Comeback From Long coursE Androgen Deprivation Therapy (ADT) With RElugolix and Darolutamide (CLEARED)

The aim of this single-arm phase 2 study is to assess testosterone recovery after completion of two years of combination treatment with relugolix and darolutamide and to describe safety, tolerability and pharmacokinetics of relugolix and darolutamide when administered in combination. Participants will select enrollment into one of two groups (Group 1 or Group 2). The purpose of Group 1 is to determine the amount of each drug in the bloodstream after 2 hours, 4 hours, and 8 hours of treatment, whereas the purpose of Group 2 is to determine the amount of each drug in the bloodstream after 1 day, 7 days, and 28 days of treatment. The US Food and Drug Administration (FDA) has approved relugolix for the treatment of advanced prostate cancer. The FDA has approved the combination of darolutamide with docetaxel for initial treatment of metastatic prostate cancer, that is, cancer that has spread to other parts of the body. The FDA has also approved darolutamide alone for treatment of non-metastatic castration-resistant prostate cancer, that is, cancer that has become resistant to testosterone lowering medications without evidence of spread of the cancer to other parts of the body that can be detected on Computerized Tomography (CT) or bone scans. While darolutamide and relugolix can be prescribed together based on the FDA-approved indications of the individual drugs, this combination has not been approved by the FDA or formally tested in clinical trials. The research study procedures include screening for eligibility, study treatment visits, questionnaires, and blood tests. Electrocardiograms (EKGs) will be performed if felt to be clinically indicated by the treating physician. Imaging using a Computerized Tomography (CT) scan, Magnetic Resonance Imaging (MRI) scan, bone scan, and/or Prostate-Specific Membrane Antigen Positron Emission Tomography (PSMA-PET) scan is required before starting study treatment, and will be performed after starting study treatment when felt to be clinically indicated by the treating physician. Participants will receive study treatment of relugolix and darolutamide for 2 years and will be followed for 18 months after the treatment period. It is expected that about 33 participants will take part in this research study. Bayer AG, Pfizer, and Sumitomo Pharma America (SMPA), Inc. are funding this research study. Bayer and SMPA are providing the study drugs darolutamide and relugolix, respectively.