China, Japan, and other Asian countries represent the regions with the highest global incidence of gastric cancer. In China, most patients are still diagnosed at advanced stages, losing the opportunity for curative surgery. Effective systemic therapies are therefore critical to improving survival. In recent years, innovative therapies—particularly antibody–drug conjugates (ADCs)—have shown promising results. Among them, the HER2-targeted ADC trastuzumab deruxtecan (T-DXd) has achieved success in key clinical studies such as DESTINY-Gastric04, and is poised to reshape treatment paradigms starting from later-line settings. Asian investigators have played an important role in these practice-changing studies.