In vivo tumor response to single and multiple exposures of adriamycin

Abstract The response of murine EMT6/Ro tumors and KHT sarcomas to adriamycin (ADR) given either as a single dose, 2 equal doses or multiple dose increments (all to the same total dose) was determined using a tumor growth delay assay. The total ADR uptake in the tumors was similar for the various drug schedules. An ld 10 60 dose of ADR (lethal to 10% of the mice in 60 days ) led to a growth delay equivalent to one doubling time in these established tumor lines as well as a first generation transplanted mammary tumor. Two doses, each equal to half the ld 10 60 dose, separated by 1–7 days or 1–2 days , were as effective against the EMT 6 /Ro tumor and KHT sarcoma respectively as a single ld 10 60 dose. These findings suggest a lack of repair of ADR damage in these tumors. However, such a total dose ( ld 10 60 ), given as multiple daily increments, resulted in a growth delay less than that following a single ld 1 60 exposure likely due to cell repopulation.