[Comparative effect of administration schedules on the antitumor activities of 3 water-soluble nitrosoureas, ACNU, GANU and MCNU against L1210 leukemia].

ACNU, GANU and MCNU, water-soluble nitrosoureas, have been evaluated in terms of influence of treatment schedule on antitumor activity in mice bearing L1210 leukemia. The results obtained were as follows: 1) ACNU produced a significant increase in life span and long-term survivors by administration on day 1 only, once every 8 days for 2 doses or once every 4 days for 3 doses, and the compound was most effective when given on day 1 only. 2) GANU produced a significant increase in life span and long-term survivors by same administration schedules as ACNU, and the compound was most effective when given every 8 days for 2 doses. 3) MCNU produced a significant increase in life span and long-term survivors by each administration including daily treatment, and the compound was most effective when given every 4 days for 3 doses. 4) ACNU and MCNU displayed the same level of activity as CCNU when the drugs were given on day 1 only. Daily treatment with MCNU was as effective as daily treatment with CCNU. Our results suggest that ACNU, GANU and MCNU should be administered by intermittent schedule as lipid-soluble nitrosoureas such as BCNU, CCNU and MeCCNU.