ABCB1 and neoplasm: We then developed a PDXO from a POBNCI_ACC004 resistant tumor and found that ABCB1 inhibitors re-sensitized the POBNCI_ACC004 resistant PDXO to PBD and ADCT-701 (Fig. 3J and Supplementary Fig. 8C) demonstrating the role of this drug efflux transporter in mediating acquired resistance to ADCT-701.