WOMBAT

Hormone therapy is a cancer treatment that slows or stops the growth of cancer by blocking the chemical (hormone) it uses to grow. Testosterone is the male sex hormone, and prostate cancer cells often rely on testosterone for their survival and growth. Treatments to reduce testosterone, also known as androgen deprivation therapy (ADT), are frequently used to treat prostate cancer. ADT can cause side effects related to the low levels of testosterone. Prostate cancer cells can work out ways to grow despite low levels of testosterone. This often shows up as an increase in the number produced from a blood test called prostate-specific antigen (PSA). If the PSA number rises without any sign of cancer on scans, the situation is known as “non-metastatic” castrate resistant prostate cancer (nmCRPC). The current standard treatment for nmCRPC is to continue ADT and to add in other treatments to block leftover effects of testosterone action. One such treatment is darolutamide, which is known to delay the time until spread of prostate cancer can be seen on scans. Bipolar Androgen Therapy (BAT) is an experimental treatment for nmCRPC where people receive standard treatment with darolutamide and ADT, and also receive cycles of treatment with testosterone injections. BAT might “resensitise” prostate cancer cells that were otherwise becoming resistant to standard treatment. 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).