Elsamitrucin is a heterocyclic antineoplastic antibiotic isolated from the bacterium Actinomycete strain J907-21. Elsamitrucin intercalates into DNA at guanine-cytosine (G-C)-rich sequences and inhibits topoisomerase I and II, resulting in single-strand breaks and inhibition of DNA replication. It demonstrated a broad spectrum of in vitro cytotoxicity against tumor cell lines. According to the results of Phase II trials elsamitrucin is not an active drug in patients with metastatic breast cancer, colorectal cancer, non-small cell lung cancer or ovarian cancer, however, it showed modest activity in patients with relapsed or refractory non-Hodgkin's lymphoma.