I could not find more details other than "APPROACH is a randomized, double-blind, placebo-controlled, 52-week Phase 3 study in 66 patients with FCS, a rare disease affecting approximately 3,000 to 5,000 patients worldwide ... Volanesorsen-treated patients with the highest documented frequency of pancreatitis attacks suffered no attacks during the 52-week treatment period (p=0.02)" ... zero pancreatitis in the treatment arm and ??? pancreatitis in the placebo arm
IONS ran two "Phase 3"s - one in FCS (for approval in FCS), and the other more general very high trig (which had some FCS patients). The latter was stat sig in a secondary endpoint for pancreatitis, the former had a meaningful 'trend' (but wasn't stat sig).
Given that the trials were tiny, that is pretty impressive.