This study aimed to assess the cost-effectiveness of avelumab maintenance treatment plus best supportive care (BSC) versus BSC alone from a Dutch societal perspective.

A partitioned survival model was developed incorporating JAVELIN Bladder 100 trial data to inform overall and progression-free survival, adverse events incidence, and health-state utilities.

Costs for drugs, healthcare resource use, adverse events, and indirect costs were obtained from national databases, the Dutch costing manual, and published literature. Assumptions were validated by clinical experts.

Avelumab 1L maintenance treatment plus BSC was estimated to have €48,186 discounted incremental costs and 0.63 discounted incremental QALYs versus BSC alone, leading to a base-case ICER of €76,450, supported by consistent scenario and sensitivity analyses.

Avelumab 1L maintenance treatment is likely to be a cost-effective treatment in advanced or metastatic urothelial carcinoma in the Netherlands.