A Phase 3, Multicenter, Randomized, Double-blind,Active-controlled, Parallel-group Trial With an Open-labelExtension Phase to Evaluate the Efficacy and Safety of OralE5501 Versus Eltrombopag, in Adults With Chronic ImmuneThrombocytopenia (Idiopathic Thrombocytopenic Purpura)

Core study: To compare the efficacy of avatrombopag (in addition to standard) of care to eltrombopag (in addition to standard of care) for the treatment of adult participants with chronic immune thrombocytopenia (idiopathic thrombocytopenic purpura \[ITP\]) as measured by durable platelet response. Open-label Extension Phase: To evaluate the safety and tolerability of long-term therapy with avatrombopag in participants with chronic ITP (cITP).