ISSN:
1432-0843
Keywords:
Key words S 9788
;
Multidrug resistance
;
Vinblastine
;
Doxorubicin
;
Leukemia
;
Bone marrow
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The triazinoaminopiperidine derivative S 9788 is a new multidrug-resistance modulator that is currently being evaluated in phase I clinical trials. In this study, the reversal effect of S 9788 in comparison with verapamil was shown in vitro in human T-leukemic CCRF-CEM/VLB cells expressing the multidrug-resistance (MDR) phenotype. S 9788 increased in a dose-dependent manner the cytotoxic activity of doxorubicin or vinblastine, with complete reversal of resistance occurring at 2 μM for a concomitant continuous exposure (96 h) to the cytotoxic drugs. At respective concentrations equivalent to the IC10 value (the concentration inhibiting 10% of cell growth), S 9788 was 44 times more potent than verapamil in CCRF-CEM/VLB cells. S 9788 at 2 μM did not enhance the in vitro toxicity of doxorubicin or vinblastine in the human normal bone-marrow erythroid (BFU-E) and myeloid (CFU-GM) progenitors. The effect of exposure duration and concentrations on the synergistic action of modulator and cytotoxic agent closely depended on the cytotoxic agent studied. Post-incubations with S 9788 alone after a 1-h coadministration with vinblastine and S 9788 dramatically increased the reversal effect (4–41 times) in proportion to both the duration of postincubation and the concentration of S 9788. In contrast, for doxorubicin resistance, post-incubation with S 9788 alone induced a maximal 2-fold increase in the reversal effect that was not proportional to the postincubation duration. In patients treated with S 9788 as a 30-min intravenous infusion during phase I trials, a good correlation was found between the serum levels of S 9788 and the ability to reverse MDR in CCRF-CEM/VLB cells. The reversal effect was dose-dependent and was effective beginning at a plasma concentration of 0.25 μM. These data form a basis for the design of phase II trials using a combination of a loading dose of S 9788 given before vinblastine or doxorubicin administration followed by a maintenance infusion of S 9788 alone for a period of 2–24 h.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002800050308
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