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Publications (4)27.2 Total impact

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    ABSTRACT: HER-2/neu, which encodes a receptor tyrosine kinase, is amplified and overexpressed in 20%-25% of human breast cancers. Such tumors are often resistant to hormone therapy. Despite a general inverse association between HER-2/neu amplification/overexpression and estrogen receptor (ER) and/or progesterone receptor (PR) expression, a fraction of patients are both HER-2/neu- and hormone receptor (HR)-positive. The efficacy of hormone therapy in this group is currently a matter of debate. To better understand the relationship between HER-2/neu positivity and HR expression, we analyzed HER-2/neu, ER, and PR as continuous variables in breast cancer cell lines and two cohorts of primary breast cancer patients. HER-2/neu and ER/PR expression was analyzed by enzyme-linked immunosorbent assay (ELISA) and enzyme immunoassay (EIA), respectively, in 14 human breast cancer cell lines, some of which had been transfected with the HER-2/neu gene. For the clinical study population, HER-2/neu protein levels were assessed by ELISA (cohort A, n = 665), and HER-2/neu gene copy number was determined using fluorescence in situ hybridization (cohort B, n = 894). ER/PR expression was analyzed by EIA (cohort A) or radioligand binding (cohort B). Associations between HER-2/neu and ER/PR expression were analyzed using Spearman's rho correlation and the chi-square test, and absolute levels were compared using the Mann-Whitney U test. All statistical tests were two-sided. HR-positive human breast cancer cell lines transfected with the HER-2/neu gene expressed statistically significantly lower levels of ER and PR than parental lines. In the clinical cohorts, levels of HER-2/neu overexpression and gene amplification were inversely correlated with ER/PR levels (Cohort A [n = 112]: for ER, r = -0.34, P<.001; for PR, r = -0.24, P =.010. Cohort B [n = 188]: for ER, r = -0.39, P<.001; for PR, r = -0.26, P<.001). Among patients with HR-positive tumors, HER-2/neu-positive tumors had statistically significantly lower ER/PR levels than HER-2/neu-negative ones (Cohort A: for ER, median = 25 fmol/mg [interquartile range [IQR] = 13-78] versus median = 38.5 fmol/mg [IQR = 17-99] and P =.031; for PR, median = 35 fmol/mg [IQR = 12-119] versus median = 88.5 fmol/mg [IQR = 22-236] and P<.001. Cohort B: for ER, median = 44 fmol/mg [IQR = 13-156] versus median = 92 fmol/mg [IQR = 35-235] and P<.001; for PR, median = 36 fmol/mg [IQR = 13-108] versus median = 84 fmol/mg [IQR = 24-250] and P<.001). Patients with higher levels of HER-2/neu overexpression or amplification had statistically significantly lower levels of ER/PR than patients with lower levels of HER-2/neu overexpression or amplification. Because absolute HR levels are strongly related to response to hormone therapy in primary and advanced breast cancer, reduced ER/PR expression may be one mechanism to explain the relative resistance of HER-2/neu-positive:HR-positive tumors to hormone therapy.
    JNCI Journal of the National Cancer Institute 01/2003; 95(2):142-53. · 14.34 Impact Factor
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    ABSTRACT: The purpose of this study was to analyze the drug interactions of paclitaxel (PTX) with epirubicin (EPI), carboplatin (CBDCA), gemcitabine (GEM) and vinorelbine (VIN) in human breast cancer cells and compare the cytotoxic activity of each drug combination in primary breast cancer samples. These experiments were intended to identify the most active agents in combination with PTX, and to provide a preclinical rational for future clinical investigations in breast cancer. Multiple drug effect/combination index (CI) isobologram analysis was applied to combinations of PTX with either CBDCA, EPI, GEM or VIN in MCF-7, MDA-MB-231 and SK-BR-3 human breast cancer cell lines. Drug concentrations were limited to the ranges achievable in humans in vivo, and the drugs were applied simultaneously at fixed molar ratios for each drug combination. Interactions were assessed at multiple effect levels (IC10–IC90). Additionally, the cytotoxic activity of these combinations was assessed in tumor samples of 50 primary breast cancer patients, utilizing the ATP-tumorchemosensitivity assay (ATP-TCA). Drug interactions were shown to be strongly dose-related in the human breast cancer cell lines investigated. At clinically relevant concentrations, CBDCA/PTX demonstrated synergistic (MCF-7) or additive (MDA-MB-231, SK-BR-3) interactions, and EPI/PTX showed additive (SK-BR-3, MCF-7) and antagonistic (MDA-MB-231) interactions. GEM/PTX and VIN/PTX, however, demonstrated antagonism over multiple dose effect levels at clinically relevant drug concentrations in all three cell lines tested. At plasma peak concentrations, EPI/PTX, CBDCA/PTX, GEM/PTX and VIN/PTX achieved 90% tumor growth inhibition in 93, 86, 63 and 50%, respectively, of primary breast cancer samples investigated with the ATP-TCA. Cumulative dose-response plots of primary breast cancer tumor cells responding in vitro with 90% growth inhibition showed a strong dose dependence for both EPI/PTX and CBDCA/PTX. In conclusion, the current data indicate favorable drug interactions for CBDCA/PTX at clinically relevant drug concentrations in breast cancer cells, and demonstrate superior in vitro cytotoxicity of EPI/PTX and CBDCA/PTX compared to GEM/PTX and VIN/PTX in primary breast cancer cultures.
    Breast Cancer Research and Treatment 05/2001; 67(3):223-233. · 4.47 Impact Factor
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    ABSTRACT: The purpose of this study was to analyze the drug interactions of paclitaxel (PTX) with epirubicin (EPI), car-boplatin (CBDCA), gemcitabine (GEM) and vinorelbine (VIN) in human breast cancer cells and compare the cytotoxic activity of each drug combination in primary breast cancer samples. These experiments were intended to identify the most active agents in combination with PTX, and to provide a preclinical rational for future clinical investigations in breast cancer. Multiple drug effect/combination index (CI) isobologram analysis was applied to combinations of PTX with either CBDCA, EPI, GEM or VIN in MCF-7, MDA-MB-231 and SK-BR-3 human breast cancer cell lines. Drug concentrations were limited to the ranges achievable in humans in vivo, and the drugs were applied simultaneously at fixed molar ratios for each drug combination. Interactions were assessed at multiple effect levels (IC 10 –IC 90). Additionally, the cytotoxic activity of these combinations was assessed in tumor samples of 50 primary breast cancer patients, utilizing the ATP-tumorchemosensitivity assay (ATP-TCA). Drug interactions were shown to be strongly dose-related in the human breast cancer cell lines investigated. At clinically relevant concentrations, CBDCA/PTX demonstrated synergistic (MCF-7) or additive (MDA-MB-231, SK-BR-3) interactions, and EPI/PTX showed additive (SK-BR-3, MCF-7) and antagonistic (MDA-MB-231) inter-actions. GEM/PTX and VIN/PTX, however, demonstrated antagonism over multiple dose effect levels at clinically relevant drug concentrations in all three cell lines tested. At plasma peak concentrations, EPI/PTX, CBDCA/PTX, GEM/PTX and VIN/PTX achieved ≥ 90% tumor growth inhibition in 93, 86, 63 and 50%, respectively, of primary breast cancer samples investigated with the ATP-TCA. Cumulative dose-response plots of primary breast cancer tumor cells responding in vitro with ≥ 90% growth inhibition showed a strong dose dependence for both EPI/PTX and CBDCA/PTX. In conclusion, the current data indicate favorable drug interactions for CBDCA/PTX at clinic-ally relevant drug concentrations in breast cancer cells, and demonstrate superior in vitro cytotoxicity of EPI/PTX and CBDCA/PTX compared to GEM/PTX and VIN/PTX in primary breast cancer cultures.
    Breast Cancer Research and Treatment 01/2001; 67:223-233. · 4.47 Impact Factor
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    ABSTRACT: Objective. Our purpose was to: (a) study the in vitro chemosensitivity of primary epithelial ovarian cancer to drug combinations with cisplatin (CDDP), carboplatin (CBDCA), paclitaxel (PTX), epirubicin (EPI), or cyclophosphamide (CTX) utilizing the ATP tumorchemosensitivity assay (ATP-TCA); (b) correlate the test results with clinical response in patients with FIGO stage III ovarian cancer; and (c) analyze the most useful parameters for interpretation of test results.Methods. CBDCA/CTX, CBDCA/PTX, CDDP/PTX, and EPI/PTX were tested in 93 fresh human primary epithelial ovarian cancer specimens. Correlations of in vitro drug sensitivity/resistance and clinical response were performed in 38 patients with FIGO stage III disease utilizing Fisher's exact test and by comparison of progression-free (PFS) and overall survival (OS) between those testing as sensitive or resistant. A progression-free interval of more than 12 months following surgery was classified as clinical response. ATP-TCA results were analyzed using the median effective dose, area under the curve, or a defined sensitivity index.Results. Evaluable test results were achieved in 83 of 93 patients (89%). EPI/PTX had the highest in vitro activity (P < 0.001). In the clinical correlation, 29 of 38 patients (76%) were classified as in vitro sensitive (sensitivity index [SI] <250) and 9 patients as in vitro resistant (SI >250). The SI was superior for interpretation of test results. Patients testing as chemosensitive had a significantly longer mean PFS (28.5 vs 12.6 months, P = 0.033) and OS (46.1 vs 17.6, P = 0.03) compared to those patients predicted to be resistant. The assay demonstrated a sensitivity, specificity, and positive and negative predictive value of 95, 44, 66, and 89%, respectively (Fisher's exact test, P = 0.007).Conclusion. The observed in vitro efficacy of EPI/PTX in primary epithelial ovarian cancer specimens warrants further clinical evaluation. The high evaluability rate and the observed correlation with PFS and OS, within the limitations of a nonrandomized study, support the use of the ATP chemosensitivity assay in future prospective assay-directed trials.
    Gynecologic Oncology 06/2000; · 3.93 Impact Factor