A red-hot anti-aging strategy quietly passed its first test earlier this year after 14 volunteers took drugs meant to kill off old, toxic cells in their bodies.

The small study in people with lung disease, reported in January, is being billed as the first attempt at “senolytics,” or employing drugs to clear people’s bodies of aged, toxic cells. Some researchers think this strategy could eventually be employed in healthy people to delay aging.

“This gives us to some extent a green light to go on to larger trials,” says James Kirkland, a Mayo Clinic professor who helped lead the trial, carried out in clinics in Texas and at Wake Forest University starting in 2016.

Patients took two pills that Kirkland and his colleagues believed could selectively get rid of aged cells: the leukemia drug dasatinib and a supplement called quercetin.
It is early days for drugs meant to slow aging, and some breathed a sigh of relief that patients in this first-of-a-kind study didn’t suffer serious side-effects from the drugs. “My worry is we should not leap into this too fast, because if there’s a mistake or something we don’t understand, it could set the field back,” says Judith Campisi, a professor at the Buck Institute for Research on Aging in Novato, California.

This was a pilot trial—not even in the first phase of a three-part sequence of trials needed to win approval by the US Food and Drug Administration. So, officially, it showed nothing about aging at all.

All 14 patients suffered from a fatal, hard-to-treat lung condition called idiopathic pulmonary fibrosis, which explains why they were willing to participate in the experiment. The doctors found that nine doses of the two pills over three weeks did seem to improve patients’ ability to walk a bit farther in the same amount of time, and several other measures of well-being.

A bubble of commercial enthusiasm has been building around the idea that aging could be postponed, or its effects tempered, using drug treatments. A company called Unity Biotechnology of Brisbane, California, is developing two senolytic drugs, the first of which is in a phase 1 clinical trial for osteoarthritis—it’s being injected into people’s knees. Campisi is a cofounder of Unity, and Kirkland also holds shares in the public company, which is currently worth about half a billion dollars.

Image Credit:  James Kirkland, Mayo Clinic professor. Mayo Clinic