AVII found some very fascinating mismatched dates between the FDA documentation for Zytiga approval and the J&J PRs etc.. The timeline seems to have gone like:
a) Jan 2010 (see dates in FDA Statistical Review): Pre-planned interim occurs for OS - Zytiga is VERY stat sig (<0.0001 when alpha was 0.0141).
b) Sept 2010: Final OS analysis for OS (kinda immaterial - but very stat sig)
c) Oct 2010: First J&J PR that they hit the interim (and thus x-over is allowed - but note PR is silent on the fact that they hit that interim 9 months ago).
The updated OS analysis was conducted per the Agency’s request to confirm the OS estimates. The cut-off date for the updated OS analysis was before the first subject crossing over