Platinum complexes as radiosensitizers of hypoxic mammalian cells.

Cis-dichlorodiammineplatinum (II), or cis-PDD, has recently been shown to be a potent radiosensitizer of bacteria, particularly under conditions of acute hypoxia. This study extends this observation to include the radiosensitization of mammalian cell (V-79) by low concentrations of cis-PDD, cis-dichlorobis(aziridine) platinum (II), and the trans-isomer of PDD as measured from survival curve analysis. This radiosensitization was obtained at concentrations of 10 micrometer, 60 micrometer, and 100 micrometer for the cis-PDD, aziridine-platinum, and trans-isomer respectively. The corresponding drug toxicity survival levels were 8, 40 and 50%. Dose modification factors of around 1.3 to 1.4 were observed.