Castration-Resistant Metastatic Prostate Carcinoma

Background: The treatment of CPRCm is still a challenge. With this retrospective study, we aim to analyse the impact of abiraterone (AA) in patients (pts) with CPRCm in a pre and post chemotherapy (QT) context. 

Methods: Cohort study including all pts undergoing treatment with AA in Central Lisbon Hospitals between January 2015 and June 2019. Demographic and clinical data were collected and the information was cross-checked with that of the pharmaceutical services. Significance (p) of less than 0.05 was considered statistically significant. Statistical analysis was performed in Stata. 

Results: Since 2015, 86 men were treated with AA. The median age at diagnosis was 71 years (49-91). The median time to recurrence or resistance to castration was 69 months (3-190). 52% were already metastasized ad initio and with initial PSA of 432 (1-3820). Disease progression was accompanied by bone metastasis in 56 (84%), lymph node in 16 (32%)and visceral in 5 (5%)cases. In 55% of the cases, AA was started after QT. 35% of pts underwent QT afterwards. 45% of pts continue treatment to date. To date, with a median follow-up of 80 months (12-250), 25% of the pts died, with a median survival of 80 months (30 - 180). Median survival from the start of AA was 24 months (4-36). As of June 2019, 35% of pts started other treatments due to disease progression, of which 30% were enzalutamide and 70% taxanes. On the multivariate survival analysis, QT after AA (p = 0.005), time to onset of AA (p = 0.015), PSA decline at 3 months after AA (p= 0.005) had statistical significance for impact on survival time from onset of AA, and QT prior to AA (p = 0.050) showed a tendency to impact survival. On the multivariate model for overall survival (since diagnosis), age (p = 0.04), QT post AA (p = 0.005) and PSA decrease at 3 months (p = 0.03) were statistically significant. 

Conclusions:  Optimum drug sequencing to maximize the benefit of the pts is not yet fully established. In the studied sample, age was a prognostic factor for survival from diagnosis, but not for post-AA survival, supporting the use of AA as beneficial in the various age groups. Regarding therapeutic sequencing, the greatest impact on survival was observed when QT was performed after AA vs before it.