Synthesis of novel pyrrolobenzodiazepine (PBD) C1-substituted monomers and dimers with DNA-binding activity and cytotoxicity.

The pyrrolobenzodiazepines (PBDs) represent a major class of sequence-selective DNA-alkylating molecules, one example of which, in its dimeric DNA-cross-linking form, is employed as the payload in the anticancer Antibody Drug Conjugate (ADC) loncastuximab tesirine-lpyl. To date, PBD analogues have been produced with substituents at every position of the tricyclic skeleton except the C1-position. We report here the first synthesis of a C1-subsitituted PBD monomer and dimer, both of which possess DNA-binding activity and cytotoxicity in a cancer cell line.