The effect of bleomycin and pentamycin in combination on the survival of EMT6 mouse tumour cells in vitro and in vivo.

The combined effect of bleomycin and the polyene antibiotic, pentamycin, upon the survival of EMT6 tumour cells has been studied both in vitro and in vivo. During growth of the cells as a monolayer in vitro, a very marked potentiation of bleomycin action is seen during the exponential and early plateau phases of growth, but little potentiation occurs in late plateau phase. The effect of exposing the cells to the two drugs consecutively in either order is greater than if the two agents are used at the same time. In vivo, it does not appear that pentamycin can greatly increase the cytocidal effect of bleomycin.