The suppression of metastases in malignant diseases is one of the major goals in targeted chemotherapy. This was achieved with an antibody drug conjugate between a novel, rationally designed enediyene antibiotic calicheamicin theta(I)1 of exceptionally high cytotoxic potency and an antiganglioside GD2 monoclonal antibody 14G2a. Effective suppression of hepatic metastases was demonstrated in a novel syngeneic model of murine neuroblastoma that simulates the situation in patients in terms of antigen heterogeneity and presence of the target antigen on normal tissues. Here, we describe the first successful use of calicheamicin theta(I)1 for targeted chemotherapy in a clinically relevant syngeneic metastasis model.