Potential predictive and prognostic factors for sequential treatment with abiraterone acetate and cabazitaxel in metastatic docetaxel-refractory castration-resistant prostate cancer (mDR-CRPC).

Abstract

e16093 Background: in recent years Abiraterone Acetate (AA) andCabazitaxel (Cbz) were shown to be efficacious agents in patients with mDR-CRPC. However, no data exist for patients treated with both these drugs in terms of best sequencing evaluation and potential predictive and prognostic factors for different treatment sequencies. Aim of our study was to analyze these data in a real world scenario. Methods: intention-to-treat (ITT) analysis of activity data deriving from all consecutive patients with mDR-CRPC treated in our unit with prednisone plus Cbz, AA or both drugs. Data analyzed were, median Progression Free Survival (mPFS) for the two single agents and their sequencies (evaluated according to PCWG2, Prostate Cancer Working Group 2, criteria) and their possible correlations with median age, Gleason score, baseline PSA, ECOG PS, visceral metastases and number of previous chemotherapy lines. Results: here we report characteristics and activity data of the initial 62 patients, 7 treated with Cbz, 32 with AA and 16 with both drugs. The median age of our study population was 71.5 years (range, 55-87), median Gleason Score 8 (4-9) and median ECOG PS 0 (0–3); visceral disease was present in 37 cases (59.7%). The mPFS, according to Kaplan Meier method (KM), was 4.7 months (m) for patients treated with Cbz, 8.6 months for cases treated with AA and 8.2 m for cases treated with both agents. Of the 16 patients treated with both drugs, 12 received a sequence Cbz-AA and 4 a sequence AA-Cbz for an overall median PFS of, respectively, 5.6 and 4.0 m. Any of the analyzed prognostic or predictive factor was found to be significant. Conclusions: in our experience AA and Cbz were showed to be effective agents in the mDR-CRPC setting also when used sequentially. No clear indication of a preferred treatment sequence was identified such as eventual prognostic/predictive factors, also because of the limited number of treated patients. These data should be analyzed in large size prospective trials.