Testing the Addition of the Drug Relugolix to the Usual Radiation Therapy for Advanced-Stage Prostate Cancer, The NRG Promethean Study

This phase II trial compares the usual treatment of radiation therapy alone to using the study drug, relugolix, plus the usual radiation therapy in patients with castration-sensitive prostate cancer that has spread to limited other parts of the body (oligometastatic). Relugolix is in a class of medications called gonadotropin-releasing hormone (GnRH) receptor antagonists. It works by decreasing the amount of testosterone (a male hormone) produced by the body. It may stop the growth of cancer cells that need testosterone to grow. Radiation therapy uses high-energy x rays or protons to kill tumor cells. The addition of relugolix to the radiation may reduce the chance of oligometastatic prostate cancer spreading further.

PRIMARY OBJECTIVE: I. Compare conventional radiological progression-free survival (rPFS) for positron emission tomography (PET)-detected, biochemically recurrent, oligometastatic, castration-sensitive prostate cancer patients treated with stereotactic ablative body radiation therapy (SABR) plus placebo versus (vs.) SABR plus relugolix. SECONDARY OBJECTIVES: I. Compare conventional or PET-based radiological progression-free survival (prPFS) between treatment arms. II. Compare patient-reported sexual and hormonal quality of life as assessed by corresponding Expanded Prostate Cancer Index Composite Short Form (EPIC-26) domains between treatment arms. III. Compare other measures of quality of life obtained from the European Quality of Life Five Dimension Five Level Scale Questionnaire (EQ5D-5L), European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire Core 30 (QLQ-30), Patient Reported Outcomes Measurement Information System (PROMIS) Fatigue instruments between the two treatment arms. IV. Compare time to salvage therapy and time to castration-resistance between treatment arms. V. Compare local progression (SABR-targeted lesion), biochemical progression, distant metastases, prostate cancer-specific mortality, metastasis-free survival, and overall survival between treatment arms. VI. Determine adverse events rates and compare rates between the two treatment arms. EXPLORATORY OBJECTIVE: I. Evaluate genomic and peripheral tissue and blood markers of treatment response. OUTLINE: Patients are randomized to 1 of 2 arms. ARM I: Patients receive placebo orally (PO) once daily (QD) on days 1-180 and undergo SABR for 1-3 weeks in the absence of disease progression or unacceptable toxicity. ARM II: Patients receive relugolix PO QD on days 1-180 and undergo SABR for 1-3 weeks in the absence of disease progression or unacceptable toxicity. Patients may also undergo bone scan, computed tomography (CT), magnetic resonance imaging (MRI), prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/CT or PET/MRI, and/or fluciclovine F18 PET/CT or PET/MRI at time of disease progression. Patients may optionally undergo urine and blood sample collection throughout the trial. After completion of study treatment, patients are followed up at 9 and 12 months, subsequently every 6 months to month 60, and then annually thereafter or at the time of progression.