The effects of cytotoxic (cyclophosphamide, CCNU, GANU), antiinvasive (vincristine, vinblastine) and antimetastatic (ICRF-159, DM-COOK) agents have been compared in mice-bearing P388 and L1210 leukemias, and TLX5 lymphoma. The drugs tested increase the survival time of the treated mice in a manner consistent with a cytotoxic action in the case of cyclophosphamide, CCNU, GANU, vincristine and vinblastine. Leukemic infiltration of the brain after i.p. tumor implantation has been determined by bioassay of this organ, and is reduced by treatment with all of the drugs tested, with the exception of ICRF-159. DM-COOK appears to increase the life-span of the treated animals by the inhibition of leukemic spread rather than by a cytotoxic action. The marked cytotoxicity of vincristine and vinblastine is sufficient to account for failure to detect any antimetastatic effects of these agents. The lack of antidisseminative effect observed for ICRF-159 under the experimental conditions employed might be connected with the observation that the antimetastatic action of this drug on solid tumors is due to its effects on tumor blood vessels.
