Could a Modified Tapeworm Drug Treat Endometriosis? Mouse Study Shows Promise

A modified version of the tapeworm drug niclosamide reduced inflammation, eased pain symptoms and slowed the growth of endometriosis lesions in laboratory mice, according to an early-stage study.

Although the treatment has not yet been tested in people, researchers are working toward clinical trials that could evaluate its safety and effectiveness in patients with endometriosis.

How endometriosis affects the body

Endometriosis is a chronic, hormone-driven disease in which tissue similar to the uterine lining grows outside the uterus. These growths, known as lesions, can cause inflammation, chronic pelvic pain, heavy menstrual bleeding and infertility.

The condition affects roughly 10% of women of reproductive age—an estimated 190 million people worldwide, according to researchers.

Current treatments are designed to control symptoms rather than cure the disease. Hormonal medications can limit menstrual cycling, lesion growth and inflammation, but they may cause side effects including nausea and mood changes. Surgery can remove lesions, although they often return.

Rogue immune cells may be a target for endometriosis treatment

Previous research identified a group of immune cells that are concentrated in endometriosis lesions. These cells can intensify inflammation and promote the growth of abnormal tissue.

The cells carry a chemical marker called a folate receptor, which gives researchers a potential way to target them without affecting other tissues.

How researchers modified niclosamide

Niclosamide is approved by the U.S. Food and Drug Administration to treat tapeworm infections. Researchers have also investigated whether the drug could be useful against other conditions, including cancer and Parkinson’s disease.

However, niclosamide has several limitations. It does not dissolve easily in water, does not remain in the body for long and does not naturally target the cells involved in endometriosis.

To address these problems, researchers collaborated with Anjali Sharma, a nanomedicine expert at the University of Michigan. Sharma used a chemical technique known as click chemistry to attach niclosamide molecules to large, tree-shaped structures called dendrimers.

The dendrimers improved the drug’s ability to dissolve in blood. The researchers also added folic acid, allowing the modified drug to bind to folate receptors on the targeted immune cells.

“The drug is bound in the systemic circulation so that nothing happens until it enters the diseased cells.”

Anjali Sharma, University of Michigan nanomedicine expert

Sharma compared the delivery system to a transportation service: the dendrimer acts like an Uber, folic acid provides the GPS coordinates and the drug is the passenger. Once inside the targeted cells, the treatment is slowly released over roughly two weeks.

What the mouse study found

The research team tested the modified drug in mice with lesions designed to mimic those seen in human endometriosis.

Imaging showed that the treatment reached the affected endometrial tissue and did not accumulate in other organs, including the liver. A single injection dramatically reduced pain symptoms compared with untreated mice.

The treatment also slowed the formation of new lesions. In some mice, the growth of new lesions stopped completely.

“We reported that niclosamide inhibits the progression of endometriosis and suppresses inflammatory mechanisms and cytokine secretion,” said study co-author Kanako Hayashi, a professor in the Department of Molecular Biosciences at Washington State University.

Why human trials are still needed

The findings are preliminary and cannot yet show whether the treatment will work in people. Mice do not naturally menstruate or develop endometriosis, so additional research is needed to determine whether the results translate to human disease.

Ioannis Simitzdelis, a postdoctoral fellow at the Center for Reproductive Health and Inflammation Research at the University of Edinburgh who was not involved in the study, said the research represents a promising step toward new treatments.

The next steps include repeating the experiments in a larger group of animals and, if the results remain encouraging, beginning a phase 1 clinical trial. The first human trial would primarily assess the treatment’s safety, while later trials would examine whether it effectively reduces endometriosis symptoms and lesion growth.

Researchers say they have already received hundreds of emails from patients asking to participate in future studies.

“Endometriosis is an under-researched, under-recognized and under-funded disease that we hope will soon be solved,” Hayashi said.

Study: Dhull, A., Shi, M., Harvey, M. E., Page, T. M., Sharma, R., Goody, K. J., Dar, A. I., Moawad, N. S., Sirohi, V. K., Cooke, P. S., Hayashi, K., and Sharma, A. (2026). “Niclosamide delivery to FRB-expressing macrophages via 2-deoxyglucose dendrimers attenuates endometriosis progression and associated hyperalgesia.” Advanced Healthcare Materials.

This article is for informational purposes only and does not provide medical advice.