IFNA1 and acquired polycythemia vera: On the basis of findings suggesting that ruxolitinib increases the efficacy and tolerability of PEG-IFN alpha-2, a phase II trial investigated the combination of ruxolitinib with low-dose PEG-IFN alpha-2 in 32 patients with PV and 18 with MF previously intolerant or refractory to PEG-IFN alpha-2.