An Experimental Therapeutic Approach to L1210 Leukemia in Mice: Combined Chemotherapy and Central Nervous System Irradiation2

Abstract

Leukemia L1210 was inoculated intracranially into CDF₁ hybrid mice. After inoculation, the animals were randomized into test groups, but no treatment was initiated until day 4 to permit the disease to become systemic. The experimental approach combined systemic chemotherapy with Cytoxan (cyclophosphamide) and electron-beam irradiation of the entire cerebrospinal axis. The median survival for the untreated controls was 10 days. Survival was not significantly prolonged with irradiation alone and the maximum median survival with drug therapy alone at the optimal dosage was only 14 days. However, the combined therapy resulted in a highly significant prolongation of survival compared with that of mice treated with either drug or irradiation alone. It also produced 70 percent apparent cures (60-day survivors). The potential clinical application of such combined treatment is discussed.