There’s a theory that tired-out cells are what make people old. That is why scientists have been developing a new generation of drugs designed to wipe them out. They call the act (strategy) of employing drugs to clear people’s bodies of aged, toxic cells “Senolytics.” Some researchers think this strategy could eventually be employed in healthy people to delay aging.
This cell-killing strategy to slow aging, senolytics, passed its first human trials. The test involved 14 volunteers who took drugs meant to kill off old, toxic cells in their bodies. By the end of the trial, all of the participants’ health had improved. As great as that may seem, this was still just 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.
That doesn’t mean they weren’t exited about the positive outcome though! “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.
- All 14 of the people that participated had a lung disease – they suffered from a fatal, hard-to-treat lung condition called idiopathic pulmonary fibrosis.
- The 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.
- The doctors found that nine doses of the pair of 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.
Campisi is a cofounder of Unity Biotechnology, a company that is currently 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. They believe their drugs will be able to postpone aging, or at least temper its effects, through drug treatments.
The cells these drugs have to take out are called senescent cells. Senescent cells have exhausted their ability to divide but remain capable of spewing out a potent mix of chemical signals.
Nicolas Musi, who participated in the new study and directs the Sam and Ann Barshop Institute for Longevity and Aging Studies at the University of Texas at Austin, says:
“It is thought that these cells and the substances they produce are involved in the process of aging. The idea is that removing these cells may be beneficial to promote healthy aging and also to prevent diseases of aging.”
Although, they must proceed with caution because not everything about senescent cells is bad. The cells and their secretions are believed to be important during the development of embryos, in the timing of labor, and in healing wounds and forming scar tissue. Campisi says:
“You wouldn’t ever want to administer senolytics to a pregnant woman. It’s now becoming clear that you need these secretions for certain good things to happen. When the secretions become chronic as opposed to periodic or episodic, that’s when it starts to drive pathology.”
At the moment, researchers are starting their tests in people with serious disease, but they eventually hope to explore whether senolytic agents could be given to healthy people. They say that if it ends up being possible, then it will a bit like a semi-annual dental cleaning to remove plaque. Campisi imagines:
“You reduce the burden of senescent cells, but it doesn’t have to go to zero. And then you get off the drugs.”
Whether or not this will lead to an anti-aging treatment, is uncertain. They are on a mission to find out though. Musi says he and Kirkland and their collaborators have begun a trial in 15 more lung patients, and the team at Mayo is testing the drug combination in 20 patients with chronic kidney disease.
Kirkland told MIT Technology Review:
“If we see effectiveness signals and don’t encounter really bad side effects, we’ll try to get to people with less and less life-threatening conditions. If everything goes right.”