2. Participants who have a mean baseline platelet count of less than 50 x 10^9/L. Platelet counts must be measured on 2 separate occasions, during the Screening Period and at Baseline, and must be performed at least one day apart with neither platelet count greater than 60 x 10^9/L. The mean of these 2 platelet counts (mean baseline platelet count) will be used for entry criteria and for assignment to the low or high baseline platelet count cohort.