Doxorubicin and paclitaxel versus fluorouracil, doxorubicin, and cyclophosphamide as first-line therapy for women with metastatic breast cancer: final results of a randomized phase III multicenter trial

Adjuvant use of taxanes for patients with breast cancer: we see the tip of the iceberg

Advances in screening techniques for breast cancer have led to the diagnosis of more patients at earlier disease stages at which time the possibility of a cure is more likely. Adjuvant chemotherapy with anthracycline-based regimens has proven to reduce the risk of relapse and cancer-related death in women with early-stage breast cancer. Recent studies have aimed at integrating the taxanes, paclitaxel and docetaxel, into the adjuvant setting, but to date, we are still in the earliest stages of the study of patients with operable breast cancer. Adjuvant trials now require thousands of patients and many years to reach maturity. Many of the trials began in the late 1990s and are not yet mature. For node-positive patients, the available evidence supports the use of taxanes as adjuvant treatment since they are safe and appear to provide benefit. Going forward, docetaxel holds significant promise in the adjuvant setting, and further trials as well as further follow-up of existing trials are eagerly awaited to help us determine whether docetaxel is best given sequentially to, or concurrently with, doxorubicin or epirubicin.

Is first-line single-agent mitoxantrone in the treatment of high-risk metastatic breast cancer patients as effective as combination chemotherapy? No difference in survival but higher quality of life were found in a multicenter randomized trial

BACKGROUND

To determine whether patients with high-risk metastatic breast cancer draw benefit from combination chemotherapy as first-line treatment.

PATIENTS AND METHODS

A total of 260 women with measurable metastatic breast cancer fulfilling high-risk criteria, previously untreated with chemotherapy for their metastatic disease, were randomized to receive either mitoxantrone 12 mg/m(2) or the combination of fluorouracil 500 mg/m(2), epirubicin 50 mg/m(2) and cyclophosphamide 500 mg/m(2) (FEC) every 3 weeks. Treatment was continued until complete remission plus two cycles, or until disease progression. In the case of partial remission or stable disease, treatment was stopped after 12 cycles. Second-line treatment was vindesine, mitomycin and prednisolone. Gain from treatment was estimated using a modified Brunner's score composed of time to progression, patients' rating of the treatment benefit, alopecia, vomiting and performance status.

RESULTS

After recruitment from 1992 to 1997 and observation from 1997 to 1999, the final evaluation showed that single-agent treatment with mitoxantrone does not differ significantly from combination treatment with FEC in terms of response, objective remission rate, remission duration, time to response, time to best response, time to progression or overall survival. There was, however, a significant difference in gain from treatment using a modified Brunner's score favoring the single-agent treatment arm. There was no evidence that any subgroup would fare better with combination treatment.

CONCLUSIONS

No significant difference was detected between the treatment with mitoxantrone as a single agent and the combination of low-dose FEC in terms of response or survival; therefore, the imperative of the necessity of first-line combination chemotherapy for patients with high-risk metastatic breast cancer may be questioned. Since toxicity and quality of life score favored the single-agent mitoxantrone treatment arm, this treatment may be offered to patients preferring quality of life to a potential small prolongation of survival.

Ongoing US cooperative group trials using taxanes in the adjuvant setting

The use of systemic adjuvant therapy in women with early-stage breast cancer has been demonstrated to have a profound impact on survival. The role of paclitaxel and docetaxel in the adjuvant setting has attracted a great deal of attention. Both of these agents are highly active in patients with advanced breast cancer. In addition, they can be utilized in combination with anthracyclines, which have been shown to provide a slightly better outcome in patients with early-stage breast cancer compared to non-anthracycline-containing regimens. Randomized trials have demonstrated a potential role for paclitaxel in adjuvant chemotherapy. In the Cancer and Leukemia Group B 9344 trial, which explored the use of doxorubicin and cyclophosphamide with or without paclitaxel, the initial analysis demonstrated a 22% reduction in the relative risk of relapse and a 26% reduction in the relative risk of death in the paclitaxel group. However, a clear role for the use of paclitaxel in adjuvant therapy remains to be defined. The Breast Cancer International Research Group trial 001 compared the combination of docetaxel/doxorubicin/cyclophosphamide to 5-fluorouracil/doxorubicin/cyclophosphamide. This trial demonstrated a promising reduction in the relative risk of recurrence of 32% for the docetaxel/doxorubicin/cyclophosphamide group. Ongoing trials will help to further define the role of taxanes in the adjuvant setting for patients with operable breast cancer.

Quality of life in patients undergoing systemic therapy for advanced breast cancer

To date no published reviews have examined the effects of systemic therapy on health-related quality of life (HRQOL) in patients with advanced breast cancer. We did a systematic review identifying 19 randomised controlled trials, with 5732 participants. Most of the trials (12) involved chemotherapy, but six involved hormonal therapies, and one a biological therapy. 15 studies assessed HRQOL as a secondary endpoint; only seven reported any significant differences in HRQOL between treatment groups. We identified several limitations with methods. Most studies reported problems with withdrawal of patients, which reduces statistical power and can lead to bias. Baseline characteristics of patients were not reported in many cases, and only three studies examined clinical significance. We conclude that HRQOL data provide some invaluable insights into the treatment and care of patients, but future studies should address several common problems with methods. We propose some approaches to overcome these limitations and improve future study designs.

Combination of taxanes and anthracyclines in first-line chemotherapy of metastatic breast cancer: an interim report

Anthracyclines and taxanes are among the most effective agents in the treatment of advanced breast cancer, refractory or non-responsive to endocrine manipulation. Several recently published phase III studies have addressed the role of these compounds in combination compared with established chemotherapy regimens. This report considering a total of 4244 patients evaluates the data of those trials with respect to the efficacy and toxicity of the treatment regimens. Currently, evidence is growing that especially patients with symptomatic visceral tumour spread may benefit from the combined application of anthracyclines and taxanes. Adequately dosed polychemotherapy appears to be more successful than monotherapy, and, at present, the combination of anthracyclines (doxorubicin, epirubicin) and taxanes (docetaxel (Doc), paclitaxel (Pac)) might lead to a promising approach to improve the course of the metastatic disease.

Which dosing scheme is suitable for the taxanes? An in vitro model

The discovery and development of the taxane class of antitumor compounds represent significant advances in the treatment of patients with a variety of malignancies. These drugs are effectively used in the treatment of breast cancer. In this study we evaluated the efficacy of fractionated usage of both paclitaxel and docetaxel as a single agent in the breast cancer cell line MCF-7. It has been shown that the cytotoxic effect of paclitaxel was increased when the divided IC50 concentrations were used sequentially and in contrast to paclitaxel, cytotoxic effect of docetaxel was decreased with the same schema and the single dose of IC50 concentration was optimal. The cause of the difference between the cytotoxic effects of two agents with this schedule is obscure. Demonstrating mechanisms, which are responsible for these differences, will be important for more rational use of taxoids and to provide basis for the following clinical trials.

Doxorubicin and paclitaxel versus doxorubicin and cyclophosphamide as first-line chemotherapy in metastatic breast cancer: The European Organization for Research and Treatment of Cancer 10961 Multicenter Phase III Trial

PURPOSE

To compare the efficacy and tolerability of the combination of doxorubicin and paclitaxel (AT) with a standard doxorubicin and cyclophosphamide (AC) regimen as first-line chemotherapy for metastatic breast cancer.

PATIENTS AND METHODS

Eligible patients were anthracycline-naive and had bidimensionally measurable metastatic breast cancer. Two hundred seventy-five patients were randomly assigned to be treated with AT (doxorubicin 60 mg/m(2) as an intravenous bolus plus paclitaxel 175 mg/m(2) as a 3-hour infusion) or AC (doxorubicin 60 mg/m(2) plus cyclophosphamide 600 mg/m(2)) every 3 weeks for a maximum of six cycles. A paclitaxel (200 mg/m(2)) and cyclophosphamide (750 mg/m(2)) dose escalation was planned at cycle 2 if no grade >or= 3 neutropenia occurred in cycle 1. The primary efficacy end point was progression-free survival (PFS). Secondary end points were response rate (RR), safety, overall survival (OS), and quality of life.

RESULTS

A median number of six cycles were delivered in the two treatment arms. The relative dose-intensity and delivered cumulative dose of doxorubicin were lower in the AT arm. Dose escalation was only possible in 17% and 20% of the AT and AC patients, respectively. Median PFS was 6 months in the two treatments arms. RR was 58% versus 54%, and median OS was 20.6 versus 20.5 months in the AT and AC arms, respectively. The AT regimen was characterized by a higher incidence of febrile neutropenia, 32% versus 9% in the AC arm.

CONCLUSION

No differences in the efficacy study end points were observed between the two treatment arms. Treatment-related toxicity compromised doxorubicin-delivered dose-intensity in the paclitaxel-based regimen

Pharmacotherapy for male breast cancer

Breast cancer in males is uncommon, occurring at approxiamtely 1% of the rate of female breast cancer. Male breast carcinomas tend to be highly positive for hormone receptors, including oestrogen, progesterone and androgen receptors. Owing to this, hormone therapy is recommended as the primary treatment modality. Adjuvant therapy is recommended for male breast cancers with large size or positive axillary nodes. For metastatic disease, options for therapy include tamoxifen, orchiectomy, anti-androgens with or without luteinising hormone releasing hormone analogues or combination chemotherapy. The newer hormonal treatments, such as the selective aromatase inhibitors or novel antioestrogens, have not yet been well studied in male breast cancer but have potential for efficacy in this disease.

Gemcitabine/anthracycline combinations in metastatic breast cancer

Gemcitabine has demonstrated single-agent efficacy in the treatment of advanced breast cancer, with response rates of up to 42%. The agent is well tolerated, with relatively mild side effects, and has limited overlapping toxicities with other drugs used in combination chemotherapy for breast cancer. It is, therefore, a good candidate for inclusion in multidrug regimens for the treatment of this disease. This article reviews results of gemcitabine/anthracycline-containing double- and triple-drug combinations used to treat patients with early-stage and advanced breast cancer. Results from phase I and II trials were promising, with good tolerability and overall response rates ranging from 33%-89% in advanced disease and up to 95% in the neoadjuvant treatment of early-stage disease. A phase III trial is currently comparing gemcitabine/epirubicin/paclitaxel and 5-fluorouracil/epirubicin/cyclophosphamide in patients with advanced breast cancer. Preliminary toxicity data on 78 patients show that both regimens were well tolerated, with similar incidences of treatment-related effects. Additional comparative studies of gemcitabine-containing drug regimens in breast cancer are warranted.

Assessment of molecular markers of clinical sensitivity to single-agent taxane therapy for metastatic breast cancer

PURPOSE

The taxanes affect tubulin polymerization and interfere with mitotic transition. A checkpoint blockade at the G(1)-S boundary would be expected to promote taxane-induced apoptotic cell death through a mechanism that may involve p27. Other proposed determinants of clinical taxane sensitivity/resistance include p53, members of the epidermal growth factor receptor (EGFR) superfamily (e.g., HER2, EGFR), and estrogen receptors and progesterone receptors. These molecular markers and their correlation with clinical taxane sensitivity are investigated in this retrospective clinicopathologic study.

PATIENTS AND METHODS

We performed immunohistochemistry (IHC) for estrogen receptors, progesterone receptors, HER2, EGFR, p53, and p27 on 144 breast tumor specimens from patients treated for metastatic breast cancer on a series of clinical trials of single-agent taxane chemotherapy for correlation with clinical response (complete or partial response). Patient characteristics that could influence response (i.e., performance status, extent of disease, and prior therapy) were also examined.

RESULTS

In univariate analysis, Karnofsky performance status > or = 90% and no prior history of anthracycline therapy correlated with a good clinical response to single-agent taxane (P =.003 and P =.041, respectively). None of the IHC variables tested were predictive of clinical response to taxane therapy, although p27 negativity showed a trend toward significance (P =.075). Concordance between the polyclonal antibody with HercepTest (DAKO, Carpinteria, CA) and the monoclonal antibody CB-11 (BioGenex, San Ramon, CA) was noted (kappa = 0.943); however, neither univariate nor multivariate analysis demonstrated an association between HER2 status and response to taxane chemotherapy.

CONCLUSION

The IHC biomarkers studied were not predictive of response to single-agent taxane chemotherapy in patients with metastatic breast cancer. Identification of molecular correlates of taxane response remains an important goal.

The choice of adjuvant combination therapies with taxanes: rationale and issues addressed in ongoing studies

The taxanes are emerging as the most powerful compounds in breast cancer. Both compounds, paclitaxel and docetaxel, have been evaluated in the metastatic setting before proceeding with adjuvant trials. Docetaxel was shown in phase III trials to be superior, in particular, in terms of time to progression and survival, to salvage polychemotherapies after failure of prior chemotherapy including anthracyclines. Also, after failure of alkylating agents, a benefit in favor of docetaxel was reported when compared to doxorubicin, whereas paclitaxel was reported to be either as efficacious or inferior to doxorubicin, while being comparable to cyclophosphamide/methotrexate/5-fluorouracil. The role of taxanes in combination with anthracyclines in first-line therapy of advanced breast cancer is still unclear although emerging. One phase III trial showed the significant superiority of doxorubicin/docetaxel (AT) versus doxorubicin/cyclophosphamide (AC) in terms of response and time to progression. Several phase II studies with paclitaxel (over 3 hours) and anthracyclines in the metastatic setting showed high efficacy, but they also showed cardiac toxicity related to a pharmacokinetic interaction between the 2 agents. This fact led to the implementation of metastatic strategies (several phase III trials) aimed at avoiding the pharmacokinetic interaction or specifically limiting the cardiac toxicity that resulted in contradictory results. Consequently, adjuvant strategies with paclitaxel focused mostly on the sequential approach (AC followed by paclitaxel). In contrast, adjuvant strategies with docetaxel/anthracycline-based programs were implemented following both sequential and combination approaches. Results of all of these trials in the adjuvant setting are eagerly awaited in order to establish the role of taxanes in adjuvant breast cancer.