Image courtesy of AFIP
Health Canada has approved the JAK1/2 inhibitor ruxolitinib (Jakavi) for the control of hematocrit in adult patients with polycythemia vera (PV) that is resistant to or intolerant of a cytoreductive agent.
Ruxolitinib is the first targeted treatment approved to treat PV in Canada.
The approval is based on results of the phase 3 RESPONSE trial, which showed that ruxolitinib could provide hematocrit control without phlebotomy in patients with PV.
For RESPONSE, researchers compared ruxolitinib to best available therapy (BAT) for PV. The trial was sponsored by Incyte Corporation and Novartis Pharmaceuticals, the companies developing ruxolitinib.
The study’s primary endpoint was the proportion of patients who achieved hematocrit control and were not eligible for phlebotomy from weeks 8 through 32 (with no more than 1 instance of phlebotomy eligibility between randomization and week 8) and who saw a 35% or greater reduction in spleen volume from baseline, as assessed by imaging at week 32.
The primary endpoint was met by significantly more patients in the ruxolitinib arm than the BAT arm— 20.9% and 0.9%, respectively (P<0.0001).
Sixty percent of patients in the ruxolitinib arm achieved hematocrit control, as did 19.6% of patients in the BAT arm. The percentage of patients who had at least a 35% reduction in spleen volume was 38.2% in the ruxolitinib arm and 0.9% in the BAT arm.
The proportion of patients achieving a complete hematologic remission at week 32 was 23.6% in the ruxolitinib arm and 8.9% in the BAT arm (P=0.0028). The proportion of patients achieving a durable primary response at week 48 was 19.1% in the ruxolitinib arm and 0.9% in the BAT arm (P<0.0001).
At 80 weeks, the most common adverse events in the ruxolitinib arm were headache (22%), diarrhea (20%), pruritus (20%), and fatigue (17%). Grade 3 or 4 anemia and thrombocytopenia occurred in 2% and 6% of patients, respectively. Five percent of patients discontinued ruxolitinib due to adverse events.
