Cost-effectiveness analysis of pembrolizumab in patients with treatment-refractory metastatic colorectal cancer in Japan

Pembrolizumab monotherapy is not a cost-effective option in late-line treatment for patients with mCRC and MSI-H/dMMR in the Japanese healthcare system. Objective The immune checkpoint inhibitor pembrolizumab has recently been recognized as a standard treatment regimen for patients with metastatic colorectal cancer and the microsatellite-instability-high/mismatch repair-deficient mutation. However, its cost-effectiveness in late-line treatment remains unclear. The aim of this study was to assess the cost-effectiveness of pembrolizumab for patients with microsatellite-instability-high/mismatch repair-deficient metastatic colorectal cancer. Methods Markov decision modeling using treatment costs, disease-free survival and overall survival was performed to examine the cost-effectiveness of pembrolizumab monotherapy compared with chemotherapy, and best supportive care. The Japanese healthcare payer's perspective was adopted. The outcomes were modeled on the basis of published literature. The primary outcome was the incremental cost-effectiveness ratio between the strategies. Sensitivity analyses were performed and the effects of uncertainty on the model parameters were investigated. Results Pembrolizumab monotherapy had incremental cost-effectiveness ratios of $408204.3 per quality-adjusted life-year gained compared with best supportive care and $489123.4 per quality-adjusted life-year gained compared with chemotherapy. Given a Japanese willingness-to-pay threshold of $69560.38 per quality-adjusted life-year, the base case results suggested that pembrolizumab monotherapy was not cost-effective. The sensitivity analysis results were in line with the base case results. Conclusion Pembrolizumab monotherapy is not a cost-effective option in late-line treatment for patients with metastatic colorectal cancer and microsatellite-instability-high/mismatch repair-deficient mutation in the Japanese healthcare system. Further studies on its cost-effectiveness in first-line treatment are warranted.