Calicheamicin
Calicheamicin is a highly potent enediyne antitumor antibiotic from Micromonospora echinospora, which cleaves DNA via sequence-specific double-strand breaks. It is employed as the cytotoxic payload in antibody–drug conjugates (ADCs) such as gemtuzumab ozogamicin and inotuzumab ozogamicin for targeted leukemia treatment.