Slater L M, Sweet P, Stupecky M, Osann K
Department of Medicine, University of California, Irvine 92717, USA.
Cancer Chemother Pharmacol. 1997;39(5):452-4. doi: 10.1007/s002800050597.
PSC-833, a non immunosuppressive analogue of cyclosporin A, is an effective modulator of the multidrug-resistant tumor phenotype. Since both PSC-833 and cyclosporin A also enhance the cytotoxicity of VP-16 against drug sensitive L1210 leukemia cells in vitro we compared these agents as modulators of VP-16 efficacy in vivo. Compared to VP-16 treatment alone both PSC-833 and cyclosporin A significantly altered the survival of L1210 leukemia-bearing BDF/1 mice and Lewis lung carcinoma-bearing C57/B1 mice. Cyclosporin A enhanced VP-16 efficacy whereas PSC-833 impaired VP-16 efficacy against these murine tumors. Possible reasons for these disparate effects are discussed.
