In an analysis reported in JAMA Oncology, Daniel E. Spratt, MD, and colleagues found that treatment with relugolix was associated with rapid achievement of sustained castration in patients with localized or advanced prostate cancer who were also receiving radiotherapy.
Study Details
The analysis included patients from a phase II trial of relugolix vs degarelix and a subset of patients from the phase III HERO trial of relugolix vs leuprolide acetate, including 65 patients who received radiotherapy and short-term (24 weeks) relugolix from 2014 to 2015 and 99 receiving radiotherapy and longer-term (48 weeks) relugolix from 2017 to 2019. The main outcome measures were rates of castration (testosterone level < 50 ng/dL) at all scheduled visits between weeks 5 and 25 for patients receiving short-term relugolix and weeks 5 and 49 for patients receiving longer-term relugolix.
Daniel E. Spratt, MD
Key Findings
In the short-term relugolix group, the castration rate with relugolix over 24 weeks was 95% (95% confidence interval [CI] = 87.1%–99.0%). Median time to achieve testosterone levels of < 50 ng/dL was 4 days; median time to achieve levels of < 20 ng/dL was 15 days.
In the longer-term relugolix group, the sustained castration rate with relugolix over 48 weeks was 96.9% (95% CI = 90.6%–99.0%). Rates of achievement of testosterone suppression to < 50 ng/dL were 59.6% at 4 days and 100% at 15 days.
Among patients receiving relugolix who were assessed for testosterone recovery, 52% had recovery to baseline levels or to > 280 ng/dL at 12 weeks after short-term treatment. At 90 days after longer-term treatment, mean testosterone levels were 310.5 ng/dL (standard deviation = 122.4 ng/dL).
Grade ≥ 3 adverse events with short-term or longer-term relugolix (headache, hypertension, and atrial fibrillation) occurred in < 5% of patients.
The investigators concluded, “The results of these two randomized clinical trials suggest that relugolix rapidly achieves sustained castration in patients with localized and advanced prostate cancer receiving radiotherapy. No new safety concerns were identified when relugolix was used with radiotherapy.”
Dr. Spratt, of the Department of Radiation Oncology, University Hospitals Seidman Cancer Center and Case Western Reserve University, Cleveland, is the corresponding author for the JAMA Oncology article.
Disclosure: The study was supported by Millenium Pharmaceuticals, Inc, and Sumitomo Pharma. For full disclosures of the study authors, visit jamanetwork.com.
