Two new drugs are the first to endometriosis treatment without harming fertility. Researchers hope they will one day help the 10 per cent of women of reproductive age who suffer from the condition, which can cause infertility and chronic pain, and costs the US $20 billion dollars each year.Endometriosis is a relatively common condition in which cells that normally grow only in the uterus travel into the abdominal cavity, where they form lesions and cysts, scarring organs such as the ovaries, fallopian tubes, bladder and rectum. These lesions also lead to inflammation and nerve growth, causing abdominal pain.
The condition causes infertility in up to 50 per cent of women who have it. Surgically removing lesions or cysts can temporarily relieve pain until they grow back, but a longer-term solution is to reduce levels of the hormone oestrogen throughout the body. Like healthy endometrial tissue in the uterus, the lesions and cysts rely heavily on oestrogen to grow and survive, but reducing the hormone throughout the body has unfortunate side effects, such as menopausal symptoms and infertility. Women with endometriosis who want to have children may face a catch 22 situation – they need to treat their condition to conceive, but this hormonal treatment makes them infertile. Stop the treatment and fertility may return, but so too do the lesions.
When given to mice, the drugs – called chloroindazole and oxabicycloheptene sulfonate – reduced the size of existing endometrial lesions and stopped the growth of new lesions. The team thinks that the drugs work in part by interfering with inflammation pathways.The compounds prevented the development of new nerves in the lesions and also decreased pain. Crucially, neither of the drugs altered the rodents’ fertility or the health of their pups.The drugs also had a similar effect on human endometrial tissue taken from cysts that had been removed from patients. “We are hopeful that these compounds will prove to be useful for women with this common disease,” says Katzenellenbogen, although she adds that it may be several years before human trials can start.
Christian Becker, a consultant gynaecologist and endometriosis specialist at the University of Oxford, says the research is encouraging. “It’s fascinating to see the drugs had very little effect on the [normal] endometrial tissue and the pups, but we have to wait to see whether this will hold up in humans.”He says it would be good to avoid surgery if possible – he has seen people who have had to endure ten rounds of keyhole surgery to treat the condition. “It’s good that this is getting some attention as it affects so many people, but it’s not historically been a cool thing to talk about,” he says.