Zynlonta is an ADC composed of a humanized monoclonal antibody directed against human CD19 and conjugated through a linker to a pyrrolobenzodiazepine (PBD) dimer cytotoxin. Upon binding to CD19, Zynlonta is internalized where enzymes release the cytotoxic PBD-based dimer, which binds to DNA to create interstrand cross-links. These cross-links are designed to disrupt DNA metabolic processes such as replication, which ultimately lead to cell death.