Table 2.
Number of patients with reticulin or collagen present in bone marrow biopsies as determined by silver or trichrome staining and the modified Bauermeister scale
| By cohort | Cohort 1 (N = 50) | Cohort 2 (N = 50) | Cohort 3 (N = 69) | Total (N = 169) |
| Bone marrow biopsies after receiving romiplostima | 39 | 40 | 58 | 137 |
| Biopsies evaluable for collagen (trichrome stain)b | 35 | 39 | 58 | 132 |
| Positive for collagen | 0 | 0 | 2 (3.4 %)c | 2 (1.5 %)c |
| Patients with biopsies evaluable for reticulin (silver stain)b | 34 | 39 | 58 | 131 |
| Increase in reticulin by at least two grades excluding collagen | 0 | 2 (5.1 %) | 5 (8.6 %)d | 7 (5.3 %) |
| By exposure at time of biopsy | 1 yeare | 2 yearse | 3 yearse | Total (N = 169) |
| Biopsies evaluable for collagen (trichrome stain)b | 42 | 38 | 52 | 132 |
| Positive for collagen | 1 (2.4 %) | 0 | 1 (1.9 %) | 2 (1.5 %)c |
| Patients with biopsies evaluable for reticulin (silver stain)b | 41 | 38 | 52 | 131 |
| Increase in reticulin by at least two grades excluding collagen | 2 (4.9 %) | 1 (2.6 %) | 4 (7.7 %) | 7 (5.3 %) |
ITP immune thrombocytopenia
aThree patients in cohort 1, three in cohort 2, and 10 in cohort 3 had biopsies at the end of treatment because of early discontinuation. Reasons included lack of response/requirement for alternative therapy (n = 9), consent withdrawn (n = 4), suspected non-Hodgkin lymphoma (n = 1), difficulty dosing (n = 1), and patient ineligibility (n = 1)
bTrichrome and silver staining results could not be obtained for all biopsies because of inadequate samples. Per bone marrow biopsy (smear and core) comments, these biopsies had insufficient cellular marrow for evaluation
cOne case: grade 4 after 25 weeks in a patient with ITP who did not respond to multiple courses of treatment; no evidence of collagen on follow-up biopsy 10 weeks later. One case: grade 4 at end of treatment; patient refused follow-up biopsy
dThe five patients with increases in reticulin by two or more grades (excluding those patients with collagen) included two patients who increased from grade 0 to 2 and three patients who increased from grade 1 to 3
eYear 1 was defined as up to 1.5 years as some patients did not have their scheduled biopsy until months later; likewise for cohorts 2 and 3