TPO and autoimmune thrombocytopenic purpura: It is possible that ruxolitinib with ibrutinib suppresses macrophages and increases platelet numbers in the same way that glucocorticoids increase platelet counts in idiopathic thrombocytopenia (ITP).28 The effect may also reflect enhanced thrombopoiesis as bone marrow TPO levels increased in all patients and PDGF levels increased in most (Figure 3C and D).