SIU 2017: Clinical Activity of Abiraterone Acetate in Docetaxel-Naïve and Docetaxel-Pretreated Asian Patients with Metastatic Castration Resistant Prostate Cancer

Lisbon, Portugal ( In this abstract, the authors assess the role of abiraterone acetate, a CYP-17A inhibitor, in chemotherapy-naïve and chemotherapy-treated patients with mCRPC. While this has been established in Level 1 evidence (COU-301 and COU-302 studies), those studies were completed with minimal inclusion of Asian patients. Knowing the disease process is different in this population, the authors assess its efficacy in these disease stages. However, they compare patients treated pre-chemo to those treated after docetaxol, likely in an effort to determine sequencing.

The authors enrolled 146 patients for the study: 103 patients (70.5%) who were chemotherapy naïve and 43 (29.5%) who were previously treated with docetaxel. After documenting baseline characteristics, clinical end points were defined according to the Prostate Cancer Working Group 2 definitions.

The confirmed PSA response rate was 54.4% in the chemo-naïve group, but only 34.9% in chemo-pretreated patients; this is consistent with prior studies, as there is sometimes cross-resistance between therapies. On survival analyses, patients who were chemo-naïve had better median PSA-progression free survival (14.0 months vs. 7.7 months), clinical or radiographic progression-free survival (17.0 months vs. 12.2 months), and overall survival (27.0 months vs. 18.0 months).

While responses were good in both group, it appeared to be better in chemo-naïve group. However, this is an unfair assessment. A better comparison would have accounted for the start time of therapy with docetaxel, as the chemotherapy also provides survival benefit – if accounted for, the group could better assess the efficacy of abiraterone vs. docetaxol-abiraterone.

While this study reassures us that abiraterone is effective in the Asian population, it does not address the sequencing question.

Speaker(s): Yunjie Yang, China

Institution(s): Fudan University, China

Written by: Thenappan Chandrasekar, MD, Clinical Fellow, University of Toronto, twitter: @tchandra_uromd, at the 37th Congress of Société Internationale d’Urologie - October 19-22, 2017- Lisbon, Portugal
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