Studies on Cyclophosphamide, Antitumor Alkylating Compound. I. Effects on Mouse Leukemias2

Abstract

Cyclophosphamide, administered intramuscularly, showed a strong inhibitory effect on growth of L4946 and C1498 ascites tumors. Repeated injections and even a single administration caused a considerable decrease in the ascites tumor-cell population. First the mitotic index dropped sharply, and then it gradually rose. At this stage, abnormal mitoses with multiple breaks predominated. Some tumor cells in ascitic fluid and especially those in other sites survived. Later, regular mitoses, with the chromosome complement of the stem-cell lineage, increased in frequency and led to generalized regrowth which finally caused death.