Hans Clevers, biomedical scientist: If I had colon cancer, I could grow my own tumor, test it with drugs, and see which one eliminates it'

"Until now, preclinical trials relied primarily on two-dimensional cell cultures and animal models, which often failed to accurately replicate human biology. Since 2023, the U.S. Food and Drug Administration (FDA) has not required animal testing, thanks in part to organoids, which Hans Clevers (Eindhoven, 68 years old), professor of molecular genetics at Utrecht University, has been researching since the beginning of the century."

"As the name suggests, it's something that resembles an organ. They're really small. We create them from stem cells in a culture dish. They grow constantly, divide into small fragments, grow again, divide again, and replicate the key functions and characteristics of an organ. For example, if I extract stem cells from a liver, I create a liver organoid with the main functions of the liver. If it were a lung, it would have the functions of the lung."

"We place the stem cells in the right environment, where they feel comfortable and begin to fully develop. For each tissue, we typically need three or four additional components. For example, for the prostate, we need to add testosterone. For breast tissue, estrogen. Once you understand that, it's easy: you take some tissue, cut it into small pieces, place it in a gel so that it has three dimensions, and then add the growth factors, and that's how you create the organoid."

Drug development has shifted from dependence on flat cell cultures and animal models toward three-dimensional organoids that better mirror human biology. Regulatory policy changed in 2023 when the FDA stopped requiring animal testing in part because organoids can replicate human organ functions. Organoids are small structures grown from stem cells in a supportive, three-dimensional gel with tissue-specific growth factors and hormonal components. Different tissues require distinct signals, such as testosterone for prostate and estrogen for breast. Organoids were first derived from the gut because intestinal mucosa renews rapidly, making gut stem cells especially amenable to cultivation.

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