JAK2 and acquired polycythemia vera: Fedratinib (SAR302503, TG101348) is an oral kinase inhibitor with activity against wild type and mutationally activated JAK2 and FMS-like tyrosine kinase 3 (FLT3) that is being developed for the treatment of intermediate or high-risk primary or secondary (post-PV or post-ET) MF [10–13].