Patients with spleen growth of greater than 25% based on an increase in spleen volume from Baseline were eligible for early unblinding, and for patients on placebo, cross over to ruxolitinib prior to the primary study endpoint being reached. If this spleen growth occurred before Week 24, it must have been accompanied by specific worsening of symptoms, based on worsening early satiety accompanied by weight loss or worsening pain requiring daily narcotic use. After Week 24, asymptomatic spleen growth alone was sufficient for early unblinding and potential cross over. Patients found to have been randomized to ruxolitinib after early unblinding prior to Week 24 were discontinued.
When half of the patients remaining in the study completed the Week 36 visit and all patients enrolled completed Week 24 or discontinued, the database was frozen and the primary analysis was conducted. Once this was complete, all patients were unblinded and patients who had been randomized to placebo were given the opportunity to cross over to ruxolitinib treatment, provided hematology laboratory parameters were adequate; Patients receiving benefit could continue treatment until the later of marketing approval or when the last randomized patient remaining in the study had completed Week 144 (36 months).
