Table 1.
Baseline characteristics
| Characteristic | Cohort 1 (N = 50) | Cohort 2 (N = 50) | Cohort 3 (N = 69) | All (N = 169) |
|---|---|---|---|---|
| Female, n (%) | 27 (54.0) | 38 (76.0) | 49 (71.0) | 114 (67.5) |
| Age, mean (SD), years | 55.5 (17.1) | 48.6 (16.5) | 46.6 (16.3) | 49.8 (16.9) |
| Platelet counta, median (range), ×109/L | 26 (0.51–30.0) | 18 (1.0–93.0) | 25 (1.0–74.0) | 23 (0.5–130.0) |
| Duration of ITP, median (range), years | 7 (0–48) | 5 (0–46) | 2 (0–31) | 4 (0–48) |
| Four or more prior ITP treatments, n (%) | 15 (30) | 10 (20) | 10 (15) | 35 (21) |
| Splenectomy prior to study, n (%) | 22 (44) | 15 (30) | 23 (33) | 60 (36) |
| Bone marrow reticulin and/or collagen grade per modified Bauermeister scaleb, n (%) | ||||
| 0 | 12 (24) | 15 (30) | 16 (23) | 43 (25) |
| 1 | 37 (74) | 32 (64) | 50 (73) | 119 (71) |
| 2 | 1 (2) | 3 (6) | 3 (4) | 7 (4) |
Per study design, patients were sequentially enrolled into three cohorts, with biopsies to be done at baseline and year 1 (cohort 1), year 2 (cohort 2), or year 3 (cohort 3). Patients from cohorts 1 and 2 had the option to continue receiving romiplostim after bone marrow biopsies for a total of 3 years
ITP immune thrombocytopenia, SD standard deviation
aDefined as the last platelet count prior to the first dose of romiplostim
bThere were no patients with grade 3 or grade 4 biopsies at baseline. Per protocol, the maximum allowable baseline grade was 3