Interim safety results of a global early access protocol (EAP) of abiraterone acetate (AA) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) progressing after taxane-based chemotherapy.

Abstract

5059 Background: The COU-AA-301 phase 3 trial showed significantly longer overall survival for AA + prednisone (P) than P alone in mCRPC pts refractory to docetaxel. This global EAP was conducted in the same setting to collect additional safety data. Methods: Open-label EAP in pts with mCRPC who progressed after 1 - 2 chemotherapy regimens (≥ 1 taxane), resided in areas where AA was unavailable and were ineligible for ongoing clinical trials of AA. Pts received AA (1000 mg PO/d) plus P (5 mg bid) in 28 d cycles until disease progression. Only serious or clinically important adverse events (AEs) were to be reported by investigators. First interim results (clinical cut-off date: December 31, 2011), reported as part of regulatory submissions, are presented. Results: 1079 pts from 15 countries were included: N. America (47%), Europe (29%), Australia (13%), Latin America (7%), and Asia (3%). Median age: 70 years (range: 47 – 93); 89% of pts were White. Median treatment exposure, incl. pts still on treatment (285 pts), was ≈ 3 months. 620 pts (58%) received ≥ 4 treatment cycles, 58 pts (5%) received ≥ 8 cycles. 441 pts (41%) reported serious or clinically important AEs, which were treatment-related in 154 pts (14%). Most common grade 3-4 AEs: ↑ALP (6%), anemia (3%), hypertension (3%), back pain (2%), and fatigue (2%). Grade 3-4 AEs of special interest were infrequent: LFT abnormalities (8%), hypertension (3%), cardiac disorders (2%), hypokalemia (< 1%), fluid retention/edema (< 1%), osteoporotic fractures (< 1%). Main reason for discontinuation (795 pts): disease progression, in 335 pts (31%). 253 pts (23%) discontinued after marketing authorization. Discontinuations due to treatment-emergent AEs, death, or withdrawal of consent were < 6% each. Conclusions: The safety profile observed in these EAP interim results was consistent with that in the COU-AA-301 randomized, placebo controlled trial conducted in the same clinical setting. No new safety signals with AA plus P were detected in this expanded patient population, which included pts from Latin America and Asia, i.e. regions that did not participate in COU-AA-301. Clinical trial information: NCT01217697.