Quercetin for Senolytic Activity (Dasatinib + Quercetin)

In March 2015, Yi Zhu, Tamar Tchkonia, Tamara Pirtskhalava, and James Kirkland at the Mayo Clinic, in collaboration with Paul Robbins and Laura Niedernhofer at Scripps Research, published the founding paper of senolytic pharmacology in Aging Cell. They identified the “Achilles heel” of senescent cells — their dependence on anti-apoptotic survival proteins (BCL-2, BCL-xL, BCL-W, PI3K, AKT) to resist the apoptosis their own DNA damage should trigger — and showed that combining dasatinib (a tyrosine kinase inhibitor approved for chronic myeloid leukemia) with quercetin selectively killed senescent cells across multiple tissues in mice. The Dasatinib + Quercetin (D+Q) combination became the founding senolytic regimen and remains the most-studied to date in human trials. Hickson 2019 (diabetic kidney disease pilot) and Justice 2019 (idiopathic pulmonary fibrosis pilot) demonstrated measurable senescent-cell-burden reduction and physical function improvement in older humans, respectively. This page walks through the senescent cell biology, the SCAP mechanism, the founding 2015 paper, the human trials, the D+Q dosing rationale, and the honest framing of where human evidence currently stands.

Table of Contents

  1. Senescent Cells — The Zombie Cell Primer
  2. The SASP — Why Senescent Cells Damage Whole Tissues
  3. SCAPs — The Anti-Apoptotic Achilles Heel
  4. The Zhu 2015 Aging Cell Paper
  5. The Dasatinib + Quercetin (D+Q) Combination
  6. Hickson 2019 — First Human Trial (Diabetic Kidney Disease)
  7. Justice 2019 — Idiopathic Pulmonary Fibrosis Pilot
  8. D+Q vs Fisetin Monotherapy
  9. Pulsed Dosing Rationale and Protocols
  10. Honest Framing — What the Human Evidence Supports
  11. Cautions, Drug Interactions, and Dasatinib-Specific Risks
  12. Key Research Papers
  13. Connections

Senescent Cells — The Zombie Cell Primer

Cellular senescence is a programmed cellular response to stress — DNA damage, telomere shortening, oncogene activation, oxidative stress, or proteotoxic stress — in which a cell exits the cell cycle permanently while remaining metabolically active and resistant to apoptosis. The cellular phenotype is well-characterized: enlarged flat morphology, persistent DNA damage foci, expression of the cell-cycle inhibitors p16-INK4a and p21-CIP1, senescence-associated beta-galactosidase activity, and a distinctive secretory profile (the senescence-associated secretory phenotype, or SASP, discussed in the next section).

Senescence is evolutionarily ancient and serves at least two beneficial roles: tumor suppression (cells with cancer-relevant mutations are forced out of the cell cycle, preventing clonal expansion) and wound healing (transient senescent cells in injured tissue secrete factors that promote tissue remodeling and regeneration, then are typically cleared by the immune system). The problem is not senescence itself; it is the failure to clear senescent cells once they have served their purpose.

Senescent cells accumulate with age in most tissues. In young healthy tissue, senescent cells are rare (perhaps 1-2% of cells in any given tissue) and most are cleared by immune surveillance (NK cells and macrophages) within days to weeks. With age, several things change: more cells reach senescence (more accumulated DNA damage, more replicative stress, more telomere shortening), immune clearance becomes less efficient (immunosenescence of the NK and macrophage compartments), and the SASP secreted by existing senescent cells actively induces senescence in neighboring cells (the “bystander effect”). The result is a slow exponential accumulation of senescent cells across decades of life, reaching 10-15% or more of cells in many tissues by the eighth decade.

The functional consequences of this accumulation became experimentally testable in 2011, when Darren Baker and Jan van Deursen at Mayo Clinic published a landmark Nature paper using a transgenic mouse model (INK-ATTAC) that allowed selective elimination of p16-INK4a-positive senescent cells on demand. Periodic clearance of senescent cells throughout life delayed the development of multiple age-related disorders including cataracts, sarcopenia, lipodystrophy, and several others — without any obvious negative effects. The Baker paper established proof-of-principle that senescent cells were causally driving aspects of aging and that their selective elimination could be therapeutically beneficial.

Back to Table of Contents

The SASP — Why Senescent Cells Damage Whole Tissues

Senescent cells exit the cell cycle but remain metabolically very active, and the key reason a small number of senescent cells damages large tissue regions is the SASP — the senescence-associated secretory phenotype, an inflammatory secretome including IL-6, IL-8, IL-1-alpha, MCP-1, MMP-3, MMP-9, GROalpha, and dozens of other cytokines, chemokines, growth factors, and matrix metalloproteinases.

The SASP has at least three consequences:

  1. Tissue inflammation (“inflammaging”) — the chronic low-grade inflammation that characterizes aging, drives atherosclerosis, accelerates cognitive decline, contributes to insulin resistance, and underlies much of the “frailty phenotype.” The SASP is the cellular source of much of this background inflammation.
  2. Bystander senescence induction — SASP factors (particularly IL-6 and IL-8) induce senescence in neighboring non-senescent cells, propagating the senescent phenotype outward like a slow wave from each senescent cell. This creates the exponential rather than linear accumulation seen with age.
  3. Stem cell exhaustion — the inflammatory and protease-rich environment created by SASP disrupts the niches that support tissue stem cells, accelerating their depletion and reducing tissue regenerative capacity.

The SASP is the reason that a senescent-cell burden of even a few percent of total cells can produce tissue-level dysfunction far out of proportion to the actual cell count. It is also why senolytic therapy works in pulsed dosing — eliminating the SASP source temporarily reduces the bystander effect and gives the surrounding tissue time to recover, even though new senescent cells will continue to accumulate.

Back to Table of Contents

SCAPs — The Anti-Apoptotic Achilles Heel

Senescent cells should die. They have damaged DNA, dysfunctional mitochondria, and persistent stress signaling that would normally trigger apoptosis in any other cell. They survive because they upregulate a constellation of anti-apoptotic survival pathways — the “senescent-cell anti-apoptotic pathways,” or SCAPs — that allow them to resist the apoptotic signals their own internal state is sending.

The Zhu 2015 paper systematically characterized these SCAPs. The dominant SCAPs in senescent cells include:

The key insight of the Zhu paper was that different senescent cell types depend on different SCAP combinations. Senescent endothelial cells were killed by quercetin alone. Senescent adipose progenitor cells were killed by dasatinib alone (acting on the ephrin-receptor pathway). Senescent fibroblasts and senescent mesenchymal stem cells required the combination to be effectively killed. The D+Q combination therefore covers a broader range of senescent cell types than either drug alone — the rationale for using both rather than either monotherapy.

Back to Table of Contents

The Zhu 2015 Aging Cell Paper

The Zhu, Tchkonia, Pirtskhalava, et al. 2015 paper in Aging Cell is the founding document of senolytic pharmacology. The methodology was an unbiased mechanistic approach:

  1. Compare gene expression profiles of senescent and non-senescent cells across multiple cell types to identify the upregulated SCAP pathways.
  2. Use RNA interference to systematically knock down candidate SCAP genes and determine which knockdowns selectively killed senescent cells.
  3. Use the validated SCAP gene list to predict which existing pharmacological agents (with known protein targets) should have senolytic activity.
  4. Test the predicted agents experimentally for selective killing of senescent vs non-senescent cells.
  5. Validate the most promising agents in vivo in mouse models of natural and accelerated aging.

The two most effective agents identified in this screen were dasatinib (a tyrosine kinase inhibitor developed for chronic myeloid leukemia, FDA-approved in 2006) and quercetin (the dietary flavonoid). Either alone showed activity against some senescent cell types; the combination showed activity across nearly all senescent cell types tested.

The in-vivo demonstration was particularly striking. Aged mice (24+ months) treated with a single 3-day course of D+Q showed:

Importantly, the benefits persisted for weeks to months after the single short course of treatment, consistent with the pulsed-dosing “hit and run” rationale that senescent cells take weeks to re-accumulate to baseline burden.

Back to Table of Contents

The Dasatinib + Quercetin (D+Q) Combination

The standard D+Q regimen in the research literature is dasatinib 100 mg + quercetin 1000 mg, taken together once daily for 2-3 consecutive days, repeated monthly. The rationale for pulsed monthly dosing is the senescent-cell repopulation kinetics — senescent cells take approximately 4-6 weeks to re-accumulate to baseline burden after a clearing event, so monthly pulses are sufficient to maintain a reduced steady-state burden without the toxicity that would come from chronic daily exposure.

Quercetin's role in the combination is dual:

  1. Direct senolytic activity against endothelial and certain other senescent cell types via BCL-xL inhibition and PI3K/AKT pathway interference.
  2. Synergy with dasatinib in killing senescent cell types (particularly senescent fibroblasts and mesenchymal stem cells) that require both ephrin-receptor inhibition (from dasatinib) and BCL-xL inhibition (from quercetin) for effective elimination.

The dasatinib component of D+Q deserves serious consideration on its own. Dasatinib is a prescription tyrosine kinase inhibitor with a well-characterized side effect profile from its oncology use: fluid retention (including potentially life-threatening pleural effusion), QT prolongation, bleeding, cytopenias, and pulmonary hypertension in rare cases. The senolytic dosing (100 mg once daily for 2 days monthly) is far less than the oncology dosing (100-140 mg daily continuously), but the same side-effect categories apply.

This is why the D+Q combination is being studied in formal clinical trials rather than promoted as an over-the-counter regimen, and why prescriptions for dasatinib for senolytic indications should come from physicians familiar with the drug class and willing to monitor for the relevant adverse effects.

For patients who want quercetin's senolytic effects without dasatinib's prescription requirement and adverse effect profile, fisetin monotherapy is the most commonly chosen alternative — see the D+Q vs Fisetin Monotherapy section below and the Fisetin Senolytic Activity page.

Back to Table of Contents

Hickson 2019 — First Human Trial (Diabetic Kidney Disease)

The Hickson et al. 2019 paper in EBioMedicine was the first published human trial of any senolytic regimen and used D+Q (dasatinib 100 mg + quercetin 1000 mg) given on 3 consecutive days, with abdominal subcutaneous adipose biopsies before and 11 days after treatment.

The population was nine adult subjects with diabetic kidney disease — chosen because diabetic kidney disease is associated with high senescent-cell burden in both adipose and renal tissue, and because the diabetic-kidney-disease patient population has multiple age-related comorbidities that would plausibly benefit from senolytic intervention.

Results:

The Hickson trial was a small open-label pilot designed primarily to demonstrate that the predicted senescent-cell elimination did in fact occur in humans, at a dose comparable to the mouse-translated dose, with a manageable safety profile. It succeeded on all three counts and motivated the subsequent larger trials that are still in progress.

Back to Table of Contents

Justice 2019 — Idiopathic Pulmonary Fibrosis Pilot

Idiopathic pulmonary fibrosis (IPF) is a devastating progressive lung disease with a median survival of approximately 3-5 years from diagnosis. The pathology involves accumulation of senescent alveolar epithelial type II cells and senescent fibroblasts in the lung interstitium, producing fibrotic remodeling that progressively destroys lung function.

The Justice et al. 2019 paper in EBioMedicine, by Jamie Justice, Anoop Nambiar, Tamar Tchkonia, and James Kirkland, used the D+Q regimen (dasatinib 100 mg + quercetin 1250 mg) given as 3 consecutive days per week for 3 weeks in 14 patients with stable IPF. Primary outcomes were safety and physical function (6-minute walk, gait speed, chair stand test, short physical performance battery, frailty index).

Results:

The physical function improvements without pulmonary function improvement is an interesting and biologically plausible pattern — the senescent-cell clearance is more likely to reduce systemic inflammaging (which affects skeletal muscle function and overall physical performance) than to reverse fibrotic remodeling that has already occurred in the lung. Whether continued treatment would slow further fibrotic progression is the question for larger and longer trials.

Back to Table of Contents

D+Q vs Fisetin Monotherapy

For patients interested in senolytic therapy outside the formal clinical trial setting, the practical alternative to D+Q is fisetin monotherapy. The Yousefzadeh 2018 paper that established fisetin as the most-potent natural senolytic among ten flavonoids screened (covered in detail on the Fisetin Senolytic Activity page) used a 5-day fisetin course at 100 mg/kg in mice, with significant senescent-cell-burden reduction and lifespan extension.

Practical advantages of fisetin monotherapy:

Practical disadvantages relative to D+Q:

The current state of the art for an adult patient interested in self-administered senolytic intervention is most often fisetin monotherapy (20 mg/kg body weight on two consecutive days monthly — e.g., approximately 1400 mg per dose for a 70-kg adult), as a compromise between mechanism evidence and practicality. D+Q is more rigorous mechanistically but requires a willing prescribing physician and accepts dasatinib's side-effect profile.

Back to Table of Contents

Pulsed Dosing Rationale and Protocols

All senolytic dosing in current research and clinical practice is pulsed rather than continuous, for several reasons:

  1. Senescent cells repopulate over weeks, not days — once senescent cells are eliminated, new senescent cells accumulate at a rate that takes approximately 4-6 weeks to return to baseline burden. Daily continuous senolytic exposure is therefore unnecessary and would only add toxicity without additional benefit.
  2. Off-target toxicity scales with cumulative exposure — the senolytic agents (especially dasatinib) have off-target effects that accumulate with continuous use. Pulsed dosing minimizes cumulative exposure while preserving the on-target senescent-cell clearance.
  3. The dasatinib mechanism is “hit and run” — dasatinib triggers apoptosis in senescent cells in the first 1-3 days of exposure; longer exposure does not kill more senescent cells but does add toxicity to healthy cells.
  4. Quercetin and fisetin's short plasma half-life is acceptable in this dosing regimen precisely because chronic steady-state levels are not the goal — brief pulses of high concentration are sufficient to trigger senescent-cell apoptosis.

Common research protocols:

Back to Table of Contents

Honest Framing — What the Human Evidence Supports

The senolytic field is in an unusual position: striking and reproducible mouse data, mechanistic clarity at the cellular level, a small handful of positive pilot human trials showing the predicted biomarker effects, and a large gap before randomized trial evidence of clinical-outcome benefit in older humans.

What the human evidence currently supports:

  1. D+Q (and likely fisetin monotherapy) reduces senescent-cell burden in human tissue (Hickson 2019 demonstrated this directly in adipose biopsies).
  2. D+Q reduces SASP-related plasma cytokines in older humans (Hickson 2019, Justice 2019).
  3. D+Q produces measurable physical function improvement in IPF patients over 3 weeks of treatment (Justice 2019).
  4. Safety profile in the short-term pilot trials has been acceptable.

What the human evidence does NOT yet support:

Reasonable patient positioning depends on individual risk tolerance, age, comorbidities, and the strength of the case for a specific indication. The Mayo Clinic and other major centers have ongoing trials open to enrollment in many of the relevant indications — an option worth considering for patients who want senolytic intervention in a rigorous research setting.

Back to Table of Contents

Cautions, Drug Interactions, and Dasatinib-Specific Risks

Back to Table of Contents

Key Research Papers

  1. Zhu Y, Tchkonia T, Pirtskhalava T, et al. (2015). The Achilles' heel of senescent cells: from transcriptome to senolytic drugs. Aging Cell. — PubMed
  2. Hickson LJ, Langhi Prata LGP, Bobart SA, et al. (2019). Senolytics decrease senescent cells in humans: preliminary report from a clinical trial of Dasatinib plus Quercetin in individuals with diabetic kidney disease. EBioMedicine. — PubMed
  3. Justice JN, Nambiar AM, Tchkonia T, et al. (2019). Senolytics in idiopathic pulmonary fibrosis: results from a first-in-human, open-label, pilot study. EBioMedicine. — PubMed
  4. Baker DJ, Wijshake T, Tchkonia T, et al. (2011). Clearance of p16Ink4a-positive senescent cells delays ageing-associated disorders. Nature. — PubMed
  5. Yousefzadeh MJ, Zhu Y, McGowan SJ, et al. (2018). Fisetin is a senotherapeutic that extends health and lifespan. EBioMedicine. — PubMed
  6. Xu M, Pirtskhalava T, Farr JN, et al. (2018). Senolytics improve physical function and increase lifespan in old age. Nature Medicine. — PubMed
  7. Kirkland JL, Tchkonia T (2020). Senolytic drugs: from discovery to translation. Journal of Internal Medicine. — PubMed
  8. Kirkland JL, Tchkonia T (2017). Cellular senescence: a translational perspective. EBioMedicine. — PubMed
  9. Childs BG, Durik M, Baker DJ, van Deursen JM (2015). Cellular senescence in aging and age-related disease: from mechanisms to therapy. Nature Medicine. — PubMed
  10. Coppe JP, Patil CK, Rodier F, et al. (2008). Senescence-associated secretory phenotypes reveal cell-nonautonomous functions of oncogenic RAS and the p53 tumor suppressor. PLoS Biology. — PubMed
  11. van Deursen JM (2014). The role of senescent cells in ageing. Nature. — PubMed
  12. Tchkonia T, Zhu Y, van Deursen J, Campisi J, Kirkland JL (2013). Cellular senescence and the senescent secretory phenotype: therapeutic opportunities. Journal of Clinical Investigation. — PubMed

PubMed Topic Searches

Back to Table of Contents

Connections

Back to Table of Contents