Investigational Drug May Offer Hope for Endometriosis Pain

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The Endometriosis Research Center (ERC) ( reports that a new, non-hormonal medical therapy is being investigated for the potential treatment of pain associated with the disease. The RAQUEL Study (Randomized Trial Assessing Quinagolide Vaginal Ring for Endometriosis-related Pain), sponsored by Ferring, is a randomized, double-blind, Phase II clinical trial evaluating the efficacy of quinagolide on the reduction of moderate to severe endometriosis-related pain compared to placebo. For enrollment details, visit the sponsor website at

Endometriosis affects an estimated 176 million individuals globally. The disease is a major cause of pain, subfertility, disability and significantly compromised quality of life in those affected. Impaired bowel, urinary, sexual and reproductive functions are common, and the systemic influences of endometriosis can significantly impact the physical, mental, emotional and social well-being of those living with the condition. Multiple comorbidities are also common in those with endometriosis. While the disease most often develops on the pelvic structures, lesions can also be found in distant locations like the lungs. Definitive causes remain elusive, and there is no prevention or universal cure. Diagnosis can only be confirmed surgically, at which time the surgeon can remove the lesions, preferably through excision.

Unfortunately, many individuals struggling with endometriosis face barriers to quality care outside the limited subspecialty centers exclusively focused on treating the disease. As a result, misdiagnosis, fragmented care and persistence of symptoms are common, and many patients will be subsequently placed on hormonal suppression to “manage” their ongoing pain. These suppressive medications only treat some symptoms - temporarily - and all have near-total recurrence rates. “Many of the existing suppressive options for endometriosis pain, like GnRH analogs, are contraindicated to pregnancy, have high costs and significantly adverse side effects,” said Michelle E. Marvel, ERC Founder and Executive Director. “Safer and more effective therapies that can eliminate the actual lesions, prevent recurrence and effectively relieve pain are desperately needed.”

Research has demonstrated that angiogenesis - the growth of new blood vessels - plays an important role in endometriosis. Given the disease’s invasive capacity and proangiogenic factors, the angiogenic process is viewed as a potential target for therapeutic intervention. Quinagolide, a non-ergot, selective dopamine-2 receptor agonist, may diminish Vascular Endothelial Growth Factor (VEGF), a potent angiogenic factor, and result in a reduction in the levels of interleukin-6 (IL-6) as well, which is related to the pathogenesis and clinical severity of the disease. Quinagolide has demonstrated an acceptable safety profile in early studies and, unlike some of the currently available suppressive medications promoted for endometriosis pain, does not affect pregnancy and has no teratogenic effects.

“Treatment options for endometriosis and pelvic pain are very limited. The currently available medical treatments for endometriosis all use a relatively crude approach of suppressing a woman’s estrogen. Unfortunately, endometriosis in some cases produces its own estrogen, rendering the medical treatments ineffective,” said Andrew Cook, M.D., an endometriosis specialist with centers in California and Colorado ( “Optimal surgical treatment requires highly specialized, wide excision of the endometriosis implants, essentially requiring a similar approach to that of cancer surgery, as there is no adjunct treatment to eliminate any disease left behind at surgery. This novel, new approach may provide a new avenue of treatment of endometriosis, either alone or in combination with surgery to eliminate any remaining microscopic disease, with the potential benefit of increasing treatment success rates and decreasing recurrence rates.”

Sponsored by Ferring, the RAQUEL study seeks to evaluate the efficacy of three doses of quinagolide administered as an extended-release vaginal ring compared to placebo on the reduction of moderate to severe endometriosis-related pain. Individuals who have been surgically diagnosed with the disease who may wish to participate can learn more about the study and inclusion criteria at ​


Source: Endometriosis Research Center

About Endometriosis Research Center

The ERC is a 501(c)3 charitable organization that was founded in early 1997 with the vision of addressing the ongoing need for international endometriosis awareness, advocacy, support, education, legislative efforts and research facilitation.