The FDA has approved Pharmaessentia Corp.'s Besremi (ropeginterferon alfa-2b) for the rare blood disorder polycythemia vera, the interferon offering an alternative to JAK inhibitor therapy. PV is a rare, chronic and life-threatening blood cancer caused by a mutation in stem cells in the bone marrow, resulting in overproduction of blood cells. Besremi, which is already approved in Taiwan, Europe and South Korea, is a monopegylated, long-acting interferon, which counteracts the effects of the mutated bone marrow cells and is initially taken fortnightly.