WOMBAT / ANZUP 2201

The intervention is bipolar androgen therapy (BAT) which will be delivered in 56-day cycles. This involves an intramuscular injection of testosterone enanthate 500mg on day 1 of each 56-day cycle and darolutamide 600mg, orally, twice per day on days 29-56 of each 56-day cycle. Participants will have concomitant castration throughout via Luteinizing hormone-releasing hormone (LHRH) agonist/antagonist. The LHRH agonist/antagonist used will be as per standard of care treatment that participants were receiving prior to enrolling in the study. Participants will continue their treatment until evidence of metastatic disease on conventional imaging unless treated beyond progression. Formal drug accountability will not be performed during the study, however, will be estimated from a narrative review with each participant at appropriate clinic visits where treatment adherence will be assessed.