Working Out M0 Bipolar Androgen Therapy

The WOMBAT study will test if BAT can prolong the time it takes for nmCRPC prostate cancer to become detectable in other areas of the body (metastatic disease). Approximately 69 participants over the age of 18 with castrate resistant prostate cancer, no evidence of metastatic disease (M0) on conventional imaging (WBBS and CT scan at screening) and PSA only progression on darolutamide will be enrolled from approximately 8 sites within Australia. Participants will receive continuous androgen deprivation therapy with LHRH agonists/antagonists. The study intervention will be IM testosterone enthanate, injected on day 1 of each 56-day cycle. Concurrent darolutamide will be taken at a dose of 600mg BD on days 29-56 of each cycle. Both LHRH and agonist/antagonist and darolutamide are supplied through the PBS as standard of care medications. Administration of both testosterone and darolutamide will continue until disease progression, beyond disease progression, unacceptable toxicity, death, withdrawal of consent or study Sponsor termination of the study. Primary objective (endpoint) is to determine the metastasis-free survival (time from commencing BAT to evidence of metastases or death)