Dinosaur Extinction Asteroid Delivered Cancer-Killing Metals to Earth

An asteroid that wiped out the dinosaurs 66 million years ago may have delivered us a cosmic cancer-killing weapon. Scientists have discovered iridium, a metal that came to Earth via the Chicxulub asteroid, can be used to kill cancer cells by filling them with a poisonous form of oxygen.

Iridium, a silvery metal, is the second densest element and can withstand temperatures up to 2,400 degrees Celsius. In the 1980s, scientists discovered iridium’s arrival on Earth coincided with the giant asteroid that wiped out the dinosaurs—indicating it was delivered at the same time.

Scientists at the University of Warwick, U.K., and Sun-Yat Sen University, China, have now used this metal to develop a way to kill cancer cells without damaging healthy ones. Their findings are published in the journal Angewandte Chemie.

asteroid impact An artist’s impression of an asteroid impacting Earth. NASA/Don Davis

The team developed a compound of iridium and organic material that when injected into cancer cells, turns the oxygen inside them into a poison known as singlet oxygen before killing the cells.

The scientists grew a model tumor of lung cancer in the laboratory. They then used a laser light to activate the iridium compound within the cells to see what would happen. Findings showed the singlet oxygen had penetrated every layer of the tumor and killed it.

The research is in the very early stages and the compound has only been used on a model of cancer—any application in the real-world will still be very far off. However, study co-author Cookson Chiu, from the University of Warwick, said the findings provide a “leap forward” in our understanding of how these iridium-based anti-cancer compounds work.

The field of photochemotherapy, where laser light is used to target cancer cells, is currently an emerging technology that has the potential to provide new treatment options targeting tumors. This is an important field of research—cancer patients are becoming increasingly resistant to current therapies.

sadler_iridium Diagram showing iridium attacking a cancer cell by making it produce singlet oxygen, University of Warwick

Peter Sadler, also from Warwick, said in a statement: “The precious metal platinum is already used in more than 50 percent of cancer chemotherapies. The potential of other precious metals such as iridium to provide new targeted drugs which attack cancer cells in completely new ways and combat resistance, and which can be used safely with the minimum of side-effects, is now being explored.

“It’s certainly now time to try to make good medical use of the iridium delivered to us by an asteroid 66 million years ago.”

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