Synergistic antineoplastic and cytogenetic effects by the combined action of two homo-aza-steroidal esters of nitrogen mustards on P388 and L1210 leukaemias in vivo and in vitro.

In order to increase the damaging effects on specific DNA sequences and decrease the subsequent toxicity, the use of homo-aza-steroidal esters of nitrogen mustards is already known. Two specific homo-aza-steroidal esters were mixed at different proportions and the resultant final mixtures were tested in vivo and in vitro. The effects of these on P388 and L1210 leukaemias, on SCE rates and on human lymphocyte proliferation kinetics were studied. The results demonstrate that the combined substances enhanced SCE induction (p < 0.05) and antitumour activity (p < 0.02) in a synergistic manner. A correlation was observed (p < 0.001) between the magnitude of the SCE response and the depression of the cell proliferation index.