Economic Evaluation of Adding Daratumumab to a Regimen of Bortezomib plus Dexamethasone in Relapsed or Refractory Multiple Myeloma: Based on the Latest Updated Analysis of CASTOR

Purpose: Adding daratumumab to a regimen of bortezomib + dexamethasone (Vd) has been reported to provide a benefit of longer progression-free survival in patients with relapsed or refractory multiple myeloma (RRMM). However, it is still unclear whether the addition of daratumumab is cost-effective in RRMM. Based on the latest updated analysis of data from the CASTOR trial, this study performed an economic evaluation of the addition of daratumumab to Vd in patients with RRMM. Methods: A Markov decision model was used for estimating the long-term costs and efficacy of Vd with or without daratumumab in patients with RRMM. Data on efficacy were taken from the CASTOR trial to compare Vd + daratumumab with Vd. Costs were taken from the US Centers for Medicare & Medicaid Services and from the literature. A series of sensitivity analyses were performed to address the robustness of the model. Variations in the price of daratumumab and subgroup analyses were conducted. Findings: The base-case analysis showed that adding daratumumab to Vd provided an additional 1.256 quality-adjusted life-years (QALYs) or 1.645 life-years (LYs), with incremental 213,164 USD (163,184 USD) per QALY (LY) gained. Univariate sensitivity analyses suggested that the subsequent treatment cost of DVd and the price of daratumumab had the greatest effect on the incremental costeffectiveness ratio. According to the variations analysis of the price of daratumumab, the addition of daratumumab would be cost-effective when daratumumab was priced at 70% (30%) of the current price at a willingness-to-pay threshold of 200,000 USD/QALY (150,000 USD/QALY). Subgroup analysis indicated that adding daratumumab to Vd was most cost-effective in patients with 1 prior line of therapy. Implications: From a US-payer perspective, daratumumab added to Vd in RRMM is likely to exceed the common accepted values of costeffectiveness (C) 2019 Elsevier Inc. All rights reserved.