Trial results for a Phase 3 study evaluating relugolix combination therapy for contraception were posted on ClinicalTrials.gov on 2025-02-25. The study reported a cumulative 1-year pregnancy rate of 1.2 percent and an At-Risk Pearl Index of 1.27 pregnancies per 100 woman-years.
Background
The study investigated relugolix combination therapy, specifically relugolix, estradiol hemihydrate, and norethindrone acetate, for contraceptive efficacy. The trial focused on women with uterine fibroids or endometriosis who were at risk for pregnancy, aiming to assess the therapy's effectiveness in preventing conception.
Trial design
The completed Phase 3 study (NCT04756037) enrolled 1164 participants. Its primary purpose was to assess the contraceptive efficacy of relugolix combination therapy in women with uterine fibroids or endometriosis who were at risk for pregnancy. The study evaluated various measures of contraceptive effectiveness, including different Pearl Index calculations and cumulative pregnancy rates.
Key results
The trial reported several key measurements for the Relugolix/E2/NETA group:
- Contraceptive Efficacy as Assessed by the At-Risk Pearl Index (PI): 1.27 pregnancies per 100 woman-years.
- Contraceptive Efficacy as Assessed by the Modified At-Risk PI: 1.10 pregnancies per 100 woman-years.
- Contraceptive Efficacy as Assessed by the Gross PI: 1.04 pregnancies per 100 woman-years.
- Contraceptive Efficacy as Assessed by the Method Failure PI: 0.64 pregnancies per 100 woman-years.
- Cumulative 1-Year Pregnancy Rates: 1.2 percent.
- The number of participants who did not complete 13 treatment cycles was 667 Participants.
- Percent Change in Bone Mineral Density (BMD) from Baseline to 6 and 12 Months On-Treatment (Least Squares Mean with Standard Error):
- -0.65 percentage change from baseline (SE 0.092)
- -0.72 percentage change from baseline (SE 0.116)
- -0.36 percentage change from baseline (SE 0.081)
- -0.47 percentage change from baseline (SE 0.101)
- -0.36 percentage change from baseline (SE 0.124)
- -0.56 percentage change from baseline (SE 0.138)
What this means
The completion of this Phase 3 study provides detailed efficacy data for relugolix combination therapy as a contraceptive option. The reported Pearl Index values and the 1-year pregnancy rate of 1.2 percent indicate its effectiveness in preventing pregnancy. The observed changes in bone mineral density, while negative, are presented with their standard errors and would be considered in the context of the therapy's overall safety profile and the known effects of hormonal contraceptives. These results could support future regulatory evaluations for the use of relugolix combination therapy in contraception.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for the study NCT04756037, titled "Study of the Safety and Contraceptive Efficacy of Relugolix Combination Therapy in Women With Uterine Fibroids or Endometriosis Who Are at Risk for Pregnancy", were posted on 2025-02-25 on clinicaltrials.gov.