Currently, trastuzumab deruxtecan is under investigation in 15 active phase I–III clinical trials registered on ClinicalTrials.gov in various solid organ malignancies including ErbB2-expressing non-small-cell lung cancer (NCT03505710), ErbB2 low breast cancer (NCT03734029), ErbB2-positive gastric cancer (NCT04014075) and with immunotherapy combination nivolumab in advanced breast and urothelial cancers (NCT03523572). The gene discussed is ERBB2; the disease is gastric cancer.