Evaluating medication adherence and testosterone suppression in patients with prostate cancer treated with relugolix: Results from the OPTYX study.

e17106 Background: Relugolix is the only oral androgen deprivation therapy (ADT) for advanced prostate cancer (PC). In the phase 3 HERO trial, it showed rapid and sustained testosterone (T) suppression with high adherence rates. Limited real-world adherence data highlights the need to monitor T suppression. One aim of OPTYX, an ongoing multi-center prospective observational study, is to assess adherence using the Simplified Medication Adherence Questionnaire (SMAQ) and T suppression in clinical practice. Methods: PC patients (pts) who initiated relugolix within 1 month prior to enrollment were enrolled from US clinical sites into OPTYX. Data on treatment patterns, clinical, safety, and patient-reported outcomes are being collected. Adherence is being assessed using the pt-reported SMAQ and T levels are being collected as part of routine care. Analyses of adherence and T levels were conducted independently. Results: From October 2022 to September 2024, 999 pts were enrolled, with a median age of 71 years; 19% were non-white. At day 30 after relugolix initiation, 87% of the pts with no prior ADT and available T results (n=173) achieved castrate levels (<50 ng/dL). By months 3 (n=219) and 6 (n=208), 97% and 93% of pts without prior ADT reached castrate levels, respectively. All pts with prior ADT had castrate levels at months 3 and 6. Using the SMAQ, the rates of pts reporting always taking relugolix at the appropriate time were 96.2% at both months 3 (n=500) and 6 (n=477). Additionally, pts feeling bad led to medication discontinuation in 4.2% and 4.8%, forgetfulness was reported by 14.2% and 16.6%, weekend doses were missed by 4.2% and 4.6% of pts, with a mean of 0.6 and 1.0 missed days of relugolix medication over the past 3 months at months 3 and 6, respectively. Conclusions: Relugolix showed T suppression and high adherence in real-world settings. Further analyses are needed as data develop. Monitoring T levels regularly may help clinicians identify non-adherence which could impact treatment response. Clinical trial information: NCT05467176 . Testosterone (ng/dL) n Mean (SD) < 50 ng/dLn (%) < 20 ng/dLn (%) ADT Naive at Baseline Baseline 297 318.9 (215.11) 34 (11) 25 (8) Day 30 173 43.8 (117.52) 150 (87) 114 (66) Month 3 219 16.2 (36.49) 213 (97) 172 (79) Month 6 208 25.2 (61.07) 194 (93) 145 (70) ADT Experienced at Baseline Baseline 39 62.8 (146.24) 31 (79) 25 (64) Day 30 18 72.4 (123.91) 14 (78) 9 (50) Month 3 29 9.6 (10.58) 29 (100) 23 (79) Month 6 16 12.7 (12.03) 16 (100) 12 (75)