Medicine (St Vincent's) - Research Publications
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ItemA phase II trial of paclitaxel and epirubicin in advanced breast cancer(NATURE PUBLISHING GROUP, 2000-08)Initial trials of paclitaxel and doxorubicin in advanced breast cancer yielded high response rates but significant cardiac toxicity was observed. In this phase II trial we investigated the efficacy and safety of paclitaxel combined with epirubicin. Patients with advanced breast cancer, performance status 0-2, measurable disease, and a normal left ventricular ejection fraction, who may have received adjuvant chemotherapy were treated with epirubicin 75 mg m(-2) followed by a 3-h infusion of paclitaxel 175 mg m(-2) repeated every 3 weeks. Forty-three eligible patients were treated at six centres. 67% patients received the maximum of six cycles. The response rate was 54% (95% CI 38-69%), 12% CR and 42% PR. Estimated median progression-free survival was 6.9 months (95% CI 5.4-10.0) and estimated median overall survival was 17.9 months (95% CI 14.2-25.7). Four patients had a decrease in the left ventricular ejection fraction (LVEF) of > or =20% of baseline value, and in two patients the LVEF decreased to below the lower limit of normal, but no patient developed clinical evidence of cardiac failure. Grade 4 neutropenia occurred in 56% cycles, but only 4% of cycles were complicated by febrile neutropenia. Grade 3 or 4 non-haematologic toxicity was uncommon. In conclusion, paclitaxel 175 mg m(-2) and epirubicin 75 mg m(-2) is a well tolerated, promising regimen for the treatment of advanced breast cancer.
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ItemInduction of MDR1 gene expression by anthracycline analogues in a human drug resistant leukaemia cell line(CHURCHILL LIVINGSTONE, 1999-02)The effects of 4-demethoxydaunorubicin (idarubicin, IDA) and MX2, a new morpholino-anthracycline, on up-regulation of the MDR1 gene in the low-level multidrug resistant (MDR) cell line CEM/A7R were compared at similar concentrations (IC10, IC50 and IC90) over a short time exposure (4 and 24 h). The chemosensitivity of each drug was determined by a 3-day cell growth inhibition assay. Compared with epirubicin (EPI), IDA and MX2 were 17- and eightfold more effective in the CEM/A7R line respectively. No cross-resistance to 5-FU was seen in the CEM/A7R line. Verapamil (5 microM) and PSC 833 (1 microM), which dramatically reversed resistance to EPI in the CEM/A7R line, had no sensitizing effect on the resistance of this line to MX2, but slightly decreased resistance to IDA. The sensitivity to 5-FU was unchanged by these modulators. The induction of MDR1 mRNA expression by IDA, MX2 and 5-FU was analysed by Northern blotting and semiquantitatively assessed by scanning Northern blots on a phosphorimager. The relative level of MDR1 expression was expressed as a ratio of MDR1 mRNA to the internal RNA control glyceraldehyde-3-phosphate dehydrogenase (GAPDH). IDA, MX2 and 5-FU differentially up-regulated MDR1 mRNA in the CEM/A7R line in a dose-dependent manner. Both IDA and MX2 induced MDR1 expression within 4 h. 5-FU up-regulated MDR1 expression only when drug exposure was prolonged to 24 h. Based on MRK 16 binding, flow cytometric analysis of P-glycoprotein (Pgp) expression paralleled the increase in MDR1 mRNA levels. For the three anthracyclines, the increase in MDR1 expression was stable in cells grown in the absence of drug for more than 3 weeks after drug treatment. The induction of MDR1 expression by 5-FU was transient, associated with a rapid decrease in the increased Pgp levels which returned to baseline 72 h after the removal of 5-FU. This study demonstrates that MDR1 expression can be induced by analogues of anthracyclines not pumped by Pgp, and that this induction appears to be stable despite a 3-week drug-free period.