Cost-effectiveness analysis of cadonilimab combined with chemotherapy as first-line treatment for HER2-negative advanced gastric or gastroesophageal junction adenocarcinoma

Objective To assess the cost-effectiveness of cadonilimab plus XELOX versus placebo plus oxaliplatin and capecitabine (XELOX) as first-line therapy for HER2-negative advanced gastric/gastroesophageal junction (G/GEJ) adenocarcinoma. Methods A partitioned survival model with three states (progression-free survival [PFS], progressed disease [PD], death) was developed over a 10-year horizon (21-day cycles, 5% discount rate). Outcomes included costs and quality-adjusted life years (QALYs). Incremental cost-effectiveness ratios (ICERs) were calculated, with sensitivity analyses (one-way, probabilistic [PSA]) to evaluate robustness. Results The base-case analysis demonstrated that adding cadonilimab to chemotherapy improved outcomes by 0.25 QALYs but increased costs by ¥217,521, leading to an ICER of ¥870,084 per QALY—surpassing the acceptable WTP threshold (3× China’s 2024 GDP per capita). One-way sensitivity analysis revealed that the model was most sensitive to changes in PD/PFS health utilities, drug cost, and body weight. Notably, probabilistic sensitivity analysis suggested 0% probability of this strategy being cost-effective. Conclusion At the current WTP threshold, cadonilimab with chemotherapy is not cost-effective for HER2-negative advanced G/GEJ adenocarcinoma. Clinical trial number Not applicable.