FOX04-DRI
FOXO4-DRI / Proxofim
FOXO4-DRI is a D-retro-inverso peptide designed to selectively induce apoptosis in senescent cells by disrupting the interaction between FOXO4 and p53 transcription factors that maintains senescent cell viability. Developed at Erasmus University Medical Center in the Netherlands, it was published in a landmark 2017 Cell paper demonstrating restoration of fitness, fur density, and renal function in naturally aged mice. The D-retro-inverso modification (all D-amino acids in reverse sequence) provides exceptional resistance to proteolytic degradation while maintaining the spatial orientation needed for protein-protein interaction disruption.
Mechanism of Action
D-retro-inverso peptide that disrupts the interaction between FOXO4 and p53 in senescent cells. Forces p53 into the mitochondria of senescent cells, triggering selective apoptosis (senolysis). Clears senescent cells without affecting healthy cells.
Research Protocols
For research purposes only. Not medical advice.
Research protocols in mice used 5mg/kg IV every 3 days for 3 doses. Human protocols not established. Extremely expensive. Some anecdotal reports use 10-20mg subcutaneously over multi-day protocols.
Research Notes
Clinical Research Status
FOXO4-DRI was described in a 2017 publication in Cell by Baar et al. from Erasmus University Medical Center, representing a proof-of-concept for targeted senolytic therapy through protein-protein interaction disruption. No human clinical trials have been initiated, and the compound remains in the academic research phase with significant challenges remaining for clinical translation including manufacturing cost, delivery, dosing, and safety characterization. The concept has inspired pharmaceutical industry investment in senolytic therapies, though most clinical programs pursue small molecule approaches rather than peptide-based senolytics.
Key Published Findings
The original Cell paper demonstrated that FOXO4-DRI selectively induces apoptosis in senescent cells by competing with endogenous FOXO4 for p53 binding, releasing p53 from nuclear exclusion and enabling it to trigger mitochondrial apoptosis. In naturally aged mice, treatment restored fitness, fur density, and renal function while reducing senescence markers in multiple tissues. Irradiation-induced senescent cells and chemotherapy-damaged cells were also effectively cleared, suggesting broad applicability across different senescence triggers. The selectivity arises because only senescent cells depend on FOXO4-p53 interaction for survival.
Safety Profile
The original publication reported no apparent toxicity in treated mice at effective senolytic doses, with selective killing of senescent cells and sparing of proliferating and quiescent normal cells. The D-retro-inverso modification provides proteolytic stability but may also complicate clearance and raise concerns about accumulation with repeated dosing. Long-term safety data beyond the original publication's observation period is not available, and potential effects on stem cell populations that share some senescence markers remain a theoretical concern.
Comparison to Related Compounds
FOXO4-DRI differs from small molecule senolytics like dasatinib + quercetin (D+Q) and navitoclax by targeting a specific protein-protein interaction rather than broad anti-apoptotic pathways (BCL-2 family). The peptide approach offers potentially greater selectivity for senescent cells compared to navitoclax's dose-limiting thrombocytopenia, but faces greater challenges in drug delivery and manufacturing cost. Fisetin, another senolytic, operates through different mechanisms and has the advantage of oral bioavailability and established safety as a dietary compound, though with lower demonstrated senolytic potency.
Community Observations
FOXO4-DRI generated enormous excitement in the longevity community upon publication, with some individuals attempting self-experimentation despite the very early stage of research and extremely high synthesis cost. The D-retro-inverso peptide is technically challenging and expensive to manufacture at high purity, with costs reported at several thousand dollars per treatment course from custom synthesis services. Most longevity researchers recommend established senolytics like dasatinib + quercetin or fisetin for those interested in senolytic therapy, given their superior safety data, oral availability, and dramatically lower cost compared to FOXO4-DRI.
Half-Life
~Unknown
Reconstitution
DMSO or PBS
Storage
Lyophilized
Store at -20C. Protect from light.
Reconstituted
Store at -20C. Prepare fresh.
US Legal Status
Also Known As
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