An antibody-drug conjugate (ADC) composed of a humanized immunoglobulin G1 (IgG1) monoclonal antibody against dipeptidase 3 (DPEP3) conjugated, via a plasma-stable valine-alanine dipeptide linker, to a cytotoxic pyrrolobenzodiazepine (PBD) dimer, with potential antineoplastic activity. Upon administration, the monoclonal antibody moiety of tamrintamab pamozirine targets DPEP3 expressed on tumor cells. Upon binding and internalization, the cytotoxic, DNA cross-linking PBD moiety is released. This inhibits DNA replication, leads to G2/M cell cycle arrest, induces cell death, and inhibits the proliferation of DPEP3-expressing tumor cells. DPEP3, a membrane-bound glycoprotein, is overexpressed in some ovarian cancers.