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.