A complete platelet response is defined as an increase in platelet counts to >150×109/L on two consecutive occasions. A partial response is defined as an increase in the platelet count to between 50 and 150×109/L on two consecutive occasions, 1 week apart. Duration of response is considered from the day of the initial infusion to the first time of relapse (platelet count <30×109/L)or to time of analysis.