Comparative effects of paclitaxel and docetaxel on the metabolism and pharmacokinetics of epirubicin in breast cancer patients

Assessment of clinical outcomes in breast cancer patients treated with taxanes: multi-analytical approach

Polymorphisms in genes encoding CYPs (Phase I) and ABCB1 (Phase III) enzymes may attribute to variability of efficacy of taxanes. The present study aims to find the influence of CYP and ABCB1 gene polymorphisms on taxanes based clinical outcomes. 132 breast cancer patients treated with taxanes based chemotherapy were genotyped for CYP3A4*1B, CYP3A5*3, CYP1B1*3, CYP2C8*3, ABCB1 1236C>T, 2677G>T/A and 3435C>T polymorphisms using PCR-RFLP. Associations of genetic variants with clinical outcomes in terms of response in 58 patients receiving neo-adjuvant chemotherapy (NACT), and chemo-toxicity in 132 patients were studied. Multifactor dimensionality reduction (MDR) analysis was performed to evaluate higher order gene-gene interactions with clinical outcomes. Pathological response to taxane based NACT was associated with GA genotype as well as A allele of CYP3A5*3 polymorphism (Pcorr=0.0465, Pcorr=0.0465). Similarly, association was found in dominant model of CYP3A5*3 polymorphism with responders (Pcorr=0.0465). Haplotype analysis further revealed ACYP3A4-ACYP3A5 haplotype to be significantly associated with responders (Pcorr=0.048). In assessing toxicity, significant association of variant (TT) genotype and T allele of ABCB1 2677G>T/A polymorphism, was found with 'grade 1 or no leucopenia' (Pcorr=0.0465, Pcorr=0.048). On evaluating higher order gene-gene interaction models by MDR analysis, CYP3A5*3; ABCB11236C>T and ABCB1 2677G>T/A; ABCB1 3435C>T and CYP1B1*3 showed significant association with treatment response, grade 2-4 anemia and dose delay/reduction due to neutropenia (P=0.024, P=0.004, P=0.026), respectively. Multi-analytical approaches may provide a better assessment of pharmacogenetic based treatment outcomes in breast cancer patients treated with taxanes.

Side effects after docetaxel treatment in Taiwanese breast cancer patients with CYP3A4, CYP3A5, and ABCB1 gene polymorphisms

BACKGROUND

Breast cancer patients initiating TEC (including docetaxel, epirubicin, and cyclophosphamide) treatment were genotyped for CYP3A4, CYP3A5, and ABCB1 to identify variability factors of side effects for docetaxel.

METHODS

The planned dose of docetaxel per course was formulated according to each patient's height and weight. Each participant had received TEC treatment for 6 consecutive cycles. The single nucleotide polymorphisms (SNPs) of CYP3A4*4 (352A > G), CYP3A4*5 (653C > G), and CYP3A4*18A (20070T > C) for the CYP3A4 gene, CYP3A5*3A (6986A > G) for the CYP3A5 gene, and -41A > G, -145C > G, 1236C > T, 2677G > T(A), and 3435C > T SNPs for the ABCB1 gene were determined by using the restriction fragment length polymorphism of polymerase chain reaction products and the restriction enzymes.

RESULTS

Fifty-nine Taiwanese women (mean age, 46 y; range, 30-64 y) treated for breast cancer with TEC were recruited. We found that patients carrying the CYP3A5*1/*3 genotype demonstrated more side effects of fever, pleural effusion, and febrile neutropenia than those with the CYP3A5*3/*3 genotype (p = 0.075, 0.077, and 0.030, respectively); moreover, patients with the ABCB1 2677G/G genotype also showed more side effects of fever and febrile neutropenia than those with other genotypes (p = 0.024 and 0.027), In regard to ABCB1 3435C>T, patients with ABCB1 3435C/C tended to suffer leucopenia (p = 0.057).

CONCLUSIONS

There could be correlations between certain side effects of docetaxel treatment and polymorphisms of these metabolic enzymes. Unfortunately, there is not so much evidence due to the small sample size of this study which restricts the statistical power.

A phase I trial of irinotecan alternating with epirubicin in patients with advanced malignancies

OBJECTIVES

This phase I study was conducted to evaluate the combination of irinotecan, a topoisomerase I inhibitor, with epirubicin, a topoisomerase II inhibitor, when administered sequentially on a once-every-three week basis.

METHODS

Irinotecan was administered at doses ranging from 100 to 150 mg/m(2) intravenously over 90 minutes, 24 hours before epirubicin, in doses from 30 to 60 mg/m(2), every 3 weeks. Toxicity assessments were performed weekly. Tumor evaluation by radiographic and physical examination was performed after every 3 cycles using Response Evaluation Criteria in Solid Tumors.

RESULTS

Eighteen patients with metastatic solid tumors were enrolled in this study. The maximum tolerated dose and recommended phase II dose was irinotecan 150 mg/m(2) and epirubicin 30 mg/m(2). Dose-limiting toxicities were primarily neutropenia. Other toxicities at this dose level were mild. Three patients with colon cancer, 1 patient with renal cell cancer and 1 patient with adenosquamous cell carcinoma of the ethmoid sinus had stable disease. No objective responses were observed.

CONCLUSIONS

The maximum tolerated dose and recommended phase II dose for irinotecan and epirubicin administered 24 hours apart every 3 weeks was 150 mg/m(2) and 30 mg/m(2), respectively. Higher doses were limited by significant hematologic toxicity and fatigue.

Early Epirubicin‐Induced Myocardial Dysfunction Revealed by Serial Tissue Doppler Echocardiography: Correlation with Inflammatory and Oxidative Stress Markers

A phase II, open, nonrandomized trial was carried out in a group of epirubicin-treated patients with cancer at different sites with the aim of detecting early preclinical changes that are predictive of the risk for heart failure. All patients underwent conventional echocardiography, as well as tissue Doppler imaging (TDI) with strain (sigma) and strain rate (SR), a very accurate technique for detecting minimal changes in cardiac left ventricular (LV) function. Moreover, echocardiographic changes identified during epirubicin treatment were compared with those of a series of biochemical markers of both myocardial damage and inflammation/oxidative stress. Sixteen patients (male-to-female ratio, 3:13; mean age +/- standard deviation, 56 +/-3 years; range, 27-75 years) with histologically confirmed tumors at different sites, scheduled to be treated with an epirubicin-based chemotherapy regimen, were enrolled in the study. A significant impairment in systolic LV function was observed after 200 mg/m2 of epirubicin; this was shown by a lower SR peak compared with baseline (1.82 +/- 0.57/second versus 1.45 +/- 0.44/second), whereas sigma remained unchanged. The following significant changes in LV diastolic function occurred only after 300 mg/m2 of epirubicin: a decrease in conventional early/late diastolic (E/A) velocities (1.16 +/- 0.31 versus 0.93 +/- 0.24) and a reduction in both the E(m) wave in the basal portion of the interventricular septum (8.86 +/- 1.73 cm/second versus 7.51 +/- 2.30 cm/second) and in the E(m)/A(m) ratio (1.09 +/- 0.51 versus 0.83 +/- 0.51), as measured using the TDI technique. No significant changes in LV ejection fraction were observed. Baseline values of brain natriuretic peptide, troponin I, myoglobin, and creatine kinase-myocardial subfraction were within the normal range and no significant changes were observed throughout the study. Levels of interleukin (IL)-6 and its soluble receptor (sIL-6R) and reactive oxygen species increased significantly, whereas glutathione peroxidase (GPx) levels decreased significantly, after 200 mg/m2 of epirubicin. Significant correlations between the reduction in the SR peak (deltaSR) after 200 mg/m2 of epirubicin and the increase in IL-6 and ROS and decrease in GPx were observed. The multiple regression analysis showed that the only independent predictive variable for deltaSR was ROS level. Our data show that: (a) subtle cardiac abnormalities may occur at epirubicin doses significantly below those known to be potentially clinically harmful and (b) the earliest myocardial impairment affects LV systolic rather than diastolic function. Early contractility impairment during epirubicin treatment was associated with high levels of ROS and markers of inflammation. The clinical meaningfulness of our findings warrants further investigations in a larger number of patients for a longer period of follow-up.

Defective Taxane Stimulation of Epirubicinol Formation in the Human Heart: Insight into the Cardiac Tolerability of Epirubicin-Taxane Chemotherapies

The antitumor anthracycline doxorubicin induces a dose-related cardiotoxicity that correlates with the myocardial levels of its secondary alcohol metabolite doxorubicinol. Combining doxorubicin with taxanes such as paclitaxel or docetaxel may aggravate cardiotoxicity, presumably because the taxanes cause an allosteric-like stimulation of cytoplasmic aldehyde reductases that convert doxorubicin to doxorubicinol in the heart. A less severe aggravation of cardiotoxicity was observed on combining taxanes with epirubicin, a closely related analog of doxorubicin; therefore, we characterized whether the cardiac tolerability of epirubicin-taxane therapies could be due to a defective taxane stimulation of the conversion of epirubicin to its secondary alcohol metabolite epirubicinol. Comparisons between doxorubicin and epirubicin in isolated human heart cytosol showed that epirubicin exhibited a lower V(max)/K(m) value for reaction with aldehyde reductases and a defective stimulation of epirubicinol formation by paclitaxel or docetaxel. A similar pattern occurred in the soluble fraction of human myocardial strips incubated in plasma with anthracyclines and paclitaxel or docetaxel, formulated in their clinical vehicles Cremophor EL or polysorbate 80. Doxorubicin, but not epirubicin, was also able to generate reactive oxygen species in the membrane fraction of myocardial strips; however, the levels of doxorubicin-derived reactive oxygen species were not further augmented by paclitaxel. These results support the notion that taxanes might aggravate the cardiotoxicity of doxorubicin through a specific stimulation of doxorubicinol formation. The failure of paclitaxel or docetaxel to stimulate epirubicinol formation therefore uncovers an important determinant of the improved cardiac tolerability of epirubicin-taxane combinations.

Clinical pharmacokinetics of docetaxel : recent developments

Docetaxel belongs to the class of taxane antineoplastic agents that act by inducing microtubular stability and disrupting the dynamics of the microtubular network. The drug has shown a broad spectrum of antitumour activity in preclinical models as well as clinically, with responses observed in various disease types, including advanced breast cancer and non-small cell lung cancer. The pharmacokinetics and metabolism of docetaxel are extremely complex and have been the subject of intensive investigation in recent years. Docetaxel is subject to extensive metabolic conversion by the cytochrome P450 (CYP) 3A isoenzymes, which results in several pharmacologically inactive oxidation products. Elimination routes of docetaxel are also dependent on the presence of drug-transporting proteins, notably P-glycoprotein, present on the bile canalicular membrane. The various processes mediating drug elimination, either through metabolic breakdown or excretion, impact substantially on interindividual variability in drug handling. Strategies to individualise docetaxel administration schedules based on phenotypic or genotype-dependent differences in CYP3A expression are underway and may ultimately lead to more selective chemotherapeutic use of this agent.

Docetaxel: a review of its use in metastatic breast cancer

Docetaxel (Taxotere), a cytotoxic taxane, is an antimicrotubule agent effective in the treatment of patients with breast cancer. The clinical profile of docetaxel as an effective cytotoxic agent in the treatment of metastatic breast cancer is well established. As yet, no single standard regimen has been identified as optimal for the treatment of patients with metastatic breast cancer after failure of prior chemotherapy. However, the efficacy of docetaxel monotherapy administered every 3 weeks as a 1-hour infusion is similar to or better than that of doxorubicin, paclitaxel and fluorouracil plus vinorelbine, and better than that of methotrexate plus fluorouracil or mitomycin plus vinblastine. Although docetaxel is associated with neutropenia and other adverse events, its overall tolerability profile is generally acceptable in the majority of patients. Docetaxel, therefore, is an effective option in the treatment of patients with metastatic breast cancer after failure of prior chemotherapy.

Docetaxel in the treatment of breast cancer: current experience and future prospects

It has become clear over the past 10 years that docetaxel, a semisynthetic taxoid antineoplastic agent, is among the most promising compounds to have been developed in the 1990s for the treatment of breast cancer. Data indicate that this drug became standard therapy in the treatment of patients with metastatic disease who have failed anthracycline treatment, and secondarily showed very encouraging results in the first-line metastatic setting either in monochemotherapy or when docetaxel was combined with an anthracycline. More recently, docetaxel also became one of the standard therapies in the adjuvant and neoadjuvant settings, and a promising partner for novel biologic therapies. Current research is further exploring the effect of docetaxel on outcome of early breast cancer in order to fully determine the extent that this chemotherapeutic agent will change the natural history of breast cancer.

Drug–drug interactions in oncology: Why are they important and can they be minimized?

Adverse drug-drug interactions are a major cause of morbidity and mortality. Cancer patients are at particularly high risk of such interactions because they commonly receive multiple medications, including cytotoxic chemotherapy, hormonal agents and supportive care drugs. In addition, the majority of cancer patients are elderly, and so require medications for co-morbid conditions such as cardiovascular, gastrointestinal, and rheumatological diseases. Furthermore, the age-related decline in hepatic and renal function reduces their ability to metabolize and clear drugs and so increases the potential for toxicity. Not all drug-drug interactions can be predicted, and those that are predictable are not always avoidable. However, increased awareness of the potential for these interactions will allow healthcare providers to minimize the risk by choosing appropriate drugs and also by monitoring for signs of interaction. This review considers the basic principles of drug-drug interactions, and presents specific examples that are relevant to oncology.

Paclitaxel chemotherapy: from empiricism to a mechanism-based formulation strategy

Paclitaxel is an anticancer agent effective for the treatment of breast, ovarian, lung, and head and neck cancer. Because of water insolubility, paclitaxel is formulated with the micelle-forming vehicle Cremophor EL to enhance drug solubility. However, the addition of Cremophor EL results in hypersensitivity reactions, neurotoxicity, and altered pharmacokinetics of paclitaxel. To circumvent these unfavorable effects resulting from the addition of Cremophor EL, efforts have been made to develop new delivery systems for paclitaxel administration. For example, ABI-007 is a Cremophor-free, albumin-stabilized, nanoparticle paclitaxel formulation that was found to have significantly less toxicity than Cremophor-containing paclitaxel in mice. Pharmacokinetic studies indicate that in contrast to Cremophor-containing paclitaxel, ABI-007 displays linear pharmacokinetics over the clinically relevant dose range of 135-300 mg/m(2). In a phase III study conducted in patients with metastatic breast cancer, patients treated with ABI-007 achieved a significantly higher objective response rate and time to progression than those treated with Cremophor-containing paclitaxel. Together these findings suggest that nanoparticle albumin-bound paclitaxel may enable clinicians to administer paclitaxel at higher doses with less toxicity than is seen with Cremophor-containing paclitaxel. The role of this novel paclitaxel formulation in combination therapy with other antineoplastic agents needs to be determined.

Pharmacokinetics of combined doxorubicin and paclitaxel in mice

Doxorubicin (DOX) has excellent antitumor activity when combined with paclitaxel (PTX) and this combination is used as first-line treatment for metastatic breast cancer. Results from clinical studies on pharmacokinetic interaction of these agents are not conclusive and pre-clinical studies are still needed. Pharmacokinetic studies were carried out in female Balb/c mice with combined DOX (6 mg/kg) and PTX (10 mg/kg) treatment. Combined treatment with PTX and DOX leads to alterations in the pharmacokinetics of both agents, with the predominant effect being elevated drug levels in liver and gut tissues. DOX levels in kidney and heart tissues were unaffected by concurrent PTX treatment. Further, plasma levels of DOX are not changed by concurrent PTX treatment suggesting that monitoring of plasma levels of DOX, when used in combination with another drug that is a P-glycoprotein (PGP) substrate, will not reflect actual pharmacokinetic changes occurring in other tissues.

Cardiac toxicity assessment in locally advanced breast cancer treated neoadjuvantly with doxorubicin/paclitaxel regimen

BACKGROUND

The psychological difficulty of accepting a mastectomy for locally advanced breast cancer (LABC) justifies the use of chemotherapy as neoadjuvant primary treatment. The aim of this prospective study was to assess the efficacy of the doxorubicin/paclitaxel (AT) schedule neoadjuvantly administered in terms of response rates and survival in patients with LABC, with a special focus on cardiac toxicity.

PATIENTS AND METHOD

All patients were treated by doxorubicin (60 mg/m2 i.v.) bolus followed by paclitaxel (200 mg/m2) as a 3-h infusion. Treatment was repeated every 3 weeks for four or six courses and followed by surgery, radiotherapy, and hormonotherapy for patients with positive hormonal receptors. Patients with significant cardiovascular history or ECG abnormalities were not eligible for the study. Measurements of left ventricular ejection fraction (LVEF) were performed at baseline and at the end of chemotherapy.

RESULTS

From 1998 to 2001, 34 consecutive patients followed up in our institution were entered into this study. Median age was 49 years (range, 32-68 years). Seventeen patients had stage IIB, 5 patients stage IIIA, and 12 patients stage IIIB disease. Twenty-one patients underwent conservative surgery, 7 radical surgery, and 6 patients no surgery due to metastatic disease occurring during treatment. An objective clinical response was noted in 22 (65%) of 34 patients (6 patients with histological complete response, 10 patients with rare malignant cells, and 6 patients with a partial response), 6 patients presented a progressive disease, and 8 patients a stable disease. Twenty-four patients have kept normal cardiac function, 7 patients had a cardiac toxicity as defined by the institution [4 (24%) of 17 patients received 360 mg/m2 of doxorubicin (A), 2 of 4 presented congestive heart failure (CHF), and 3 (21%) of 14 patients received 240 mg/m(2) of A without CHF]. Three patients did not receive four or six cycles as initially planned due to the progressive disease during the chemotherapy courses. These patients were excluded from the final analysis, particularly cardiac toxicity analysis. At time of median follow-up (42 months), 28 of 34 patients were alive (one death due to CHF, five others due to progressive disease).

CONCLUSION

The AT regimen in neoadjuvant treatment for LABC remains efficient, but cardiac toxicity reported in this study underlies the necessity to optimize the schedule of AT combination.

Model Describing the Relationship Between Pharmacokinetics and Hematologic Toxicity of the Epirubicin-Docetaxel Regimen in Breast Cancer Patients

Purpose

The aims of the present study were (1) to characterize the pharmacokinetics of both component drugs and (2) to describe the relationship between the pharmacokinetics and the dose-limiting hematologic toxicity for the epirubicin (EPI)/docetaxel (DTX) regimen in breast cancer patients.

Patients and Methods

Forty-four patients with advanced disease received EPI and DTX every 3 weeks for up to nine cycles. The initial doses (EPI/DTX) were 75/70 mg/m2. Based on leukocyte (WBC) and platelet counts, the subsequent doses were, stepwise, either escalated (maximum, 120/100 mg/m2) or reduced (minimum, 40/50 mg/m2). Hematologic toxicity was monitored in all patients, whereas pharmacokinetics was studied in 16 patients. A semiphysiological model, including physiological parameters as well as drug-specific parameters, was used to describe the time course of WBC count following treatment.

Results

In the final pharmacokinetic model, interoccasion variability was estimated to be less than interindividual variability in the clearances for both drugs. The sum of the individual EPI and DTX areas under concentration-time curve correlated stronger to WBC survival fraction than did the corresponding sum of doses. A pharmacokinetic-pharmacodynamic (PK-PD) model with additive effects of EPI and DTX could adequately describe the data.

Conclusion

The final PK-PD model might provide a tool for calculation of WBC time course, and hence, for prediction of nadir day and duration of leukopenia in breast cancer patients treated with the EPI/DTX regimen.

Preclinical pharmacology of the taxanes: implications of the differences

Taxanes are one of the most powerful classes of compounds among all chemotherapeutic drugs. Only 30 years separate the isolation of the first taxane from the results of direct clinical comparisons in metastatic breast, ovarian, and lung cancer between the two taxanes available in routine clinical practice. These results suggest a more favorable benefit-to-risk ratio for docetaxel compared to paclitaxel when these drugs are used as single agents or in combination with other chemotherapeutic agents in an every-3-week dosing regimen. Pharmacological data support the difference between the taxanes, likely explaining the clinical results. Considering the molecular pharmacology of the two drugs, docetaxel appears to bind to beta-tubulin with greater affinity and has a wider cell cycle activity than paclitaxel. Docetaxel also appears to have direct antitumoral activity via an apoptotic effect mediated by bcl-2 phosphorylation. In addition, docetaxel has a longer retention time in tumor cells than paclitaxel because of greater uptake and slower efflux. Pharmacokinetics and pharmacodynamics of the taxanes show both agents to be extensively metabolized in the liver, and paclitaxel has a nonlinear pharmacokinetic behavior while docetaxel has linear pharmacokinetics. These differences explain the more simple treatment schedule and favorable results for docetaxel as a single agent and in combination therapy. Last, but not least, there is a pharmacokinetic interaction between paclitaxel and the anthracyclines, an active class of compounds commonly used in the treatment of breast cancer. This pharmacokinetic interaction is associated with greater cardio- and myelotoxicities, which are sequence dependent. These pharmacological data likely explain the different clinical development strategies for the two molecules as well as the different clinical results from individual trials and direct comparisons.

Pharmacological effects of formulation vehicles : implications for cancer chemotherapy

The non-ionic surfactants Cremophor EL (CrEL; polyoxyethyleneglycerol triricinoleate 35) and polysorbate 80 (Tween) 80; polyoxyethylene-sorbitan-20-monooleate) are widely used as drug formulation vehicles, including for the taxane anticancer agents paclitaxel and docetaxel. A wealth of recent experimental data has indicated that both solubilisers are biologically and pharmacologically active compounds, and their use as drug formulation vehicles has been implicated in clinically important adverse effects, including acute hypersensitivity reactions and peripheral neuropathy.CrEL and Tween 80 have also been demonstrated to influence the disposition of solubilised drugs that are administered intravenously. The overall resulting effect is a highly increased systemic drug exposure and a simultaneously decreased clearance, leading to alteration in the pharmacodynamic characteristics of the solubilised drug. Kinetic experiments revealed that this effect is primarily caused by reduced cellular uptake of the drug from large spherical micellar-like structures with a highly hydrophobic interior, which act as the principal carrier of circulating drug. Within the central blood compartment, this results in a profound alteration of drug accumulation in erythrocytes, thereby reducing the free drug fraction available for cellular partitioning and influencing drug distribution as well as elimination routes. The existence of CrEL and Tween 80 in blood as large polar micelles has also raised additional complexities in the case of combination chemotherapy regimens with taxanes, such that the disposition of several coadministered drugs, including anthracyclines and epipodophyllotoxins, is significantly altered. In contrast to the enhancing effects of Tween 80, addition of CrEL to the formulation of oral drug preparations seems to result in significantly diminished drug uptake and reduced circulating concentrations. The drawbacks presented by the presence of CrEL or Tween 80 in drug formulations have instigated extensive research to develop alternative delivery forms. Currently, several strategies are in progress to develop Tween 80- and CrEL-free formulations of docetaxel and paclitaxel, which are based on pharmaceutical (e.g. albumin nanoparticles, emulsions and liposomes), chemical (e.g. polyglutamates, analogues and prodrugs), or biological (e.g. oral drug administration) strategies. These continued investigations should eventually lead to more rational and selective chemotherapeutic treatment.

Influence of trastuzumab on epirubicin pharmacokinetics in metastatic breast cancer patients

BACKGROUND

Anthracycline cardiotoxicity is increased by the contemporaneous administration of trastuzumab. The mechanism by which it occurs is as yet unknown. The aim of this study was to evaluate whether trastuzumab modifies the pharmacokinetics of epirubicin and its metabolites.

PATIENTS AND METHODS

Women with HER2-positive metastatic breast cancer were treated with epirubicin 75 mg/m(2) i.v. bolus followed by docetaxel 75 mg/m(2) in a 1-h infusion, every 3 weeks for six cycles, and trastuzumab (once at 4 mg/m(2), then 2 mg/m(2) weekly thereafter) in a 30-min infusion. Epirubicin pharmacokinetic data of seven patients were evaluated at the first cycle of therapy (baseline, with trastuzumab administered 24 h after epirubicin), and at the sixth cycle (i.e. 15 weeks after baseline, with trastuzumab administered immediately before epirubicin).

RESULTS

No pharmacokinetic change in the parent compound epirubicin was detected. The area under the plasma concentration-time curve (AUC(0-24 h)) was 1230 +/- 318 [mean +/- standard deviation (SD)] at the first cycle and 1287 +/- 385 h. micro g/l at the sixth. The mean (+/-SD) maximum plasma concentration (C(max)) and the terminal elimination half-life at the first cycle (1303 +/- 490 micro g/l and 12.5 +/- 3.1 h, respectively) were similar to those obtained at the sixth cycle (1229 +/- 580 micro g/l and 11.5 +/- 2.9 h, respectively). Pharmacokinetic data of epirubicin metabolites evaluated at the first and sixth cycle of chemotherapy were superimposable without any statistical difference.

CONCLUSION

Enhanced anthracycline cardiotoxicity related to trastuzumab administration was not linked to pharmacokinetic interferences with epirubicin and its metabolites.

Cardiotoxic effects of anthracycline-taxane combinations

The association of doxorubicin (DOX) and paclitaxel (PTX) is very active in breast cancer. Unfortunately, PTX may potentiate the cardiotoxic effects of anthracyclines: it causes nonlinear disposition of DOX and its metabolites, leading to persistant of elevated plasma concentrations of the anthracyclines. However, this pharmacokinetic interference is not sufficient to explain the enhanced cardiotoxicity of the combination. Recent data suggest that PTX stimulates the conversion of DOX to cardiotoxic metabolites (namely doxorubicinol) inside cardiomyocytes. Docetaxel (DTX) does not have a major influence on DOX plasma concentration because it does not interfere with its elimination. Clinical data suggest that DTX may not enhance anthracycline cardiotoxicity, but patients seldom received a total anthracycline dose compatible with increased risk. Furthermore, there are experimental data indicating that DTX can also stimulate the metabolism of DOX to toxic species in human heart.

Docetaxel with epirubicin--investigations on cardiac safety

The aim was to evaluate clinical and subclinical cardiac toxicity of epirubicin-docetaxel (ET) combination. Breast cancer patients were given epirubicin (75 mg/m2 for 15 min), followed 1 h later by a 1-h infusion of docetaxel (75 mg/m2) q3w as first-line treatment. Cardiac function was monitored using a 24-h ambulatory electrocardiogram (ECG), left ventricular ejection fraction (LVEF), physical examination and chest radiography. The median LVEF did not decrease during the course of the treatment: median LVEF was 64% prior to treatment and 68% after cycle 8. The 24-h ECG did not reveal any significant changes in heart rate variability. The number of extrasystoles or cardiac arrhythmia did not increase with the ET treatment. No patient experienced congestive heart failure during treatment or the mean follow-up of 34 months. We conclude that first-line ET caused no major cardiac changes during 6 months of treatment (8 cycles) or during follow-up. Twenty-four-hour ECG, combined with echocardiography to measure LVEF, was a feasible method for the close monitoring of the cardiac effects during chemotherapy.

Phase I and pharmacokinetic study of docetaxel in combination with epirubicin and cyclophosphamide in advanced cancer: dose escalation possible with granulocyte colony-stimulating factor, but not with prophylactic antibiotics

BACKGROUND

The objective of this phase I trial was to determine the maximally tolerated doses of the combination of docetaxel, epirubicin and cyclophosphamide.

PATIENTS AND METHODS

Patients with advanced cancer, World Health Organization (WHO) performance status 0 to 2, who had received up to one prior chemotherapy regimen were treated with docetaxel, epirubicin and cyclophosphamide repeated every 21 days. The cyclophosphamide dose was fixed at 600 mg/m(2) and the dose levels studied were: docetaxel/epirubicin; 60/60, 75/60, 75/75, 75/90, 85/90 and 85/105 mg/m(2). There was provision for the addition of prophylactic ciprofloxacin and granulocyte colony-stimulating factor (G-CSF) in separate steps if dose-limiting toxicity (DLT) was neutropenia related.

RESULTS

Forty-three patients were entered and all were assessable for toxicity. Dose-limiting toxicity, predominantly febrile neutropenia, was surprisingly seen at the first dose level. The addition of prophylactic ciprofloxacin did not permit dose escalation, but dose escalation was possible with the addition of G-CSF. The highest administered dose level with G-CSF was docetaxel 85 mg/m(2) and epirubicin 105 mg/m(2) with DLTs in five of six patients. Treatment was well tolerated in 10 patients treated at the recommended dose level (85/90) with only one patient experiencing DLT. Responses were seen in a range of malignancies including breast and anaplastic thyroid cancers. No significant pharmacokinetic interaction was observed, but a transient increase in epirubicinol plasma concentration occurred during and after docetaxel infusion.

CONCLUSIONS

The recommended dose level of docetaxel 85 mg/m(2), epirubicin 90 mg/m(2) and cyclophosphamide 600 mg/m(2) with G-CSF support has a favorable toxicity profile and is suitable for further investigation in phase II and III trials.

Phase II study of docetaxel and epirubicin in Chinese patients with metastatic breast cancer

The efficacy and safety of docetaxel-epirubicin chemotherapy in the treatment of metastatic breast cancer was investigated in Chinese women. Three-weekly cycles comprised epirubicin 75 mg/m2 i.v. followed 1 h later by docetaxel 75 mg/m2 i.v. After 3 cycles, responding patients received a further 3 cycles, followed by 3 cycles of docetaxel alone. Forty-six patients entered the study, of whom 37% had received prior adjuvant chemotherapy. Three patients withdrew due to toxicity and were not evaluable for response. There were five complete responses and 31 partial responses, giving an overall response rate of 83.7% (95% CI 72.7-94.8%). The median time to progression was 10.96 months (95% CI 7.76-12.86) and median survival was 24.2 months (95% CI 16.6-). The most common grade 3/4 adverse events were neutropenia (96% of patients) and neutropenia with fever (39%). Hepatotoxicity occurred in six patients, two being attributable to hepatitis B virus reactivation. No patients suffered grade 3/4 cardiac toxicity and there were no treatment-related mortalities. Quality of life aspects deteriorated after 3 cycles, but there was a trend towards improved emotional aspects after 9 cycles. We conclude that docetaxel-epirubicin chemotherapy is highly effective for recurrent metastatic/locoregional breast cancer, with myelosuppression being the main toxicity.

Doxorubicin pharmacokinetics: Macromolecule binding, metabolism, and excretion in the context of a physiologic model

The studies described herein were designed to determine whether doxorubicin (DOX) pharmacokinetics (PKs) could be described by a physiologically based PK model that incorporated macromolecule-specific binding and organ-specific metabolism and excretion. Model parameters were determined experimentally, or were gathered from the literature, in a species-specific manner, and were incorporated into a physiologically based description of DOX blood and tissue distribution for mice, dogs, and humans. The resulting model simulation data were compared with experimentally determined data using PK parameters calculated using compartmental or noncompartmental analysis to assess the predictability of the models. The resulting physiologically based PK model that was developed could accurately predict blood and tissue PKs of DOX in mice. When this model was interspecies extrapolated to predict DOX levels in dogs and humans undergoing treatment for cancer, predictions in dog plasma or human serum were also consistent with the actual clinical data. This model has potential utility for predicting the magnitude of PK interactions of DOX with other drugs, and for predicting changes in DOX PKs in any number of clinical situations.

First-line treatment with epirubicin and vinorelbine in metastatic breast cancer

PURPOSE

This phase II multicenter trial was aimed at investigating the activity of epirubicin-vinorelbine combination as first-line chemotherapy in metastatic breast cancer patients.

PATIENTS AND METHODS

Ninety-seven patients with metastatic breast cancer and no prior exposure to anthracyclines received the following regimen: epirubicin 100 mg/m(2) by intravenous (IV) bolus infusion on day 1 plus vinorelbine 25 mg/m(2) by 30-minute IV infusion on days 1 and 5, every 3 weeks for up to eight cycles. All patients also received granulocyte colony-stimulating factor (G- CSF) on days 7 to 12 of every cycle.

RESULTS

Objective responses, confirmed at least 4 weeks after the first documentation, were observed in 65 out of 92 assessable patients (70.6%; 95% CI, 62% to 80%). Disease remained stable in 17 patients (18.5%). Responses were observed in all disease sites, being 94% in soft tissue, 60% in bone, and 66% in visceral disease. Median time to response, median duration of response, median time to progression, and median overall survival were 2, 9, 10, and 26 months, respectively. The dose-limiting toxicity was neutropenia, which was grade 4 in 36% of the patients, and was accompanied by fever in 26% of the cases. Grade 3 to 4 mucositis was encountered in 28% of the patients. Other toxicities were mild to moderate. No cardiotoxicity was observed.

CONCLUSION

The epirubicin-vinorelbine combination with G-CSF support has been shown in this study to be highly active as first-line treatment of metastatic breast cancer patients, with significant although transient toxicity. This justifies further evaluation in the neoadjuvant setting and in early-stage breast cancer.

Gemcitabine, epirubicin and paclitaxel: pharmacokinetic and pharmacodynamic interactions in advanced breast cancer

BACKGROUND

The objectives of this study were to investigate the disposition of gemcitabine, epirubicin, paclitaxel, 2',2'-difluorodeoxyuridine and epirubicinol, and characterize the pharmacokinetic and pharmacodynamic profile of treatment in patients with breast cancer.

PATIENTS AND METHODS

The drug dispostion in 15 patients who received gemcitabine 1000 mg/m2, epirubicin 90 mg/m2 and paclitaxel 175 mg/m2 (GEP) on day 1 of a 21-day cycle, was compared with that of patients treated with epirubicin 90 mg/m2 and paclitaxel 175 mg/m2 (EP, n = 6) and epirubicin 90 mg/m2 alone (n = 6). Drug and metabolite levels in plasma and urine were assessed by high-performance liquid chromatography and parameters of drug exposure were related to hematological toxicity by a sigmoid-maximum effect (Emax) model.

RESULTS

Paclitaxel administration significantly increased the epirubicinol area under the concentration-time curve, from 357+/-146 (epirubicin) to 603+/-107 (EP) and 640+/-81 h x ng/ml (GEP), and reduced the renal clearance of epirubicin and epirubicinol by 38 and 52.2% and 34.5 and 53% in GEP- and EP-treated patients, respectively, compared with epirubicin alone. Gemcitabine had no apparent effect on paclitaxel and epirubicin pharmacokinetics, and renal clearance of epirubicin and epirubicinol. The only pharmacokinetic/pharmacodynamic relationship observed was between neutropenia and the time spent above the threshold plasma level of 0.1 micromol/l (tC0.1) of paclitaxel, with the time required to obtain a 50% decrease in neutrophil count (Et50) of GEP being 7.8 h, similar to that of EP.

CONCLUSIONS

Paclitaxel and/or its vehicle, Cremophor EL, interferes with the disposition and renal excretion of epirubicin and epirubicinol; gemcitabine has no affect on epirubicin and paclitaxel plasma pharmacokinetics and renal excretion of epirubicin, while neutropenia is not enhanced by gemcitabine.

Pharmacokinetics and pharmacodynamics of combination chemotherapy with paclitaxel and epirubicin in breast cancer patients

AIMS

To investigate the pharmacokinetics and pharmacodynamics of epirubicin and paclitaxel in combination, as well as the effects of paclitaxel and its vehicle Cremophor EL on epirubicin metabolism.

METHODS

Twenty-seven female patients with metastatic breast cancer received epirubicin 90 mg m-2 i.v. followed 15 min or 30 h later by a 3 h i.v. infusion of paclitaxel 175, 200 and 225 mg m-2. Plasma concentrations of paclitaxel, epirubicin and epirubicinol were measured and the relationship between neutropenia and drug pharmacokinetics was evaluated using a sigmoid maximum effect (Emax) model. Finally, the influence of paclitaxel and Cremophor EL on epirubicin metabolism by whole blood was examined.

RESULTS

An increase in epirubicinol plasma concentrations occurred after the start of the paclitaxel infusion, resulting in a significant increase in the area under the plasma concentration-time curve (AUC) of epirubicinol (+0.5 micromol l-1 h [95% CI for the difference: 0.29, 0.71],+0.66 micromol l-1 h [95% CI for the difference: 0.47, 0.85] and +0.82 micromol l-1 h [95% CI for the difference: 0.53, 1.11] at paclitaxel doses of 175, 200 and 225 mg m-2, respectively), compared with epirubicin followed by paclitaxel 30 h later (0.61+/-0.1 micromol l-1 h). A significant increase in epirubicin AUC (+0.74 micromol l-1 h [95% CI for the difference: 0.14, 1.34] and +1.09 micromol l-1 h [95% CI for the difference: 0.44, 1.74]) and decrease in drug clearance (CLTB) (-25.35 l h-1 m-2[95% CI for the difference: -50.18, -0.52] and -35.9 l h-1 m-2[95% CI for the difference -63,4,-8,36]) occurred in combination with paclitaxel 200 and 225 mg m-2 with respect to the AUC (3.16+/-0.6 micromol l-1 h) and CLTB (74.4+/-28.4 l h-1 m-2) of epirubicin followed by paclitaxel 30 h later. An Emax relationship was observed between neutropaenia and the time over which paclitaxel plasma concentrations were equal to or greater than 0.1 micromol l-1 (tC0.1). The tC0.1 value predicted to yield a 50% decrease in neutrophil count was 7.7 h. Finally, Cremophor EL markedly inhibited the metabolism of epirubicin to epirubicinol in whole blood.

CONCLUSIONS

Paclitaxel/Cremophor EL affects the disposition of epirubicinol and epirubicin. Furthermore, the slope factor of the Emax relationship between neutropenia and tC0.1 of paclitaxel suggests that the drugs might also interact at the pharmacodynamic level.

The expanding role of epirubicin in the treatment of breast cancer

Adjuvant treatment of early breast cancer has experienced major changes in the last 25 years. Since the mid 1970s, when cyclophosphamide, methotrexate and fluorouracil (CMF) resulted in statistically significant and clinically meaningful improvements in disease-free and overall survival, the use of adjuvant chemotherapy has become common practice worldwide. Anthracyclines are considered to be among the most active available agents to treat breast cancer and have become core components of adjuvant regimens. Anthracycline-containing polychemotherapy regimens provide a significant benefit over CMF. Regimens containing epirubicin are generally associated with prolongation in relapse-free and overall survival rates compared with standard therapies including CMF. Epirubicin-taxane combinations are active in treating metastatic breast cancer and do not appear to be associated with any pharmacokinetic interactions. Ongoing research is focusing on combining anthracyclines with taxanes in an effort to continue to improve outcomes following adjuvant therapy.

Phase I pharmacokinetic and sequence finding study of the combination of docetaxel and methotrexate in patients with solid tumours

This phase I study was performed to assess the feasibility and possible enhanced antitumour activity of the sequential administration of methotrexate (MTX) and docetaxel (D) in patients with solid tumours. Pharmacokinetic analysis was performed to investigate the pharmacokinetic interaction of the two agents. A total of 22 patients were enrolled, a total of six dose levels were investigated. MTX (days 1+15) 30, 40 and 50 mg/m(2)+D (day 2 or day 1) 75 and 85 mg/m(2) with supportive care measures. Both haematological and non-haematological toxicities were significant, preventing dose escalation above MTX 40 mg/m(2)+D 75 mg/m(2). Four partial responses were documented, three in patients with breast cancer, one in a patient with urothelial cell cancer. Pharmacokinetic data did not give an explanation for the significant toxicity as they revealed no interaction of D and MTX kinetics. Methotrexate and 7-OH MTX kinetics seemed to be independent of the administration of D and the moment of D administration appeared not to influence MTX kinetics. The sequential administration of MTX and D results in significant toxicity without any evidence of a clinical benefit.

The worldwide perspective in the adjuvant treatment of primary lymph node positive breast cancer

Adjuvant treatment of early breast cancer has experienced major changes in the last 25 years. Since the mid 1970s when cyclophosphamide, methotrexate and 5-fluorouracil (CMF) resulted in statistically significant and clinically meaningful improvements in disease-free and overall survival, the use of adjuvant chemotherapy has become common practice worldwide. Anthracyclines have long been considered to be among the most active available agents to treat breast cancer and they have become a core component of adjuvant regimens. Anthracycline-containing polychemotherapy regimens provide a significant benefit over CMF. Regimens containing epirubicin are associated with a significant prolongation in relapse-free and overall survival rates compared with standard therapies including CMF. Epirubicin-taxane combinations are highly active in treating metastatic breast cancer and do not appear to be associated with any pharmacokinetic interactions. Epirubicin is a unique anthracycline whose introduction to the US market represents a significant advance in breast cancer treatment. Ongoing research efforts are focusing on combining anthracyclines with taxanes in an effort to continue to improve outcomes following adjuvant therapy.

Influence of alternate sequences of epirubicin and docetaxel on the pharmacokinetic behaviour of both drugs in advanced breast cancer

BACKGROUND

Previously we observed a pharmacokinetic interference of epirubicin elimination when paclitaxel is given in combination in a sequence-dependent manner (i.e. when paclitaxel is administered as first drug). The aim of this study was to determine whether these sequence-dependent pharmacological effects were also evident when epirubicin was combined with docetaxel.

PATIENTS AND METHODS

Patients who received epirubicin 75 mg/m2 or 90 mg/m2 as an intravenous bolus followed immediately by docetaxel 70 mg/m2 or 80 mg/m2 over a 1-h infusion, or the opposite sequence, every 3 weeks were eligible for this study. The pharmacokinetics of docetaxel, epirubicin and its metabolites were studied at the first and second cycle of treatment. Pharmacokinetic data were normalised to the lower dose of each drug. Toxicity was recorded at nadir and graded according to National Cancer Institute Common Toxicity Criteria.

RESULTS

Twelve consecutive patients, each acting as their own control, entered the study. The sequence of drug administration of docetaxel and epirubicin did not affect the pharmacokinetics of the parent anthracycline. Statistically significant lower glucuronidation metabolism of epirubicin was observed in patients who received docetaxel before epirubicin. The pharmacokinetics of docetaxel were not influenced by the sequence of drug administration. No difference in haematological and non-haematological toxicity was observed in the two sequences of treatment.

CONCLUSIONS

The pharmacokinetics of the parent anthracycline and of docetaxel were similar between the two schemes of treatment. The metabolic variations observed, i.e. differences in the plasma levels of epirubicin glucuronides, seem not to have clinical relevance.

Identification of the highest dose of docetaxel associable with active doses of epirubicin. Results from a dose-finding study in advanced breast cancer patients

PURPOSE

To determine the maximum tolerated dose (MTD) and the dose limiting toxicity (DLT) of docetaxel in combination with fixed doses of epirubicin.

PATIENTS AND METHODS

Women with locally advanced or metastatic breast cancer were given docetaxel, 60 mg/m2 in escalated doses by steps of 10 mg/m2, in association with two fixed doses of epirubicin (90 mg/m2, and 75 mg/m2). Since neutropenia was foreseen to be the most likely DLT, a third group with prophylactic G-CSF support was planned to define the MTD of docetaxel with 90 mg/m2 of epirubicin. Selected patients underwent pharmacokinetic evaluation of docetaxel.

RESULTS

Fifty-eight patients entered the study. At the first step (90 mg/m2 of epirubicin) the MTD was obtained at 60 mg/m2 of docetaxel. At the second step (75 mg/m2 of epirubicin) the MTD of docetaxel was 80 mg/m2. At the third step (epirubicin 90 mg/m2) G-CSF allowed a safe escalation of docetaxel up to 90 mg/m2. Neutropenia was the most common hematological adverse event. Without G-CSF, grade 4 neutropenia occurred in 69% of cycles, of which 11% was complicated by fever. In G-CSF group, grade 4 neutropenia and neutropenic fever occurred in 31% and 3%, respectively. Most frequent non-hematological adverse effects were asthenia (45%), nausea (39%) and mucositis (36%). No patient developed congestive heart failure. Two toxic deaths occurred. Overall response rate was 73% in 42 out of 58 patients, with no apparent epirubicin dose-related effect. No statistically significant effect of the two doses of epirubicin was observed in docetaxel pharmacokinetics.

CONCLUSIONS

On the basis of the toxicity profile, the docetaxel pharmacokinetics and the response rate observed, epirubicin 75 mg/m2 combined with docetaxel 80 mg/m2 can be recommended for further studies.

Epirubicin--docetaxel combination in first-line chemotherapy for patients with metastatic breast cancer: final results of a dose-finding and efficacy study

The aim of the study was to define a regular and tolerable dose of the epirubicin-docetaxel combination in first-line chemotherapy of patients with metastatic breast cancer. Sixty-five women with measurable and/or evaluable disease were treated with epirubicin escalated from 60 to 110 mg/m(2) according to 5 dose levels, in combination with a fixed dose of 75 mg/m(2) docetaxel, every 21 days for 6 cycles, without preventive use of hematopoietic growth factors or antibiotics. Forty-three women received adjuvant chemotherapy, consisting of anthracyline- or anthracenedione-based regimens in 39 cases (60%). Twenty-seven women were treated in the phase I study (3 at epirubicin 60 mg/m(2), and 6 at each subsequent dose level). Dose-limiting toxicity consisted of grade III asthenia and febrile neutropenia (epirubicin 75 mg/m(2)), grade IV thrombopenia and grade III asthenia (epirubicin 90 mg/m(2)), grade IV stomatitis and grade III diarrhea (epirubicin 100 mg/m(2)), and grade III diarrhea (epirubicin 110 mg/m(2)). In the phase II study, an additional 38 women were treated at epirubicin 90 mg/m(2) and epirubicin 100 mg/m(2). During the 349 cycles delivered, grade IV neutropenia occurred in 90%; febrile neutropenia requiring hospitalization occurred in 62 (17.8%) and lasted more than 3 days in 12 (3.4%). Nonhematologic toxicity was acceptable. Three left ventricular ejection fraction depressions occurred and normalized during follow-up. The overall response rate in the 62 evaluable women was 69.4% (range: 58--81%), with a median duration of 7.8 months. After 26 months of follow-up, the median time to progression was 9.1 months and median overall survival was 22.7 months. On the basis of efficacy and toxicity, the recommended dose of the combination is epirubicin 100 mg/m(2) plus docetaxel 75 mg/m(2).

Drug interactions with the taxanes: clinical implications

BACKGROUND

The taxanes paclitaxel and docetaxel are among the most active antitumor agents. Clinically important pharmacodynamic interactions have been reported to occur with these agents that are sequence or schedule dependent. Because the taxanes undergo hepatic oxidation via the cytochrome P450 system, pharmacokinetic interactions due to enzyme induction or inhibition can also occur.

METHODS

A comprehensive literature search was conducted using Medline to identify clinically important drug-interactions with the taxanes.

RESULTS

Clinically significant taxane interactions were identified for carboplatin, cisplatin, doxorubicin, docetaxel, epirubicin and anticonvulsants. Doxorubicin and epirubicin should be administered 24 h before paclitaxel, and the cumulative anthracycline dose limited to 360 mg/m(2). This will prevent the enhanced toxicities due to sequence and schedule dependent interactions between anthracyclines and paclitaxel. Conversely, paclitaxel should be administered at least 24 h before cisplatin to avoid a decrease in clearance and increase in myelosuppression. With concurrent anticonvulsant therapy, cytochrome p450 enzyme induction results in decreased paclitaxel plasma steady state concentrations, possibly requiring an increased dose of paclitaxel. A number of other drug interactions have been reported in preliminary studies for which clinical significance has yet to be established.

CONCLUSION

Clinically significant drug interactions have been reported to occur when paclitaxel is administered with doxorubicin, cisplatin, or anticonvulsants (phenytoin, carbamazepine, and phenobarbital).

Drug interactions of paclitaxel and docetaxel and their relevance for the design of combination therapy

The taxanes' interaction with other anticancer drugs have been extensively investigated in in vitro and in animal models as well as in humans due to the outstanding antitumor activity in a broad range of malignancies. Paclitaxel and docetaxel are endowed of a rich and complex pharmacology whereby different pharmacodynamic effects are observed depending on the sequence of their administration in respect with the companion drug, and the type of drug that is combined. Pharmacokinetic interference is often but not always a basis of the pharmacodynamic effect. In addition, the vehicle of clinical formulation, especially Cremophor EL for paclitaxel, influence the pharmacological effect. Finally, new interaction based on as yet unknown mechanisms drive the two taxanes to multiple additive/synergistic relationships with new signal transduction drugs, such as modulators of the epidermal-growth-factor family of receptors and farnesyl-transferase inhibitors. The ongoing effort to better understanding such a rich pharmacology is worth continuing in view of designing new and better combinations of the taxanes.

Paclitaxel: epirubicin in metastatic breast cancer--a review

BACKGROUND

Treatment of metastatic breast cancer (MBC) with paclitaxel (T) and doxorubicin has yielded high response rates but the regimen is associated with significant cardiac toxicity. Epirubicin (E) is a less cardiotoxic anthracycline which has also been combined with paclitaxel in the treatment of MBC.

MATERIALS AND METHODS

This paper is a review of studies evaluating the pharmacokinetics, toxicity profile, and efficacy of the ET combination in MBC.

RESULTS

The ET combination has been studied extensively in Europe. The unique pharmacokinetics of the combination do not lead to the accumulation of cardiotoxic metabolites as in the case of the doxorubicin-paclitaxel combination. In terms of efficacy, the ET combination yields an overall response rate of 50%-70% and complete response rate (CR) 10%-15% in MBC in the same range as the more recent doxorubicin paclitaxel studies.

CONCLUSION

In summary the ET combination is safe and effective in MBC. It is less cardiotoxic than the doxorubicin paclitaxel combination. Further studies with ET in both the adjuvant setting and in MBC are in progress.

Role of formulation vehicles in taxane pharmacology

The non-ionic surfactants Cremophor EL (CrEL) and Tween 80, both used as formulation vehicles of many (anticancer) agents including paclitaxel and docetaxel, are not physiological inert compounds. We describe their biological properties, especially the toxic side effects, and their pharmacological properties, such as modulation of P-glycoprotein activity. In detail, we discuss their influence on the disposition of the solubilized drugs, with focus on CrEL and paclitaxel, and of concomitantly administered drugs. The ability of the surfactants to form micelles in aqueous solution as well as biological fluids (e.g. plasma) appears to be of great importance with respect to the pharmacokinetic behavior of the formulated drugs. Due to drug entrapment in the micelles, plasma concentrations and clearance of free drug change significant leading to alteration in pharmacodynamic characteristics. We conclude with some perspectives related to further investigation and development of alternative methods of administration.

Clinical and pharmacologic study of the epirubicin and paclitaxel combination in women with metastatic breast cancer

PURPOSE

A pharmacokinetic interaction may cause increased cardiotoxicity of paclitaxel (PTX) and high cumulative dose of doxorubicin. We tested antitumor activity, tolerability, and pharmacokinetics of the lesser cardiotoxic epirubicin (EPI) and PTX (ET combination).

PATIENTS AND METHODS

Twenty-seven women with untreated metastatic breast cancer, median age of 56 years, and prominent visceral involvement (74%) were studied. Three-weekly EPI (90 mg/m(2)) and PTX (200 mg/m(2) over 3 hours) were given for a maximum nine cycles. EPI was administered 24 hours before PTX (E --> T) in cycle 1, and 15 minutes before PTX (ET) thereafter. EPI, epirubicinol (EOL), EPI-glucuronide (EPI-glu), EOL-glucuronide (EOL-glu), PTX, and 6alpha-OH-PTX were measured in plasma and urine in 14 women.

RESULTS

Patients received 205 cycles of ET and a median EPI dose of 720 mg/m(2). Grade 4 neutropenia (49% of cycles) was the most frequent toxicity. Cardiac contractility was decreased in five patients. Mild congestive heart failure occurred in two (7.4%). Response rate was 76% (28% complete). Median overall survival was 29 months. On the basis of intrapatient comparison in the first 24 hours of E --> T and ET cycles, PTX did not affect EPI disposition, but significantly increased plasma exposure to EOL (by 137%), EPI-glu (threefold) and EOL-glu (twofold). Urinary excretion of EPI dose went from 8.2% in E --> T to 11.8% in ET cycles. Clearance of PTX was 30% slower in ET than E --> T. ET cycles caused lower neutrophil nadir than E --> T (644 +/- 327 v 195 +/- 91, P <.05)

CONCLUSION

ET is feasible, devoid of excessive cardiac toxicity, and active. A reciprocal pharmacokinetic interference between the two drugs has pharmacodynamic consequences, and suggests a direct effect of PTX on EPI metabolism requiring ad hoc investigation.

Systemic therapy

Our knowledge base on systemic therapy for breast cancer continues to expand, including further information regarding hormonal prevention in high-risk women, beneficial effects of tamoxifen in noninvasive disease, an update on primary systemic therapy, and optimization of adjuvant strategies, including data on adjuvant chemoendocrine regimens. The proper evaluation of high-dose strategies has been jeopardized by a serious episode of scientific misconduct. New data are also available on palliative options, bisphosphonates, antibody therapies, and novel targets. Data continue to evolve on the role and optimal schedules of taxanes in early-stage and advanced breast cancer. These and other important recent findings are discussed in this review article.

Front-line treatment of advanced breast cancer with docetaxel and epirubicin: a multicenter phase II study

PURPOSE

In a previous phase I trial we evaluated the toxicity and determined the maximum tolerated doses of the docetaxel (D)-epirubicin (Epi) combination. We conducted a multicenter phase II study to evaluate the efficacy and tolerability of this regimen as front-line treatment in women with advanced breast cancer (ABC).

PATIENTS AND METHODS

Fifty-four women with ABC stage IIIB (4 patients) or IV (50 patients) received front-line treatment with Epi 70 mg/m2 on day 1 and D 90 mg/m2 on day 2. The median age was 55 years, performance status (WHO) was 0-1 in 49 patients and visceral disease was present in 45 (83%).

RESULTS

All patients were evaluable for toxicity and 50 for response. In an intent-to-treat analysis complete remission was observed in 5(9%) patients, partial remission in 31 (57%) (overall response rate 66%, 95% confidence interval: 54% 79%), stable disease in 9 (17%) and disease progression in 9 (17%). After a median follow-up of 11.5 months, the median duration of responses was 8 months, the median time to disease progression 11.5 months and the median survival has not yet been reached. The probability of one-year survival was 65%. Three hundred six cycles of treatment were administered (median 6 cycles per patient). Grade 3 and 4 neutropenia was observed in 8 (15%) and 31 (57%) patients, respectively, and febrile neutropenia in 19 (35%). Prophylactic rh-G-CSF was used in 45 (83%) patients or 226 (74%) cycles. Other hematologic or non-hematologic toxicities were usually mild. In five (9%) patients the left ventricular ejection fraction (LVEF) was decreased by more than 10% with the treatment. Two patients died during the treatment of respiratory failure without associated neutropenia.

CONCLUSIONS

The combination of docetaxel epirubicin is an effective and well tolerated front-line treatment in patients with ABC.

Epirubicin in breast cancer: present and future

Epirubicin, a member of the anthracycline family of chemotherapeutic agents, has been widely used throughout the world both as adjuvant therapy in early breast cancer and in metastatic breast cancer. Clinical trials with epirubicin have examined the importance of a dose-response relationship, therapeutic dose, and optimum duration of chemotherapy. In addition, pharmacokinetic studies have provided data on ideal combinations with other agents. Epirubicin-containing regimens are considered to be superior to those containing cyclophosphamide, methotrexate, and fluorouracil (CMF) and are also used in patients with locally advanced stage IIIA/IIIB breast cancer. Combinations with other chemotherapeutic agents (eg, epirubicin plus a taxane, sequential or combined use of these agents) are being evaluated in ongoing clinical trials. Moreover, recent studies have suggested that biologic markers, such as tumor HER2/neu overexpression, predict responses to dose-intensive anthracycline chemotherapy, and combinations with nonchemotherapeutic regimens (eg, trastuzumab) may provide additional benefits, but such strategies require further evaluation.