Cell Cycle Phase Sensitivity to Cis-Dichloro-Bis (Isopropylamine) Trans-Dihydroxy Platinum (Iv) (Chip)

Abstract. Cis-dichloro-bis (isopropylamine) trans-dihydroxy platinum (IV) (CHIP) is a second generation platinum coordination complex now in Phase II clinical trials. In vitro studies with Chinese Hamster Ovary cell cultures show that CHIP is a phase-sensitive drug, being most cytotoxic to cells in early G₁ phase and least toxic to late S and G₁ phase cells. the dose-modifying factor between the drug sensitivity of cells treated in G₁ and in late S phase is 1.6. These findings and their clinical significance are discussed with respect to the phase sensitivity of other cytotoxic agents.