In the near term, traditional hormonal drugs and surgery (a last resort) will continue to be the main treatments for endometriosis, in which tissue from the lining of the uterus grows around the ovaries, Fallopian tubes and elsewhere, triggering pain and infertility. Overall, an estimated 10 to 12 million American women of reproductive age have chronic pelvic pain, most of which is caused by endometriosis.
But new, non-hormonal drugs are now being tested in baboons, and even the hormonal options are improving. In March, the US Food and Drug Administration announced approval of depo-subQprovera104, a new, easier-to-use formulation by Pfizer of an existing injectable contraceptive.
Both the old and new Depo-Provera drugs work by stopping the pituitary gland from pumping out the hormones that stimulate ovulation, essentially creating a state of “pseudo pregnancy.” Without ovulation, the ovaries also pump out less estrogen, and less estrogen means less stimulation of uterine tissue, both inside and outside the uterus. The result is less swelling and pain.
On the downside, these hormonal drugs – and a stronger one called Lupron – can decrease bone mineral density, but so far this has not been linked to an actual increase in fractures, said Dr. Lee Shulman, a reproductive geneticists at Northwestern University and a consultant to Pfizer on the new drug formulation.
Researchers are now pursuing other hormonal approaches, including the use of selective estrogen receptor modulators such as Evista and other drugs that block estrogen known as aromatase inhibitors.
A completely different approach is also showing promise in baboons – controlling pelvic inflammation and pain by blocking certain chemicals pumped out by the immune system. If all goes well with this and other research, “the landscape for medical treatment for endometriosis will be dramatically different in the next five to seven years,” said Dr. Mark Hornstein, director of the division of reproductive endocrinology and infertility at Brigham and Women’s Hospital.