Since our experiments revealed that combination of Trastuzumab and Rituximab may result in additive effects, Trastuzumab treatment represents a feasible strategy not only in patients with CD20−HER2/neu+ ALL which cannot be treated with Rituximab, but also for combined application with Rituximab in CD20+HER2/neu+ ALL. The gene discussed is ERBB2; the disease is acute lymphoblastic leukemia.