The following article features coverage from the ASCO Genitourinary Cancers Symposium 2022. Click here to read more of MPR‘s conference coverage.

Relugolix was found to be effective and well tolerated in Black men with advanced prostate cancer, according to findings presented at the 2022 American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium.

To better understand the efficacy and safety of relugolix in Black men with advanced prostate cancer, researchers conducted a subgroup analysis of the phase 3 HERO study (ClinicalTrials.gov Identifier: NCT03085095). The randomized, open-label, parallel group trial evaluated the efficacy and safety of relugolix, an oral gonadotropin-releasing hormone (GnRH) receptor antagonist, in men with advanced prostate cancer. Patients were randomly assigned 2:1 to receive either relugolix 120mg orally once daily following an oral loading dose of 360mg on day 1 or leuprolide 22.5mg subcutaneously every 3 months (n=16) for 48 weeks.

Of the 930 study participants, 46 patients were Black men (median age, 66 years); 30 patients were enrolled in the relugolix group and 16 were enrolled in the leuprolide group. Patient demographic information showed that at study entry, more Black men in the relugolix arm had metastatic disease (30% vs 25%, respectively), prior androgen deprivation therapy (13.3% vs 6.3%), and prior prostatectomy (53.3% vs 18.8%) compared with the leuprolide arm. Additionally, median prostate-specific antigen levels (PSA; 12.8 vs 16.0ng/mL) and median testosterone levels (375.2 vs 419.2ng/dL) were found to be lower at baseline in the relugolix arm vs the leuprolide arm.

Efficacy was assessed based on sustained castration rate (defined as the cumulative probability of testosterone suppression to <50ng/dL from day 29 through 48 weeks), early castration rate (day 4 and day 15), PSA response (>50% reduction from baseline at day 15 with confirmation at day 29), profound castration rate (<20ng/dL at day 15), and follicle stimulating hormone (FSH) level at the end of week 24.

Findings demonstrated that 93.3% (95% CI, 75.9-98.3) of Black men treated with relugolix maintained castration through 48 weeks compared with 93.3% (95% CI, 61.3-99.0) of those treated with leuprolide (difference: 0%; 95% CI, -15.5, 15.5). Relugolix was also associated with improvements on the following secondary endpoints vs leuprolide: castration rate at day 4 (53% vs 0%), castration rate at day 15 (97% vs 13%), and profound castration rate on day 15 (67% vs 6%). 

Additionally, 83.3% of patients in the relugolix arm had a PSA response at day 15 compared with 6.3% of those in the leuprolide arm. The median FSH levels were 1.75 IU/L for relugolix and 3.72 IU/L for leuprolide at the end of week 24.

Adverse events (all grade) occurred in 96.7% of patients in the relugolix arm and 87.5% of patients in the leuprolide arm. Grade 3 or greater adverse events occurred less frequently with relugolix compared with leuprolide (16.7% vs 25%).

Based on these findings, study authors concluded that “relugolix was effective and generally well tolerated in a cohort of Black men, consistent with the relugolix results in the overall population. Given the limited size of the subgroup, additional research is warranted in this population.”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

Reference

George DJ, Saad F, Pieczonka CM, et al. Efficacy and safety of relugolix in black men with advanced prostate cancer: A subgroup analysis from the randomized, phase 3 HERO study versus leuprolide. Presented at: ASCO GU 2022; February 17-19, 2022; Abstract 105.