Space-based research may lead to cancer ‘kill switch’

In space, the weak pull of gravity, also known as microgravity, places cells under incredible stress, causing them to age more rapidly. This phenomenon allows scientists to witness the progression of cancer growth—and the effect of cancer treatments—much more rapidly than they could on Earth.

When the Axiom 3 spaceflight launched from Kennedy Space Center in Cape Canaveral, Fla., on Jan. 18, bound for the International Space Station, it took with it four crewmembers and some other unusual passengers—miniature tumor organoids produced from the cells of cancer patients, grown in the lab by scientists at the University of California San Diego.

Axiom 3 was slated for splashdown on Saturday but has been delayed until Tuesday, at the earliest, due to weather, according to SpaceX, which manufactured the Crew Dragon spacecraft used for the mission.

It wasn’t the first time the team—led by Dr. Catriona H.M. Jamieson, a hematologist and medical professor at the college—sent such samples into space. It previously launched stem cells on multiple Space X flights and noticed that pre-leukemic changes occurred, unseen during the same timeframe in controls on the ground.

“We said, ‘Wait, what if you send cancer up?’” Jamieson tells Fortune. “‘Will the cancer go from bad to worse?’ And the answer is yes, under conditions of stress” caused by microgravity.

A promising ‘kill switch’—in space, anyway

When cancer progresses under stress, it’s due—at least in part—to a cloning gene it turns on, known as ADAR1, according to Jamieson. On previous missions, her team noticed that mini tumors sent to space activated the gene before tripling in size in just 10 days, a much faster rate of growth than seen on the ground. Further testing revealed that ADAR1 “proliferated…