In these studies, HER2(+) cancer cells were prelabeled with a trastuzumab mAb, functionalized with a bioorthogonal, click-reactive, TCO group, and the drug-carrier albumin component with the complementary click-reactive Tt group is delivered after free antibodies have cleared the body, to ensure that the toxic drug component accumulates only at the tumor site (Figure 2A). The gene discussed is ERBB2; the disease is neoplasm.