705 Abiraterone Acetate Plus Low-dose Prednisone Has a Favorable Safety Profile, Improves Survival and Produces Psa and Radiographic Responses in Metastatic Castration-resistant Prostate Cancer Progressing After Docetaxel-based Chemotherapy: Results From Cou-aa-301, a Randomized, Double-blind, Placebo-controlled, Phase Iii Study