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 both ADCT-701 and PBD (Fig. 4J and Supplementary Fig. 8C), demonstrating the role of this drug efflux transporter in mediating acquired resistance to ADCT-701.