Levels of progesterone receptor in endometrial lesions can help predict which endometriosis patients are more likely to respond to progestin-based therapy, a study shows.
The study, “Progesterone Receptor Status Predicts Response to Progestin Therapy in Endometriosis,” was published in the Journal of Clinical Endocrinology & Metabolism.
Women with endometriosis usually have significant pain, for which progestin-based therapy — such as oral contraceptives — is the initial treatment.
However, the general response to progestin-based therapy among these patients is often variable and unpredictable. Therefore, finding biomarkers that can predict the response to progestin-based therapy can help physicians design a treatment tailored to the patient.
As progestin acts by binding to the progesterone receptor (PR) in cells, the scientists hypothesized that PR levels in endometrial lesions can be a predictive marker for response to this type of therapy. They then conducted a retrospective study with 52 patients who had histologically (tissue analysis) confirmed endometriosis and a documented response to hormonal therapy.
Researchers performed immunohistochemistry (IHC), a method that uses antibodies to identify specific proteins, on sections of endometrial lesions. They then used the Histo (H)-score to quantify the levels of PR in these lesions. The response to progestin-based therapies was determined by reviewing medical records.
Patients were categorized into three groups — high PR levels (H-score higher than 80, seven patients), medium PR levels, (H-score of 6-80, 28 patients) and low PR levels (H-score equal to or lower than 5, 17 patients).
Results indicated that, as hypothesized, the H-score was higher in responders to treatment.
The threshold of PR >80 was associated with a 100% positive response predictive value. The threshold of PR <5 was associated with a 94% negative predictive value.
“Progesterone receptor status is strongly associated with response to progestin-based therapy,” the authors wrote.
“Receptor status in endometriosis could be used in a similar way to how estrogen receptor and progesterone receptor status is used in breast cancer for personalizing treatment options,” Dr. Valerie A. Flores, MD, Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, Yale University, and the study’s author, said in a press release.
“Such an approach to endometriosis management could better determine which medication each individual patient responds to and minimize delays in providing the optimal medical therapy.
“Examining progesterone receptor status in endometriotic lesions may allow for a novel, targeted approach to treating endometriosis,” Flores concluded.