Using the clinically approved T-DM1 as proof of concept, we found, that delivering the potent DM1 microtubule destabilizing payload via trastuzumab increases viral spread and bystander killing in HER2+ human cancer cells, analogously to what we have previously shown with “free” small molecule MDAs like colchicine (Figs. 1 and 2). The gene discussed is ERBB2; the disease is cancer.