Purpose The combination of paclitaxel + ramucirumab is a standard second-line treatment in patients with advanced gastric cancer. This therapy has been associated with increased median overall survival and progression-free survival compared with those with paclitaxel monotherapy. We evaluated the cost-effectiveness of paclitaxel + ramucirumab combination therapy in patients with advanced gastric cancer, from the perspective of health care payers in Japan. Methods We constructed a Markov model to compare, over a time horizon of 3 years, the costs and effectiveness of the combination of paclitaxel + ramucirumab and paclitaxel alone as second-line therapies for advanced gastric cancer in Japan. Health outcomes were measured in life-years (LYs) and quality-adjusted (QA) LYs gained. Costs were calculated using year-2016 Japanese yen (\1 = US $17.79) according to the social insurance reimbursement schedule and drug tariff of the fee-for-service system in Japan. Model robustness was addressed through 1-way and probabilistic sensitivity analyses. The costs and QALYs were discounted at a rate of 2% per year. The willingness-to-pay threshold was set at the World Health Organization's criterion of \12 million, because no consensus exists regarding the threshold for acceptable cost per QALY ratios in Japan's health policy. Findings Paclitaxel + ramucirumab combination therapy was estimated to provide an additional 0.09 QALYs (0.10 LYs) at a cost of \3,870,077, resulting in an incremental cost-effectiveness ratio of \43,010,248/QALY. The incremental cost-effectiveness ratio for the combination therapy was &gt
\12 million/QALY in all of the 1-way and probabilistic sensitivity analyses. Implications Adding ramucirumab to a regimen of paclitaxel in the second-line treatment of advanced gastric cancer is expected to provide a minimal incremental benefit at a high incremental cost per QALY. Based on our findings, adjustments in the price of ramucirumab, as well as improves in other clinical parameters such as survival time and adverse event in advanced gastric cancer therapy, are needed.