FOXO4-DRI

The FOXO4-DRI evidence base cited here is 6 sources — 5 preclinical, 1 review. Critically, that evidence is almost entirely preclinical (animal and in-vitro) — no human clinical trials are cited, so efficacy and safety in people remain unproven. Regulatory status: Not FDA-approved.

• FOXO4-DRI is a synthetic 46-amino-acid SENOLYTIC peptide — designed to selectively kill senescent ('zombie') cells that accumulate with age and drive inflammation, while sparing healthy cells.
• It works by disrupting the FOXO4-p53 interaction that keeps senescent cells alive: p53 is freed to relocate to mitochondria and trigger apoptosis. A reported ~11.7-fold selectivity for senescent over healthy cells is its signature finding.
• It uses a D-Retro-Inverso design (reversed sequence built from D-amino acids), which resists protease breakdown while preserving the binding shape — plus a cell-penetrating tail to get inside cells.

FOXO4-DRI is one of the most mechanistically distinctive peptides in research: a senolytic, meaning its goal is to selectively eliminate senescent cells rather than to signal growth, repair, or metabolism like most peptides here. Senescent cells are damaged cells that stop dividing but don't die, accumulating with age and secreting inflammatory SASP factors that degrade surrounding tissue. FOXO4-DRI is designed to clear them.

First described by Peter de Keizer's group at Erasmus University Medical Center in 2017, it restored fur density, kidney function, and physical fitness in aged mice and protected against chemotherapy toxicity. Crucially, all of that is preclinical — there are no human trials. It is not FDA-approved, and everything below is research context, not medical guidance.

FOXO4-DRI is a 46-amino-acid peptide (~5,358 Da) built with an unusual chemistry: D-Retro-Inverso (DRI). The sequence is reversed and assembled from D-amino acids (the mirror-image form), which makes it highly resistant to the proteases that would normally chew up a peptide this size, while still presenting the same side-chain topology needed to bind its target. It also carries a C-terminal HIV-TAT-derived cell-penetrating peptide that ferries it across the cell membrane.

That DRI design plus the cell-penetrating tail is what lets a large 46-mer actually reach an intracellular protein-protein interaction — a hard thing to drug — and is the reason it's costly to synthesize (a counterfeit consideration).

In senescent cells, the transcription factor FOXO4 binds and sequesters p53 in the nucleus, which keeps those cells from undergoing apoptosis — it's part of what makes them persist. FOXO4-DRI competitively disrupts the FOXO4-p53 interaction. Freed p53 is excluded from the nucleus and translocates to the mitochondria, where it triggers caspase-dependent apoptosis — but selectively in senescent cells, which depend on that FOXO4-p53 survival axis. Healthy cells, which don't rely on it, are largely spared, giving the reported ~11.7-fold selectivity.

There is no human dosing. The figures below are mouse-study doses and anecdotal human translations, included strictly for research context — the absence of human data here is more pronounced than for almost any other compound on this site.

• Mouse studies: ~5 mg/kg IV (or IP) every other day × 3 doses
• Anecdotal human translation: ~25 mg per injection every other day × 3 (≈75 mg per cycle) — extrapolated, not validated
• Senolytics are typically dosed intermittently ('hit-and-run') rather than continuously, since the goal is to clear a population of cells, not maintain a level

• Large (~5.3 kDa) peptide — handle gently. Reconstitute with sterile or bacteriostatic water added down the vial wall; swirl gently, never shake (aggregation risk); solution should be clear (discard if cloudy or precipitated).
• Store lyophilized at −20°C; bring to room temperature before reconstituting.
• Use reconstituted solution within ~7–10 days, stored at 2–8°C.

No human safety data exists — this is the central caveat. In mice, FOXO4-DRI notably did NOT cause the thrombocytopenia seen with some other senolytics (e.g. ABT-737), showed no cardiac abnormalities, and did not sensitize healthy cells to DNA damage. Anecdotal human reports mention burning or itching at the injection site. The key theoretical concern is its reliance on the p53 tumor-suppressor pathway, whose long-term manipulation is not understood; immunogenicity with repeated dosing is also unknown. It is generally considered unlikely to benefit healthy people under ~40 with a low senescent-cell burden.

• Targeted apoptosis of senescent cells (Baar et al., Cell 2017): mouse, 5 mg/kg IV × 3 doses; ~11.7-fold selectivity; restored fur and renal function, increased running capacity, and protected against doxorubicin liver damage.
• Age-related testosterone insufficiency (2020, mouse): 5 mg/kg IP raised serum testosterone and reduced senescence/inflammatory markers with no Leydig-cell toxicity.
• Senescent human chondrocytes (2021, in vitro): cleared >50% of highly-passaged senescent chondrocytes while sparing minimally-passaged cells, improving cartilage quality.

These are mouse and cell-culture results. FOXO4-DRI has never been tested in a human trial.

FOXO4-DRI is not approved by the FDA or any regulatory agency for any indication. It is sold as a research chemical for laboratory use only and is not intended for human consumption.

All citations link to the original source (PubMed, journal site, or regulatory filing). Independent research database — no vendor influence on what's cited.