OBJECTIVES:

Relugolix was FDA approved in December 2020 as the first oral gonadotropin releasing hormone (GnRH) receptor antagonist to treat advanced prostate cancer and became commercially available in January 2021. Previous studies have documented transitions between injectable GnRH agonists and antagonists. This study examined the real-world utilization of relugolix during its first year of availability (January – December 2021) and documented transitions between injectable and oral androgen deprivation therapy (ADT).

METHODS:

An observational retrospective analysis was conducted using de-identified electronic medical records. PPS Analytics data from 536,539 patients in 89 US community urology practices were analyzed. Patients with at least one record for ADT in 2021 were included. Excluded from the analysis were patients whose ADT initiation date could not be determined. Results were stratified by drug class and initiator status, where new initiators were defined as patients with no exposure to ADT in the prior 180 days.

RESULTS:

In 2021, 51,735 patients, mean age 73.0 (SD:8.5) years, were prescribed ADT. Most were continuing users (29,867, 57.7%) and were prescribed a GnRH agonist (46,368, 89.6%). Relugolix was prescribed to 3096 (6.0%) patients, mean age 71.5 (8.3) years; 2169 (70.1%) were new initiators. Over a third of the patients prescribed relugolix (1241, 40.1%) had exposure to at least one injectable ADT; 534 (17.2%) transitioned from leuprolide and 335 (10.8%) transitioned from degarelix. Conversely, fewer patients transitioned from relugolix to leuprolide [148 (4.8%)] and to degarelix [46 (1.5%)].

CONCLUSIONS:

This descriptive analysis of the first year of availability of the oral GnRH receptor antagonist showed that most patients prescribed novel relugolix were new to ADT. Transitions to and from relugolix did occur, with the most frequent transition occurring from leuprolide to relugolix.