A drug that clears aged cells relieves knee osteoarthritis
Osteoarthritis of the knee, the wearing-away of the cartilage that cushions the joint, is the most common reason an older person cannot walk without pain. Aged cells (cells that have stopped dividing but will not die, and inflame their neighbours) gather in the joint after an injury and with age, and in 2017 a Mayo Clinic and Unity Biotechnology group showed that killing them in the knees of mice eased pain and let cartilage regrow. The company took its drug UBX0101 into people, injecting it into the knee, and in 2020 its controlled trial found no more relief than a placebo injection at twelve weeks. The leaf stays at the animal rung: a person has had the drug, but no person has had the result.
What would count
A controlled trial in people with knee osteoarthritis reports that a drug meant to kill aged cells, injected into the joint or given by mouth, reduces pain or improves function more than a placebo on the trial's pre-stated main measure, in a peer-reviewed report. The animal rung is pain or cartilage improvement in a living animal with the condition. For the clinic rung: a regulator approves such a drug for osteoarthritis.
Who settles it: The peer-reviewed trial report; the trial registry's posted results; the regulator's approval record for the clinic rung.
Where it stands
Shown in animals. Reached 24 April 2017, on the record of doi.org. Next rung within 5 to 20 years.
When it reaches the clinic: the project's estimate
This is the one thing on this page that is a judgment rather than a record. The project's estimate of the year it reaches the clinic is 2039, no earlier than 2032 and no later than 2080; the model draws from that range every run, with the likely year the most probable draw. Set 16 October 2026, a first pass awaiting an outside review.
| Rung | No earlier than | Most likely | No later than | |
|---|---|---|---|---|
| First human | 2028 | 2031 | 2050 | |
| In clinical use | 2032 | 2039 | 2080 | feeds the year at the top |
Why. Osteoarthritis is a large market with no disease-modifying drug, so a drug of this class that works would be carried to approval quickly; the problem is that the one proper trial failed and no company trial has replaced it. The likely year assumes an academic trial with an oral drug reports a positive result around 2030 and a company carries it to approval in the mid to late 2030s; the earliest assumes a trial already recruiting reads out positive by 2028; the latest allows for the 2020 result being the true answer and the leaf never moving.
Changes to this record
None since it was written on 16 October 2026. Every change to the stage or the estimate lands here with its date, the old value, the new one and the reason, and a change to the estimate never happens because a number looked wrong: it needs a dated reason and a source.
The last readings
- 17 October 2026 Quiet
Nothing in the window. The searches returned only the 2020 UBX0101 failure the record already holds and the fisetin trials. One of those, named ROPE (registry number NCT04770064, 74 adults aged 40 to 80 with knee osteoarthritis, two fisetin dose schedules against placebo), is a different registry entry from the one the record's notes name (NCT04210986, 75 people, Steadman Philippon), and a supplement retailer's page says ROPE found no benefit over placebo on either schedule, with results in a conference-proceedings issue of Osteoarthritis and Cartilage; that rests on secondary reporting, has no date seen, and a null result would not move the leaf, so it is offered here only as something the notes might name once checked. A 2025 mouse paper on an intra-joint senolytic prodrug (SSK1) is animal work the leaf already stands on.source 1, source 2, source 3
What the story so far says about it
On the record
Notes
The 2020 failure is the one most often cited against the whole class, and it is on the record here for that reason. It was a single injection of a short-lived drug, judged at twelve weeks; the company said afterwards that the drug may not have stayed in the joint long enough. That is a reason to keep the leaf tracked rather than withdrawn: the test can still be met by a better drug or a longer course. A small randomised, placebo-controlled trial of fisetin, a plant compound some researchers use to clear aged cells, in knee osteoarthritis (75 people, run by the Steadman Philippon Research Institute; registry number NCT04210986) finished in February 2023; its main measure was safety, so it does not meet the test above.