Isotachophoretic determination of phosphate splitting from amifostine and p-nitrophenyl phosphate in serum and neuroblastoma cells

Amifostine [WR-2721; H2N-(CH2)(3)-NH-(CH2)(2)-S-PO3H2] is used as a protect ing agent in the chemotherapy of neuroblastoma. It is supposed that Amifost ine will be transformed into its active form, the free thiol (WR-1065), eas ier by normal cells than by tumour cells. Analytical capillary isotachophor esis was used to determine the dephosphorylation of Amifostine in serum and on neuroblastoma cells and peripheral blood cells. Furthermore, the biolog ical effects of Amifostine and its free thiol, on cell proliferation of neu roblastoma cells were measured in combination with Carboplatin. It was foun d that neuroblastoma cells did not split phosphate less efficiently than no rmal peripheral blood cells. Furthermore, neither Amifostine (as expected) nor the free thiol (not expected according to the theory) were able to inhi bit the effects of Carboplatin. Therefore, the current hypothesis concernin g the mode of action of Amifostine must be questioned. (C) 1999 Elsevier Sc ience B.V. All rights reserved.