FOXO4-DRI came out of a single high-profile experiment. In 2017, Marjolein Baar, Peter de Keizer, and colleagues published a paper in Cell showing that a short peptide could selectively kill senescent cells and, in aged mice, restore fur growth, kidney function, and running fitness. That paper is why the compound exists and why people keep talking about it.
The name describes the chemistry. "DRI" stands for D-retro-inverso: the peptide is built from D-amino acids in reverse sequence, a trick that makes it resistant to the enzymes that would otherwise chew up a normal peptide. It is also a cell-penetrating peptide, fused to a stretch of arginine and lysine residues that carry it across the cell membrane. The sequence is derived from FOXO4 itself, so it acts as a decoy.
What it's meant to do
Senescent cells are aged or damaged cells that stop dividing but refuse to die. They accumulate with age and secrete inflammatory signals. A senolytic is anything that clears them out.
FOXO4-DRI targets one specific interaction. In senescent cells, the transcription factor FOXO4 binds the tumor-suppressor p53 and holds it in the nucleus, which keeps the cell alive. The peptide gets in the way of that binding. According to Baar et al., 201730293-3), disrupting the FOXO4–p53 complex causes p53 to be excluded from the nucleus and routed toward mitochondria, where it triggers apoptosis. Healthy cells, which don't depend on this interaction, are largely spared.
A 2025 structural study in *Nature Communications* used solution NMR to look at how the peptide actually binds. Both FOXO4-DRI and the p53 region it grabs (the p53 transactivation domain) are intrinsically disordered, and they form a transiently folded complex rather than a rigid lock-and-key fit. The same work found that phosphorylation of p53 at certain sites increases binding affinity.
State of the evidence
The 2017 mouse data are the headline: in naturally aged and fast-aging mice, dosing improved renal markers, coat density, and spontaneous activity. The peptide also blunted doxorubicin chemotoxicity in mice.
Since then the work has stayed preclinical. Follow-up studies have tested the peptide in cell culture and animal models, including in-vitro removal of senescent human chondrocytes, keloid fibroblasts, endothelial cells, and aged-mouse Leydig cells. These are early-stage findings in cells and animals.
What does not exist is human evidence. FOXO4-DRI has not gone through clinical trials and is not approved by any regulator for any use. There are open questions in the literature about dosing, off-target effects, and whether the dramatic mouse results translate. Anything sold under this name is a research chemical, not for human consumption, and nothing here is medical or dosing advice.
The buyer-quality angle
Because there is real demand from the longevity crowd, FOXO4-DRI is sold by research-chemical suppliers. It carries CAS number 2460055-10-9. Two things make purity and identity hard to take on faith:
- It's a long peptide (roughly 46 residues), and longer peptides are harder to synthesize cleanly, so truncated or deletion sequences are a real concern.
- The all-D, retro-inverso design is unusual. Identity testing has to confirm not just the sequence but the correct stereochemistry, which a basic mass check won't fully establish.
If you're evaluating a vendor, look for a recent third-party certificate of analysis with mass spectrometry and HPLC purity for the specific lot, and treat marketing claims about anti-aging benefits as unsupported by human data. peptideone aggregates published COAs and independent vendor ratings so you can compare what suppliers actually document rather than what they advertise.