Real-World Relugolix Adherence Rates Are High in Patients on Medicare With Prostate Cancer

More than 90% of patients on Medicare with prostate cancer adhered to relugolix (Orgovyx) through 24 months when receiving therapy regardless of metastatic disease status, supporting the use of the androgen deprivation therapy (ADT) in this patient population, according to findings from a real-world study presented at the 2025 Genitourinary Cancers Symposium.1

The retrospective cohort study found that the probability of being adherent as well as persistent to relugolix in the first 3 months was 86% in each group. Respective adherence and persistence rates among those with metastatic (n = 1599) vs nonmetastatic (n = 3512) disease who had at least an 80% proportion of days covered were as follows at 6-months (82% vs 76%), 9-months (71% vs 55%), 12-months (67% vs 49%), 18-months (58% vs 38%), and 24-months (55% vs 28%). Notably, in both groups of patients, rates of adherence improved the longer patients received therapy; the overall rate of adherence was 93% and rates were 90% at month 3 and 98% at month 24.

Additionally, patients with metastatic prostate cancer (n = 1671) remained on relugolix for longer compared with patients who had nonmetastatic disease (n = 3603) as the median duration of relugolix was 9 months (IQR, 5-15) in the metastatic cohort vs 7 months (IQR, 4-12) and in the nonmetastatic group. The median follow-ups were 14 months (IQR, 8-23) and 15 months (IQR, 9-23), respectively.

“[The] mean (standard deviation) time to discontinuation [was] 10.9 (8.1) and 9.2 (6.8) months, respectively (log-rank test, P < .0001),” Rana R. McKay, MD, FASCO, medical oncologist, UC San Diego Health, and professor, Department of Medicine and Urology, UC San Diego School of Medicine, and lead study author, wrote in a poster presentation of the data. “These findings, along with the adherence results from the randomized, phase 3 HERO trial [NCT03085095], support the use of relugolix in patients with prostate cancer.”

Background to the Study and Evaluating Persistence/Adherence Outcomes

Relugolix is the only oral once-daily dosed ADT and is a highly, selective gonadotropin-releasing hormone receptor antagonist. Data from HERO showed that the treatment adherence rate was more than 99% with relugolix and 90.2% of the patients completed 48 weeks of treatment compared with 89.0% of those who received leuprolide.2 Although the adherence rate to relugolix was greater than 99% in HERO, investigators of the retrospective study noted that further research was warranted to understand persistence and adherence rates associated with oral ADTs outside of the clinical trial setting.1

Patients with metastatic and nonmetastatic prostate cancer were evaluated separately in this analysis during the study period of December 1, 2019, to December 31, 2023, as the treatment protocols for these groups differ; those with recurrent nonmetastatic disease receive intermittent ADT and those with metastatic disease receive continuous ADT as the backbone of their treatment. Those included in the study had initiated relugolix and were in the US Medicare fee-for-service beneficiary population with prostate cancer (n = 5274). The baseline period was 1 year before the index date, defined as the first observed prescription fill of relugolix. Patients must have filled 2 or more pharmacy claims for the ADT to be evaluated in the study.

Additionally, patients in the analysis were adult males with at least 1 diagnosis code for prostate cancer based on International Classification of Diseases, 10th Revision, Clinical Modification, in the baseline period through 90 days after the index date. Exclusion criteria included those who had bilateral orchiectomy, participated in a clinical trial, or had been diagnosed with other cancers aside from nonmelanoma skin cancer during the baseline period.

“Persistence on relugolix was assessed from index date to first discontinuation, defined as the earliest of 1) switch to a different ADT, 2) a gap of [at least] 90 days between prescription end and next relugolix claim, 3) death, or 4) end of the study period,” McKay and coauthors noted.

The study defined adherence using a proportion of days covered calculation of at least 80% which was assessed as the “percentage of nonoverlapping days patients had access to relugolix based on prescriptions filled and days supplied.” Additionally, calculations were adjusted for inpatient and skilled nursing facility stays, and adherence outcomes were assessed via 2 ways. The first way evaluated them at 3-, 6-, 9-, 12-, 18-, and 24-months among those with follow-up where outcomes “provide the probability of being both adherent and persistent on relugolix in each time period, provided that patients did not die during the entirety of the time period.” Second, they were examined every 3 months through month 24 following the index date among patients who persisted on the ADT where “outcomes provide the proportions of patients adherent on relugolix while remaining on therapy.”

Baseline Patient Characteristics and Limitations of the Retrospective Analysis

Of the 5274 patients included in the study, 32% had metastatic disease and 68% had nonmetastatic. Patients had previously received ADT therapy (39% vs 21%), were predominately White (81% vs 79%), were eligible for the Medicare Part D low-income subsidy (11% vs 12%), and had a COVID-19 diagnosis during the baseline period (10% vs 10%), respectively. Additionally, the median age was 75 years in both arms.

Regarding limitations of the study, investigators noted that reasons for discontinuation and confirmed medication ingestion information was unavailable as the results were based on administrative claims data which does not include this information. They also added that “the generalizability of the results may be limited to the US Medicare population captured in the Centers for Medicare and Medicaid Services Medicare 100% research identifiable data source.”

Disclosures: McKay has a consulting or advisory role with Ambrx, Arcus Biosciences, Astellas Medivation, AstraZeneca, AVEO, Bayer, Blue Earth Diagnostics, Bristol-Myers Squibb, Calithera Biosciences, Caris Life Sciences, Dendreon, Esiai, Exelixis, Janssen, Lilly, Merck, Myovant Sciences, NeoMorph, Novartis, Pfizer, Sanofi, Seagen, Sorrento Therapeutics, Sumitomo Pharma Oncology, Telix Pharmaceuticals, Tempus, and Vividion Therapeutics. She has also received institutional research funding from Artera, AstraZeneca, Bayer, Bristol Myers Squibb, Exelixis, Oncternal Therapeutics, and Tempus.

References

1. McKay RR, Hong A, Razo JF, et al. Real-world persistence and adherence to relugolix (REL) in US patients with nonmetastatic (nm) vs metastatic (m) prostate cancer (PC). J Clin Oncol. 2025;43(suppl 5):88. doi:10.1200/JCO.2025.43.5_suppl.88
2. Shore ND, Saad F, Cookson MS, et al; HERO Study Investigators. Oral relugolix for androgen-deprivation therapy in advanced prostate cancer. N Engl J Med. 2020;382(23):2187-2196. doi:10.1056/NEJMoa2004325