BiTEs have been designed to target a variety of tumor antigens such as CD19 [2, 10, 11], EphA2 receptor tyrosine kinase [12], EpCAM [13, 14], EGFR [15], melanoma-associated chondroitin sulfate proteoglycan [16], and CD33 [17], among others, and have shown therapeutic efficacy in mouse tumor models [3, 4, 13, 14]. This evidence concerns the gene CD33 and neoplasm.