Dexrazoxane was found effective in reducing doxorubicin cardiotoxicity when given at a dose ratio (dexrazoxane: doxorubicin) of 20:1. Preclinical studies indicated that dexrazoxane at a dose ratio of ...10 to 15:1 also protected against epirubicin-induced cardiotoxicity. The main objective of this study was to investigate the efficacy of dexrazoxane, given at a dose ratio of 10:1 against epirubicin cardiotoxicity.
One hundred sixty-two advanced breast cancer patients were randomized to receive epirubicin-based chemotherapy with or without dexrazoxane. Patients who had previously received adjuvant chemotherapy that contained anthracyclines were treated with cyclophosphamide 600 mg/m2 intravenously (IV), epirubicin 60 mg/m2 IV, and fluorouracil 600 mg/m2 IV, on day 1 every 3 weeks. The other patients were treated with epirubicin 120 mg/m2 IV on day 1 every 3 weeks. Cardiac toxicity was defined as clinical signs of congestive heart failure, a decrease in resting left ventricular ejection fraction (LVEF) to < or = 45%, or a decrease from baseline resting LVEF of > or = 20 EF units.
One hundred sixty patients were evaluated. Cardiotoxicity was recorded in 18 of 78 patients (23.1%) in the control arm and in six of 82 (7.3%) in the dexrazoxone arm. The cumulative probability of developing cardiotoxicity was significantly lower in dexrazoxane-treated patients than in control patients (P = .006; odds ratio, 0.29; 95% confidence limit CL, 0.09 to 0.78). Noncardiac toxicity, objective response, progression-free survival, and overall survival were similar in both arms.
Dexrazoxane given at a dexrazoxane:epirubicin dose ratio of 10:1 protects against epirubicin-induced cardiotoxicity and does not affect the clinical activity and the noncardiac toxicity of epirubicin. The clinical use of dexrazoxane should be recommended in patients whose risk of developing cardiotoxicity could hamper the eventual use and possible benefit of epirubicin.
The objective of our study was to evaluate the effects of the apolipoprotein E (ApoE) phenotype and gender on the response to tacrine treatment in Alzheimer’s disease (AD). ApoE phenotyping was ...performed on 76 patients treated with tacrine for AD. This group comprised 33 ApoE ε4 allele carriers (ε4+) and 43 non‐ε4 carriers (ε4–). Patients were treated blindly in relation to the ApoE phenotype, with incremental tacrine dosages ranging from 40 mg/day up to the highest dosage (160 mg) tolerated without side‐effects. At least 6 weeks elapsed between each increase. Changes in the scores for the Alzheimer Disease Assessment Scale‐Cognitive Component (ADAS‐Cog) between baseline and each increment in dosage were assessed in the ε4– and ε4+ groups. The cut‐off point for being considered as responsive to tacrine treatment was a 4‐point decrease in the ADAS‐Cog score.
There was no tendency for the ε4– carriers to respond better than the ε4+ carriers. When patients were stratified by gender, no differences were found between the effects of the treatment on men and women. Consequently, these results do not support the hypothesis that the ApoE phenotype and gender are predictors of the response to tacrine in AD patients.
ABSTRACT The aim of this study was to characterize the mechanism of toxicity of fipronil on hepatocytes isolated from the rat and the effect of its biotransformation on the toxicological potential. ...The toxicity of fipronil was assessed by monitoring the oxygen consumption and mitochondrial membrane potential, intracellular ATP concentration, Ca2+ homeostasis and cell viability. The cell viability was evaluated by trypan blue exclusion in hepatocytes that were isolated from the normal rats and by the release of the enzymes alanine transaminase and aspartate transaminase in hepatocytes that were isolated from the normal rats or proadifen-pretreated rats. Fipronil reduced mitochondrial respiration in the cells that were energized with glutamate plus malate in a dose-dependent manner and dissipated the mitochondrial membrane potential that was accompanied by a reduction in ATP concentration and a disruption of intracellular Ca2+ homeostasis. The cell viability was affected by fipronil with higher potency in hepatocytes that were isolated from the normal rats, which indicated that the metabolism of this insecticide increased its toxicological potential. The results of this study indicated that the toxicity of fipronil to the hepatocytes was related to the inhibition of mitochondrial activity, which led to decreased ATP synthesis and a consequent alteration in intracellular Ca2+ homeostasis and ultimately resulted in cell death.
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► ABA is cytotoxic to rat isolated hepatocytes at concentrations from 25–100μM. ► ABA affects the mitochondrial bioenergetics in rat isolated hepatocytes. ► ABA treatment alters ...intracellular Ca2+ homeostasis. ► ABA caused cellular death by necrosis. ► Biotransformation of ABA reduces its toxicity.
Abamectin (ABA), which belongs to the family of avermectins, is used as a parasiticide; however, ABA poisoning can impair liver function. In a previous study using isolated rat liver mitochondria, we observed that ABA inhibited the activity of adenine nucleotide translocator and FoF1-ATPase. The aim of this study was to characterize the mechanism of ABA toxicity in isolated rat hepatocytes and to evaluate whether this effect is dependent on its metabolism. The toxicity of ABA was assessed by monitoring oxygen consumption and mitochondrial membrane potential, intracellular ATP concentration, cell viability, intracellular Ca2+ homeostasis, release of cytochrome c, caspase 3 activity and necrotic cell death. ABA reduces cellular respiration in cells energized with glutamate and malate or succinate. The hepatocytes that were previously incubated with proadifen, a cytochrome P450 inhibitor, are more sensitive to the compound as observed by a rapid decrease in the mitochondrial membrane potential accompanied by reductions in ATP concentration and cell viability and a disruption of intracellular Ca2+ homeostasis followed by necrosis. Our results indicate that ABA biotransformation reduces its toxicity, and its toxic action is related to the inhibition of mitochondrial activity, which leads to decreased synthesis of ATP followed by cell death.
To evaluate the effect of previous adjuvant chemotherapy with or without anthracyclines on overall survival (OS), progression-free survival (PFS), and objective response (OR) rates of metastatic ...breast cancer patients treated with cyclophosphamide, epidoxorubicin, and fluorouracil (CEF) as first-line chemotherapy.
Three-hundred twenty-six assessable metastatic breast cancer patients entered onto four consecutive randomized trials performed in our Institution and North-West Oncology Group (GONO) cooperative centers from 1983 to 1994. Patients received CEF-based chemotherapy as first-line therapy and were then evaluated. One hundred forty-four patients (44%) did not receive previous adjuvant chemotherapy, and 143 (44%) and 39 (12%) patients received cyclophosphamide, methotrexate, and fluorouracil (CMF)-based and anthracycline-based adjuvant chemotherapy, respectively.
ORs to CEF chemotherapy were observed in 161 patients (49.4%). On univariate analysis, patients who had received prior adjuvant chemotherapy had a significantly lower probability of response than patients who did not: 43% versus 58% (P=.02). No difference between CMF-based (OR rate, 43%) and anthracycline-based (OR rate, 44%) adjuvant chemotherapy was observed. Stepwise logistic regression analysis indicated that adjuvant chemotherapy (P=.005), bone as dominant metastatic site (P=.02), and previous hormonotherapy for metastatic disease (P=.005) were the most important factors in predicting a poor OR rate. The median PFS and OS times of the whole group were 9.8 and 17.9 months, respectively. Patients who did not receive adjuvant chemotherapy had a longer survival time (21.1 months) compared with patients previously treated with CMF-based (15.3 months) or anthracycline-based (15.8 months) adjuvant chemotherapy. Multivariate analysis confirmed adjuvant chemotherapy to be among the strongest prognostic factors associated with both a poor PFS and OS.
Previous adjuvant chemotherapy adversely affects OR, PFS, and OS in metastatic breast cancer patients treated with the CEF regimen as first-line chemotherapy. No difference was observed between patients previously treated with CMF-based or anthracycline-based adjuvant chemotherapy.
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