Cost-effectiveness of disitamab vedotin plus toripalimab versus chemotherapy alone as first-line treatment for HER2-overexpressing advanced urothelial carcinoma: a cost-effectiveness analysis from the Chinese healthcare system perspective

Background The antibody-drug conjugate disitamab vedotin (DV) in combination with the programmed death receptor-1 (PD-1) inhibitor toripalimab has demonstrated favorable efficacy and a manageable safety profile in patients with HER2-expressing advanced urothelial carcinoma (AUC), as evidenced by the pivotal RC48–016 clinical trial. Nevertheless, the economic viability of this combination strategy relative to conventional chemotherapy remains inadequately characterized. This study sought to evaluate the cost-effectiveness of the aforementioned combination regimen as first-line therapy for HER2-overexpressing AUC patients within the Chinese healthcare system. Methods Leveraging clinical data derived from the RC48–016 trial, a partitioned survival model (PSM) was developed to project long-term survival outcomes and healthcare resource consumption among HER2-overexpressing AUC patients receiving either DV plus toripalimab or chemotherapy alone. Primary outcome measures encompassed total costs, quality-adjusted life years (QALYs), and the incremental cost-effectiveness ratio (ICER). The willingness-to-pay (WTP) threshold was established at twice China’s 2024 per capita gross domestic product (GDP), amounting to $26,889.37 per QALY. Sensitivity analyses were undertaken to ascertain the robustness of the model findings. Results The chemotherapy-alone arm incurred total costs of $80,979.23, yielding 1.54 QALYs. Relative to chemotherapy alone, the DV plus toripalimab regimen was associated with an incremental cost of $5,696.81 and an incremental health gain of 0.89 QALYs, translating to an ICER of $6,433.19 per QALY—substantially below the prespecified WTP threshold. Sensitivity analyses identified the discount rate and the acquisition cost of disitamab vedotin as the principal drivers of ICER variation; nonetheless, ICER estimates remained below the WTP threshold across all scenarios examined, attesting to the robustness of the model conclusions. Conclusion Within the Chinese healthcare context, DV plus toripalimab as first-line treatment for HER2-overexpressing AUC confers meaningful survival benefits without imposing a prohibitive economic burden, thereby demonstrating favorable cost-effectiveness and representing a therapeutically valuable strategy with economic merit.