Abstract
BACKGROUND: The GEMSTONE-303 trial demonstrated that sugemalimab combined with capecitabine and oxaliplatin (CAPOX) improved survival benefit in patients with advanced gastric/gastroesophageal junction cancer (GC/GEJC) and a programmed death-ligand 1 (PD-L1) combined positive score (CPS) ≥5. However, its cost-effectiveness in China remains unassessed. METHODS: A partitioned survival model was developed from the Chinese healthcare payer perspective using data from the GEMSTONE-303 trial. Costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs) were evaluated over a 10-year horizon. Sensitivity analyses assessed model uncertainty, while subgroup and scenario analyses examined the impact of PD-L1 expression, drug pricing, and patient assistance programs (PAPs). RESULTS: In the PD-L1 CPS ≥ 5 group, sugemalimab plus CAPOX yielded an incremental cost of $44,455.46 and 0.22 additional QALYs compared to chemotherapy, resulting in an ICER of $206,024.50/QALY. For patients with CPS ≥10, the ICER dropped to $173,182.90/QALY, but still exceeded the willingness-to-pay (WTP) threshold. One-way sensitivity analysis revealed sugemalimab price as the most influential parameter, requiring a 75.6% price reduction to achieve cost-effectiveness. A PAP reduced ICERs to $44,926.00/QALY and $39,513.96/QALY in the CPS ≥5 and CPS ≥10 subgroups, respectively. CONCLUSION: At current prices, sugemalimab plus CAPOX is not cost-effective as a first-line treatment for advanced GC/GEJC in China. It is essential to adopt a combination of targeted patient selection, price negotiation, and broader PAP access to bring the ICER below the WTP threshold. These findings inform reimbursement negotiations and highlight the need for stratified pricing strategies to optimize accessibility in economically diverse populations.