Study of Dose Escalation of Abiraterone Actetate in Prostate Cancer

Inclusion Criteria: Step 1 * Male 18 years and older. * Voluntary signed informed consents of the patient before any study-specific procedure. * Histologically confirmed prostate adenocarcinoma. * Presence of bone and/or soft-tissue and/or visceral metastases through CT scan, MRI, scintigraphy scan. * Progressive disease assessed by PSA, CT scan, MRI or bone scan according to the PCGW3 criteria PSA progression is defined as a 25% or greater increase and an absolute increase of 2 ng/mL or more from the nadir, which is confirmed by a second value obtained 1 or more weeks later. Bone scan: at least two or more new lesions are seen on bone scan compared with a prior scan. * Patient with no or moderate symptoms (no need for continuous opioid treatment) * Effective castration confirmed by testosterone plasma level \< 50 ng/dL * ECOG performance status: 0-2 * Life expectancy \> 3 months * Patient affiliate to french social assurance * Laboratory criteria within 14 days before inclusion: * SGPT and SGOT \< 5 fold the upper normal value * Kaliemia \> 3 mM * Patient using an effective contraceptive method during treatment Step2 * Patients receiving ABI 1000 mg/day + prednisone/prednisolone 10 mg once a day through step 1 for at least two months * At least two measures of ABI plasma concentrations available within the first three months of treatment * Mean of ABI concentration \< 8,5 ng/mL. * Progressive disease occuring within 28 weeks following starting of ABI in the step 1. …