damage and dysfunction in multiple organs, in particular the kidney15

  • animalFOXO4-DRI peptide-induced senescent cell depletion increased performance and lifespan15

  • animalFOXO4-DRI ameliorates the consequences of senescence-associated loss of tissue homeostasis16

  • animalShort treatment blocks produced rapid and visible improvements: better kidney function, restored physical activity, improved fur density, normalized weight after chemotherapy, and reductions in molecular senescence markers such as p16 and SASP cytokines in mice17

  • animalAnti-senescence compounds have shown ability to restore tissue homeostasis in old mice19

  • animalAnti-senescence compounds improve kidney function and general health- and lifespan in mice19

  • in vitroCPP-CAND showed high selectivity and potency in inducing apoptosis in senescent cells by disrupting FOXO4-p53 foci and activating caspase pathways2

  • in vitroCPP-CAND has improved selectivity, efficacy, and cost-effectiveness as a therapeutic candidate2

  • in vitroFOXO4-DRI treatment removed more than half of the cells in PDL9 chondrocytes3

  • in vitroFOXO4-DRI did not significantly affect the cell number of PDL3 chondrocytes3

  • in vitroSenescence level in FOXO4-DRI treated PDL9 chondrocytes was significantly reduced compared to untreated control3

  • in vitroFOXO4-DRI pre-treatment did not enhance the chondrogenic potential of PDL9 chondrocytes based on standard pellet culture3

  • in vitroCartilage tissue generated from FOXO4-DRI pretreated PDL9 cells displayed lower expression of senescence-relevant secretory factors than untreated control3

  • in vitroFOXO4-DRI treatment removed more than half of the cells in PDL9 (highly expanded chondrocytes) but did not significantly affect the cell number of PDL3 (minimally expanded) chondrocytes3

  • in vitroCompared to untreated control, senescence level in FOXO4-DRI treated PDL9 chondrocytes was significantly reduced3

  • in vitroCartilage tissue generated from FOXO4-DRI pretreated PDL9 cells displayed lower expression of senescence-relevant secretory factors than untreated control group3

  • in vitroFOXO4-DRI promotes apoptosis in pro-senescence models of keloid organ cultures and fibroblasts5

  • in vitroFOXO4-DRI treatment removed more than half of the cells in PDL9 chondrocytes13

  • in vitroFOXO4-DRI did not significantly affect the cell number of PDL3 chondrocytes13

  • in vitroSenescence level in FOXO4-DRI treated PDL9 chondrocytes was significantly reduced compared to untreated control13

  • in vitroFOXO4-DRI pre-treatment did not enhance the chondrogenic potential of PDL9 chondrocytes based on standard pellet culture13

  • in vitroCartilage tissue generated from FOXO4-DRI pretreated PDL9 cells displayed lower expression of senescence-relevant secretory factors than untreated control group13

  • expert opinionThe evidence scope for FOXO4-DRI's efficacy for longevity is 6.5 / 10 mechanistic and animal data strongly support senolytic and functional benefits, but there are no human trials17

  • expert opinionFOXO4-DRI is experimental with no human evidence17

How it works

Based on 3 human study findings, 25 animal findings, 25 in vitro findings, 3 expert opinion findings and 4 theoretical findings.

  • human studyp53 signaling pathway is activated in fibroblasts isolated from IPF fibrotic lung tissues11

  • human studyFOXO4 transcription factor is specially expressed in human Leydig cells14

  • human studyFOXO4 translocation to the nucleus in the elderly is related to decreased testosterone synthesis14

  • animalFOXO4-DRI is a cell-penetrating peptide that selectively targets senescent cells for apoptosis1

  • animalDoxorubicin increased FOXO4 expression in senescent fibroblasts and hepatocytes1

  • animalFOXO4-DRI specifically disrupts the interaction between FOXO4 and P53, thereby inducing apoptosis in senescent cells6

  • animalFOXO4-DRI functions by activating the p53/BCL-2/Caspase-3 signaling pathway to promote selective apoptosis of senescent endothelial cells6

  • animalFOXO4-DRI prevents the binding of FOXO4 to P53, facilitating the phosphorylated P53 nuclear exclusion, which subsequently trigger BAX and cleaved caspase-3, leading to the apoptosis of senescent cells6

Show 52 more findings

  • animalFOXO4-DRI promotes the nuclear export of phosphorylated P53 by inhibiting the binding of FOXO4 to P53 in endothelial cells, thereby facilitating the apoptosis of senescent endothelial cells and alleviating aging6

  • animalCellular senescence increases in rat and human BPD lungs, as evidenced by increased oxidative DNA damage, tumor suppressors, GL-13 stain, and inflammatory cytokines with decreased cell proliferation and lamin B expression8

  • animalCellular senescence-related transcripts in BPD rat lungs were enriched at P10 and P218

  • animalSingle-cell RNA sequencing showed increased cellular senescence in several cell types, including type 2 alveolar cells8

  • animalFoxo4-p53 binding increased in BPD rat lungs8

  • animalFOXO4 is highly expressed in senescent cells9

  • animalFOXO4 binds p53 in the nucleus, preventing senescent cell apoptosis and maintaining senescent cells in situ9

  • animalLeydig cell senescence leads to deterioration of the microenvironment of the testes and impairs spermatogenesis9

  • animalFOXO4-DRI is a specific FOXO4-p53 binding blocker9

  • animalFOXO4-DRI is a cell-permeable FOXO4-p53 interfering peptide used for senescent cell clearance10

  • animalFOXO4-DRI resets the distribution of intranuclear p5311

  • animalFOXO4-DRI decreases total ECM proteins content11

  • animalFOXO4-DRI selectively kills senescent cells in aged mice12

  • animalFOXO4-DRI downregulated the expression of senescence-associated secretory phenotype (SASP)12

  • animalFOXO4-DRI increased the percentage of type 2 alveolar epithelial cells (AEC2) and fibroblasts12

  • animalFOXO4-DRI inhibition of myofibroblast leads to downregulation of extracellular matrix (ECM) receptor interaction pathway12

  • animalCell-penetrating FOXO4-DRI peptide induced forced apoptosis15

  • animalFOXO4 protects senescent cell viability by keeping p53 sequestered in nuclear bodies, preventing it from inducing apoptosis16

  • animalDisrupting the interaction between FOXO4 and p53 with an all-D amino acid peptide (FOXO4-DRI) restores p53's apoptotic role16

  • animalThe 2017 FOXO4-DRI mouse study (Baar et al., Cell) tested whether a designer peptide could selectively induce apoptosis in senescent cells and thereby improve health in aged, progeroid, and chemotherapy-damaged mice17

  • in vitroFOXO4 expression was markedly increased in senescent fibroblasts compared with other FOXOs1

  • in vitroInhibiting FOXO4 expression promoted apoptotic events and reduced senescent fibroblasts' viability and colony density1

  • in vitroFOXO4-DRI targets the interaction between FOXO4 and p531

  • in vitroFOXO4-DRI's apoptotic activity is caspase-dependent1

  • in vitroThe interaction between FOXO4 and p53 sustains cell survival2

  • in vitroThe peptide inhibitor was designed by identifying key regions in the p53 transactivation domain (TAD) involved in FOXO4 binding2

  • in vitroFOXO4-DRI selectively kills senescent cells3

  • in vitroFOXO4-DRI is a senolytic peptide that selectively kills senescent fibroblasts3

  • in vitroKeloids show enhanced expression of senescence-associated secretory phenotype genes5

  • in vitroKeloids have elevated p16 protein and more β-galactosidase-positive cells5

  • in vitroKeloids show up-regulated p53-serine15 phosphorylation (p53-pS15)5

  • in vitroFOXO4-DRI decreases G0/G1 phase cells in pro-senescence models of keloid organ cultures and fibroblasts5

  • in vitroFOXO4-DRI treatment is accompanied with p53-pS15 nuclear exclusion5

  • in vitroThe FOXO4-p53 axis is pivotal in maintaining the viability of senescent cells7

  • in vitroFOXO4-DRI binds to p53 and forms a transiently folded complex7

  • in vitroBoth the FOXO4-derived region and the cationic cell permeability peptide contribute to the interaction with p537

  • in vitrop53 phosphorylation enhances the affinity for both FOXO4 and FOXO4-DRI7

  • in vitroFOXO4-DRI is a synthesis peptide that acts as a specific FOXO4 blocker11

  • in vitroFOXO4-DRI selectively induces dissociation of the FOXO4-p53 complex and nuclear exclusion of p5311

  • in vitroFOXO4-DRI kills TGF-β-induced myofibroblast in vitro12

  • in vitroFOXO4-DRI is a senolytic peptide that selectively kills senescent fibroblasts13

  • in vitroFOXO4-DRI is able to remove senescent cells in PDL9 chondrocytes13

  • in vitroFOXO4 maintains the viability of senescent Leydig cells and suppresses their apoptosis14

  • in vitroFOXO4-DRI disrupts the FOXO4-p53 interaction14

  • in vitroFOXO4-DRI selectively induces p53 nuclear exclusion and apoptosis in senescent Leydig cells14

  • expert opinionFOXO4-DRI was previously reported to selectively kill senescent fibroblasts3

  • expert opinionFOXO4-DRI is a synthetic D-retro-inverso peptide designed to disrupt the FOXO4–p53 interaction and trigger apoptosis in senescent cells17

  • expert opinionFOXO4‑DRI is a D‑retro‑inverso peptide engineered to mimic the FOXO4 region that binds p53, but with reversed and D‑amino‑acid structure for stability17

  • theoreticalCellular senescence is marked by irreversible cell cycle arrest and the secretion of proinflammatory factors, contributing to aging and cancer recurrence2

  • theoreticalFOXO4-DRI selectively disrupts the FOXO4-p53 complex, inducing apoptosis in senescent cells while preserving healthy tissue4

  • theoreticalFOXO4-dependent senescence significantly contributes to neuroinflammation, synaptic dysfunction, and impaired neurogenesis in the aging brain4

  • theoreticalIschemia-reperfusion injury during transplantation can induce senescence and accelerate aging19

How the body handles it

Based on 1 in vitro finding.

  • in vitroFOXO4-DRI dose-dependently competed with FOXO4 for p53 binding and had higher affinity for p531

Safety and side effects

Based on 2 animal findings, 1 in vitro finding and 2 expert opinion findings.

  • animalElimination of senescent pulmonary endothelial cells by FOXO4-DRI senolytic intervention may worsen pulmonary hemodynamics10

  • animalAcross all reported cohorts, there were zero adverse reactions recorded and 100% of treated mice showed positive responses17

  • in vitroFOXO4-DRI reduced cellular viability only in senescent fibroblasts, not normal fibroblasts1

  • expert opinionThe evidence scope for FOXO4-DRI's long term human safety is −1.9 / 10 because there are no human safety trials and there are strong mechanistic reasons to worry about disrupting FOXO4–p53 signaling17

  • expert opinionThere have been no human trials, no chronic toxicity studies, and only very limited animal testing, all with short follow-up windows measured in weeks17

What people use it for

Based on 10 animal findings, 7 in vitro findings, 2 expert opinion findings and 5 theoretical findings.

  • animalFOXO4-DRI treatment reversed doxorubicin-induced effects including hepatic IL-6 expression increase and plasma AST level elevation1

  • animalFOXO4-DRI treatment improved accelerated hair loss and exploratory behavior in fast-aging mice1

  • animalFOXO4-DRI treatment increased apoptosis of senescent renal tubular cells and restored kidney function in aging mice1

  • animalFOXO4-DRI treatment effects were similar in naturally aging mice as in fast-aging mice1

  • animalFoxo4 dri was administered intraperitoneally to mitigate cellular senescence8

  • animalAttenuating cellular senescence via Foxo4 dri is a potential therapeutic strategy for halting BPD progression8

  • animalIn naturally aged mice, FOXO4-DRI-treated aged mice exhibited increased sperm quality9

  • animalFOXO4-DRI improved spermatogenesis in naturally aged mice9

Show 16 more findings

  • animalFOXO4-DRI may be a promising therapeutic approach to treating pulmonary fibrosis11

  • animalFOXO4-DRI has therapeutic potential for the treatment of male late-onset hypogonadism14

  • in vitroCPP-CAND is a peptide inhibitor targeting FOXO4-p53 interaction designed with improved cell permeability2

  • in vitroCPP-CAND is effective against senescent cancer cells induced by doxorubicin and cisplatin2

  • in vitroFOXO4-DRI is able to remove senescent cells in PDL9 chondrocytes3

  • in vitroFOXO4-DRI pre-treatment did not enhance the chondrogenic potential of PDL9 chondrocytes based on standard pellet culture results3

  • in vitroFOXO4-DRI is able to remove senescent cells in PDL9 chondrocytes but its utility in promoting cartilage formation from in vitro expanded chondrocytes needs further investigation3

  • in vitroKeloids exhibit increased proportion of pro-inflammatory and mesenchymal fibroblast subpopulations and senescent fibroblasts5

  • in vitroFOXO4-DRI is a senolytic peptide that can target senescent cells selectively7

  • expert opinionSenescent cell depletion through cell-penetrating FOXO4-DRI peptide is a therapeutic strategy for senescence depletion in the context of renal aging and disease15

  • expert opinionFOXO4-DRI was never intended for human clinical use, it was explicitly designed as a research probe17

  • theoreticalFOXO4-DRI shows potential as a treatment targeting senescence and apoptosis resistance in keloids5

  • theoreticalFOXO4-DRI may serve as a basis for development of p53 inhibitors to treat diseases linked to cellular senescence such as cancers7

  • theoreticalSenescent cell removal may increase the donor pool and improve long-term transplantation outcome19

  • theoreticalAnti-senescence compounds hold promise to improve quality of marginal donor kidneys19

  • theoreticalFOXO4-DRI is a peptide of anti-aging20

Other findings

Based on 1 theoretical finding.

  • theoreticalFOXO4-DRI is a senolytic FOXO4-D-retro-inverso-isoform peptide5

Points of contention

Where the evidence is unsettled, thin, or says less than the popular claim — worth knowing before you draw conclusions.

Contested

The founding 2017 Cell paper is cited with two different PubMed IDs

Some sources cite Baar et al. 2017 as PMID 28340339 (FOXO4-DRI Peptide Guide 2026: Senolytic Evidence Review, FOXO4-DRI Dosage Chart, Schedule & Reconstitution Protocol) while others cite PMID 28340347 (FOXO4-DRI Research Guide — Senolytic Peptide, FOXO4–p53 Protein-Protein Interaction Disruption & Senescent Cell Clearance (2026) - Your Peptide Brand, Rejuvenation by Therapeutic Elimination of Senescent Cells.), creating ambiguity about the exact reference.

Contested

Safety picture differs between sources: some report zero adverse events, others report measurable toxicity and a potential harm signal

FOXO4-DRI Available for Research Use Only 25 mg on ... states zero adverse reactions across all mouse cohorts with 100% positive response; FOX04-DRI Peptide Side Effects: Overview (tier-3 vendor) reports transient ALT elevation in ~30% of animals, injection site reactions in 15-20%, fatigue in 10-15%, and GI upset in 5-10%; and Eliminating Senescent Cells Can Promote Pulmonary Hypertension Development and Progression. (peer-reviewed) reports that FOXO4-DRI eliminating senescent pulmonary endothelial cells may WORSEN pulmonary hemodynamics. The unsourced quantitative side-effect percentages in FOX04-DRI Peptide Side Effects: Overview are not corroborated by higher-tier sources.

Limited evidence

No human data of any kind exists; all efficacy and safety evidence is animal or in vitro

Every source agrees there are zero completed or registered human clinical trials and no human pharmacokinetic data. The developer (de Keizer) has reportedly discouraged human self-experimentation and stated mouse data does not translate to humans, and has moved the clinical program to next-generation candidates rather than FOXO4-DRI itself.

Single source

The 10:1 senescent-vs-healthy selectivity figure traces to informal commentary, not a published measurement

FOXO4-DRI Peptide Guide 2026: Senolytic Evidence Review explicitly notes the claim that FOXO4-DRI kills senescent cells 10 times more readily than healthy cells comes from de Keizer's public commentary rather than a peer-reviewed quantification.

Preprint

Next-generation successor data comes from an unreviewed preprint

The CPP-CAND peptide (an improved FOXO4-p53 inhibitor) claims of high selectivity, potency and cost-effectiveness are from a 2024 biorxiv preprint (Peptide inhibitors targeting FOXO4-p53 interactions and inducing senescent cancer cell-specific apoptosis | bioRxiv) that has not been peer-reviewed.

Limited evidence

A key half-life claim (48+ hours) is a vendor assertion, not a measured value

FOXO4-DRI Research Guide — Senolytic Peptide, FOXO4–p53 Protein-Protein Interaction Disruption & Senescent Cell Clearance (2026) - Your Peptide Brand asserts plasma half-life extends to 48+ hours, and FOXO4-DRI - Research Peptide infers 48-72 hours functional persistence from dosing frequency, but FOXO4-DRI - Research Peptide and FOXO4-DRI Dosage Chart, Schedule & Reconstitution Protocol also state no formal PK study measuring half-life, distribution or clearance has ever been published in any species.

Using it with other compounds

Check a stack
  • GonadorelinSame downstream effect

    May be complementary

    FOXO4-DRI is reported to restore testosterone and spermatogenesis in aged animals by clearing senescent testicular (Leydig/germline) cells, while gonadorelin drives the same output from the top down by stimulating pituitary LH/FSH release. Different upstream mechanisms converging on androgen production, so they can be additive for restoring the testosterone axis.

    Tier 4Theoretical — not established

    Timing Gonadorelin requires pulsatile dosing to avoid pituitary downregulation; FOXO4-DRI is typically pulsed as a senolytic — the two schedules do not conflict.

    Shares testosterone axis

  • HCGSame downstream effect

    May be complementary

    Both can raise testosterone but by unrelated mechanisms: HCG directly stimulates Leydig-cell steroidogenesis via the LH receptor, whereas FOXO4-DRI is reported to improve testicular function by removing senescent cells that impair it. They converge on the same endpoint and may complement each other.

    Tier 4Theoretical — not established

    Shares testosterone axis

  • TriptorelinStack with caution

    Worth caution

    These pull the testosterone axis in opposite directions. FOXO4-DRI is reported to restore testosterone in aged animals, whereas chronic triptorelin (a long-acting GnRH agonist) suppresses LH/FSH and drives testosterone down to castration levels. Combining them would work against FOXO4-DRI's androgen-restoring effect.

    Tier 4Theoretical — not established

    Shares testosterone axis

  • HumaninStack with caution

    Worth caution

    FOXO4-DRI kills senescent cells specifically by activating the p53/BAX/caspase intrinsic apoptosis pathway. Humanin is a broadly cytoprotective, anti-apoptotic peptide that directly inhibits BAX and related pro-apoptotic Bcl-2 family proteins — the very machinery FOXO4-DRI relies on. In theory humanin could blunt the senolytic (apoptosis-inducing) effect, so co-dosing may reduce senescent-cell clearance.

    Tier 4Theoretical — not established

    Timing If combined, consider separating so senolytic pulses of FOXO4-DRI are not overlapped by anti-apoptotic humanin dosing.

    Shares anti inflammatory

  • KlothoComplementary

    No documented conflict

    Both target biological aging but through different levers: FOXO4-DRI actively removes existing senescent cells and lowers the inflammatory SASP, while klotho is an anti-senescence, anti-inflammatory longevity protein acting through FGF23/Wnt/IGF-1 and NLRP3 pathways. Different mechanisms converging on reduced inflammaging and healthier tissue.

    Tier 4Theoretical — not established

    Shares anti inflammatory

  • Palmitoyl Tetrapeptide-7Same downstream effect

    No documented conflict

    Both act on the senescence-associated secretory phenotype (SASP)/inflammaging output, but differently: FOXO4-DRI reduces SASP by eliminating the senescent cells that produce it, while palmitoyl tetrapeptide-7 suppresses SASP-type inflammatory cytokines (IL-6, IL-1β) in skin cells. Converging on lower inflammatory secretion, though the tetrapeptide is a topical cosmetic acting locally.

    Tier 4Theoretical — not established

    Shares anti inflammatory

  • PTD-DBMSame downstream effect

    No documented conflict

    Both peptides can restore hair density but by opposite logic: PTD-DBM stimulates follicle stem cells via Wnt/beta-catenin, while FOXO4-DRI clears senescent cells that suppress regeneration (it restored fur density in aged and chemotherapy-alopecia mice). They reach a similar hair/tissue-restoration endpoint through unrelated mechanisms.

    Tier 4Theoretical — not established

    Shares tissue repair

  • EpithalonComplementary

    No documented conflict

    Both are anti-aging tools working from opposite ends of cellular senescence: FOXO4-DRI clears already-senescent p16/p21-positive cells (senolytic), whereas epithalon is reported to activate telomerase and delay cells from becoming senescent in the first place. Clearing existing senescent cells plus slowing new senescence is a mechanistically complementary pairing.

    Tier 4Theoretical — not established

Safety and side effects

Safety & Side Effects

No human safety data of any kind exists. Multiple sources state FOXO4-DRI has no FDA, EMA, PMDA or MHRA approval, no active publicly disclosed IND, and is sold in the United States exclusively as a research chemical for in vitro use, not for human consumption. A longevity source states the peptide was never intended for human clinical use and was explicitly designed as a research probe, rating its evidence scope for long-term human safety at −1.9/10 (no human safety trials, strong mechanistic reasons to worry) while rating its efficacy scope for longevity at 6.5/10 (mechanistic and animal data supportive but no human trials)17.

Reported Animal Safety (Conflicting)

The safety picture differs sharply between sources. A longevity source states that across all reported mouse cohorts there were zero adverse reactions recorded and 100% of treated mice showed positive responses, while noting there have been no human trials, no chronic toxicity studies, and only very limited animal testing with short follow-up measured in weeks17. A vendor guide reports no gross toxicity at the doses used in the Baar study, though the observation window was short, and that selective clearance of p21-positive senescent cells was confirmed with no significant damage to normal cells documented(vendor claim).

In contrast, a tier-3 side-effects vendor page reports specific (uncorroborated) figures: preclinical aged mice receiving 5 mg/kg showed no immediate adverse reactions within 24-48 hours, but longer observation revealed transient liver enzyme elevation (ALT increased 1.5-2.0x baseline) in about 30% of treated animals after 7 days, injection site reactions in roughly 15-20% (mild erythema and swelling lasting 2-3 days), transient fatigue in 10-15%, and gastrointestinal upset in 5-10%(vendor claim). The same page reports cell-culture dose-dependent cytotoxicity beginning above 10 μM, with an IC50 around 25-30 μM in non-senescent lines, minimal effects below 5 μM, and senescent-cell selectivity diminishing significantly above 15 μM. These quantitative percentages are not corroborated by higher-tier sources.

Potential Harm Signals & Theoretical Risks

A peer-reviewed study reported that in SM22-5-HTT mice, FOXO4-DRI caused pulmonary hemodynamic alterations and lung endothelial cell loss versus controls, noting about 30% of lung senescent cells are pulmonary endothelial cells in normoxia, and concluded that eliminating senescent pulmonary endothelial cells may worsen pulmonary hemodynamics10. A vendor guide cautions that off-target apoptosis in stem cell compartments is a theoretical risk requiring systematic evaluation before human use, and that SASP heterogeneity across cell types means FOXO4-DRI may not be universally effective in all senescent cell populations(vendor claim). A side-effects vendor page states that no serious adverse events have been documented in the limited animal research, that documented human side effects and animal studies beyond 30 days are unavailable, and that theoretical modeling suggests chronic administration could cause DNA damage response alterations, interfere with normal cellular stress responses potentially increasing cancer risk, and lead to cumulative damage in high-turnover organs including the gastrointestinal tract, bone marrow, and skin(vendor claim).

Market & Access Notes

A vendor guide reports that FOXO4-DRI compounding access was curtailed by 2024 FDA guidance, and that grey-market cost ranges from USD 80 to 300 per vial with highly variable purity(vendor claim).

Reconstitution and handling

Dosing

No dose has been established for this compound. No regulatory label exists for FOXO4-DRI, and multiple sources confirm there are zero completed or registered human clinical trials, no validated human dose, and no validated human delivery route17. The figures below are what sources report — not guidance.

Published animal dosing

  • A vendor guide reports FOXO4-DRI was tested in fast-aging XpdTTD/TTD mice, irradiation-damaged mice, and naturally aged mice at approximately 5 mg/kg intraperitoneally three times per week for 10 days(vendor claim).
  • A tier-2 vendor source states the Baar et al. 2017 Cell study used 5 mg/kg intraperitoneal injection three times per week in aged mice, and that all published studies used intraperitoneal injection in mice(vendor claim).
  • One vendor guide instead describes the preclinical mouse protocol as 5 mg/kg subcutaneous every other day for 3 doses(vendor claim) — there is disagreement over frequency.
  • A dosing vendor page states the original mouse studies used intraperitoneal injection while subcutaneous and intravenous routes appear in subsequent preclinical work(vendor claim).
  • A bronchopulmonary dysplasia study dosed rat pups intraperitoneally at postnatal days P4, P6, P8, and P108.

Unvalidated human-oriented protocols (from vendor/longevity pages)

  • A dosing vendor page suggests a typical dose of 250-500 mcg once daily subcutaneously with no validated human dose, and outlines an unvalidated escalation protocol of 250 mcg daily (weeks 1-4), 375 mcg daily (weeks 5-8), and 500 mcg daily (weeks 9-16)(vendor claim).
  • A longevity-focused source lists an unvalidated human-oriented regimen of 25 mg on Days 1, 3, 5, 7, and 9 for a total of 125 mg administered intramuscularly — an implausibly large total for an injectable peptide that may reflect a microgram/milligram error in the source17.

No human trial has tested any of these, and the two circulating protocols differ by roughly two orders of magnitude in total exposure.

Reconstitution Arithmetic

A dosing vendor page describes reconstituting a 10 mg vial in 3 mL bacteriostatic water for a 3.33 mg/mL concentration, giving 0.075 mL (7.5 units on a U-100 syringe) per 250 mcg dose, and estimates the escalation protocol requires 3 vials for 8 weeks, 4 vials for 12 weeks, or 5 vials for 16 weeks(vendor claim). An educational guide (tier-3 vendor/educational source) notes that molecular weight matters for dosing arithmetic because a 1 mg dose of FOXO4-DRI would correspond to only ~0.187 µmol of compound if its molecular weight is ~5,358 Da(vendor claim) — though, as noted elsewhere, sources disagree substantially on the peptide's molecular weight.

Pharmacokinetics

Vendor and study sources state the D-retro-inverso modification confers resistance to proteases, extending in vivo stability versus L-amino-acid equivalents while preserving side-chain spatial arrangement1. One vendor guide claims the modification produces a peptide resistant to all natural proteases, extending plasma half-life to 48+ hours versus minutes for unmodified peptides; a tier-2 vendor source infers functional persistence of at least 48-72 hours per dose from three-times-weekly dosing, while a side-effects page states the modification typically increases half-life from minutes to 'several hours'(vendor claim). A tier-2 vendor source notes the peptide is above the typical renal filtration threshold, suggesting renal clearance may contribute to elimination, and that oral bioavailability is expected to be negligible given its size; another vendor page estimates theoretical subcutaneous bioavailability at 15-30% based on similar peptide structures(vendor claim). Critically, multiple sources state that no formal pharmacokinetic study measuring plasma half-life, volume of distribution, or clearance has been published for FOXO4-DRI in any species, and human PK data are entirely unknown.

Sources

Ordered by evidence quality — the strongest first.

  1. Cell-Penetrating Peptide Targets Senescent Cells to Restore Tissue Function | dvm360(opens in a new tab)
    Tier 2Web · dvm360.com
  2. Peptide inhibitors targeting FOXO4-p53 interactions and inducing senescent cancer cell-specific apoptosis | bioRxiv(opens in a new tab)
    Tier 2Web · biorxiv.org
  3. Senolytic Peptide FOXO4-DRI Selectively Removes Senescent ...(opens in a new tab)
    Tier 2Web · pmc.ncbi.nlm.nih.gov
  4. Targeting the FOXO4-p53 axis by retro-inverso peptide senolytic agents: a pharmacological strategy to mitigate brain aging and cognitive decline.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2026
  5. FOXO4-DRI induces keloid senescent fibroblast apoptosis by promoting nuclear exclusion of upregulated p53-serine 15 phosphorylation.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2025
  6. FOXO4-DRI regulates endothelial cell senescence via the P53 signaling pathway.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2025
  7. The disordered p53 transactivation domain is the target of FOXO4 and the senolytic compound FOXO4-DRI.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2025
  8. Cellular Senescence Contributes to the Progression of Hyperoxic Bronchopulmonary Dysplasia.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2024
  9. FOXO4-DRI improves spermatogenesis in aged mice through reducing senescence-associated secretory phenotype secretion from Leydig cells.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2024
  10. Eliminating Senescent Cells Can Promote Pulmonary Hypertension Development and Progression.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2023
  11. FOXO4-D-Retro-Inverso targets extracellular matrix production in fibroblasts and ameliorates bleomycin-induced pulmonary fibrosis in mice.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2023
  12. FOXO4 peptide targets myofibroblast ameliorates bleomycin-induced pulmonary fibrosis in mice through ECM-receptor interaction pathway.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2022
  13. Senolytic Peptide FOXO4-DRI Selectively Removes Senescent Cells FromExpanded Human Chondrocytes.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2021
  14. FOXO4-DRI alleviates age-related testosterone secretion insufficiency by targeting senescent Leydig cells in aged mice.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2020
  15. Cellular senescence in the aging and diseased kidney.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2018
  16. Rejuvenation by Therapeutic Elimination of Senescent Cells.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2017
  17. FOXO4-DRI Available for Research Use Only 25 mg on ...(opens in a new tab)
    Tier 3Web · rapamycin.news
  18. Instagram(opens in a new tab)
    Tier 3Web · instagram.com
  19. Cellular senescence as a therapeutic target to improve renal transplantation outcome.(opens in a new tab)
    Tier 4PubMed · pubmed.ncbi.nlm.nih.gov · 2018
  20. [Molecular regulative mechanisms of aging and interventional effects of Chinese herbal medicine].(opens in a new tab)
    Tier 4PubMed · pubmed.ncbi.nlm.nih.gov · 2017

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