RESUMO
OBJECTIVE To evaluate the cost-effectiveness of tislelizumab combined with chemotherapy as first-line treatment for locally advanced unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma. METHODS The data of RATIONALE-305 study and related literature were used to establish a partitioned survival model from the perspective of China’s health system. The cycle was 3 weeks， the simulation time was set as 10 years， and the discount rate was 5%. The quality-adjusted life years （QALYs） were used as the health outcome indicator to evaluate the cost-effectiveness of tislelizumab combined with chemotherapy versus placebo combined with chemotherapy as first-line treatment for locally advanced unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma， and one-way sensitivity analysis and probabilistic sensitivity analysis were also conducted. RESULTS The base analysis showed that the patients received more 0.268 QALYs with tislelizumab plus chemotherapy， compared with placebo plus chemotherapy， but the cost increased by 70 404.81 yuan with an incremental cost- effectiveness ratio （ICER） of 262 431.62 yuan/QALY， which was less than three times China’s gross domestic product （GDP） per capita in 2023 as the willingness-to-pay （WTP） threshold （268 074 yuan/QALY）. One-way sensitivity analysis showed that the efficacy value of progress free survive and the price of tislelizumab had a greater impact on the ICER value. The results of probability sensitivity analysis showed that when the WTP threshold was 3 times China’s GDP per capita in 2023， the probability of tislelizumab being cost-effective was 53.3%. CONCLUSIONS When the WTP threshold is 3 times China’s GDP per capita in 2023， tislelizumab plus chemotherapy is cost-effective for first-line treatment of locally advanced unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma， compared with placebo plus chemotherapy.