951 - Reponse to Cabazitaxel in the Postchemotherapy Setting in Crpc Patients Previously Treated with Docetaxel and Abiraterone Acetate

Abstract

ABSTRACT Background Cabazitaxel (a tubulin-binding taxane chemotherapy) and Abiraterone acetate (AA) have recently been approved for patients with metastatic castration resistant prostate cancer (CRPC) following docetaxel chemotherapy. Recent studies suggest that taxane also impact AR signalling such as AA, and could explain cross-resistance between new hormonal manipulations and taxane chemotherapy. The aim of this study is to evaluate the antitumor activity of cabazitaxel in patients whose disease progresses on AA. Patients and methods Eligible pts had metastatic CRPC and progression disease after docetaxel and AA. All the patients received cabazitaxel 20 mg/m2 every 3 weeks + prednisone 5 mg BID. Radiological response by RECIST, PSA response by PSAWG2 criteria and symptomatic benefit were evaluated. Results In the 38 pts treated with cabazitaxel, baseline median age was 69 years (48-81), ECOG PS 0 or 1 in 90% of pts, and median PSA 350 ng/ml (3,75-9150). Bone, lymph nodes and visceral metastases were present in 30 pts (90%), 5 pts (15%), and 5 pts (15%) respectively. An average of 4 cycles of cabazitaxel (range 1-9) were given, 85% patients received granulocyte-colony stimulating factor prophylaxis from cycle 1, and 15 pts (39%) continue on cabazitaxel at the time of safety analysis. Out of 38 patients, 16 patients stopped before completing the full course, 15 of these patients were due to disease progression. No major toxicities were noticed. Of 32 patients with PSA data available, 18 (56%) pts have had a 50% or greater PSA decline, 5 pts (15%) have had a partial response. Conclusion Cabazitaxel appears active and well tolerated in pts with metastatic CRPC who are resistant to AA. Our data do not provide any evidence for cross-resistance between these two agents. Final results will be reported. Disclosure All authors have declared no conflicts of interest.