Impact of concomitant prostate cancer therapy on efficacy and safety of relugolix versus leuprolide in men with advanced prostate cancer: Subgroup analysis from the phase III HERO study.

Abstract

106 Background: In the phase 3 HERO study, the oral GnRH receptor antagonist, relugolix, demonstrated suppression of testosterone to castrate levels in 96.7% of patients, which was superior to leuprolide, and a 54% lower risk of major adverse cardiovascular events relative to leuprolide. To characterize the impact of concomitant prostate cancer treatments with the use of relugolix in advanced prostate cancer from the HERO study, a subgroup analysis for patients receiving various therapies was undertaken. Methods: The HERO study was designed to evaluate relugolix in men with advanced prostate cancer. Overall, 934 patients were randomized 2:1 to receive relugolix 120 mg orally once daily or leuprolide injections every 12 weeks for 48 weeks. In the setting of rising PSA, patients could receive enzalutamide (ENZ) or docetaxel (DOC) 2 months after study initiation. Assessments included sustained testosterone suppression to castrate levels (<50 ng/dL) through 48 weeks and safety parameters. Subgroups analyzed included patients with or without concomitant ENZ, DOC, and any radiation therapy (RT). A sensitivity analysis of the primary endpoint was performed excluding patients who received concomitant therapies that may affect testosterone. Results: Overall, 125 patients (13.4%) took at least one concomitant therapy that could impact testosterone levels. RT was received by 15.9% and 18.8% of patients in the relugolix and leuprolide groups, respectively. ENZ was the most frequently used therapy in the relugolix group (2.7%), with similar use in the leuprolide group (1.9%). DOC was used by 1.3% and 1.6% of patients in the relugolix and leuprolide groups, respectively. All other relevant concomitant therapy were used in <1% of population. The sensitivity analysis results indicated that use of these concomitant therapy that could affect testosterone levels did not impact the primary endpoint. Castration rates were similar with and without concomitant use of ENZ and DOC, or RT (table). No clinically relevant differences in adverse events were observed between patients with or without concomitant use of ENZ, DOC, or RT in either treatment group. Conclusions: While the numbers are small, treatment with relugolix was associated with a similar efficacy and safety profiles in patients who received concomitant administration of ENZ, DOC, or RT to that observed in patients not receiving those concomitant treatments. Clinical trial information: NCT03085095. [Table: see text]