Mean platelet count from baseline to end-of-study treatment with sutimlimab. The value at part A baseline is the average of all platelet counts during the screening period, including day 0 before dosing. The value at part B baseline is the average of all platelet counts during the screening period in part B. N numbers at each point vary according to data availability. In part A, data were available for 5 to 12 patients at each time point, except as follows: n = 4 on days 70, 84, and 154 and n = 1 on day 196. In part B, data were available for 5 to 7 patients at each time point, except as follows: n = 4 for doses 15 to 49, 51, and 53; n = 3 for doses 52, 54, and 55; n = 2 for doses 56 and 57; and n = 1 for doses 58 to 61. OS, end of study; EOT, end of treatment; SEM, standard error of the mean. ^aFor patients enrolled in protocol version 3 or higher, the washout period starts on day 147 and ends on day 196.