The threat of fungal infections is growing. Why is it so hard to make new drugs?

Last summer, the Food and Drug Administration denied an application for a new antifungal drug called olorofim, sending it back to the company with a request for more data. If approved, it would have been the first time since the early 2000s that the FDA cleared an antifungal that works in an entirely novel way.

It couldn’t come at a more important time: In recent years, the potential danger fungal infections pose to human health has become more and more apparent, as fungi either evolve to evade treatments or spread beyond their typical geographical regions. Doctors around the world are desperate for new medicines to combat the growing threat.

“The problem with fungal diseases has gotten to the point where the World Health Organization has recognized it as a widespread threat,” said Dr. Arturo Casadevall, a microbiologist and chair of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health in Baltimore.

In late 2022, the WHO published their first-ever list of fungal priority pathogens — 19 fungi the agency said pose a significant threat to human health. It includes the highly drug-resistant yeast Candida auris, which infects critically ill hospital patients; in 2021 alone, the number of infections in the U.S. tripled, according to the Centers for Disease Control and Prevention.

Also on the WHO’s list is coccidioides, a fungus that causes an infection called Valley fever. Historically found in the southwestern U.S., scientists have predicted that its range could spread north to the Canadian border and east to the Great Plains by the end of the century.

The situation is complicated by the impact fungi can have on the global food system.

Fungi thrive in soil, and fungal diseases have