An experimental model for meningeal leukemia in rats (L5222). Effect of treatment with BCNU and cyclophosphamide.

An experimental model of meningeal leukemia in rats is developed by intracerebral (IC) inoculation of leukemic cells from the transplantable acute leukemia L5222. The L5222 proliferates exponentially in the central nervous system (CNS) and the disease becomes systemic 2 days following IC inoculation. Chemotherapeutic studies with BCNU and cyclophosphamide yielded cures in a high percentage of cases when treatment began at an early stage of meningeal leukemia. When treatment was started at the advanced stage, only BCNU showed a large number of cures. However, cyclophosphamide resulted in a marked increase of life-span. The activity of cyclophosphamide against meningeal leukemia, which is in contrast to the results obtained by Skipper et. al. (1961) in the L1210 mouse leukemia, suggests that cyclophosphamide crosses in part the blood--brain barrier in a rat bearing meningeal leukemia. After subcutaneous inoculation, BCNU and cyclophosphamide showed the same rate of cures.