Long-term data on relugolix combination therapy for endometriosis pain show sustained symptom relief and a manageable safety profile, according to Phase 3 clinical trial results evaluated by researchers in the medical community.

Clinical Trial Design and Patient Population

The evaluation stems from the SPIRIT 1 and SPIRIT 2 Phase 3 clinical trials, which spanned 219 community and hospital research centers across Africa, Australasia, Europe, North America, and South America, according to study findings published in The Lancet. Researchers randomized female participants aged 18 to 50 years with surgically, visually, or histologically confirmed endometriosis who experienced moderate to severe pain. Patients received either once-daily oral relugolix combination therapy (relugolix 40 mg, estradiol 1 mg, and norethindrone acetate 0.5 mg), placebo, or a delayed combination treatment over a 24-week double-blind period.

Efficacy Results for Dysmenorrhea and Pelvic Pain

In the SPIRIT 1 trial, 158 out of 212 patients (75 percent) receiving the combination therapy met response criteria for dysmenorrhea at week 24, compared to 57 out of 212 patients (27 percent) in the placebo group, yielding a treatment difference of 47.6 percent according to the published data. Similar efficacy outcomes were tracked for non-menstrual pelvic pain across both trials. Coprimary endpoints measured participant response rates using numeric rating scales and analgesic use over the 24-week treatment window.

Long-Term Extension and Safety Monitoring

Eligible patients who completed the initial 24-week SPIRIT trials had the option to enroll in an ongoing 80-week open-label extension study known as SPIRIT EXTENSION, registered under ClinicalTrials.gov identifiers NCT03654274 and EudraCT 2017-004066-10. Safety evaluations during these extended phases focus heavily on bone mineral density and the return of normal menstruation following treatment cessation. Investigators continue to monitor adverse events and long-term tolerability parameters in the patient cohorts.

Frequently Asked Questions

What is relugolix combination therapy?

Relugolix combination therapy consists of relugolix, an oral gonadotropin-releasing hormone (GnRH) receptor antagonist, combined with estradiol and norethindrone acetate to mitigate bone mineral density loss and vasomotor symptoms.

Who was eligible for the SPIRIT trials?

The trials enrolled women aged 18 to 50 with surgically or histologically confirmed endometriosis who reported moderate to severe dysmenorrhea and non-menstrual pelvic pain.

What are the primary endpoints of the study?

The coprimary endpoints evaluated the proportion of patients achieving clinically meaningful reductions in dysmenorrhea and non-menstrual pelvic pain at 24 weeks based on validated rating scales and rescue analgesic use.