Cellular senescence & senolytics

What actually decides this outcome, in order of size

The biology here is better established than almost anything else in the Vault and the human dosing is worse. Ranked by how much of the outcome each one owns:

1. Senescent cell burden, which is what the dose was chosen against and which nobody can measure in you. The intermittent dosing strategy exists because senescent cells do not divide, so clearing them does not require continuous exposure. That logic is sound and it presupposes knowing the burden. There is no clinical assay for it, which means every human schedule in circulation is an extrapolation from a mouse's tissue burden.
2. Whether the target cells are even susceptible, because senolytics are not a class. The senescent cell anti-apoptotic pathways differ between cell types, which is the finding the original transcriptome-to-senolytic work is built on Zhu 2015. A drug that clears senescent preadipocytes may do nothing to senescent endothelium, and no product on this page says which cells it is aimed at.
3. What the human trials actually were. The first-in-human senolytic work was an open-label study in idiopathic pulmonary fibrosis with physical function endpoints Justice 2019, and the strategy for late preclinical and early clinical trials of senolytics has been set out as an open problem Wissler Gerdes 2021. These are early-phase studies in disease populations, not longevity results.
4. Sex, which turns out to matter here as it does across this goal. Metabolic and cognitive responses to fisetin or to a dasatinib-and-quercetin cocktail were sexually dimorphic in mice Fang 2023. That is a direct warning against reading a single reported effect as a general one.
5. Absorption, which decides whether the flavonoid arm is a dose at all. Quercetin's bioavailability is low and formulation-dependent; a phytosome formulation improved oral absorption Riva 2019 and the general question has been systematically reviewed and meta-analyzed Liu 2025. A gram of unformulated quercetin powder is not the exposure a trial used.

The order to run these in, and what has to be true first

Understand that this is an experiment, choose the arm with human exposure data, and set the stopping rule before the first dose. The intermittent schedule is the one thing here that is well reasoned.

1. Baseline panel before anything, because the plausible harms are hematological and hepatic. Complete Blood Count (CBC) with Differential with differential, Comprehensive Metabolic Panel (CMP), hs-CRP (High-Sensitivity C-Reactive Protein) and a Lipid Panel (Cholesterol, HDL, LDL, Triglycerides). Dasatinib is a tyrosine kinase inhibitor with known cytopenia, bleeding and effusion effects, and it is the one item here where a baseline is not optional.
2. Fisetin is the arm with the most human exposure and the least toxicity. Senolytic trials of fisetin were run in skilled nursing facilities during the COVID era Verdoorn 2021, which is the largest deliberate human exposure this class has had. It is also a flavonoid with the same absorption problem as quercetin.
3. Dasatinib + Quercetin is prescription oncology plus a flavonoid and belongs to a physician. The combination is what the first-in-human study used Justice 2019, the dasatinib half is a licensed drug with a monitoring requirement, and obtaining it outside that setting removes the only safety structure the trials had.
4. Intermittent dosing rather than daily, and the reason is mechanistic. Senescent cells are post-mitotic, so a short exposure that triggers apoptosis is sufficient and continuous exposure adds toxicity without adding clearance. This hit-and-run logic is the design principle behind the trial strategy literature Wissler Gerdes 2021.
5. Quercetin alone is not a senolytic at supplement exposures. Its safety as a dietary supplement has been reviewed Andres 2018, and the bioavailability work explains why the labeled milligrams and the delivered exposure diverge so far Riva 2019 Liu 2025.
6. Foxo4-DRI is the most theoretically interesting and least supported item on the page. It is a peptide designed to disrupt a specific protein interaction in senescent cells. There is no human pharmacokinetic data, no human trial and no dosing rationale that is not reverse-engineered from a mouse experiment.
7. Curcumin, Luteolin and Tocotrienols are senomorphic rather than senolytic, which is a different claim. Dietary luteolin reduced proinflammatory microglia in aged animals Burton 2016. Suppressing the secretory phenotype is not the same as removing the cell, and the two strategies have different expected durations of effect.
8. Write the stopping rule down, because there is no marker to stop you. One agent, one schedule, twelve months, and a pre-committed list of what would end the experiment. Without a burden assay this is the only discipline available.

What gets bought for this that cannot move it

The category fails on measurement rather than on mechanism, and the distinction matters. Transplanting senescent cells into young animals causes dysfunction and clearing them reverses it; that part is well demonstrated. What cannot be done is measuring your own senescent cell burden, before or after. Every other page on this site can at least propose a marker. Here there is none, which means a personal senolytic protocol cannot be shown to have worked or failed at the level of its own mechanism.

Quercetin sold as a senolytic is the option whose marketing most exceeds its pharmacology. In the human study it was a partner to dasatinib, not a standalone agent Justice 2019, and the exposures achieved from ordinary oral quercetin are far below what the combination delivered Riva 2019 Liu 2025. Buying the flavonoid half of a two-drug protocol and expecting the protocol's effect is the specific error this page should prevent.

Here is the extrapolation, labeled as one. IF senescent cell clearance in humans worked as it does in mice, THEN the first detectable human signal would plausibly be a fall in the circulating inflammatory profile — hs-CRP (High-Sensitivity C-Reactive Protein) and TNF-Alpha — over roughly a month, followed later by function. That is a prediction, it has not been tested against placebo in a general population, and the early-phase human work used physical function rather than inflammatory markers as its endpoint Justice 2019. It is not evidence.

If the goal underneath is different, so is the page. Clearing damaged organelles rather than damaged cells is Autophagy & mitochondrial quality control. Nutrient sensing is Nutrient sensing — mTOR, AMPK & caloric restriction mimetics. Interventions with human mortality endpoints are at The unglamorous evidence — what actually has mortality data. And joint pain or breathlessness that prompted the interest is a diagnosis to make rather than a senescence hypothesis to treat.

How you would know it was working, on a real read-out and a real timescale

This page makes a prediction it cannot fully test, and saying so is the honest position. There is no senescent cell burden assay. What can be checked is that nothing was harmed and that the inflammatory profile and physical function moved in the predicted direction over months rather than days.

• Complete Blood Count (CBC) with Differential with differential before and 2 weeks after each cycle, if dasatinib is involved. Cytopenias are the documented hematological effect of that drug class, and two weeks is chosen because the neutrophil and platelet nadirs after a short exposure fall inside that window.
• Comprehensive Metabolic Panel (CMP) on the same schedule. Hepatic handling matters for the flavonoids as well as the kinase inhibitor, and quercetin's safety review is written around exactly this kind of monitoring Andres 2018.
• hs-CRP (High-Sensitivity C-Reactive Protein) with TNF-Alpha at baseline and at 12 weeks. These are the closest available proxies for the secretory phenotype the mechanism targets. Neither is specific to senescence, which is why a change in them is suggestive rather than confirmatory.
• A physical function test, monthly, unchanged in protocol. Six minutes of walking, a timed chair-stand, or grip strength. Physical function is what the first-in-human study measured Justice 2019, so it is the endpoint with any precedent at all.
• 12 weeks minimum before any judgment, and the number has a reason. If cells are cleared, the downstream benefit depends on tissue repopulation and on the secretory environment settling, which are months-scale processes. Judging at two weeks measures the acute effect of a flavonoid.

What will fool you. There is no burden assay, so anything you feel is uncontrolled and unblinded. hs-CRP moves with any infection and with a hard training week. Animal responses to these agents were sexually dimorphic Fang 2023, so a reported benefit may not be about somebody like you. Quercetin exposure varies several-fold between formulations at the same labeled dose Liu 2025, which means a null result on a cheap capsule says nothing about the mechanism. And the human fisetin work was conducted in an acute illness setting Verdoorn 2021, which is not the population reading this page.

Sources read for these sections

• Zhu Y, et al. The Achilles' heel of senescent cells: from transcriptome to senolytic drugs.. Aging Cell 2015 · PMID 25754370
• Justice JN, et al. Senolytics in idiopathic pulmonary fibrosis: Results from a first-in-human, open-label, pilot study. EBioMedicine, 2019 · PMID 30616998
• Wissler Gerdes EO. Strategies for late phase preclinical and early clinical trials of senolytics. Mechanisms of Ageing and Development 2021 · PMID 34699859
• Verdoorn BP. Fisetin for COVID-19 in skilled nursing facilities: Senolytic trials in the COVID era. Journal of the American Geriatrics Society 2021 · PMID 34375437
• Fang Y. Sexual dimorphic metabolic and cognitive responses of C57BL/6 mice to Fisetin or Dasatinib and quercetin cocktail oral treatment. GeroScience 2023 · PMID 37296266
• Andres S, et al. Safety Aspects of the Use of Quercetin as a Dietary Supplement.. Molecular Nutrition & Food Research 2018 · PMID 29127724
• Riva A, et al. Improved Oral Absorption of Quercetin from Quercetin Phytosome, a New Delivery System Based on Food Grade Lecithin. European Journal of Drug Metabolism and Pharmacokinetics 2019 · PMID 30328058
• Liu L, et al. Improving quercetin bioavailability: A systematic review and meta-analysis of human intervention studies. Food Chemistry 2025 · PMID 40037045
• Burton MD, Rytych JL, et al. Dietary Luteolin Reduces Proinflammatory Microglia in the Brain of Senescent Mice. Rejuvenation Research 2016 · PMID 26918466