TPO and autoimmune thrombocytopenic purpura: Avatrombopag, an oral TPO-RA, has been studied in healthy adults in 2 single- and multiple-dose phase 1 dose-rising, safety and tolerability studies [24], and in patients with persistent (3–12 months [1]) and chronic (> 12 months [1]) ITP in a phase 2 randomised study [25].