Unlike lung cancer and breast cancer, gastric cancer has been regarded as one type of cancer that has not benefited from the development of new anticancer drugs. For the past decade, chemotherapy has been the standard first-line treatment for patients with HER2 gene-negative metastatic gastric cancer. This means that there were no suitable new drugs other than HER2-targeting anticancer drugs available for its treatment. However, changes have recently occurred in the treatment of gastric cancer. The immuno-oncology drug ‘Opdivo’ emerged as a first-line option, another immuno-oncology drug 'Keytruda' also obtained positive results. A targeted therapy that targets a new protein is also expected to enter the ma