The coordinated gold compound, 2,3,4,6-tetra-O-acetyl-1-thio-β-D-glucopyranosato-S-triethylphosphine gold (auranofin; Ridaura), was evaluated for antitumor activity in a variety of mouse tumor models. Of the 15 tumor models evaluated, auranofin was found to be active only against i.p. P388 leukemia. A number of dose schedules was used to measure activity against P388 with optimal activity observed at 12 mg/kg given daily, i.p., on Days 1 to 5. Auranofin was active against i.p. P388 leukemia only when administered i.p.; the drug was completely inactive when administered i.v., s.c., or p.o. on Days 1 to 5.
Evaluation of the effects of auranofin in vitro demonstrated that (a) survival curves for B16 melanoma cells as measured by the clongenic and dye exclusion assays were exponential and monophasic; (b) cell cycle distribution was not altered, and auranofin displayed no preferential cytotoxicity to logarithmic or plateau growth phase cell populations; (c) auranofin inhibited DNA, RNA, and protein synthesis at cytotoxic concentrations but showed no selective effect; (d) the cytotoxic activity and cellular association of gold from auranofin were dose, time, and temperature dependent; and (e) binding of auranofin gold to serum proteins markedly decreased cellular uptake of gold and cytotoxicity of auranofin in vitro.