Smart Science

A new drug only switches on inside cancer cells and destroys them — leaving healthy cells entirely intact This means fewer of the side effects that make treatment so brutal. Many cancer cells give off unusually high amounts of carbon monoxide, a byproduct of their stressed metabolism, while healthy cells make very little. A team at RIKEN in Japan led by chemist Katsunori Tanaka turned that difference into a trap. They tucked a palladium catalyst, a metal compound that speeds up chemical reactions, inside albumin, a common blood protein that shields it on the way into cells. Once inside, the catalyst uses the cell's own carbon monoxide to assemble phenanthridinone, a compound that kills cells. The drug formed in liver, cervical, breast and lung cancer cells, but not in healthy cells. A modified version made an even more toxic compound that damaged liver cancer cells from within. Because the drug is only built where the gas is, the idea could one day target tumors while sparing healthy tissue, which is what causes many chemotherapy side effects. So far this has only been shown in cells in a dish, and animal tests are next. source: Kawai, M., et al. (2026). Harnessing endogenous carbon monoxide for cancer-selective drug synthesis. Nature Communications.