Efficacy and safety of trastuzumab

The human epidermal growth factor receptor (HER) 2 is overexpressed in approximately 20-25% of human breast cancers and is an independent adverse prognostic factor. Targeted therapy directed against this receptor has been developed in the form of a humanised monoclonal antibody, trastuzumab. This antibody has shown activity as a single agent in metastatic breast cancer both prior to chemotherapy and in heavily pretreated patients. A pivotal Phase III trial has demonstrated that its use in combination with an anthracycline or paclitaxel results in a significant improvement in survival, time to progression, and response. This has recently been reinforced by another trial with docetaxel. The HER2 status of a tumour is a critical determinant of response to trastuzumab-based treatment. Those that express HER2 at the highest level on immunohistochemistry (IHC), 3+, derive more benefit from treatment with trastuzumab than those with overexpression at the 2+ level. Benefit correlates best with tumours that are positive on fluorescence in situ hybridisation for HER2, regardless of IHC status. Treatment with trastuzumab is generally well tolerated with a low incidence of adverse events. Some patients may experience fever, chills, dyspnoea and pain, particularly with the first administration. Unexpectedly, cardiac toxicity has developed in some patients treated with trastuzumab, and this has a higher incidence in those treated in combination with an anthracycline. 'Cross-talk' between the oestrogen receptor and HER2 pathway has stimulated interest in using trastuzumab in combination with endocrine therapy. Current clinical trials are investigating the role of this agent in the adjuvant setting.     

Trastuzumab: a review of its use in the treatment of metastatic breast cancer overexpressing HER2.

Trastuzumab is a humanised monoclonal antibody developed to target the HER2 receptor which is overexpressed by some cancer cells, including 25 to 30% of breast cancers. Binding with high affinity to the extracellular domain of HER2, trastuzumab inhibits the proliferation of tumour cells that overexpress HER2. A large well designed multicentre study found that the addition of trastuzumab to either an anthracycline plus cyclophosphamide or to paclitaxel, as first-line therapy for metastatic breast cancer overexpressing the HER2 receptor, significantly increased time to disease progression, rate of objective response, duration of response and survival compared with chemotherapy alone. Single-agent trastuzumab was associated with an objective response in 15% of extensively pretreated patients with metastatic breast cancer overexpressing HER2, and 26% of previously untreated patients. Patients with a HER2 overexpression level of 3+ using immunohistochemical (IHC) assay or a positive HER2 result using fluorescence in situ hybridisation (FISH), benefit more from trastuzumab therapy than those with tumours overexpressing at a level of 2+. Trastuzumab has demonstrated synergistic action with several chemotherapy agents preclinically but the optimal combination clinically is yet to be determined. Trastuzumab is generally well tolerated by most patients; the most significant adverse effects being acute fever and/or chills and the potential to cause cardiac dysfunction. Serious adverse events, including anaphylaxis and death, have occurred in 0.25% of patients. Symptomatic or asymptomatic cardiac dysfunction occurred in 27% of patients receiving an anthracycline and cyclophosphamide combined with trastuzumab. Thus, combination therapy with anthracyclines is not recommended. Symptomatic or asymptomatic cardiac dysfunction occurred in 13% of patients receiving trastuzumab plus paclitaxel and in 4.7% of patients receiving trastuzumab alone. CONCLUSION: Intravenous trastuzumab is effective as a single-agent, and in combination with chemotherapy it significantly improves the median time to disease progression and survival time in patients with metastatic breast cancer overexpressing the HER2 receptor compared with chemotherapy alone. Cardiotoxicity is the main concern with therapy; particularly in patients with pre-existing cardiac dysfunction, the elderly and in combination with, or following, anthracyclines. Trastuzumab is indicated for use with paclitaxel as first-line therapy or as a single agent in second- or third-line treatment regimens for patients with metastatic breast cancer overexpressing HER2. Investigation is ongoing to ascertain the optimal combination regimen containing trastuzumab and antineoplastic agents. In addition, current research is focusing on the optimal timing, sequencing and duration of therapy as well as administration in the neoadjuvant and adjuvant setting.     

Anti-erbB-2 antibody trastuzumab in the treatment of HER2-amplified breast cancer

Human epidermal growth factor receptor-2 (HER2/erbB-2) is a member of a family of four transmembrane receptor tyrosine kinases that regulate cell growth, survival and differentiation via multiple signal transduction pathways. Amplification of the HER2 gene occurs in 20–25% of human breast cancers. This amplification event is an independent adverse prognostic factor as well as a predictive factor for increased response to doxorubicin-based combination chemotherapy, response to trastuzumab and decreased response to hormonal therapy. Methods for detecting protein overexpression or gene amplification in clinical tumor specimens include immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) techniques, with the latter considered by some to be more accurate. Trastuzumab (Herceptin) is a recombinant humanized monoclonal antibody which targets an epitope in the extracellular domain of the HER2 protein. Preclinical models demonstrated that this antibody has significant anti-tumor activity as a single agent and has synergy with certain chemotherapeutic drugs. Phase II and III clinical trials performed in women with metastatic breast cancer that overexpress HER2 have shown that trastuzumab has clinical activity when used as first-, second- or third-line monotherapy, and improves survival when used as first-line therapy in combination with chemotherapy. Newer combinations with numerous chemotherapeutic drugs have also shown significant clinical activity in phase II studies. In all of these trials, trastuzumab was generally well-tolerated, but cardiac toxicity (particularly when the antibody was combined with anthracyclines) was an unexpected adverse effect. Although trastuzumab is currently usually administered on a weekly intravenous schedule, evidence suggests that a triple dose of the drug given once every three weeks has a pharmacokinetic profile expected to be equally efficacious. Neither the optimal schedule nor the optimal duration of trastuzumab therapy has yet been clearly defined in controlled clinical trials. Current clinical investigations of trastuzumab include its use in both the adjuvant and neoadjuvant settings as well as in combination with other chemotherapy drugs or new biologic targeted agents.     

Trastuzumab : in HER2 and hormone receptor co-positive metastatic breast cancer

Trastuzumab is a humanised IgG1 monoclonal antibody, which selectively binds to the human epidermal growth factor receptor 2 (HER2), inhibiting cell proliferation and survival in HER2-dependent tumours. In a randomised phase III trial in postmenopausal women with HER2 and hormone receptor (HR) co-positive metastatic breast cancer, median progression-free survival (primary endpoint) was significantly longer in patients receiving intravenous trastuzumab plus oral anastrozole than in those receiving anastrozole alone. Overall response rate and clinical benefit rate were also significantly higher, and median time to disease progression was significantly longer with trastuzumab plus anastrozole versus anastrozole alone. There were no reports of new or unexpected adverse events with trastuzumab plus anastrozole combination therapy in the randomised phase III trial. In a noncomparative phase II study of trastuzumab plus letrozole in postmenopausal women with HER2 and HR co-positive metastatic breast cancer, the majority of adverse events were mild or moderate in severity.     

Role of trastuzumab in adjuvant therapy for locally invasive breast cancer.

PURPOSE: The role of trastuzumab in adjuvant therapy for locally invasive breast cancer is discussed. SUMMARY: Trastuzumab is a humanized monoclonal antibody that binds to the extracellular domain of human epidermal growth factor receptor-2 (HER2). Currently, trastuzumab is indicated for use in HER2-positive patients with metastatic breast cancer. Because trastuzumab specifically targets a receptor that is overexpressed in tumor cells, it is less likely to cause the cytotoxic adverse effects of traditional chemotherapy. Cardiotoxicity has been a major concern, however. Several trials were started to evaluate trastuzumab in the adjuvant setting in patients diagnosed with early-stage breast cancer. The interim results of these trials have shown a promising effect of adjuvant therapy with trastuzumab in improving overall survival, disease-free survival, relapse-free survival, and distant-disease-free survival. CONCLUSION: The use of trastuzumab as adjuvant therapy in patients with HER2-positive breast cancer can lead to increased survival. The appropriateness of trastuzumab therapy should be considered based on HER2 status, cost, and risk of toxicity.     

Lapatinib ditosylate: expanding therapeutic options for receptor tyrosine-protein kinase erbB-2-positive breast cancer

Receptor tyrosine-protein kinase erbB-2 (HER2)-positive breast cancer is a specific entity with an aggressive behavior. Trastuzumab, a monoclonal antibody targeting erbB-2 (HER2) deeply transformed the outcome in patients. Nevertheless, resistance to trastuzumab is still a major concern. Lapatinib ditosylate is an orally available, small molecule targeting the tyrosine activity of the HER2 receptor. Lapatinib as a single agent and in combination therapy showed interesting activity in trastuzumab-resistant advanced tumors. In addition, lapatinib use seemed suitable in recurrent locally advanced inflammatory breast cancer and brain metastases. More recently, the Neo-ALTTO (NeoAdjuvant Lapatinib and/or Trastuzumab Treatment Optimisation) trial showed that lapatinib in combination with trastuzumab and paclitaxel significantly improved the pathological complete response in a neoadjuvant setting. Several clinical trials are still ongoing and data that may change current clinical practice are awaited with much interest.     

Trastuzumab,a humanized anti-HER2 monoclonal antibody,for the treatment of breast cancer

The HER2/neu gene encodes a 185 kDa transmembrane receptor (HER2) that belongs to the epidermal growth factor receptor family and has intrinsic tyrosine kinase activity. HER2 is overexpressed in 25-30% of breast cancers and is suggested to have a direct role in the pathogenesis and clinical aggressiveness of HER2 overexpressing tumors. A murine monoclonal antibody, 4D5, directed against the extracellular domain of HER2, is a potent inhibitor of growth of human breast cancer cells overexpressing HER2 in vitro and in xenograft models. To facilitate clinical investigation, 4D5 was humanized by inserting the complementary determining regions of 4D5 into the framework of a consensus human IgG1. The resulting recombinant humanized anti-HER2 MAb, trastuzumab, was found to inhibit the growth of human cancer cells and tumor xenografts overexpressing HER2. Data from phase II trials in women with breast cancer whose tumors overexpress HER2 have shown that trastuzumab has a favorable toxicity profile, is active as a single agent and induces long-lasting objective tumor responses. In combination studies, there was no evidence that trastuzumab enhanced the toxicity of cisplatin and the pharmacokinetic parameters of trastuzumab were unaltered by coadministration of cisplatin. Furthermore, clinical response rates were higher than those reported with either agent alone in a similar patient population. Results of a multicenter, phase III clinical trial of chemotherapy (doxorubicin- or paclitaxel-based) plus trastuzumab as compared to chemotherapy alone in patients with advanced breast cancers overexpressing HER2 showed a significant enhancement in the effects of chemotherapy on time to disease progression, response rates and survival with coadministration of trastuzumab, without increases in overall severe adverse events. Myocardial dysfunction syndrome, similar to that observed with anthracyclines, was reported more commonly with chemotherapy plus trastuzumab. Positive results from clinical studies led to the approval of trastuzumab in the U.S in October 1998 for the treatment of metastatic breast cancer in patients with tumors overexpressing HER2. Since then, the MAb has also been marketed in Switzerland and Canada.     

Pertuzumab: in the first-line treatment of HER2-positive metastatic breast cancer

The humanized monoclonal antibody pertuzumab is the first in a new class of drugs, the human epidermal growth factor receptor (HER) dimerization inhibitors. Given that pertuzumab binds to a different epitope of the HER2 extracellular domain than trastuzumab, combination therapy with pertuzumab plus trastuzumab may result in more comprehensive blockade of HER2 signalling than can be achieved with trastuzumab alone. The efficacy of adding pertuzumab to trastuzumab plus docetaxel for the first-line treatment of HER2-positive metastatic breast cancer was demonstrated in the randomized, double-blind, multinational, phase III CLEOPATRA trial. Both independently assessed progression-free survival (primary endpoint) and investigator-assessed progression-free survival were significantly improved in patients receiving pertuzumab plus trastuzumab and docetaxel compared with those receiving placebo plus trastuzumab and docetaxel. The prespecified interim analysis of survival revealed a strong trend towards a survival benefit associated with pertuzumab, although this was not considered statistically significant. The objective response rate was higher with pertuzumab than with placebo. Intravenous pertuzumab had an acceptable tolerability profile when added to trastuzumab and docetaxel in the CLEOPATRA trial.     

HER2-positive breast cancer: current and future treatment strategies

In the year 2006, breast cancer was estimated to affect >200,000 American women and cause nearly 56,000 deaths. Furthermore, breast cancer is the most common cancer diagnosed and second most common cause of cancer-related deaths in women. The current treatment armamentarium for breast cancer includes chemotherapy, endocrine therapy and biological therapy. Treatment has become more individualised based on characteristics of the tumour including overexpression of the human epidermal growth factor receptor (HER)-2. Between 20 and 30% of all breast cancers overexpress HER2, which means 40,000 - 60,000 patients will have this type of cancer.Previously, overexpression of HER2 was a negative prognostic and predictive risk factor for survival; however, with the advent of trastuzumab, patients' prognosis is improving in all treatment settings. Much controversy exists in the use of trastuzumab, including (i) the sequence of adjuvant trastuzumab (concurrent with chemotherapy or sequential); (ii) the treatment duration (<1 year, 1 year or 2 years); and (iii) the treatment choice upon disease progression (whether to continue or not with trastuzumab and add another cytotoxic agent). Current trials are ongoing to help answer these questions.Furthermore, there has been interest in predicting which HER2-positive patients would require anthracycline therapy, and which could avoid anthracycline therapy and its toxicities. Novel therapeutics, such as lapatinib, an oral tyrosine kinase inhibitor, which blocks both the epidermal growth factor receptor and HER2 receptor has recently been approved by the US FDA. Whereas pertuzumab, a humanised monoclonal antibody, directed against heterodimerisation of HER2 and HER3 has entered phase II and III clinical trials.     

Maximizing the response to Herceptin therapy through optimal use and patient selection

The aggressiveness of human epidermal growth factor receptor-2 (HER2)-positive breast cancer and the poor prognosis of women with this disease demand the availability of accurate and reliable tests for HER2 status and the optimization of HER2-targeted therapy. The distinctive clinical pattern of HER2-positive breast cancer underlines the importance of testing for HER2 status and efforts are ongoing to validate the two major methods in use-immunohistochemistry (IHC), which measures cell membrane HER2 expression, and fluorescence in situ hybridization (FISH), which measures gene copy number. Clinical trial results demonstrate that there is an association between strong HER2 overexpression (IHC 3+) and optimal response to therapy with the novel recombinant HER2 antibody Herceptin. High levels of concordance between IHC 3+ and FISH-positive status have been observed, and response to treatment with Herceptin is similar for patients whose breast cancers are IHC 3+ and those who are FISH-positive. Observations to date have led to the formulation of an algorithm for HER2 status determination and Herceptin use which recommends that: (i) the HER2 status of all women with breast cancer be determined at presentation, (ii) all IHC 3+ and FISH-positive patients with metastatic disease should receive Herceptin, (iii) Herceptin should be used early in the course of metastatic breast cancer and preferably first line, and (iv) Herceptin therapy should be continued until disease progression.     

Pharmacology and therapeutic use of trastuzumab in breast cancer.

The development, pharmacology, safety, efficacy, and dosage and administration of trastuzumab are reviewed. The discovery of HER2 gene amplification in up to 30% of women with breast cancer led to the development of trastuzumab, a humanized recombinant monoclonal antibody directed against the HER2-receptor protein on breast cancer cells. In large, multicenter trials of trastuzumab as a single agent or in combination with chemotherapy as first-line or second-line therapy for metastatic breast cancer (MBC), response rates have ranged from 12% to 23% for single-agent trastuzumab and from 25% to 62% for trastuzumab plus chemotherapy. Trastuzumab increased time to disease progression and survival time when administered in combination with chemotherapy. The National Comprehensive Cancer Network guidelines for the treatment of breast cancer now include trastuzumab and paclitaxel as an option for patients with MBC or recurrent breast cancer in which the HER2-receptor protein is overexpressed. Trastuzumab is administered weekly, with an initial i.v. dose of 4 mg/kg followed by weekly doses of 2 mg/kg. Most clinical trials continued treatment until disease progression occurred. Adverse effects include infusion-related reactions manifested by fever and chills, exacerbation of chemotherapy-induced gastrointestinal toxicity and myelosuppression, and cardiotoxicity. Trastuzumab, either as a single agent or in combination with chemotherapy, can be an effective therapeutic option for MBC patients who overexpress the HER2-receptor protein and has changed the standard of care.     

Trastuzumab: in HER2-positive metastatic gastric cancer

Trastuzumab is a recombinant humanized IgG? monoclonal antibody directed against the extracellular domain of the human epidermal growth factor receptor type 2 (HER2) that inhibits HER2-dependent tumour cell proliferation and survival. Proliferation of gastric cancer cells overexpressing HER2 is inhibited by trastuzumab in vitro and in vivo. HER2-positive expression (defined as immunohistochemistry 3+ or fluorescence in situ hybridization-positive) was observed in 22.1% of almost 4000 metastatic gastric cancers in patients who were screened for randomization in the open-label, multicentre, phase III ToGA trial. In patients with HER2-positive metastatic gastric cancer (n?=?584), median overall survival (primary endpoint) was significantly longer for recipients of intravenous trastuzumab plus chemotherapy (comprising cisplatin and either fluorouracil or capecitabine) than in those receiving chemotherapy alone in the ToGA trial. Furthermore, the overall response rate was significantly higher and the median time to disease progression and median time of progression-free survival were also significantly longer with trastuzumab plus chemotherapy than with chemotherapy alone. In general, combination therapy with trastuzumab and chemotherapy was relatively well tolerated in patients with metastatic gastric cancer with no reports of new or unexpected adverse events.     

Trastuzumab: a review of its use in the management of HER2-positive metastatic and early-stage breast cancer

Trastuzumab (Herceptin) is a humanised monoclonal antibody used in the treatment of breast cancer that overexpresses human epidermal growth factor receptor 2 (HER2), which is associated with clinically aggressive disease and a poor prognosis. The addition of intravenous trastuzumab to first-line chemotherapy improved the time to disease progression, objective response rate, duration of response, and overall survival in randomised, multicentre trials in women with HER2-positive metastatic breast cancer. As such, trastuzumab has become the standard of care in this setting, despite its high acquisition cost and potential for cardiac events, and is licensed for use in combination with paclitaxel (Europe and the US) or docetaxel (Europe). In addition, trastuzumab monotherapy is approved for use in patients with HER2-positive metastatic breast cancer who have previously received chemotherapy for their metastatic disease. Recent data from large phase III trials with trastuzumab in the adjuvant setting revealed significant improvements in disease-free and overall survival. Thus, trastuzumab is also rapidly becoming a standard component of adjuvant therapy for patients with HER2-positive early-stage breast cancer.     

Trastuzumab emtansine (T-DM1) for HER2-positive breast cancer

Abstract

Background:

Trastuzumab emtansine (T-DM1), a novel drug developed for the treatment of HER2-positive breast cancer, is a human epidermal growth factor receptor (HER2) targeted antibody drug conjugate, composed of trastuzumab, a stable thioether linker, and the potent cytotoxic agent DM1 (derivative of maytansine). It has been shown that, in preclinical studies, it has anti-tumor activity in trastuzumab refractory cancer cells. In this review, we aim to show the clinical data about trastuzumab-DM1 (T-DM1) therapy and to discuss the therapy advantages for the management of patients with HER2-positive breast cancer.     

Recent advances in novel targeted therapies for HER2-positive breast cancer

The monoclonal antibody trastuzumab has improved the outcomes of patients with breast cancer that overexpresses the human epidermal growth factor receptor 2 (HER2). However, despite this advancement, many tumors develop resistance and novel approaches are needed. Recently, a greater understanding of cellular biology has translated into the development of novel anti-HER2 agents with varying mechanisms of action. The small molecule tyrosine kinase inhibitor lapatinib has demonstrated activity in HER2-positive metastatic breast cancer (MBC) and in the preoperative setting. Pertuzumab is a monoclonal antibody with a distinct binding site from trastuzumab, which inhibits receptor dimerization. In recent studies, the addition of pertuzumab to combination therapy has led to improvements in progression-free survival in patients with HER2-positive MBC and higher response rates in the preoperative setting. An alternative approach is the use of novel antibody-drug conjugates such as trastuzumab-emtansine, which recently demonstrated activity in MBC. Neratinib, a pan-HER tyrosine kinase inhibitor, which irreversibly inhibits HER1 and HER2, also has proven activity in MBC. A range of compounds is being developed to attempt to overcome trastuzumab resistance by targeting heat shock protein 90, a molecular chaperone required for the stabilization of cellular proteins. Furthermore, agents are being developed to inhibit the mammalian target of rapamycin, a downstream component of the PTEN/PI3K pathway, which has been implicated in trastuzumab resistance. Finally, there are emerging data indicating that combinations of anti-HER2 agents may circumvent resistance mechanisms and improve patient outcomes. In this review, recent data on these emerging agents and novel combinations for HER2-positive breast cancer are discussed.     

Trastuzumab: a pharmacoeconomic review of its use in early breast cancer

Trastuzumab (Herceptin) is a monoclonal antibody approved for the treatment of breast cancer that overexpresses human epidermal growth factor receptor 2 (HER2). Well designed clinical trials in women with early breast cancer have demonstrated that 1 years' therapy with adjuvant intravenous trastuzumab (a loading dose followed by 6 mg/kg every 3 weeks or 2 mg/kg weekly) significantly improves disease-free survival and overall survival compared with observation (subsequent to chemotherapy) or chemotherapy alone in women with HER2-positive disease. In the HERA trial, disease-free survival was estimated to improve by 6.3% at 3 years in the trastuzumab group compared with the observation group. Trastuzumab is generally well tolerated. The most common adverse events are infusion-related symptoms, such as fever and chills, which usually occur with administration of the first dose. Cardiotoxicity occurs in a small proportion of patients receiving trastuzumab, particularly when coadministered with anthracyclines, and cardiac assessment is recommended for all patients at baseline and at 3-monthly intervals. In modelled cost-effectiveness analyses based on data from clinical trials in patients with HER2-positive early breast cancer, adjuvant trastuzumab was predicted to be cost effective from a healthcare payer or societal perspective in several countries. Incremental costs per QALY or life-year gained with trastuzumab administered subsequent to or concurrent with chemotherapy compared with chemotherapy alone were consistently within accepted local thresholds for cost effectiveness. Sensitivity analyses demonstrated that these results remained generally robust to plausible changes in key model assumptions. In conclusion, in patients with HER2-positive early breast cancer, the addition of adjuvant trastuzumab is clinically effective in improving disease-free survival. Available pharmacoeconomic data from several countries, despite some inherent limitations, support the use of adjuvant trastuzumab for 1 year as a cost-effective treatment relative to chemotherapy alone in this patient population.     

What's so special about [symbol: see text] trastuzumab?

The growth and multiplication of cells are regulated, in part, by polypeptide growth factors that bind to high-affinity receptors typically found on the plasma membrane. One such receptor is human epidermal growth factor receptor 2 (HER2). In around a quarter of all primary breast cancers, cells possess abnormally high numbers of (overexpress) HER2. [symbol: see text] Trastuzumab (pronounced tra-stoo-zoo-mab; Herceptin-Roche), a recombinant humanised mouse monoclonal antibody directed against HER2, is available as a treatment for certain patients with metastatic breast cancer. It is licensed as a first-line treatment in combination with [symbol: see text] paclitaxel for those whose cancer cells overexpress HER2 and for whom an anthracycline is unsuitable, and as a third-line treatment used alone when treatment with (where appropriate) an anthracycline, a taxane and hormonal therapy has failed. The National Institute for Clinical Excellence (NICE) has recommended trastuzumab as a treatment option for metastatic breast cancer in accordance with the licensed indications. What does trastuzumab offer?     

HER2阳性乳腺癌靶向治疗药物的临床研究进展

乳腺癌已成为全球最常见的癌症,人表皮生长因子受体2（HER2）阳性乳腺癌恶性程度较高,早期易复发和转移,总体预后较差。HER2阳性乳腺癌的治疗因靶向药物的不断问世而呈现更多可能,这类药物包括单克隆抗体（曲妥珠单抗、帕妥珠单抗）、酪氨酸激酶抑制剂（奈拉替尼、拉帕替尼、吡咯替尼、图卡替尼）、抗体药物偶联物（T-DM1、DS-8201）。对HER2阳性乳腺癌靶向治疗药物的最新临床试验结果进行综述,以期为该类乳腺癌的临床用药提供参考。     

Trastuzumab and chemotherapy after the treatment failure of lapatinib for HER2-positive metastatic breast cancer

We describe a patient with human epidermal growth factor receptor type 2 (HER2/c-erbB-2)-positive metastatic breast cancer who survived for approximately 6 years after the initiation of combination therapy with trastuzumab and varying types of chemotherapeutic agents. The patient was a 48-year-old postmenopausal female who underwent partial mastectomy with axillary node dissection for cancer of the right breast in March 1994. She developed lung metastases 2 years thereafter, but survived free of relapse for 8 years following chemotherapy and pulmonary lobectomy. The patient failed to respond to lapatinib, a HER1 (EGFR)/HER2 tyrosine kinase inhibitor, received during the course of her treatment but then again responded to subsequently administered trastuzumab. Primary treatment with trastuzumab and paclitaxel was initiated in April 2004 when the patient developed hepatic metastases 8 years after undergoing surgery for lung metastases. Long-term combination therapy with continued trastuzumab and a variety of chemotherapeutic agents was administered for 6 years without any significant adverse events. We discuss the treatment strategies for HER2-positive breast cancer and the role of lapatinib, a recently approved anticancer drug.     

Trastuzumab: new indication. Metastatic breast cancer, in combination with docetaxel: promising, but more evaluation is needed

(1) There is no consensus on the optimal chemotherapy for metastatic breast cancer. Patients who have never previously received chemotherapy are generally given an anthracycline-based combination of cytotoxic agents. Options for patients who have already received an anthracycline include a taxane such as paclitaxel or docetaxel. The median survival time with these treatments is only about 2 to 2.5 years. (2) Trastuzumab is a monoclonal antibody directed against HER-2, a protein overexpressed by certain tumours, including about 25% of breast tumours. In 2000, the approved indications included first-line treatment of metastatic breast cancer in combination with paclitaxel. One clinical trial had shown, albeit with a low level of evidence, a median increase in survival of about 4 to 5 months. Trastuzumab is now approved for first-line treatment of metastatic breast cancer, in combination with docetaxel. (3) Evaluation data include the results of an open-label trial comparing docetaxel + trastuzumab with docetaxel monotherapy in 186 patients. The median survival time was significantly longer with the combination (31.2 versus 22.7 months). There are no relevant comparisons with other widely used cytotoxic drugs. Indirect comparison suggests that survival is similar with docetaxel + trastuzumab and paclitaxel + trastuzumab. (4) Data on the trastuzumab-docetaxel combination confirm the known adverse effects of trastuzumab, which include heart failure and diarrhea. Trastuzumab increases the frequency of docetaxel-induced neutropenia, which carries a risk of infections. (5) In summary, the results of clinical trials show that median survival time is increased by a few months when trastuzumab is added to a cytotoxic drug. However, the best cytotoxic agent is not known, and adverse effects are poorly documented. (6) In practice, trastuzumab has only been shown to benefit a minority of women with breast cancer, namely those whose tumours overexpress HER-2. Trastuzumab therapy is an option for metastatic breast cancer treatment, provided patients are enrolled in studies designed to answer the many outstanding questions.