Cardiac function following combination therapy with paclitaxel and doxorubicin: an analysis of 657 women with advanced breast cancer

Concomitant versus sequential administration of epirubicin and paclitaxel as first-line therapy in metastatic breast carcinoma

BACKGROUND

The authors performed a randomized trial comprising patients with metastatic breast carcinoma (MBC). They used a noninferiority design to evaluate whether the results of sequential administration of epirubicin and paclitaxel were not markedly worse than the concomitant administration in terms of objective response rates (ORRs). Toxicity profile, quality of life (QOL), and pharmacoeconomic evaluations were evaluated as well.

METHODS

In the current study, 202 patients with MBC were randomized to receive either the combination of epirubicin at a dose of 90 mg/m2 plus paclitaxel at a dose of 200 mg/m2 for 8 cycles (concomitant arm, n = 108) or epirubicin at a dose of 120 mg/m2 for 4 cycles followed by paclitaxel at a dose of 250 mg/m2 over 3 hours for 4 cycles every 21 days (sequential arm, n = 94).

RESULTS

The authors rejected the null hypothesis that the sequential treatment is less active than the standard concomitant regimen (ORRs: concomitant = 58.5%, sequential = 57.6%). The median progression-free and overall survival periods were 11.0 months (95% confidence interval [95% CI], 9.7-12.3) and 20.0 months (95% CI, 17.2-22.6), respectively, in the concomitant arm and 10.8 months (95% CI, 7.9-13.6) and 26 months (95% CI, 18.1-33.8), respectively, in the sequential arm (P = not significant). Patients who received the sequential regimen experienced a higher incidence of Grade 3/4 (according to the World Health Organization grading system) neutropenia (62.2% of courses vs. 50.62%; P = 0.003) and Grade > or = 2 neuropathy (45.5% vs. 30.4% of patients; P = 0.03), whereas 6 patients who received the concomitant regimen developed Grade II cardiotoxicity according to New York Heart Association criteria. QOL analyses failed to provide clear differences.

CONCLUSIONS

The sequential administration of epirubicin and paclitaxel at full doses was found to be as active as their association. Therefore, both the sequential and the combined administration were acceptable options.

Doxorubicin-paclitaxel: a safe regimen in terms of cardiac toxicity in metastatic breast carcinoma patients. Results from a European Organization for Research and Treatment of Cancer multicenter trial

BACKGROUND

The potential cardiotoxicity of the doxorubicin-paclitaxel regimen, when paclitaxel is given shortly after the end of the anthracycline infusion, is an issue of concern, as suggested by small single institution Phase II studies.

METHODS

In a large multicenter Phase III trial, 275 anthracycline naive metastatic breast carcinoma patients were randomized to receive either doxorubicin (60 mg/m(2)) followed 30 minutes later by paclitaxel (175 mg/m(2) 3-hour infusion; AT) or a standard doxorubicin-cyclophosphamide regimen (AC; 60/600 mg/m(2)). Both treatments were given once every 3 weeks for a maximum of six cycles. Close cardiac monitoring was implemented in the study design.

RESULTS

Congestive heart failure (CHF) occurred in three patients in the AT arm and in one patient in the AC arm (P = 0.62). Decreases in left ventricular ejection fraction to below the limit of normal were documented in 33% AT and 19% AC patients and were not predictive of CHF development.

CONCLUSIONS

AT is devoid of excessive cardiac risk among metastatic breast carcinoma patients, when the maximum planned cumulative dose of doxorubicin does not exceed 360 mg/m(2).

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.

Docetaxel does not impair cardiac autonomic function in breast cancer patients previously treated with anthracyclines

The effects of docetaxel treatment on autonomic cardiac function was studied with 24-h ECG recordings in breast cancer patients pretreated with anthracyclines. Twenty-four women were evaluated before docetaxel treatment and after 3-4 courses of docetaxel 100 mg/m(2). The heart rate, cardiac extrasystoles and heart rate variability (HRV) in both the time and frequency domain were assessed from 24-h ECG recordings. The acute effects of docetaxel were calculated from 1-h recordings immediately prior to, during and after infusion. Long-term effects were evaluated from 24-h recordings performed before treatment and after 3-4 courses of docetaxel. There was no increase in the number of cardiac extrasystoles during docetaxel infusion. The number of ventricular extrasystoles decreased from 14 (23) to 7 (14) during and 5 (10) after the first infusion (p=0.02). The heart rate, HRV and extrasystoles were similar before and after 3-4 courses of docetaxel. The treatment did not abolish circadian variability of the heart rate. Docetaxel did not deteriorate autonomic cardiac function. In conclusion, our findings suggest that docetaxel does not have harmful cumulative effects on autonomic control of the heart and is therefore unlikely to be cardiotoxic.