Treating Tissue Factor-Positive Cancers with Antibody-Drug Conjugates That Do Not Affect Blood Clotting

The primary function of tissue factor (TF) resides in the vasculature as a cofactor of blood clotting; however, multiple solid tumors aberrantly express this transmembrane receptor on the cell surface. Here, we developed anti-TF antibody-drug conjugates (ADC) that did not interfere with the coagulation cascade and benchmarked them against previously developed anti-TF ADCs. After screening an affinity-matured antibody panel of diverse paratopes and affinities, we identified one primary paratope family that did not inhibit conversion of Factor X (FX) to activated Factor X (FXa) and did not affect conversion of prothrombin to thrombin. The rest of the antibody panel and previously developed anti-TF antibodies were found to perturb coagulation to varying degrees. To compare the anticancer activity of coagulation-inert and -inhibitory antibodies as ADCs, a selection of antibodies was conjugated to the prototypic cytotoxic agent monomethyl auristatin E (MMAE) through a protease-cleavable linker. The coagulation-inert and -inhibitory anti-TF ADCs both killed cancer cells effectively. Importantly, the coagulation-inert ADCs were as efficacious as tisotumab vedotin, a clinical stage ADC that affected blood clotting, including in patient-derived xenografts from three solid tumor indications with a need for new therapeutic treatments-squamous cell carcinoma of the head and neck (SCCHN), ovarian, and gastric adenocarcinoma. Furthermore, a subset of the anti-TF antibodies could also be considered for the treatment of other diseases associated with upregulation of membranous TF expression, such as macular degeneration. Mol Cancer Ther; 17(11); 2412-26. ©2018 AACR.