Clinical trial biobanks hold an untested signal that drugs are already slowing aging
Clinical trial biobanks hold an untested signal that drugs are already slowing aging
On September 24, biological age researcher Kristin Glorioso published an analysis: drug trials almost always collect and store participants' blood, yet almost never use it to check whether the treatment slowed aging itself. She examines two cases where that check was performed retrospectively, on semaglutide and on rentocertib, an experimental drug for pulmonary fibrosis, and in both cases aging clocks showed deceleration in treated patients.
A drug trial works like this: at every visit, participants give blood for safety monitoring and disease endpoints, and the samples then sit in a biobank. Aging clocks, models that estimate age from the composition of blood rather than from a birth certificate, can be computed on those samples at any point without recruiting new participants. This is rarely done. No regulator, including the FDA, accepts aging clocks as grounds for drug approval, so sponsors have no direct incentive to pay for reanalysis of blood that has already been drawn.
A telling example is a semaglutide trial in 108 people with HIV: the drug was tested for its ability to reduce the abdominal fat deposits characteristic of HIV, and paired samples suitable for aging analysis survived from 84 participants. A preliminary version of this analysis appeared in 2025 as an unreviewed preprint; in May 2026 the paper passed peer review and was published in Nature Communications. Seventeen aging clocks were computed from blood samples at baseline and at week 32: on the PhenoAge scale the semaglutide group was on average 4.9 years younger than the placebo group, and the pace of aging measured by DunedinPACE slowed by 9%. The effect did not appear in every clock: mortality risk models showed deceleration, while clocks targeting a specific mechanism of cellular damage did not.
More valuable than the numbers themselves is where the effect appeared. The trial measured abdominal fat, not brain or heart. Yet dedicated clocks for 11 organ systems showed significant deceleration in seven of them, including brain, heart, kidneys, and liver. Random noise does not shift systematically in one direction across several independent clocks at once, and this is a strong argument for genuine slowing of aging. Among the seven authors of the paper, two are employees and one is a consultant of TruDiagnostic, the developer of these same epigenetic tests.
Glorioso's second example is rentocertib, a TNIK enzyme inhibitor from Insilico Medicine: six proteomic clocks computed from archived phase IIa serum also showed a concordant decrease in biological age in treated patients. Two drugs with different mechanisms of action, a hormonal agonist and an enzyme inhibitor, are compared by Glorioso deliberately: the same signal from both speaks to the reliability of the method. Null results are worth publishing too: in the RAPA-EX-01 trial, rapamycin combined with exercise, none of the four clocks showed significant deceleration.
Two days ago, another study applied protein aging clocks to five semaglutide trials enrolling 10,052 participants and found the same effect. Accumulating reanalyses like these from completed trials is the cheapest path to eventually convincing regulators to recognize aging clock deceleration as grounds for approval, Glorioso argues.
The same drug, tested for one disease, turns out to be an aging drug candidate if you simply run the blood already drawn through a different instrument. Every unanalyzed trial sitting in a biobank is a question about aging that has already been paid for but never asked.