Journal Article

Characterization of Human Senescent Cell Biomarkers for Clinical Trials

Ruan, Ming, LeBrasseur, Nathan K., Atkinson, Elizabeth J., Monroe, David G., Farr, Joshua N., Froemming, Mitchell N., Khosla, Sundeep

2025

Overview

There is an increasing need for biomarkers of senescent cell burden to facilitate the selection of participants for clinical trials. p16Ink4a is encoded by the CDKN2A locus, which produces five variant transcripts in humans, two of which encode homologous p16 proteins: p16Inka4a, encoded by p16_variant 1, and p16ɣ, encoded by p16_variant 5. While distinct quantitative polymerase chain reaction primers can be designed for p16_variant 5, primers for p16_variant 1 also measure p16_variant 5 (p16_variant 1 + 5). In a recent clinical trial evaluating the effects of the senolytic combination, dasatinib + quercetin (D + Q), on bone metabolism in postmenopausal women, we found that women in the highest tertile for T‐cell expression of p16_variant 5 had the most robust skeletal responses to D + Q. Importantly, the assessment of p16_variant 5 was more predictive of these responses than p16_variant 1 + 5. Here, we demonstrate that in vitro, p16_variant 1 + 5 increased rapidly (Week 1) following the induction of DNA damage, whereas p16_variant 5 increased later (Week 4), suggesting that p16_variant 5 becomes detectable only when the abundance of senescent cells reaches some threshold. Further analysis identified a SASP panel in plasma that performed as well in identifying postmenopausal women with a positive skeletal response to D + Q. Collectively, our findings provide further support for the T‐cell p16_variant 5 assay as a biomarker for selecting participants in clinical trials of senolytic interventions. In addition, our data indicate that correlated plasma SASP markers could be used in lieu of the more technically challenging T‐cell p16 assay. Trial Registration: ClinicalTrials.gov identifier: NCT04313634. Assessment of T‐cell p16_variant 5 expression may be useful for selecting participants in clinical trials of senolytics. We further characterize p16_variant 5 expression in the context of senescence and demonstrate that correlated plasma senescence‐associated secretory phenotype factors could be used in lieu of the technically challenging T‐cell p16_variant 5 assay.

• Publisher: John Wiley & Sons, Inc,John Wiley and Sons Inc
• Subject: Aged / Aging / Biological markers / Biomarkers / Biomarkers - blood / Biomarkers - metabolism / Bone turnover / Cells / Cellular Senescence - drug effects / Clinical trials / Clinical Trials as Topic / Cyclin-Dependent Kinase Inhibitor p16 - genetics / Cyclin-Dependent Kinase Inhibitor p16 - metabolism / Dasatinib - pharmacology / Dasatinib - therapeutic use / DNA damage / Female / Genomes / Humans / INK4a protein / Kinases / Middle Aged / p16 / p16 Protein / Physiological aspects / Polymerase chain reaction / Post-menopause / Postmenopausal women / Potassium / Proteins / Quercetin / Quercetin - pharmacology / SASP / Senescence / Software / T cells