Treatment with trastuzumab deruxtecan, a drug-conjugated anti-HER2 antibody, showed a significantly higher response rate and longer overall survival than physician-chosen conventional chemotherapy (irinotecan or paclitaxel) in the randomized phase II trial in Asia for HER2-positive gastric cancer patients who were treated with two or more prior regimens. The gene discussed is ERBB2; the disease is gastric cancer.