In a laboratory and animal studies reviewed by Bond University researchers, a humble deworming drug has revealed an unexpected second act: fighting brain cancer. Mebendazole, an oral medicine used for decades to treat threadworm, roundworm, and whipworm infections, showed surprising promise against some of the deadliest tumors known to medicine. A systematic review of 22 studies, published in the British Journal of Clinical Pharmacology, found that the drug consistently slowed tumor growth in cells and animal models, and in one striking example, when combined with radiotherapy, it left more than half of treated mice tumor-free over the long term.
Brain cancers like glioblastoma, diffuse midline glioma, medulloblastoma, and meningioma remain among the most difficult cancers to treat. Even with aggressive intervention—surgery, radiotherapy, and chemotherapy—only 22 percent of patients survive five years. For glioblastoma, the most common and aggressive form, the median survival is just 12 to 16 months after diagnosis. The stakes could hardly be higher, which is why researchers are examining every possible avenue to improve outcomes.
What makes mebendazole particularly intriguing is its multi-pronged approach. Laboratory evidence suggests the drug attacks tumor cells through at least six distinct mechanisms simultaneously. It disrupts the structural scaffolding that cancer cells need to divide, blocks the formation of new blood vessels that feed tumors, disrupts the chemical signals that drive tumor growth, and impairs the DNA repair processes that allow tumors to survive radiotherapy. "I thought it was interesting that it seemed to act on the cancer cells in several different ways rather than just one single pathway," said Dr. Liam O'Callaghan, a cancer researcher at Bond University and one of the paper's authors. The drug also appears to enhance the effects of both chemotherapy and radiotherapy, potentially making existing treatments more effective.
Yet the path from laboratory promise to human medicine remains uncertain. Early clinical trials in both adults and children show that high doses of oral mebendazole are generally safe—a crucial starting point—but the evidence that it actually slows or reduces tumor growth in humans remains modest, inconsistent, and inconclusive. This gap between animal models and human results is familiar to anyone who follows cancer research, but it is also humbling. "We've got quite a lot of research in animals and cell lines which look promising, but the human studies, it's still quite limited," Dr. O'Callaghan acknowledged.
The authors are careful not to overstate their findings. They concluded that mebendazole should be regarded as a promising but unproven candidate and should not be used outside research settings—a caution that protects patients while leaving the door open for further investigation. The real work now lies ahead: designing larger, better-designed clinical trials that can determine whether this old deworming drug might genuinely help brain cancer patients. Mebendazole joins a growing roster of repurposed medicines being studied for cancer treatment, alongside metformin and aspirin, suggesting that sometimes the most valuable cures may already be sitting on pharmacy shelves, waiting for a second chance.