JAK2 and Thrombocytopenia: The thrombocytopenia and anemia associated with fedratinib may be related to its on-target inhibition of WT JAK2 and off-target inhibition of FMS-like tyrosine kinase 3 (FLT3) and bromodomain-containing protein 4 (BRD4) (Talpaz and Kiladjian, 2021).