Cost-effectiveness analysis of adding durvalumab to chemotherapy as first-line treatment for advanced biliary tract cancer based on the TOPAZ-1 trial

BACKGROUND: Durvalumab plus gemcitabine and cisplatin has a significant clinical benefit for advanced biliary tract cancer (BTC). However, the high price of durvalumab warrants an exploration of the economics. OBJECTIVE: To investigate the cost-effectiveness of adding durvalumab to gemcitabine and cisplatin compared with gemcitabine and cisplatin in first-line therapy of advanced BTC from the perspective of the Chinese healthcare system. METHODS: According to the TOPAZ-1 trial, a three-state Markov model was built by the TreeAge Pro 2022 software. The total costs and quality-adjusted life years (QALYs) were estimated, and the incremental cost-effectiveness ratio (ICER) was used as the evaluation index. The triple 2021 Chinese per capita gross domestic product (GDP) of $37,663.26/QALY was used as the willingness-to-pay (WTP) threshold. Outputs were analyzed for two scenarios with and without a durvalumab drug charity assistance policy. In the scenario analysis, the base-case model was run multiple times with different prices of durvalumab to determine the effect on the ICER. Moreover, the robustness of the model was tested through sensitivity analyses. RESULTS: Compared with chemotherapy alone, durvalumab plus chemotherapy resulted in an additional 0.12 QALY and an incremental cost of $18,555.19, the ICER was $159,644.70/QALY under the situation of charity assistance, and the ICER was $696,571.11/QALY without charity assistance, both exceeding the WTP threshold in China. The scenario analysis demonstrated that when the price of durvalumab fell by more than 94.2% to less than $0.33/mg, durvalumab plus chemotherapy will be more economical compared with chemotherapy alone under the situation of no charity assistance. One-way sensitivity analyses suggested that the cost of durvalumab had the greatest influence on the ICERs, and the probabilistic sensitivity analyses demonstrated that durvalumab plus chemotherapy was impossible to be cost-effective at the WTP threshold whether the charity assistance was available or not. CONCLUSIONS: Adding durvalumab to gemcitabine and cisplatin was not cost-effective for advanced BTC regardless of receiving and not receiving charitable assistance.