Enzalutamide in the treatment of metastatic castrate-sensitive prostate cancer

Prostate cancer is the most common non-cutaneous malignancy in men with more than 57 000 cases diagnosed in the UK each year. It is the second leading cause of cancer deaths (Kessel et al, 2021; Kinnaird et al, 2021). The majority of patients present with localised disease confined to the prostate, where the 5-year survival rate is up to 99%. In contrast, when metastatic disease develops, the 5-year survival rate decreases to 30%. Prostate cancer cells depend on the androgen hormone testosterone to grow and survive. The mainstay of treatment for metastatic castrate-sensitive prostate cancer has been androgen deprivation therapy (ADT), which controls the disease by lowering androgen levels. ADT was originally discovered by Higgins and Hodges in 1940. It is achieved using either surgical bilateral orchidectomy or medical gonadotropin-releasing hormone agonists (GnRH). The use of continous, rather than intermittent, ADT is recommended as data show this leads to a higher overall survival rate (Hussain et al, 2013). In the majority of cases of metastatic castrate-sensitive prostate cancer, tumours stop responding to androgen deprivation after 2–3 years, becoming castrate-resistant (Dela Rama and Pratz, 2015).