Calicheamicins, a novel family of antitumor antibiotics. Taxonomy, fermentation and biological properties.

A novel family of antitumor antibiotics, the calicheamicins, were isolated from the fermentation broth of Micromonospora echinospora subsp. calichensis. These antibiotics exhibited significant activity against Gram-positive and Gram-negative bacteria in vitro. Calicheamicin gamma 1I demonstrated antitumor activity against P388 leukemia and B16 melanoma in vivo.