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

Real-world use of first-generation antiandrogens: impact on patient outcomes and subsequent therapies in metastatic castration-resistant prostate cancer

OBJECTIVES

To investigate the recent real-world use of first-generation antiandrogens (FGAs) in metastatic castration-resistant prostate cancer (mCRPC) using a retrospective multicentre cohort study.

PATIENTS AND METHODS

The electronic CRPC Australian Database (ePAD) was interrogated to identify patients with mCRPC. Clinicopathological features, treatment and outcome data, stratified by FGA use, were retrieved and reported through descriptive statistics. Survival analyses were calculated using the Kaplan-Meier method and groups compared using log-rank tests. Factors influencing overall survival (OS) were analysed using Cox proportional hazards regression model.

RESULTS

We identified 634 patients with mCRPC, enrolled in ePAD between January 2016 and March 2019, including 322 (51%) who received FGAs. The median follow-up was 21.9 months. Patients treated with FGAs were more likely to have lower International Society of Urological Pathologists (ISUP) grade group (P = 0.04), longer median time to CRPC (25.6 vs 16.0 months, P < 0.001), and were less likely to have visceral metastases (5.0% vs 11.2%, P = 0.005) or to have received upfront docetaxel (P < 0.001). A ≥50% reduction from pre-treatment prostate-specific antigen (PSA) level (PSA50 response) during FGA treatment occurred in 119 (37%) patients and was independently associated with improved OS (hazard ratio 0.233, P < 0.001). Prior FGA treatment did not significantly influence the selection of subsequent life-prolonging treatments for mCRPC or their PSA50 response rates.

CONCLUSION

In our present cohort, FGAs were commonly used in lower-risk mCRPC and their use did not significantly influence the choice or duration of subsequent systemic therapy. A PSA50 response to FGA therapy was an independent favourable prognostic marker associated with improved OS.

The effects of new life-prolonging drugs for metastatic castration-resistant prostate cancer (mCRPC) patients in a real-world population

BACKGROUND

In 2004 docetaxel was the first life-prolonging drug (LPD) registered for metastatic castration-resistant prostate cancer (mCRPC) patients. Between 2011 and 2014 new LPDs for mCRPC (cabazitaxel, abiraterone, enzalutamide, and radium-223) were introduced in the Netherlands. The objective of this study is to assess the impact of the introduction of new LPDs on treatment patterns and overall survival (OS) over time.

PATIENTS AND METHODS

CRPC patients diagnosed in the years 2010-2016 in the observational, retrospective CAPRI registry (20 hospitals) were included and followed up to 2018. Two subgroups were analyzed: treatment-naïve patients (subgroup 1, n = 3600) and post-docetaxel patients (subgroup 2, n = 1355).

RESULTS

In both subgroups, the use of any LPD increased: from 57% (2010-2011) to 69% (2014-2015) in subgroup 1 and from 65% (2011-2012) to 79% (2015-2016) in subgroup 2. Chemotherapy as first mCRPC-treatment (i.e., docetaxel) and first post-docetaxel treatment (i.e., cabazitaxel or docetaxel rechallenge) decreased (46-29% and 20-9% in subgroup 1 and 2, respectively), while the use of androgen-receptor targeting treatments (ART) increased from 11% to 39% and 46% to 64% in subgroup 1 and 2, respectively. In subgroup 1, median OS (mOS) from diagnosis CRPC increased from 28.5 months to 31.0 months (p = 0.196). In subgroup 2, mOS from progression on docetaxel increased from 7.9 months to 12.5 months (p < 0.001). After multiple imputations of missing values, in multivariable cox-regression analysis with known prognostic parameters, the treatment period was independent significant for OS in subgroup 1 (2014-2015 vs. 2010-2011 with HR 0.749, p < 0.001) and subgroup 2 (2015-2016 vs. 2011-2012 with HR 0.811, p = 0.037).

CONCLUSION

Since 2010, a larger proportion of mCRPC patients was treated with LPDs, which was related to an increased mOS.