Pyrrolobenzodiazepine (PBD) dimer, is a new generation of cytotoxic payload used in antibody-drug conjugates (ADCs). The PBD dimer binds to the minor groove of DNA to form effective cytotoxic DNA interstrand crosslinks, which can block cell division and kill cancer cells. This mechanism of action utilizes a completely different cellular target from that of tubulin inhibitors, as well as a different DNA damage pattern from other DNA-targeting payloads. Anti-PBD antibody is a rabbit monoclonal antibody specially reacts with PBD, which is more sensitive than mouse antibody. The anti-PBD antibody is a useful reagent in PK assay to determine conjugated antibodies.