CGP 6809 is a water-soluble nitrosourea derivative with quite distinct chemical and
biological properties as compared with the well-known representatives of this class of compounds. It is related to the
antibiotic streptozotocin, from which it is distinguished in the structure of the
sugar moiety and the position of the
methylnitrosourea residue.
CGP 6809 possesses practically the same alkylating potential as
streptozotocin; however, its carbamoylating activity is comparable with that of
CCNU. In contrast to other nitrosourea derivatives,
CGP 6809 showed relatively little activity in murine
leukemias but was markedly active in solid transplantable
melanomas (Harding-Passay, B16), in the 11095 prostate
carcinoma, and in a substrain of Yoshida
hepatoma (AH 7974) resistant to
BCNU and
CCNU. In the Ehrlich and Yoshida ascitic
tumors complete responses were seen with no toxic death. Dose-dependent activity was found in the human lung
carcinoma MBA 9812 and almost complete growth inhibition was achieved in the human
melanoma WM 47 by both the oral and parenteral routes of administration. However, mammary
tumor lines (Ca 755, 2661/61, R-3230AC), the Guerin-T8 uterus
epithelioma, and the
Rous sarcoma/S-R proved to be relatively refractory to this
drug. This was also the case for the
Lewis lung carcinoma implanted i.m. or s.c. However, development of lung
metastases was markedly inhibited. Combination
therapy using
CGP 6809 with
cyclophosphamide,
5-fluorouracil, or
chlorambucil in the same model led to partial responses of the primary
tumor as well as almost total eradication of lung
metastases.