This is a Phase 3 multicenter, double-blind, double-dummy, randomized study. Only subjects with PV who have received HU for at least 12 weeks, have been receiving a stable dose before screening, and still have symptoms related to PV will be enrolled.
Subjects will be randomized (1:1) to 1 of 2 treatment arms:
A: ruxolitinib and HU-placebo B: HU and ruxolitinib-placebo
Subjects randomized to either arm may be eligible to transition to open-label ruxolitinib after Week 16.