Impact of access to novel therapies on the initial management of castrate-resistant prostate cancer: an Australian multicentre study

Background: The impact of regulatory approvals of new therapies for castration-resistant prostate cancer (CRPC) in Australia is unclear. Aims: To determine if changes in novel therapy access in Australia affected how clinicians initially managed men with newly diagnosed CRPC. Methods: Data from patients diagnosed with CRPC from 2013 to 2016 across three Australian hospitals were retrospectively collected. Baseline clinicopathological factors and initial management decision at the time of CRPC development (early treatment (ET) vs deferred treatment (DT)) were recorded. Categorical variables between cohorts were compared by Chi-squared analysis. Cox regression analysis was performed to assess the impact of CRPC diagnosis year on time to commencing life-prolonging systemic treatment (TTT). Results: Our study identified 137 CRPC patients, with 126 (92%) patients receiving life-prolonging systemic treatment. The median age was 73 years. The initial management decision was DT in 71 (52%) patients and ET in 66 (48%) patients. There was a significant shift from DT to ET during the study period (2013–2014: DT 61% vs ET 33%; 2015–2016: DT 39% vs ET 67%; P = 0.004), with a rise in novel androgen receptor signalling inhibitor use and simultaneous reduction in first-generation antiandrogen use at CRPC development. Each successive CRPC diagnosis year was associated with shorter TTT on univariate analysis (HR: 1.5, 95% CI: 1.3–1.7, P < 0.001). Conclusion: Over time, clinicians are favouring earlier introduction of life-prolonging systemic treatment at the development of CRPC. This trend is largely driven by substantial uptake of novel androgen receptor signalling inhibitors as the preferred initial treatment for CRPC patients.