Vadastuximab talirine is an antibody-drug conjugate (ADC) directed to CD33 (siglec-3) which is a transmembrane receptor expressed on cells of myeloid lineage.

The experimental drug, being developed by Seattle Genetics, was in clinical trials for the treatment of acute myeloid leukemia (AML).

The CD33 antibody is attached to a highly potent DNA binding agent, a pyrrolobenzodiazepine (PBD) dimer (SGD-1882), via a proprietary site-specific conjugation chemistry via a cleavable (valine-alanine dipeptide as cathepsin B cleavage site) maleimidocaproyl type linker, to a monoclonal antibody with engineered cysteines (EC-mAb).

This phase III study is expected to evaluate vadastuximab talirine in combination with hypomethylating agents (HMAs; azacitidine, decitabine) in previously untreated older AML patients.

[4] A phase III clinical trial of Vadastuximab talirine in combination with hypomethylating agents, was terminated, however, in June 2017 due to a higher rate of deaths resulting from fatal infections.