FOXO4-DRI is a synthetic peptide designed to break a specific protein–protein contact inside senescent cells: the binding of the transcription factor FOXO4 to the tumor suppressor p53. It is built in D-retro-inverso form, meaning its amino acids are D-isomers assembled in reverse order, which makes it resistant to the proteases that would quickly degrade an ordinary peptide.
The compound comes from a single influential 2017 study on cellular senescence, and nearly all later work uses it as a tool to test that study’s model in other cell types and tissues. This overview explains senescence and the FOXO4–p53 hypothesis, the peptide’s design, the experimental systems used, and why the evidence base, though widely discussed, is still narrow.
At a glance
- Class: Synthetic D-retro-inverso peptide with a cell-penetrating segment; FOXO4–p53 interaction disruptor
- Origin: Described in 2017 by Baar, de Keizer and colleagues (Baar et al., 2017)
- Structure: C228H388N86O64; 5358.0 g/mol; about 5.4 kDa; no CAS number assigned in the catalog
- Main research areas: senescent-cell survival pathways, p53 localization and apoptosis, rodent models of chemotherapy-induced and age-associated senescence, peptide stability
- Regulatory status: Not FDA approved; not approved as a drug anywhere
Structure and origin
Cellular senescence is a durable state of growth arrest. Cells enter it after persistent DNA damage, oncogene activation, critical telomere shortening and other stresses. Senescent cells stop dividing but remain metabolically active, resist apoptosis and release inflammatory and matrix-remodeling factors known collectively as the senescence-associated secretory phenotype (SASP). They accumulate in tissues of aged animals and after some chemotherapies, which has led researchers to ask whether removing them selectively would change tissue function in those models. Compounds that kill senescent cells preferentially are called senolytics.
Baar and colleagues looked for survival factors specific to senescent cells and found that FOXO4 levels increased in senescent human fibroblasts. In these cells FOXO4 bound p53 at nuclear sites associated with DNA damage, which appeared to favor arrest over apoptosis. To test this, the group designed a peptide mimicking the part of FOXO4 that contacts p53, synthesized it in D-retro-inverso form, and added a cell-penetrating sequence derived from HIV TAT so it could enter cells (Baar et al., 2017).
The D-retro-inverso trick is a general strategy in peptide design. Reversing the sequence while switching every residue from L to D roughly preserves the side-chain layout of the parent peptide, so it can still occupy the same binding surface, while the backbone becomes unrecognizable to most proteases. The cost is size: with its interacting and penetrating segments, FOXO4-DRI is a large peptide for a research reagent.
Mechanism: what the research shows
In the original study, FOXO4-DRI competed with endogenous FOXO4 for p53 binding. In senescent fibroblasts, this led to exclusion of active p53 from the nucleus, followed by cell-intrinsic apoptosis. Non-senescent fibroblasts treated in parallel were affected much less, giving the selectivity that defines a senolytic (Baar et al., 2017).
That selectivity rests on FOXO4 being elevated and engaged with p53 specifically in senescent cells. If a given senescent cell population does not rely on this interaction, the peptide would not be expected to act there, and later studies have tested the model one cell type at a time. The mechanism is therefore best described as a hypothesis supported in particular cell systems, not a general property of all senescent cells.
Key areas of study
Cell-culture senescence models
Human fibroblasts made senescent by irradiation or by the chemotherapy drug doxorubicin, compared with proliferating controls, are the standard system. Readouts include senescence-associated β-galactosidase staining, p53 localization, caspase activity and cell viability (Baar et al., 2017).
Chemotherapy-induced senescence in mice
Baar and colleagues treated mice exposed to doxorubicin and examined senescence markers and liver toxicity measures, testing whether removing senescent cells altered chemotherapy-induced tissue damage in that model (Baar et al., 2017).
Accelerated-aging and aged mouse models
The same study used a mouse strain with a DNA-repair defect that develops features of premature aging, as well as naturally aged mice, and reported changes in fur, physical activity and kidney function markers. These are findings in specific mouse models and do not show any effect on human aging or lifespan (Baar et al., 2017).
Senescent Leydig cells
Zhang and colleagues extended the FOXO4–p53 model to testicular Leydig cells. In senescent TM3 Leydig cells, FOXO4-DRI preferentially triggered apoptosis, and in naturally aged mice it was associated with changes in serum testosterone and the testicular microenvironment (Zhang et al., 2020).
What the evidence does not show
- All published work is preclinical. No controlled human studies of FOXO4-DRI have been reported, and model findings do not establish effects on aging, lifespan or disease in people.
- The foundational data come from one 2017 study; independent replication across laboratories and tissues is still limited.
- Senescent cells are heterogeneous. Selectivity shown in fibroblasts or Leydig cells does not mean the peptide acts on every senescent population.
- Senescent cells also have roles in normal processes such as tissue repair, so their removal is not uniformly beneficial in models.
- The peptide’s large size and cell-penetrating segment raise open questions about distribution and off-target effects that have not been fully characterized.
Regulatory status
FOXO4-DRI is not approved by the FDA for any use and has not been approved as a drug in any country. Rogue Compounds sells it as a research reagent only, not for human use.
Handling and storage in the lab
Lyophilized FOXO4-DRI should be kept sealed and refrigerated at 2–8°C (36–46°F), protected from light.
Sourcing and documentation
Rogue Compounds has FOXO4-DRI made in small batches. Every vial carries a batch number and a QR code that opens the independent U.S. testing lab’s own report for that batch, and the same batch COA is on the product page and in the COA Library.
View FOXO4-DRI on Rogue Compounds
References
- Baar MP, et al. Targeted apoptosis of senescent cells restores tissue homeostasis in response to chemotoxicity and aging. Cell. 2017;169(1):132-147.e16. PMID 28340339
- Zhang C, et al. FOXO4-DRI alleviates age-related testosterone secretion insufficiency by targeting senescent Leydig cells in aged mice. Aging (Albany NY). 2020;12(2):1272-1284. PMID 31959736
Research use only. Rogue Compounds products are sold strictly for laboratory research. They are not for human or veterinary use, and nothing in this article is medical advice. The studies cited here describe published research, not this product or any use of it.