Endometriosis could be controlled with monthly antibody injections

An antibody that eases inflammation partly reverses endometriosis when given as a monthly injection. After successful tests in monkeys, it is now being trialled in people.

Endometriosis occurs when tissue from the endometrium – the lining of the uterus – grows in other parts of the body, usually inside the pelvis. It affects around 1 in 10 women of a reproductive age and can cause severe pain and infertility.

Ayako Nishimoto-Kakiuchi at Chugai Pharmaceutical, a company in Japan, and her colleagues found that endometriosis tissue contains elevated levels of a gene called IL8, which produces an inflammatory protein called interleukin-8 (IL-8). This made them wonder whether blocking IL-8 could reduce the inflammation associated with endometriosis and slow or even reverse its progression.

To find out, the researchers developed an antibody called AMY109 that inhibits IL-8. They then surgically induced endometriosis in a group of macaques by moving tissue from their endometrium to other sites within the pelvis, mimicking endometriosis lesions in people.

Eleven of these monkeys received an injection of AMY109 and six received a placebo every four weeks for six months.

By the end of the study, the endometriosis lesions in the AMY109-treated monkeys had shrunk to about half their original size, whereas those in the placebo group continued to grow.

To investigate the treatment’s safety, the researchers injected high doses of AMY109 into male macaques and females without endometriosis. AMY109 had no impact on a range of health measures, including the animals’ weight and food consumption, as well as the males’ sperm quality and the females’ menstrual cycles.

Chugai Pharmaceutical is now running a clinical trial of AMY109 in human volunteers with and without endometriosis in Japan and Taiwan to further evaluate its safety and investigate if it shrinks endometriosis lesions in people.

This will be important in order to establish whether there are any human side effects, says Pav Nanayakkara at Jean Hailes East Melbourne, Australia.

Endometriosis is usually treated with hormone-suppressing drugs that can shrink lesions, but often cause side effects such as headaches and mood swings. They also prevent menstruation, making them unsuitable for anyone trying to become pregnant.

Surgery can also remove endometriosis lesions, but they can return.

“The researchers [who are developing AMY109] give hope to the long-term goal of providing a non-invasive treatment to help manage the symptoms of endometriosis,” says Nanayakkara.