When Maria Chen first read about mebendazole, she thought it was a mistake. The drug treats parasitic worms in children, not lung cancer. Yet in a lab in Singapore, mice with drug-resistant tumors were responding to a combination of this old dewormer and a targeted lung cancer drug. Their tumors shrank. Their cancer cells faltered. And scientists began to wonder: could an inexpensive, widely available pill help beat one of the world’s deadliest cancers?
Lung cancer kills more people each year than any other cancer—1.8 million in 2020 alone. For patients with a specific mutation in the EGFR gene, drugs like gefitinib once offered hope. But too often, the cancer adapts, becoming resistant and unstoppable. Now, researchers have found that pairing gefitinib with mebendazole, a deworming drug used for decades, can break down the cancer’s defenses.
The breakthrough came from testing on HCC827 GR5 cells—lung cancer cells with EGFR mutations that no longer respond to gefitinib. In mice, gefitinib alone left 92.7% of these resistant cells alive. Mebendazole alone allowed 80% survival. But together, even at a low dose, they slashed cell survival to just 37.7%. The combo didn’t just slow the cancer—it overwhelmed it.
The reason lies in how the two drugs work. Gefitinib blocks the signal telling cancer cells to grow. Mebendazole attacks the cell’s internal skeleton, called microtubules, which it needs to divide and move proteins. Together, they create chaos inside the cell. DNA damage spikes. Single-strand and double-strand breaks pile up. The cancer’s stress-buffering system—the very thing that helps it survive—collapses under the pressure.
This isn’t the first time mebendazole has surprised scientists. Known for its safety and low cost, it’s been on the World Health Organization’s list of essential medicines since 1977. Now, it may have a new role. The study, published in PLOS One, shows that repurposing existing drugs can be a fast, affordable path to new treatments—especially for cancers that evolve resistance too quickly.
The road to human trials is still ahead, but the results are hard to ignore. If this combo works in people, it could extend lives without the high cost of new biotech drugs. For millions facing lung cancer, especially in low-resource countries, that could make all the difference. And it might start with a pill that’s already in medicine cabinets around the world.