OBJECTIVES: Adjuvant cancer therapy is additional treatment administered after the primary treatment (usually surgery) to lower the risk of recurrence. The mechanism of action of the recently developed immune checkpoint inhibitors suggests they have potential as adjuvant therapies: by their action in enhancing the anti-tumor immune response, residual tumor cells may be eliminated. In this study, we identified potential challenges to pricing and reimbursement (P&R) assessment of these drugs as adjuvant given the likely high cost of these innovative agents. METHODS: We searched clinicaltrials.gov to identify current trials of immune checkpoint inhibitors as adjuvant therapies. We then searched the website of the UK health technology assessment agency, NICE, for appraisals of adjuvant cancer therapies, identified the corresponding evaluations by PBAC (Australia) and the SMC (Scotland) on these agencies’ websites, and identified key challenges. RESULTS: We identified nine trials with an immune checkpoint inhibitor used as adjuvant therapy, only one of which was Phase 3. Six NICE appraisals of pharmacological agents used as adjuvants were identified, all of which had also been assessed by PBAC and the SMC. Particular areas of concern in evaluations were the extrapolation of disease-free survival to overall survival, and the balance between safety and benefit in disease prevention. Restrictions were imposed in several decisions on the duration of adjuvant treatment and the risk status of patients, dependent on the available clinical evidence. So far, adjuvant therapies have rarely tested acceptable cost-effectiveness thresholds. CONCLUSIONS: Development of immune checkpoint inhibitors as adjuvant therapies is still at an early stage, but consideration of the economic and clinical case for these drugs will be needed to ensure successful P&R. Experience with the evaluation of high-cost therapies in this context is limited, so engagement will be needed between manufacturers and agencies to define the required evidence and willingness to pay.