Cost-Effectiveness of ⁹⁰Y-Ibritumomab Tiuxetan (⁹⁰Y-Zevalin) Versus Rituximab Monotherapy in Patients with Relapsed Follicular Lymphoma.

PURPOSE: Currently, there are no cost-effectiveness data comparing the use of ⁹⁰Y-Zevalin with rituximab in follicular lymphoma (FL). The objective of this analysis was to estimate the incremental cost-effectiveness of a single dose of ⁹⁰Y-Zevalin 0.4 mCi/kg compared with: 1) standard rituximab treatment of 375 mg/m² weekly for 4 weeks (4-dose rituximab) and 2) standard rituximab followed by 4 weeks of maintenance therapy (8-dose rituximab) in patients with FL.

METHODS: The effectiveness evidence used for the analysis was derived from the only 2 clinical studies published to date enrolling comparable populations where patients had received either ⁹⁰Y-Zevalin or rituximab monotherapy. In both cases, the patients had received a median of 2 prior chemotherapies. “Disease-free” months was used to assess effectiveness or “health benefit.” Results were derived from a randomized phase III study that compared ⁹⁰Y-Zevalin and 4-cycle rituximab, the final results of which were recently published by Gordon et al (2005). The evidence of health benefit for the 8-dose rituximab arm was derived from a phase II study published by Ghielmini et al (2004). Disease-free months were estimated by multiplying the overall response rates for each therapy by the median number of months of response duration. To estimate the resources involved in the management of grade 3 or 4 adverse events we consulted a panel of experts and applied their recommendations to the incidence rates reported in the clinical studies. All other resource use estimates (costs for administration, prophylaxis and monitoring) were derived from established guidelines for both ⁹⁰Y-Zevalin and rituximab. Unit costs for The Netherlands were derived from local hospital accounting systems, tariffs, and listed wholesale prices for medication. The price year was 2001.

RESULTS: The mean total cost of treatment with ⁹⁰Y-Zevalin was estimated to be approximately EUR 16,345. The mean total cost of treatment with 4 doses of rituximab was estimated to be lower at EUR 9,510, whereas the cost associated with an 8-dose rituximab treatment was EUR 19,020. In terms of health benefits, the average number of disease-free months per patient treated was highest for ⁹⁰Y-Zevalin at 14.4 months followed by 11.4 months for the 8-dose rituximab and 6.2 months for the 4-dose rituximab. When the estimates of health benefit are combined with costs, the analysis demonstrates a mean cost per disease-free month for ⁹⁰Y-Zevalin of EUR 1,138, the lowest of the 3 therapies, followed by EUR 1,544 for 4-dose rituximab therapy, and EUR 1,674 for 8-dose rituximab.

CONCLUSIONS: The findings imply that for each third line follicular NHL treatment where ⁹⁰Y-Zevalin is used rather than 4 doses of rituximab, the additional cost to the payer would be, on average, EUR 6,835. For this additional cost, the benefit to the patient would be an average 8.2 additional disease-free months, over and above what would have been gained with 4-dose rituximab therapy. Furthermore, when the costs and benefits of ⁹⁰Y-Zevalin are compared with the 8-dose rituximab regimen, ⁹⁰Y-Zevalin is the more cost-effective strategy.