Study of persistence and adherence to ADT in prostate cancer: relugolix, degarelix, and GnRH agonists in the US

Androgen deprivation therapy (ADT) is standard for advanced prostate cancer. Relugolix, a gonadotropin-releasing hormone (GnRH) receptor antagonist, is the only oral ADT, with limited real-world data on therapy persistence and adherence. This retrospective study evaluates persistence and adherence of relugolix, degarelix, and GnRH agonists (leuprolide, goserelin, triptorelin, histrelin) using data from the IBM MarketScan Research Database (Jan 2017 - Dec 2022). The IBM MarketScan Research Database (1 January 2017 - 31 December 2022) was used for enrollment history and claims. ADT adherence was measured by the proportion of days covered (PDC) at 3, 6, and 12 months, calculated as days on ADT divided by period duration. Kaplan-Meier analysis assessed treatment persistence by measuring time to treatment discontinuation. Relugolix had higher adherence (PDC ≥ 80%) at 12 months (60.8%) compared to degarelix (13.0%) and GnRH agonists (46.3%). Median time to discontinuation was also longer for relugolix (13.5 months) than degarelix (3.1 months) and GnRH agonists (8.8 months). Persistence and adherence rates were higher in metastatic prostate cancer. Findings support relugolix use as an oral treatment due to its favorable persistence and long-term adherence profiles. Prostate cancer is the second most common cancer among men in the US. Androgen deprivation therapy (ADT), a key treatment for advanced prostate cancer, lowers testosterone levels, a hormone that helps prostate cancer grow.  ADT includes injectable gonadotropin-releasing hormone (GnRH) receptor agonists like leuprolide, which initially raise testosterone before lowering it, and antagonists like degarelix, (injectable) and relugolix (oral), which rapidly lower testosterone. A large clinical trial (phase III) showed relugolix rapidly and consistently lowered testosterone, with similar side effects to leuprolide but fewer major cardiovascular events (nonfatal myocardial infarction, nonfatal stroke, and death from any cause). There is limited published real-world data, including healthcare information like medical records and insurance claims, on how well patients stay on treatment (persistence) and take their medication as prescribed (adherence) for different forms of ADT, especially oral relugolix. Data from the IBM MarketScan Research Database (January 2017 to December 2022) was used to compare persistence and adherence among patients taking oral relugolix, injectable degarelix, and injectable GnRH receptor agonists. Patients taking relugolix had a higher rate of adherence to their treatment (60.8%) after 12 months versus those receiving injectable degarelix (13.0%) and other injectables, GnRH receptor agonists (46.3%). Patients on relugolix also stayed on their treatment longer (13.5 months) compared to those on injectable degarelix (3.1 months) and GnRH receptor agonists (8.8 months). These results were especially notable in patients with metastatic prostate cancer. This study demonstrates favorable persistence and adherence rates with oral relugolix in patients receiving ADT for advanced prostate cancer.