Rational use of trastuzumab in metastatic and locally advanced breast cancer: implications of recent research

The management of HER2-positive metastatic breast cancer, a disease renowned for its aggressive natural history, has been revolutionized by the introduction of trastuzumab. Indeed, outcomes for patients with HER2-positive advanced breast cancer are now equivalent to, if not better than, those of their HER2-negative counterparts. Since the pivotal registration trial, a wealth of new clinical data has emerged regarding the use of trastuzumab in a variety of clinical contexts - adding to the evidence but also highlighting areas of uncertainly and debate. These include the optimal partner chemotherapy(ies) to trastuzumab; the effectiveness of combining trastuzumab with endocrine therapy; the benefits of continuing trastuzumab after progression on a trastuzumab-containing regimen; and the role of trastuzumab in locally advanced and inflammatory breast cancer. In this paper we review major clinical trials addressing these questions, clinical recommendations that can be made as a result, and the strength of evidence that supports them. Finally, we identify areas of ongoing uncertainty, and propose recommendations for future research in this field.

Pharmacology and therapeutic efficacy of capecitabine: focus on breast and colorectal cancer. Anticancer Drugs. 2009;20:217-229. [PMID: 19247178 DOI: 10.1097/cad.0b013e3283293fd4]

Capecitabine (N -pentyloxycarbonyl-5-deoxy-5-fluorocytidine), an oral prodrug of 5-fluorouracil, has provided compelling efficacy data for the treatment of metastatic breast cancer and stage III or IV colorectal cancer, both as monotherapy and in combination regimens. The preferential conversion of capecitabine to 5-fluorouracil in neoplastic tissues renders this fluoropyrimidine particularly appealing for clinical use. The enzyme thymidine phosphorylase, which mediates the final step of the capecitabine activation pathway, is expressed in higher concentration in neoplastic than in healthy tissues. This makes capecitabine more tumor specific than other chemotherapeutic agents. Accordingly, capecitabine is generally well tolerated. In particular, the incidence of myelosuppression and alopecia is low, and the most common side effects, hand-foot syndrome and diarrhea, are usually manageable. Given its good toxicity profile, capecitabine was assessed in combination with several chemotherapeutic or biologic agents. In addition, the observation that thymidine phosphorylase is upregulated after treatment with other anticancer drugs, namely taxanes, provided a rationale for the prominent antitumor activity recently observed for the combination of capecitabine with these agents. This review provides an evidence-based update of clinical trials investigating the role of capecitabine in the treatment of breast and colorectal cancer, with special emphasis on pharmacological and safety issues that form the basis of currently used schedules.

Capecitabine and Trastuzumab in Heavily Pretreated Metastatic Breast Cancer

Purpose

In human epidermal growth factor 2 (HER-2)–positive advanced breast cancer, taxanes or vinorelbine plus trastuzumab are among the most widely applied options in the first-line setting. We evaluated the efficacy and tolerability of capecitabine plus trastuzumab after anthracycline and docetaxel or vinorelbine failure and prior trastuzumab exposure.

Patients and Methods

Forty consecutive patients were included. Capecitabine was administered at a dose of 1,250 mg/m2bid for 14 consecutive days in 3-week cycles, with dose modifications if necessary. Trastuzumab was administered every 3 weeks. Time to progression (TTP) was defined as primary end point. Response was evaluated every 3 months using International Union Against Cancer criteria.

Results

TTP was a median of 8 months, and overall survival was 24 months. No significant difference was found for second-line and beyond second-line treatment. A complete response (CR) was observed in 2.5%, partial response (PR) in 17.5%, stable disease lasting at least 6 months (SD) in 50%, resulting in a clinical benefit rate (CR + PR + SD ≥ 6 months) of 70%. Diarrhea (5%) and hand-foot syndrome (15%) were the only treatment-related adverse events that occurred with grade 3 or 4 intensity. Three patients (7.5%) developed brain metastases while receiving therapy.

Conclusion

Capecitabine plus trastuzumab appears to be an effective and safe option in a heavily pretreated population. Therefore, a direct comparison of this regimen with capecitabine monotherapy in this setting is warranted.

Phase II Study of Capecitabine Plus Trastuzumab in Human Epidermal Growth Factor Receptor 2–Overexpressing Metastatic Breast Cancer Pretreated With Anthracyclines or Taxanes

Purpose

The oral fluoropyrimidine carbamate, capecitabine, is a highly active and well-tolerated treatment for metastatic breast cancer. In patients treated previously with anthracyclines and taxanes, capecitabine is an approved single-agent therapy. Trastuzumab, a monoclonal antibody targeting the human epidermal growth factor receptor 2 (HER-2), is also highly active in HER-2–overexpressing breast cancer. We have conducted a phase II study to confirm activity and feasibility of capecitabine and trastuzumab in combination in HER-2–overexpressing advanced/metastatic breast cancer.

Patients and Methods

Twenty-seven patients with HER-2–overexpressing metastatic breast cancer previously treated with anthracyclines and/or taxanes received oral capecitabine 1,250 mg/m2bid for 14 days followed by a 7-day rest period combined with intravenous trastuzumab 4 mg/kg body weight on day 1 (loading dose) followed by 2 mg/kg weekly.

Results

Capecitabine/trastuzumab treatment achieved objective responses in 12 patients (45%), including complete response in four patients (15%) and partial response in eight patients (30%). Disease was stabilized in an additional nine patients (33%). The median overall survival time was 28 months, and the median progression-free survival time was 6.7 months. The safety profile of the combination was favorable and predictable, with a low incidence of grade 3/4 adverse events. The most common adverse events were pain, hand-foot syndrome, and GI toxicities. Severe myelosuppression was rare and severe alopecia did not occur.

Conclusion

These data confirm that the combination of capecitabine and trastuzumab is highly active in patients with HER-2–overexpressing anthracycline- and/or taxane-pretreated breast cancer, with only slight restrictions regarding quality of life.

A phase II study of trastuzumab and capecitabine for patients with HER2-overexpressing metastatic breast cancer: Japan Breast Cancer Research Network (JBCRN) 00 Trial

PURPOSE

To determine the response rate and toxicity profile of trastuzumab and capecitabine in women with HER2-overexpressing advanced breast cancer.

PATIENTS AND METHODS

A total of 59 patients from 6 participating centers in Japan entered onto the study of trastuzumab and capecitabine. Eighty six percent of women had received prior chemotherapy as part of adjuvant (21.4%) or metastatic treatment (48.2%), or both (16.1%), including substantial portions of patients who had previously received either CMF (7.1%), anthracyclines (28.6%), taxanes (25.0%), or both types (25.0%) of chemotherapy.

RESULTS

Responses were observed in 28 of 56 patients (overall response rate, 50%). The response rate was 65.0% in patients treated with trastuzumab and capecitabine as first-line therapy for metastatic disease, and 62.5% among HER2 +3 positive patients, while high response rates were also seen in women treated with second- or third-line therapy. Patients receiving trastuzumab and capecitabine as first-line therapy had a longer TTP than did patients receiving this treatment as second- or third-line therapy (median TTP, 280 vs. 130 days, P < 0.05). Further, patients receiving trastuzumab and capecitabine as first-line therapy had longer OS than did patients receiving this treatment as second- or third-line therapy (median OS, 780 days vs. 480 weeks, P < 0.05). The treatment-related adverse events were hand-foot syndrome (30.4%), nausea (25%), diarrhea (10.7%), stomatitis (10.7%), fatigue (7.1%), and vomiting (5.4%). However, the majority were Grade 1-2 adverse events and only six patients experienced Grade 3 adverse events. Further Grade 1 cardiac toxicity was observed in one patient, while there were no cases of alopecia and treatment-related death.

CONCLUSION

Trastuzumab in combination with capecitabine is highly active in women with HER2-overexpressing metastatic breast cancer and is well tolerated.