Concurrent vs. Sequential Sipuleucel-T & Abiraterone Treatment in Men With Metastatic Castrate Resistant Prostate Cancer

Subjects underwent screening procedures at the Screening Visit to ensure that they met the inclusion and exclusion criteria outlined in the protocol. Subjects were evaluated for eligibility criteria, and if eligible, were registered and randomized in a 1:1 into either the Concurrent Arm or the Sequential Arm. Subjects in both arms underwent a standard 1.5 to 2.0 blood volume leukapheresis, followed approximately 3 days later by an intravenous (IV) infusion of sipuleucel-T. This process occurred at approximately 2-week intervals. A course of sipuleucel-T treatment comprised three infusions. Following the first infusion, subjects were limited to a maximum of three total product failures for all subsequent infusions, due specifically to insufficient total nucleated cell (TNC) count and/or CD54 upregulation. These subjects received no further leukaphereses or sipuleucel-T infusions, but did receive abiraterone acetate plus prednisone per the schedule of the arm to which they were randomized. All subjects received a total of 26 weeks of abiraterone acetate plus prednisone therapy. All immune monitoring (IM) endpoints were collected from all subjects who received at least one infusion. Cellular and serological immune responses were assessed for subjects in both arms. In both arms, IM blood samples were collected at baseline (screening); pre-leukapheresis 2 and 3; post-infusion 1, 2, and 3; and weeks 6, 10, 14, and 26, with the timing of IM visits based on the onset of treatment (Day 0). Day 0 was the day of the first infusion. Post-infusion blood draws occurred at 3 hours (allowable window 1-24 hours) after each infusion. If a subject received only one or two infusions, immune samples were still drawn at the scheduled time points based on the first infusion (Day 0). If the subject was not scheduled to undergo further leukapheresis, no other pre-leukapheresis procedures were conducted. During the active follow-up phase, subjects were followed from registration through the Post-Treatment Visit (30-37 days post-last study treatment), or until disease progression, unacceptable toxicity, or death, whichever occurred first. During the long-term follow-up (LTFU) phase, subjects were followed from the Post-Treatment Visit for up to 3 years from the date of registration/randomization. During the LTFU phase, only new treatment-related serious adverse event (SAE)s, cerebrovascular event (CVE)s (regardless of causality), the first anti-cancer therapy and first chemotherapy, and survival status were collected via a quarterly telephone call. Overall survival was measured as the time from randomization until death over a 3-year period.