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In the COU-AA-302 trial, abiraterone acetate plus prednisone significantly increased overall survival for patients with chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC). Limited information exists regarding response to subsequent androgen signaling-directed therapies following abiraterone acetate plus prednisone in patients with mCRPC. We investigated clinical outcomes associated with subsequent abiraterone acetate plus prednisone (55 patients) and enzalutamide (33 patients) in a post hoc analysis of COU-AA-302. Prostate-specific antigen (PSA) response was assessed. Median time to PSA progression was estimated using the Kaplan-Meier method. The PSA response rate (≥50% PSA decline, unconfirmed) was 44% and 67%, respectively. The median time to PSA progression was 3.9 mo (range 2.6-not estimable) for subsequent abiraterone acetate plus prednisone and 2.8 mo (range 1.8-not estimable) for subsequent enzalutamide. The majority of patients (68%) received intervening chemotherapy before subsequent abiraterone acetate plus prednisone or enzalutamide. While acknowledging the limitations of post hoc analyses and high censoring (>75%) in both treatment groups, these results suggest that subsequent therapy with abiraterone acetate plus prednisone or enzalutamide for patients who progressed on abiraterone acetate is associated with limited clinical benefit., Patient Summary: This analysis showed limited clinical benefit for subsequent abiraterone acetate plus prednisone or enzalutamide in patients with metastatic castration-resistant prostate cancer following initial treatment with abiraterone acetate plus prednisone. This analysis does not support prioritization of subsequent abiraterone acetate plus prednisone or enzalutamide following initial therapy with abiraterone acetate plus prednisone., (Copyright © 2017 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

Coadministration of docetaxel and abiraterone acetate plus prednisone (AA + P) may benefit patients with metastatic castration-resistant prostate cancer (mCRPC) because of complementary mechanisms of action. COU-AA-206 was a phase 1b study to determine the safe dose combination of docetaxel and AA + P in three cohorts of chemotherapy-naïve mCRPC patients. Twenty-two patients received escalating doses of docetaxel plus AA + P. The primary endpoint was the proportion of patients with a dose-limiting toxicity (DLT) between weeks 2 and 7. The recommended phase 2 dose (RP2D) was the highest safe combination of docetaxel plus AA + P. Prostate-specific antigen (PSA) changes and intensive pharmacokinetic parameters for each drug were evaluated. Docetaxel 75mg/m 2 + AA 1000mg + P 10mg was deemed the RP2D, with DLT in one of six patients. PSA declines from baseline of ≥50% and ≥90% were observed for 85.7% and 66.7% of patients, respectively. During median follow-up of 14.5 mo, eight patients had PSA progression and six had radiographic progression or died. Systemic exposure was comparable for docetaxel and abiraterone when given alone or in combination. Studies are ongoing to confirm the efficacy of potent androgen receptor-targeted therapy plus taxane in early mCRPC., Patient Summary: The combination of hormonal therapy and chemotherapy may improve outcomes in men with metastatic prostate cancer. This study demonstrates the ability to combine the hormonal therapy agent abiraterone acetate, plus prednisone, and the chemotherapy drug docetaxel with an acceptable side effect profile. A high rate of prostate-specific antigen decline was seen, but the study was small and additional research is needed before this becomes a standard approach., (Copyright © 2016 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

Background: Metastatic castration-resistant prostate cancer (mCRPC) often involves bone, and bone-targeted therapy (BTT) has become part of the overall treatment strategy., Objective: Investigation of outcomes for concomitant BTT in a post hoc analysis of the COU-AA-302 trial, which demonstrated an overall clinical benefit of abiraterone acetate (AA) plus prednisone over placebo plus prednisone in asymptomatic or mildly symptomatic chemotherapy-naïve mCRPC patients., Design, Setting, and Participants: This report describes the third interim analysis (prespecified at 55% overall survival [OS] events) for the COU-AA-302 trial., Intervention: Patients were grouped by concomitant BTT use or no BTT use., Outcome Measurements and Statistical Analysis: Radiographic progression-free survival and OS were coprimary end points. This report describes the third interim analysis (prespecified at 55% OS events) and involves patients treated with or without concomitant BTT during the COU-AA-302 study. Median follow-up for OS was 27.1 mo. Median time-to-event variables with 95% confidence intervals (CIs) were estimated using the Kaplan-Meier method. Adjusted hazard ratios (HRs), 95% CIs, and p values for concomitant BTT versus no BTT were obtained via Cox models., Results and Limitations: While the post hoc nature of the analysis is a limitation, superiority of AA and prednisone versus prednisone alone was demonstrated for clinical outcomes with or without BTT use. Compared with no BTT use, concomitant BTT significantly improved OS (HR 0.75; p=0.01) and increased the time to ECOG deterioration (HR 0.75; p<0.001) and time to opiate use for cancer-related pain (HR 0.80; p=0.036). The safety profile of concomitant BTT with AA was similar to that reported for AA in the overall intent-to-treat population. Osteonecrosis of the jaw (all grade 1/2) with concomitant BTT use was reported in <3% of patients., Conclusions: AA with concomitant BTT was safe and well tolerated in men with chemotherapy-naïve mCRPC. The benefits of AA on clinical outcomes were increased with concomitant BTT., Patient Summary: Treatment of advanced prostate cancer often includes bone-targeted therapy. This post hoc analysis showed that in patients with advanced prostate cancer who were treated with abiraterone acetate and prednisone in combination with bone-targeted therapy, there was a continued trend in prolongation of life when compared with patients treated with prednisone alone., Trial Registration: ClinicalTrials.gov NCT00887198., (Copyright © 2015 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

Background: Although abiraterone acetate (abiraterone) has proven efficacy in two randomised phase 3 trials in metastatic castration-resistant prostate cancer (mCRPC), patients who had an Eastern Cooperative Oncology Group (ECOG) performance status (PS) ≥2 were either excluded or under-represented in these trials., Objective: To compare outcomes in ECOG PS 0-1 and ≥2 in mCRPC patients treated with abiraterone., Design, Setting, and Participants: Cancer registries from three Canadian centres were used to retrospectively identify mCRPC patients (postdocetaxel and docetaxel-naïve) treated with abiraterone. ECOG PS, clinicopathologic characteristics, prostate-specific antigen (PSA) response, and survival data were collected., Outcome Measurements and Statistical Analysis: Survival outcomes were estimated using the Kaplan-Meier method and compared using the log-rank test. Cox proportional hazards modelling was used to examine the effect of clinicopathologic characteristics on overall survival (OS) and time to PSA progression., Results and Limitations: A total of 519 patients were identified; 61% (n=318) and 39% (n=201) were ECOG PS 0-1 and ≥2, respectively. ECOG PS 0-1 patients were significantly more likely than PS ≥2 patients to achieve a PSA decline ≥50% from baseline (45% vs 32%; p=0.003, Fisher exact test) and had significantly longer median time to PSA progression (5.2 mo vs 4.1 mo; p=0.023), median treatment duration (7.4 mo vs 4.5 mo; p<0.001), and median OS (20.0 mo vs 9.1 mo; p<0.001). On multivariate analysis, ECOG PS was a significant factor for OS (p<0.001), time to PSA progression (p=0.043), and PSA decline (p=0.002). Potential limitations include the retrospective study design and subjective nature of ECOG PS classification., Conclusions: ECOG PS ≥2 mCRPC patients treated with abiraterone have inferior outcomes compared with ECOG 0-1 patients, especially in regard to OS. These data indicate that early initiation of abiraterone prior to a decline in PS may be warranted., Patient Summary: We found that advanced prostate cancer patients who have worse performance status (PS) derive less benefit from abiraterone, indicating that earlier treatment before PS declines could improve outcomes., (Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.)