daunorubicinol and idarubicinol

Recent results show that the intracellular uptake pattern of idarubicin (IDA) in multidrug-resistant (MDR) cells is nearly identical to that seen in the drug-sensitive parent cell line, whereas the MDR cells have minimal daunorubicin (DNR) uptake compared with the drug-sensitive parent cells. It is known that the major metabolite of IDA, idarubicinol (IDA-OL), has nearly the same cytotoxicity as IDA, while the cytotoxicity of daunorubicinol (DNR-OL) is about 1/30th of that of DNR. We examined the effect of the MDR modifiers verapamil and dexniguldipine on the efflux of IDA, DNR and their hydroxylated metabolites IDA-OL and DNR-OL in blast populations of acute myeloid leukemia (AML), in the MDR-negative cell line CEM-CCRF and in their MDR-positive counterpart (CEM-VBL). All patients with relapsed or persistent AML had been pretreated with IDA and cytosine arabinoside. The efflux of the anthracyclines was estimated by flow cytometry. A total of 36 patients with AML were investigated; 18 out of 36 AML blast populations showed an efflux of DNR, DNR-OL and IDA-OL. The efflux of DNR, DNR-OL and particularly IDA-OL could be reversed by 10 microM verapamil or 1 microM dexniguldipine. For IDA we found an effusion of 40 +/- 11% in all blast populations which could not be significantly inhibited by the modulators. Similar results for IDA were found in the MDR-positive cell line (CEM-VBL 100) and in their MDR-negative counterpart (CEM-CCRF). The incubation of CEM-CCRF cells with DNR, DNR-OL, IDA-OL and especially IDA led to MDR induction as determined by reverse transcription/polymerase chain reaction analysis with MDR-specific primer and by cellular efflux studies. We conclude that the outcome of chemotherapy with idarubicin is influenced by MDR, although IDA is not essentially MDR-dependent itself, but because IDA-OL is actively involved in multidrug resistance. Further investigations should consider the question of whether the combination of IDA and MDR modifiers can enhance the serum level of the active metabolite IDA-OL and can reverse the MDR pattern in cells treated with IDA.

Topics: Antineoplastic Agents; Blast Crisis; Calcium Channel Blockers; Daunorubicin; Dihydropyridines; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Humans; Idarubicin; Leukemia, Myeloid, Acute; Tumor Cells, Cultured; Verapamil

To study the effect of the main metabolites on the cytotoxic effect of daunorubicin and idarubicin in human HL-60 cells, drug-sensitive and multidrug-resistant HL60 cells were incubated with idarubicin and daunorubicin and their metabolites idarubicinol and daunorubicinol over a wide range of concentrations. The intracellular uptake of the drugs was determined by photofluorometry, and the cytotoxic effect in vitro was determined by a bioluminescence assay of intracellular adenosine triphosphate (ATP) after 4 days of culture in liquid medium. The effect of intracellular drugs was calculated from the incubation-concentration versus intracellular-uptake and cytotoxic-effect curves. The intracellular uptake of idarubicin was 6 times that of daunorubicin in drug-sensitive cells and 25 times higher in resistant cells. For idarubicinol as compared with daunorubicinol the corresponding factors were 25 and 7, respectively. As compared with the parent substances, the uptake of idarubicinol and daunorubicinol was 16% and 4%, respectively, in sensitive cells and 40% and > 100%, respectively, in resistant cells. An intracellular concentration of 0.5 nmol/mg protein of both parent substances caused a 50% growth inhibition in drug-sensitive cells as compared with 10 nmol/mg protein for drug-resistant cells. For the metabolites an intracellular concentration of 0.4 nmol/mg protein of idarubicinol and 2.0 nmol/mg protein of daunorubicinol was required to inhibit cells' growth by 50% in drug-sensitive HL60 cells. In the resistant HL60 cells the corresponding values were 30 nmol/mg protein for idarubicinol and 40 nmol/mg protein for daunorubicinol. These results confirm that idarubicinol may significantly contribute to the clinical effect of idarubicin. However, in combination with previous results that have shown low intracellular concentrations of the metabolites in vivo, it appears that the pharmacokinetic properties of the mother substances provide the major explanation for the clinical effect of idarubicin.

Topics: Antibiotics, Antineoplastic; Antineoplastic Agents; Cell Division; Daunorubicin; Dose-Response Relationship, Drug; Drug Resistance, Multiple; HL-60 Cells; Humans; Idarubicin

The intracellular pharmacokinetics and cytotoxicity of idarubicin (IDA), daunorubicin (DNR), and their corresponding C-13 alcohol metabolites, idarubicinol (IDAol) and daunorubicinol (DNRol), were studied in drug-sensitive HL-60/W human leukemia cells, and in two multidrug-resistant (MDR) sublines, HL-60/Vinc (overexpress P-glycoprotein, Pgp) and HL-60/Adr (overexpress multidrug resistance-associated protein, MRP). Intracellular drug accumulation (1 micrograms/mL) and retention were measured by flow cytometry. Mean intracellular steady-state concentration (Css, fluorescence units/cell) and area under the intracellular drug concentration x time curve (AUC, Fl.U/cell.min) were calculated. Relative to the values for the respective drugs in HL-60/W cells, the Css and AUC of IDA were much higher than those of DNR in the MDR cell lines, with Css and AUC of IDAol intermediate between IDA and DNR. In the MDR cell lines, the MDR modulator cyclosporine A (CsA), in concentrations of 0.3 to 30 mumol/L, caused minimal effects on 3-hr IDA accumulation, intermediate enhancement of IDAol accumulation, and greatest enhancement of DNR accumulation. The MDR cell lines were much less resistant to IDA (3- to 16-fold) than to DNR (65- to 117-fold). This difference was not the result of IDA being more potent than DNR, since the sensitivity of HL-60/W cells to IDA differed from their sensitivity to DNR by < 2-fold. The cellular pharmacokinetics and cytotoxicity of IDA in MDR human breast carcinoma cells MCF-7/AdrVp, which overexpress the putative MDR transporter P-95, were far superior to those of DNR, and were comparable to these parameters for IDA in parental MCF-7/W cells. These studies demonstrate that the cellular pharmacology and cytotoxicity of IDA in MDR cell lines that overexpress MRP, Pgp, or P-95 are more advantageous than those of DNR, suggesting that IDA is less susceptible to the transport-mediated MDR mechanism manifested. IDA is not completely invulnerable to MDR, however, since the MDR sublines studied did display a demonstrable level of resistance to IDA, compared with their drug-sensitive counterparts. IDAol, the major plasma metabolite of IDA, demonstrated behavior intermediate between the MDR-susceptible drug DNR and its parent compound, suggesting that its cytotoxic action is subject to transport-mediated cellular defenses.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Antibiotics, Antineoplastic; ATP Binding Cassette Transporter, Subfamily B, Member 1; Biological Transport; Breast Neoplasms; Cell Survival; Culture Media; Cyclosporine; Daunorubicin; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Drug Stability; HL-60 Cells; Humans; Idarubicin; Intracellular Fluid; Tumor Cells, Cultured

Five patients with acute non-lymphoblastic leukemia were treated with a mixture of daunorubicin 50 mg/m2 and idarubicin 10 mg/m2 given as a short-time infusion. Daunorubicin, idarubicin and the main metabolites daunorubicinol and idarubicinol were separated and the concentrations in plasma and leukemic cells were determined by HPLC. Although idarubicin was given in one-fifth of the dose, the intracellular peak concentration was 70% of that of daunorubicin. The initial elimination of idarubicin from leukemic cells was somewhat faster but in the terminal phase the drug was retained longer than daunorubicin. Intracellular concentrations of both metabolites were low and probably of little importance for the activity of the drug. We conclude that the intracellular pharmacokinetics of idarubicin, with higher peak concentration and longer terminal retention, is a possible explanation for the higher toxicity and suggested better antileukemic effect of this drug.

Topics: Acute Disease; Aged; Daunorubicin; Female; Humans; Idarubicin; Leukemia, Myeloid, Acute; Male; Middle Aged

We have studied the growth inhibition, DNA synthesis inhibition and cell incorporation of five 13-dihydrometabolites of anthracyclines in a model of doxorubicin-sensitive and -resistant rat C6 glioblastoma cells. These compounds were major metabolites for doxorubicin, epirubicin, daunorubicin, idarubicin and the new anthracycline 4'-deoxy-4'-iododoxorubicin and are known to be present in appreciable amounts in the plasma of patients treated with these drugs. We have shown that in vitro growth inhibition in sensitive cells was either much lower than that of the parent drug (doxorubicinol, epirubicinol, daunorubicinol), or similar to it (idarubicinol, 4'-iodoxorubicinol). In resistant cells, growth inhibition was about 100 times lower than in wild cells, and was always lower than that of the parent anthracycline. DNA synthesis inhibition occurred in sensitive cells for doses about 100 times higher than those required for growth inhibition, but in resistant cells, similar doses provided growth inhibition and DNA synthesis inhibition. Metabolite incorporation was always lower than that of the corresponding parent anthracycline; it was greatly reduced in resistant cells as compared to sensitive ones. The calculated intracellular concentrations obtained for the same growth inhibition are higher in resistant cells than in sensitive cells; in contrast, the calculated intracellular concentrations obtained for the same DNA synthesis inhibition are similar in resistant and sensitive cells, and similar for all the metabolites studied. These results suggest that the amount of drug incorporated is primarily responsible for DNA synthesis inhibition, which is directly correlated to growth inhibition in resistant cells, but not in sensitive cells.

Topics: Animals; Antibiotics, Antineoplastic; Cell Division; Daunorubicin; DNA, Neoplasm; Doxorubicin; Drug Resistance; Epirubicin; Glioma; Rats; Tumor Cells, Cultured