Trial results for a Phase 3 study evaluating relugolix combination therapy for contraception were posted on ClinicalTrials.gov on 2026-05-13. The study assessed contraceptive efficacy, reporting an At-Risk Pearl Index of 1.27 pregnancies per 100 woman-years.
Background
The study investigated relugolix combination therapy for its contraceptive efficacy. This therapy was evaluated in women who were at risk for pregnancy, including those with uterine fibroids or endometriosis, to assess its effectiveness in preventing conception.
Trial design
The completed Phase 3 study (NCT04756037) enrolled 1164 participants. The trial's primary purpose was to assess the contraceptive efficacy of relugolix combination therapy in women at risk for pregnancy.
Key results
The trial reported several key measurements related to contraceptive efficacy and bone mineral density for the Relugolix/E2/NETA group:
- Contraceptive Efficacy of Relugolix Combination Therapy as Assessed by the At-Risk Pearl Index (PI): 1.27 pregnancies per 100 woman-years
- Contraceptive Efficacy of Relugolix Combination Therapy as Assessed by the Modified At-Risk PI: 1.10 pregnancies per 100 woman-years
- Contraceptive Efficacy of Relugolix Combination Therapy as Assessed by the Gross PI: 1.04 pregnancies per 100 woman-years
- Contraceptive Efficacy of Relugolix Combination Therapy as Assessed by the Method Failure PI: 0.64 pregnancies per 100 woman-years
- Contraceptive Efficacy of Relugolix Combination Therapy as Assessed by the Cumulative 1-Year Pregnancy Rates: 1.2 percent
- Number of Participants Who Do Not Complete 13 Treatment Cycles: 667 Participants
- Percent Change in Bone Mineral Density From Baseline to 6 and 12 Months On-Treatment: -0.65 percentage change from baseline (Standard Error 0.092)
- Percent Change in Bone Mineral Density From Baseline to 6 and 12 Months On-Treatment: -0.72 percentage change from baseline (Standard Error 0.116)
- Percent Change in Bone Mineral Density From Baseline to 6 and 12 Months On-Treatment: -0.36 percentage change from baseline (Standard Error 0.081)
- Percent Change in Bone Mineral Density From Baseline to 6 and 12 Months On-Treatment: -0.47 percentage change from baseline (Standard Error 0.101)
- Percent Change in Bone Mineral Density From Baseline to 6 and 12 Months On-Treatment: -0.36 percentage change from baseline (Standard Error 0.124)
- Percent Change in Bone Mineral Density From Baseline to 6 and 12 Months On-Treatment: -0.56 percentage change from baseline (Standard Error 0.138)
What this means
The results from this Phase 3 trial indicate that relugolix combination therapy demonstrates contraceptive efficacy, with the At-Risk Pearl Index reported at 1.27 pregnancies per 100 woman-years. Other measures of efficacy, such as the Modified At-Risk PI at 1.10 and the Gross PI at 1.04, further support its potential as a contraceptive option. The cumulative 1-year pregnancy rate was 1.2 percent. Additionally, the trial provided data on bone mineral density, showing small percentage decreases from baseline ranging from -0.36 to -0.72 across different measurements, which will be important for evaluating the overall safety profile of long-term use. The finding that 667 participants did not complete 13 treatment cycles suggests a need for further analysis into reasons for discontinuation.
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 2026-05-13 on clinicaltrials.gov.