A medicine used for decades to treat intestinal worms slowed the growth of drug-resistant lung tumors in mice when it was given alongside a standard targeted cancer drug. The study, published Oct. 8 in PLOS ONE, tested the deworming drug mebendazole with gefitinib against a form of lung cancer that had stopped responding to gefitinib alone.

In the mice, tumors on the combination took about 25 days to double in size, compared with 6.2 days for untreated tumors and 15.5 days for tumors on gefitinib alone. The combination did not eliminate the tumors.

The finding is early, preclinical work in mice and human cancer cells in the lab, not people. The researchers say much more testing is needed, and no one should take mebendazole for cancer outside a supervised clinical trial.

Repurposing an Old Drug Against a New Problem

The study focused on EGFR-mutant non-small cell lung cancer, a form of the disease driven by changes in a growth-signal protein called EGFR. Drugs such as gefitinib block that signal, but tumors often find ways around them and become resistant over time.

Mebendazole, sold in the United States under brand names including Emverm and Vermox, is a prescription medicine used to treat roundworm, whipworm, pinworm and hookworm infections, according to MedlinePlus from the National Library of Medicine. In this study, researchers targeted its ability to disrupt microtubules, the internal scaffolding that cells use to divide.

The research team, from RAK Medical and Health Sciences University in the United Arab Emirates with collaborators in India and the United Kingdom, wanted to know whether attacking cancer cells on two fronts could overcome resistance. "Our idea was to attack the cancer from two directions simultaneously," researcher Shakta Mani Satyam told ScienceAlert.

Resistance is one of the central problems in modern cancer care. A targeted drug can shrink a tumor for months, but cancer cells that survive often carry or acquire changes that let them keep growing despite the drug. Doctors then switch to other treatments, and each switch can bring new side effects and fewer remaining options. Finding ways to restore or extend the usefulness of existing targeted drugs is a major goal for researchers.

Results in Cells and Mice

In lab dishes, the team tested human lung cancer cells that had become resistant to gefitinib. After 72 hours, gefitinib alone left about 93% of cells alive, and a low dose of mebendazole alone left about 80%. The two together cut survival to about 38%, according to the paper.

The combination also caused far more DNA damage in the cancer cells than either drug alone, consistent with the idea that the cells struggled to copy their DNA safely while both drugs were at work. A higher dose of mebendazole alone killed a similar share of cells, which raises the question of whether the benefit comes from the pairing or simply from mebendazole's own effect.

In the mice, which carried tumors grown from the resistant human cells, eight animals received each treatment over 40 days. The combination delayed tumor growth by about 18.8 days compared with untreated mice, versus 9.3 days for gefitinib alone and 4.1 days for mebendazole alone. Mice on the combination lost about 2 to 3% of their body weight for a short time and then recovered.

The Fine Print on an Early Result

The study has major limits, and the authors list many of them. It tested a single resistant cancer cell line in one mouse model, and it did not test patient-derived tumors or resistance to osimertinib, a newer EGFR drug now widely used. The researchers did not formally measure whether the two drugs work together synergistically, and they did not directly track the DNA-copying failure they proposed as the mechanism.

Mebendazole also poses a practical challenge. The body absorbs it unevenly when taken by mouth, so it is not clear whether people could reach effective levels safely. Long-term safety, effects on organs and interactions with other cancer drugs were not established in the study.

Satyam said the team cannot yet say conclusively that mebendazole fully restores sensitivity to gefitinib. In other words, the study shows the pairing slowed resistant tumors in mice, but not yet why, or whether the same effect would appear in human patients. The paper reports no specific funding and no competing interests.

A Hopeful Lead, Not a Treatment

Drug repurposing appeals to researchers because older medicines already have years of safety data, which can speed testing. But many repurposed drugs that look promising in mice never work in people, and cancer is especially hard to translate from animal models — a pattern that makes caution essential here.

For patients and families, the most important message is to avoid self-medicating. Mebendazole is a prescription drug with side effects, and taking it alongside cancer treatment without medical supervision could cause harm or interfere with therapy. Anyone interested in drug-repurposing research should talk with their oncologist about clinical trials, which can be searched through the federal ClinicalTrials.gov registry.

Lung cancer patients whose disease has stopped responding to targeted drugs face difficult choices, which is why even early findings draw attention. Their care decisions belong with their medical team, not with headlines about a mouse study.

The next steps the authors describe are testing more cell lines and patient-derived models, checking the combination against osimertinib resistance and studying drug levels and safety. The bottom line is that a familiar worm medicine showed promise against resistant lung tumors in mice — an encouraging lead that is still years away from any possible use in patients.

What Readers Want to Know

What did the study find?

In mice with drug-resistant lung tumors, combining the deworming drug mebendazole with the cancer drug gefitinib slowed tumor growth more than either drug alone. Tumors on the combination took about 25 days to double in size versus 6.2 days untreated.

Did the treatment cure the tumors?

No. The tumors kept growing, just more slowly. The study was done in mice and lab-grown cells, not people.

What is mebendazole?

A prescription medicine used to treat intestinal worm infections such as roundworm, whipworm, pinworm, and hookworm. It is sold in the U.S. under brand names including Emverm and Vermox.

Should cancer patients take mebendazole?

No, not on their own. The research is early, and taking it without medical supervision could cause harm or interfere with treatment. Patients should discuss clinical trials with their oncologist.

What type of lung cancer was studied?

EGFR-mutant non-small cell lung cancer that had become resistant to gefitinib, a targeted EGFR-blocking drug.

What are the next steps?

Testing in more cancer models, including patient-derived tumors and resistance to the newer drug osimertinib, plus studies of safe and effective dosing.