Researchers Test New Drug to Block Pain Receptors in Endometriosis Patients

Phase II trial will help determine optimal dose of P2X3 antagonist

James Liu, MD

University Hospitals researchers and Bayer Pharmaceuticals are currently involved in a phase II clinical trial of a drug that could offer endometriosis patients a new treatment option.

“We are trying to get these newer drugs and compounds on the market in hopes of really helping women overall achieve a better life,” says James H. Liu, MD, Chair of the Department of Obstetrics and Gynecology at UH Cleveland Medical Center and the Arthur H. Bill Chair of Reproductive Biology at Case Western Reserve University School of Medicine.

A DIFFERENT KIND OF TREATMENT

Endometriosis can cause disabling pain, severely impacting quality of life. Women with the condition can undergo surgical treatment and use medication to suppress the growth of endometrial tissue. These treatments do not always address a patient’s pain, and they can affect estrogen and progesterone levels.

Researchers have identified a group of pain receptors associated with the pelvic pain caused by endometriosis, and the drug currently undergoing the phase II clinical trial at UH blocks those receptors. The current clinical trial will help to determine the optimal dose of the P2X3 antagonist, taken as an oral tablet, for effective treatment and minimal side effects.

Researchers are in the process of screening and recruiting women for the clinical trial, according to Dr. Liu. The target candidates are women who have been diagnosed via laparoscopy and are experiencing significant pain due to endometriosis. The trial will not include pregnant women or women who are trying to conceive.

The trial will place participants into three groups. One group will be treated with the P2X3 antagonist, while a comparative group will receive the FDA-approved drug Elagolix, which suppresses the growth of endometrial tissue. The third group will receive a placebo.

LOOKING TO THE FUTURE

While the phase II clinical trial is relatively small, it is laying the groundwork for the next step. “We are asking the question: what is the right dose we should be targeting to use in a phase III trial?” Dr. Liu says. In the future, researchers will want to know how effective the drug is at reducing endometriosis pain in a larger population.

This drug could represent a future option for two large groups of endometriosis patients. First, any women who have decided not to purse pregnancy in the immediate future could opt for this medication to manage their pain rather than using a medication to suppress tissue growth. “They may not want the suppressive medications because of the significant side effects, like hot flashes and menopausal symptoms,” Dr. Liu says.

The second group that could potentially benefit from this drug includes women who do not need suppressive medications. They may be diagnosed with mild endometriosis but still experience significant pain. The P2X3 antagonist could help to manage those painful symptoms.

Though further in the future, research may be done to better understand how this drug would affect pregnant women and women trying to conceive.

UH is also advancing patient care and clinical research for endometriosis patients through the UH Endometriosis-Pelvic Pain Center of Excellence. This center — led by Megan Billow, DO, Division of Minimally Invasive Gynecologic Surgery, Department of Obstetrics and Gynecology, UH Cleveland Medical Center and Assistant Professor, Obstetrics and Gynecology, School of Medicine — develops individualized care plans for endometriosis patients. The center’s fellowship-trained physicians are actively exploring clinical research on new drugs for endometriosis treatment.

UH supports this kind of research in gynecology and many other specialties through its Clinical Research Center. The clinical trials unit manages paperwork, contracts with pharmaceutical companies like Bayer, and streamlines the Institutional Review Board process. “The UH clinical trials unit provides a lot of detailed, necessary components to starting clinical trials that investigators would otherwise have to do on their own,” Dr. Liu says.

Many other healthcare organizations have attempted to launch this kind of program, to varying degrees of success, according to Dr. Liu. But, the UH model is one of the most successful in his experience. “It is overall part of the goal of UH to promote development of new compounds and push the envelope in terms of helping to bring new and innovative medications to market for specific disease states.

To contact Megan Billow, call 216-553-1537.