Effectiveness and safety of romiplostim among patients with newly diagnosed, persistent and chronic ITP in routine clinical practice in central and Eastern Europe: an analysis of the PLATON study

The objective of this analysis was to assess the effectiveness and safety of romiplostim in the real-world by duration of primary immune thrombocytopenia (ITP): 12 ('chronic') months. This was a post-hoc analysis of the PLATON single-arm, observational cohort study of adults from five Central and Eastern European countries receiving ≥1 romiplostim dose as second-line therapy, or where surgery was contraindicated. Durable (≥75% of measurements with ≥50 × 10 9 platelets/L during weeks 14-24) and overall platelet response (≥30 or ≥50 × 10 9 platelets/L at least once), rescue therapy, bleeding, discontinuation of other ITP medications, and adverse drug reactions (ADRs) were assessed. Of 100 participants, 22.0% had newly diagnosed, 17.0% had persistent, and 61.0% had chronic ITP. Prior splenectomy was most frequently reported in chronic ITP (32.8%), prior bleeding was predominant in newly diagnosed patients (68.2%). Durable platelet response was achieved in 50.0% (95% confidence interval [CI]: 28.2-71.8%) of newly diagnosed, 35.3% (95% CI: 14.2-61.7%) of persistent, and 31.1% (95% CI: 19.9-44.3%) of chronic ITP patients. Overall platelet response was achieved in >80% across all strata. Safety was comparable across groups, with a low incidence of thrombotic ADRs and no bone marrow ADRs. In this real-world study, platelet response to romiplostim was consistent across all strata of ITP duration. ADRs were infrequent and similar across ITP settings. These findings support the utilization of romiplostim in patients with newly diagnosed and persistent ITP in accordance with recent guidelines and the recent romiplostim label extension.