phase-2 efficacy measured at 78 weeks, specifically, was quite good
Not sure I agree with this - it was only the completer analysis that was respectable, and that was likely skewed by more APOE4 dropouts. In the mITT groups there was only efficacy in the lowest dosage group, and that seemed more placebo-related than drug related.
It's not the type of Phase 2 result that gives me any great confidence in their Phase 3. OTOH, they likely have access to more detailed data (brain scans etc.), and so maybe they saw something that increases their confidence level. The fact that it's JNJ calling the shots here does count for something.