Prior Endocrine Therapy Impact on Abiraterone Acetate Clinical Efficacy in Metastatic Castration-resistant Prostate Cancer: Post-hoc Analysis of Randomised Phase 3 Studies.
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ICR Authors
Authors
Bellmunt, J
Kheoh, T
Yu, MK
Smith, MR
Small, EJ
Mulders, PFA
Fizazi, K
Rathkopf, DE
Saad, F
Scher, HI
Taplin, M-E
Davis, ID
Schrijvers, D
Protheroe, A
Molina, A
De Porre, P
Griffin, TW
de Bono, JS
Ryan, CJ
Oudard, S
Kheoh, T
Yu, MK
Smith, MR
Small, EJ
Mulders, PFA
Fizazi, K
Rathkopf, DE
Saad, F
Scher, HI
Taplin, M-E
Davis, ID
Schrijvers, D
Protheroe, A
Molina, A
De Porre, P
Griffin, TW
de Bono, JS
Ryan, CJ
Oudard, S
Document Type
Journal Article
Date
2016-05-01
Date Accepted
2015-10-06
Abstract
BACKGROUND: The duration of prior hormonal treatment can predict responses to subsequent therapy in patients with metastatic castration-resistant prostate cancer (mCRPC). OBJECTIVE: To determine if prior endocrine therapy duration is an indicator of abiraterone acetate (AA) sensitivity. DESIGN, SETTING, AND PARTICIPANTS: Post-hoc exploratory analysis of randomised phase 3 studies examining post-docetaxel (COU-AA-301) or chemotherapy-naïve mCRPC (COU-AA-302) patients receiving AA. The treatment effect on overall survival (OS), radiographic progression-free survival (rPFS), and prostate-specific antigen (PSA) response analysed by quartile duration of prior gonadotropin-releasing hormone agonists (GnRHa) or androgen receptor (AR) antagonist. INTERVENTION: Patients were randomised to AA (1000mg, orally once daily) plus prednisone (5mg, orally twice daily) or placebo plus prednisone. Prior endocrine therapy was GnRHa (COU-AA-301, n=1127 [94%]; COU-AA-302, n=1057 [97%], 45.1 mo or 36.7 mo median duration, respectively) and/or orchiectomy (COU-AA-301, n=78 [7%] COU-AA-302, n=44 [4%]); castrated patients received prior AR antagonists (COU-AA-301, n=1015 [85%]; COU-AA-302, n=1078 [99%], 15.7 mo or 16.1 mo median duration, respectively). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Cox model was used to obtain hazard ratio and associated 95% confidence interval with statistical inference by log rank statistic. RESULTS AND LIMITATIONS: Clinical benefit with AA was observed for OS, rPFS, and PSA response for nearly all quartiles with GnRHa or AR antagonists in both COU-AA-301 and COU-AA-302. In COU-AA-301, patients with a longer duration of prior endocrine therapy tended to have greater AA OS, rPFS, and PSA response benefit, with lead-time chemotherapy bias potentially impacting COU-AA-301 results. Time to castration resistance was not captured. This analysis is limited as a post-hoc exploratory analysis. CONCLUSIONS: In the COU-AA-301 and COU-AA-302 studies, AA produced clinical benefits regardless of prior endocrine therapy duration in patients with mCRPC. PATIENT SUMMARY: Metastatic castration-resistant prostate cancer patients derived clinical benefits with abiraterone acetate regardless of prior endocrine therapy duration.
Citation
European urology, 2016, 69 (5), pp. 924 - 932
Source Title
Publisher
ELSEVIER SCIENCE BV
ISSN
0302-2838
eISSN
1873-7560
Collections
Research Team
Prostate Cancer Targeted Therapy Group