Comparing the Cost Per Treatment Success of Thrombopoietin Receptor Agonists to Watch & Rescue for the Treatment of Primary Adult Chronic Immune Thrombocytopenia (ITP) in the US
Authors: Northridge Kelly , Danese Mark , Deuson Robert 
Published: October 2019

Abstract
Abstract 4640

OBJECTIVES:
To compare the drug costs relative to response of two thrombopoietin receptor agonists, romiplostim and eltrombopag, to Watch & Rescue for the treatment of chronic immune thrombocytopenia (ITP), from a health plan perspective. ITP, a diagnosis of exclusion, is characterized by low platelet counts and, depending on platelet count level, increased risk of bleeding (Rodeghiero F, et al. Blood. 2009:113(11):2386–2393).

METHODS:
An Excel® model compared 2011 US drug costs (wholesale acquisition cost) to the overall patient response rates (four or more weekly platelet counts of ≥50 × 109/L during the study from week 2 to 25) observed in individual 6-month placebo-controlled trials for romiplostim, eltrombopag, and placebo (or Watch & Rescue) (http://www.nice.org.uk/nicemedia/live/12025/50715/50715.pdf). These trials studied patients with median baseline platelet counts of 16 × 109/L (in both the romiplostim and eltrombopag trials) with 51% of the eltrombopag and 64% of the romiplostim patients receiving ≥3 previous treatments prior to joining each respective trial (Kuter, D, et al. Lancet. 2008:371:395–403; Cheng G, et al. Lancet. 2011:377:393–402; Bussel, J, et al. Lancet. 2009:373:641–648). The model considers a 55 mg daily dose of eltrombopag, and an average dose (including wastage) derived from a trial-based simulation for the US of 286 mcg per weekly administration of romiplostim. It assumes that 30% of US patients are splenectomized. The model considers a 1 g/kg overall dose of IVIg per rescue event at an average romiplostim trial-based weighted average (by splenectomy status) rate of 2.29 administrations per 6-month period (Weitz, I, et al. Curr Med Res Opin. 2012:28(5):789–796).

RESULTS:
For romiplostim patients, the expected cost of treating a patient with romiplostim over a 6-month period (trial period) is $34,655, with an overall response rate of 83%, or a cost per patient with an overall response of $41,753 ($34,655÷83%). The expected 6-month cost of treating the same patient with eltrombopag is $28,516, for an overall response rate of 57%, or a cost per patient with an overall response of $50,028 ($28,516÷57%). Comparatively, the expected 6-month cost of treating the same patient with Watch & Rescue is $11,681, with an overall response rate of 9%, or a cost per patient with an overall response of $129,789 ($11,681÷9%). Patients treated with thrombopoietin receptor agonists experience a 48 to 74% higher overall response rates than patients treated with Watch & Rescue, at a 153 to 196% reduction in resources to achieve the response. Sensitivity analyses were performed on key variables; a ±50% change in the average 6-month cost of IVIg (from either a decrease in cost or a decrease in the average number of administrations) resulted in ±50% change in the Watch & Rescue cost per response ($64,894 to $194,683). A decrease of 25% to the response rates for romiplostim and eltrombopag individually resulted in a 33% increase in the overall cost per patient with an overall response to $55,670 for romiplostim and $66,704 for eltrombopag.

CONCLUSIONS:
In chronic adult ITP, the use of thrombopoietin receptor agonists represents an efficient use of healthcare resources, with better health outcomes at a significantly lower cost per treatment success than treatment with Watch & Rescue.

Disclosures:
Northridge: Amgen Inc.: Consultancy, Research Funding. Danese:Amgen Inc.: Consultancy, Research Funding. Deuson:Amgen Inc.: Employment, Equity Ownership.