PB0330 - Romiplostim (Nplate) Use for Thrombocytopenia at a Large Academic Medical Center

Background: Romiplostim (Nplate®) is an injectable thrombopoietin (TPO) peptide mimetic used for immune thrombocytopenia (ITP) dosed at 1 mcg/kg, with dose adjustments made in 1 mcg/kg/week increments. It is indicated for ITP for ≥3 months and who are corticosteroid dependent and or unresponsive. In practice, romiplostim is often initiated at higher doses. Furthermore, doses may be administered within a 3-5 day period interval and/or increased at 1 - 2 mcg/kg increments. Romiplostim is used off-label in: hematopoietic stem cell transplant (HSCT), chemotherapy induced thrombocytopenia (CIT), and cirrhosis.

Aims: To analyze the utilization of romiplostim in patients with ITP or off-label.

Methods: This was a retrospective review of romiplostim at NYU Langone Health from January 2019 to July 2021. The primary outcome was percent of patients achieving platelet counts ≥50 by week 1 and maintaining platelet counts ≥50 by end of each week. Secondary outcomes included tolerability.

Results: There were a total of 150 romiplostim administrations in 84 patients. The top three romiplostim indications include: ITP, HSCT, and CIT. The majority of patients receiving romiplostim for ITP adjunctive received corticosteroids and/or IVIG. Baseline platelet values may be confounded by concomitant platelet transfusions. A median dose of 2.4 mcg/kg was sufficient to achieve goal platelets by week 1, however providers at NYULH initiate romiplostim at a median dose of 3.8 mcg/kg (250 mcg) for the purposes of dose rounding. Majority of patients were not re-dosed within a week, however many had >1 mcg/kg dose increases from week to week. There were two thrombotic adverse events; however, not attributed to romiplostim use.

Conclusion(s): Higher than package label doses of romiplostim do not seem to be associated with an increased incidence of adverse events, and were well tolerated.
A flat dosing policy rounding to the nearest vial size should be implemented in order to minimize drug waste, given tolerability.