TF-011-MMAE (HuMax-TF-ADC), an antibody-drug conjugate composed of a tissue factor-specific antibody, a protease-cleavable linker, and the microtubule disrupting agent monomethyl auristatin E, is a novel antitumor agent with promise as a broad-acting therapeutic in many types of human cancer. The antitumor activity of TF-011-MMAE is dependent on binding to tissue factor-positive tumor cells, followed by highly efficient internalization and lysosomal targeting, which allows intracellular release of the auristatin and subsequent tumor cell killing. After three hours of incubation with tissue factor-expressing ovarian cancer cells, TF-011 (green), the antibody backbone of TF-011-MMAE, colocalized with the lysosomal marker LAMP-1 (red). Colocalization of TF-011 and LAMP-1 (yellow) demonstrates that, upon target binding, TF-011 is rapidly targeted to the lysosomal compartment. For details, see article by Breij and colleagues on page 1214.