Adjuvant therapy for HER2 positive breast cancer: are anthracyclines still necessary?

Anthracyclines are integral components of most adjuvant chemotherapy regimens for surgically removed early breast cancer and are central to the accepted treatment standards. Recently the standard anthracycline regimen of doxorubicin plus cyclophosphamide was found to be inferior in preventing recurrence of breast cancer when compared to cyclophosphamide and docetaxel, questioning the necessity to expose patients to the potential cardiotoxicity of anthracycline in the adjuvant setting. Trastuzumab, a humanized monoclonal antibody against the extracellular domain of the human epidermal growth factor receptor 2 (HER2) has become the cornerstone of treatment of breast cancers that overexpress HER2 in the neo-adjuvant and metastatic setting. Unfortunately, the combination of anthracyclines and trastuzumab produces a high incidence of cardiotoxicity as seen in early trials of metastatic breast cancer. Five adjuvant trials combining trastuzumab with different anthracycline-based regimens have been reported, all of them revealing similar efficacy in reducing recurrence of breast cancer. The trastuzumab adjuvant trial 006 from the Breast Cancer International Research Group shows for the first time that a nonanthracycline-containing regimen with trastuzumab has equivalent efficacy in decreasing the recurrence of breast cancer, with less incidence of cardiotoxicity when compared to anthracycline-containing trastuzumab adjuvant regimens. Further trials are needed to determine the optimal length of adjuvant therapy with trastuzumab, as well as long-term side effects with special attention to cardiotoxicity.     

Use of Pertuzumab for the Treatment of HER2-Positive Metastatic Breast Cancer

Introduction

Targeting the human epidermal growth factor receptor (HER) family of tyrosine kinase receptors has proven to be effective as a therapeutic strategy for HER type 2 (HER2)-positive breast cancer. Since resistance to trastuzumab occurs relatively frequently, particularly in the metastatic setting, novel anti-HER2 targeted therapies with complementary and/or synergistic mechanisms of action have been under development. Pertuzumab, a HER2-targeted monoclonal antibody that prevents HER2 dimerisation, is the first of a class of promising targeted agents for the treatment of HER2-positive breast cancer.

Methods

A review of the biomedical literature published prior to February 2013 was conducted in English using PubMed. ClinicalTrials.gov was searched for appropriate clinical trials. The search terms used included breast neoplasm, pertuzumab, dimerisation, and HER2-positive. Abstracts of studies presented at the ASCO and ESMO Annual Meetings, and San Antonio Breast Cancer Symposium were also included.

Results

Pertuzumab represents a novel anti-HER2 targeted therapy for HER2-positive breast cancers. In this article, we describe the mechanism of action of pertuzumab, as well as its drug development process and preclinical testing results. Based on the results of ancillary studies, dual inhibition using pertuzumab and trastuzumab was shown to be effective for the management of HER2-positive metastatic breast cancers pre-treated with trastuzumab-based therapy. For the first-line setting, the combination of both pertuzumab and trastuzumab with docetaxel (CLEOPATRA trial; clinical evaluation of pertuzumab and trastuzumab) has changed the paradigm of patient management.

Conclusion

Pertuzumab provided a more comprehensive inhibition of HER2-driven signalling pathways. When administered together with trastuzumab, pertuzumab represent a significant advancement for the treatment of HER2-positive metastatic breast cancer patients.     

An Overview of Letrozole in Postmenopausal Women with Hormone-Responsive Breast Cancer

Third-generation aromatase inhibitors (AIs) have proven to be superior to tamoxifen in terms of time to disease progression in patients with hormone receptor (HR) positive (HR+) status and, nowadays, are used in the adjuvant and neoadjuvant settings, and first-line therapy for advanced breast cancer. Letrozole is a third generation AI, as are anastrozole and exemestane. In the past, clinical studies had demonstrated that letrozole was effective as a second-line treatment of metastatic breast cancer. In this paper, pharmacokinetic and pharmacodynamic properties of letrozole are reviewed along with its activity in preclinical and clinical settings. Additionally, the results of important clinical trials such as Breast International Group (BIG) 1-98, which tested the optimal initial adjuvant endocrine treatment and the sequential therapy with letrozole and tamoxifen, MA-17 that evaluates the benefits of extended adjuvant therapy, and other important studies in advanced and neoadjuvant disease, are reviewed. Safety comparisons of treatments are also addressed. Interestingly, about 50% of human epidermal growth factor receptor 2-positive (HER2+) breast cancers are HR+. However, HER2 positivity is a marker of antiestrogen treatment resistance. Because of this, a dual treatment is a logical approach when both receptors are overexpressed. The combination of lapatinib and letrozole leads to a significant improvement in the overall disease outcome. Also, the combination of everolimus plus letrozole has been tested in this setting. In fact, the coadministration of both agents seems to increase the efficacy of letrozole in newly-diagnosed HR+ patients. Once resistance to sequential trastuzumab and AI as monotherapy has been found, trastuzumab and letrozole combined in HR+ and HER2+ patients with advanced breast cancer can overcome resistance to both drugs administered as single agents, according to recently reported results.     

An overview of HER-targeted therapy with lapatinib in breast cancer

Breast cancer is a global public health burden with more than one million new diagnoses worldwide each year. As a significant proportion of women with early-stage breast cancer experience a relapse and metastatic breast cancer is generally incurable, therapeutic innovations are ongoing. One notable innovation in recent decades has been the identification of a subset of breast cancers that overexpress the transmembrane glycoprotein human epidermal growth factor receptor 2 (HER2) and the consequent development of HER2-targeted therapy. Given the significant benefits demonstrated with the HER2-targeted monoclonal antibody, trastuzumab, in the adjuvant and metastatic settings, investigators have endeavored to develop novel mechanisms for disrupting HER2-mediated signaling. Lapatinib, an orally available HER1- and HER2-targeted tyrosine kinase inhibitor, represents one such notable innovation. Lapatinib is currently being evaluated in both the adjuvant and metastatic settings and was recently approved by the United States Food and Drug Administration in combination with capecitabine, for the treatment of women with HER2-positive, pretreated, metastatic breast cancer. However, the ideal strategy for incorporating novel HER2-targeted agents, including lapatinib, into existing management paradigms is uncertain.     

Adjuvant treatment of breast cancer: impact of monoclonal antibody therapy directed against the HER2 receptor

The use of chemotherapy and endocrine therapies as adjuncts to the treatment of early-stage breast cancer has yielded small but significant improvements in disease-free and overall survival. Increased understanding of the role of growth factor receptors enabled the rational development of agents that are capable of modulating their function. A humanised monoclonal antibody to the HER2 receptor, trastuzumab, has demonstrable single-agent activity in metastatic breast cancer and enhances the antitumour effects of chemotherapy. As a consequence, trastuzumab has been tested in the adjuvant setting the results of which have been presented recently. This review briefly summarises the use of trastuzumab in advanced breast cancer and describes recent studies of its use in the adjuvant setting.     

Adjuvant treatment of breast cancer: impact of monoclonal antibody therapy directed against the HER2 receptor

The use of chemotherapy and endocrine therapies as adjuncts to the treatment of early-stage breast cancer has yielded small but significant improvements in disease-free and overall survival. Increased understanding of the role of growth factor receptors enabled the rational development of agents that are capable of modulating their function. A humanised monoclonal antibody to the HER2 receptor, trastuzumab, has demonstrable single-agent activity in metastatic breast cancer and enhances the antitumour effects of chemotherapy. As a consequence, trastuzumab has been tested in the adjuvant setting the results of which have been presented recently. This review briefly summarises the use of trastuzumab in advanced breast cancer and describes recent studies of its use in the adjuvant setting.     

Safety and efficacy of the combination of trastuzumab with docetaxel for HER2-positive women with advanced breast cancer. A review of the existing clinical trials and results of the expanded access programme in the UK

Trastuzumab is a humanised monoclonal antibody against the extracellular domain of HER2 (human epidermal growth factor receptor-2) that is overexpressed in about 25% of human breast cancers. It has shown clinical benefit in HER2-positive breast cancer cases when used alone or in combination with chemotherapy. Trastuzumab increases the response rate to chemotherapy and prolongs survival when used in combination with taxanes. In this article, we review the clinical trials where trastuzumab has been administered together with docetaxel, and we present the results of the trastuzumab expanded access programme (EAP) in the UK. Combination of trastuzumab with docetaxel results in similar response rates and time-to-progression with the trastuzumab/paclitaxel combinations. The toxicity of the combination and the risk of heart failure are low. The clinical data for the docetaxel/trastuzumab combination indicate a favourable profile from both the efficacy and the safety point of view and confirm the feasibility and safety of trastuzumab administration both as monotherapy and in combination with docetaxel.     

Mechanism of action of the trastuzumab biosimilar CT-P6

ABSTRACT

Objectives: Therapeutic monoclonal antibody biosimilars are expected to help reduce the sizeable economic burden of targeted treatments. Trastuzumab (Herceptin®), a recombinant humanized monoclonal antibody that binds to the extracellular domain of HER2, is approved for use in HER2-overexpressing breast cancer (in both the adjuvant and metastatic settings) and HER2-positive gastric cancer. CT-P6 (Herzuma®) is a biosimilar of trastuzumab, designed to bind with high affinity and specificity to the same HER2 epitope as the reference product. We investigated whether CT-P6 exerts its effects through the same mechanism of action as trastuzumab.

Methods: The mechanism of action of CT-P6 and trastuzumab, both as monotherapy and in combination with paclitaxel or pertuzumab, was compared in HER2-overexpressing breast cancer and gastric cancer cell models.

Results: We confirmed that CT-P6 functions in a manner similar to trastuzumab by binding to the HER2 receptor, which is central to the effects of trastuzumab in all indications.

Conclusions: Collectively, the results of this study show that the mechanisms of action of CT-P6 and trastuzumab are similar in HER2-positive breast cancer and gastric cancer models and, therefore, CT-P6 can be expected to perform similarly in the clinical setting.     

Monitoring the introduction of new drugs--Herceptin to cardiotoxicity

Trastuzumab (Herceptin), currently prescribed for metastatic breast cancer, has recently been shown to be effective as adjuvant therapy in early receptor 2 (HER2)-positive breast cancer. Cardiotoxicity is a serious adverse effect. A decrease in left ventricular ejection fraction (LVEF) occurs in as many as 27% of women treated with trastuzumab when combined with standard chemotherapy. The pathophysiology of this effect, which differs from the cardiotoxicity of anthracyclines, remains poorly understood. While overt heart failure is reversed with standard therapy, the longer-term consequences of asymptomatic declines in LVEF remain unknown. Monitoring 3-monthly for 5-10% changes in LVEF, the criteria for cessation of trastuzumab therapy in the clinical trials, is not possible for the population of women who might benefit from trastuzumab for early breast cancer. Extension of this therapy to an older and less fit population than those enrolled in the trials, with less rigorous cardiac screening, may result in significantly more cardiotoxicity.     

Herceptin-based therapy for breast cancer

HER2 gene is overexpressed or amplified in approximately 30% of breast cancer. Breast cancer patients with HER2-overexpression or amplification have shortened disease free and overall survival. The HER2 protein is a useful target for antibody therapy of cancers overexpressing the HER2 gene. Since the recombinant humanized anti-HER2 monoclonal antibody, trastuzumab (Herceptin) was introduced into clinical practice, trastuzumab has become one of the key drugs in the treatment for HER2 positive metastatic breast cancer(MBC). However, much controversy exists on the optimal use of trastuzumab. In this paper, positioning of trastuzumab in the treatment algorithm for HER2 positive MBC as well as early breast cancer will be reviewed and discussed on the basis of our experience.     

Trastuzumab cardio-oncology: lessons learned

Treatment with the humanized monoclonal antibody trastuzumab can significantly improve outcomes for patients with early or metastatic HER2-positive breast cancer. In a small proportion of patients, trastuzumab is associated with an increased risk of cardiac dysfunction. Although the mechanisms have yet to be fully established, trastuzumab may block HER2 signaling in cardiomyocytes, which is believed to be important for protecting the cardiomyocytes from stress such as that induced by treatment with anthracyclines. The risk of trastuzumab-associated cardiac dysfunction can be reduced if patients are evaluated thoroughly for risk factors before treatment (e.g., hypertension, low ejection fraction at onset, hyperglycemia, prior congestive heart failure). In addition, cardiac function must be assessed before and during the treatment period. If cardiac dysfunction occurs during treatment, early intervention can expand the possibilities of reinstitution of trastuzumab treatment. The integration of nonanthracycline adjuvant regimens offers opportunities for cardiac-compromised patients.     

Recent advances in the HER2 targeted therapy of gastric cancer

Recent advances in molecular targeted therapies, including targeting human epidermal growth factor receptor 2(HER2), had a major forward step in the therapy for gastric cancer patients. Application of HER2-targeted therapies, in particular trastuzumab in combination with chemotherapy in metastatic HER2-positive gastric cancers, resulted in improvements in response rates, time to progression and overall survival. Nevertheless, as with breast cancer, many patients with gastric cancer develop resistance to trastuzumab. Several promising therapies are currently being developed in combination with chemotherapy to increase the efficacy and overcome the cancerresistance. Here we review the current overview of clinical application of agents targeting HER2 in gastric cancer. We also discuss the ongoing trials supporting the use of HER2-targeted agents combined with cytotoxic agents or other monoclonal antibodies.     

Treatment of brain metastases in patients with HER2+ breast cancer

Brain metastases are a frequent complication of cancer. However, effective treatments are available. This article aims to review clinical aspects of patients with brain metastases discussing the various treatment options for such patients. It will address the importance and significance of brain metastases in patients with breast cancer and, finally, review the problem of brain metastasis associated with human epidermal growth factor receptor 2-positive (HER2+) breast cancer. With ever-improving survival rates of patients with cancer, there is a greater likelihood that many will develop brain metastases. Treatments such as whole brain or stereotactic radiotherapy and surgery have been shown to be effective against brain metastases. In HER2+ breast cancer, trastuzumab has been shown to be very effective, although it cannot cross the blood-brain barrier. If patients with breast cancer who are being treated with trastuzumab and are responding systemically, develop brain metastases, then patient prognosis does need to be taken into account; however, maintaining treatment with trastuzumab while using available therapies to treat intracranial lesions should be considered as an option.     

Treatment of brain metastases in patients with HER2+ breast cancer

Brain metastases are a frequent complication of cancer. However, effective treatments are available. This article aims to review clinical aspects of patients with brain metastases discussing the various treatment options for such patients. It will address the importance and significance of brain metastases in patients with breast cancer and, finally, review the problem of brain metastasis associated with human epidermal growth factor receptor 2-positive (HER2+) breast cancer. With ever-improving survival rates of patients with cancer, there is a greater likelihood that many will develop brain metastases. Treatments such as whole brain or stereotactic radiotherapy and surgery have been shown to be effective against brain metastases. In HER2+ breast cancer, trastuzumab has been shown to be very effective, although it cannot cross the blood-brain barrier. If patients with breast cancer who are being treated with trastuzumab and are responding systemically, develop brain metastases, then patient prognosis does need to be taken into account; however, maintaining treatment with trastuzumab while using available therapies to treat intracranial lesions should be considered as an option.     

Dacomitinib (PF-00299804), an Irreversible Pan-HER Inhibitor, Inhibits Proliferation of HER2-Amplified Breast Cancer Cell Lines Resistant to Trastuzumab and Lapatinib

The human EGF (HER) family of receptors has been pursued as therapeutic targets in breast cancer and other malignancies. Trastuzumab and lapatinib are standard treatments for HER2-amplified breast cancer, but a significant number of patients do not respond or develop resistance to these drugs. Here we evaluate the in vitro activity of dacomitinib (PF-00299804), an irreversible small molecule pan-HER inhibitor, in a large panel of human breast cancer cell lines with variable expression of the HER family receptors and ligands, and with variable sensitivity to trastuzumab and lapatinib. Forty-seven human breast cancer and immortalized breast epithelial lines representing the known molecular subgroups of breast cancer were treated with dacomitinib to determine IC(50) values. HER2-amplified lines were far more likely to respond to dacomitinib than nonamplified lines (RR, 3.39; P < 0.0001). Furthermore, HER2 mRNA and protein expression were quantitatively associated with response. Dacomitinib reduced the phosphorylation of HER2, EGFR, HER4, AKT, and ERK in the majority of sensitive lines. Dacomitinib exerted its antiproliferative effect through a combined G(0)-G(1) arrest and an induction of apoptosis. Dacomitinib inhibited growth in several HER2-amplified lines with de novo and acquired resistance to trastuzumab. Dacomitinib maintained a high activity in lines with acquired resistance to lapatinib. This study identifies HER2-amplified breast cancer lines as most sensitive to the antiproliferative effect of dacomitinib and provides a strong rationale for its clinical testing in HER2-amplified breast cancers resistant to trastuzumab and lapatinib. Mol Cancer Ther; 11(9); 1978-87. ?2012 AACR.     

Breast cancer

The HER2/neu protein is thought to be a unique and useful target for antibody therapy of cancers overexpressing the HER2/neu gene. The recombinant humanized anti-HER2 monoclonal antibody, trastuzumab(Herceptin) has recently been available for clinical use in Japan. In this paper, the details of this novel biologic agent are reviewed in conjunction with the results of the clinical trials for breast cancer.     

Lapatinib induces apoptosis in trastuzumab-resistant breast cancer cells: effects on insulin-like growth factor I signaling

The majority of breast cancer patients who achieve an initial therapeutic response to the HER2-targeted antibody trastuzumab will show disease progression within 1 year. Thus, the identification of novel agents that effectively inhibit survival of cancer cells that have progressed on trastuzumab is critical. In the current study, we show that the dual epidermal growth factor receptor (EGFR)/human EGFR-2 (HER2) kinase inhibitor lapatinib induces apoptosis in trastuzumab-resistant cells derived from the HER2-overexpressing SKBR3 breast cancer line. Lapatinib inhibited EGFR and HER2 signaling in resistant cells, blocking activation of downstream Akt, mitogen-activated protein kinase, and S6 kinases and inducing expression of p27kip1. Importantly, lapatinib also inhibited insulin-like growth factor I (IGF-I) signaling and growth-promoting effects in parental and resistant cells, and the cytotoxic effects of lapatinib were further enhanced by the IGF-I receptor-blocking antibody alphaIR3. As increased IGF-I receptor signaling has been implicated in trastuzumab resistance, our data strongly support further study of lapatinib as a potential therapeutic in breast cancers that have progressed on trastuzumab.     

Rationale for Herceptin in the clinical use

The human epidermal growth factor receptor-2(HER2) is overexpressed/amplified in a number of cancers. HER2 is implicated in disease initiation and progression and associated with poor prognosis. Trastuzumab(Herceptin) is a recombinant DNA-derived humanized anti-HER2 monoclonal antibody that selectively binds with high affinity to extra-cellular domain. In vitro assay, trastuzumab has been shown to inhibit the proliferation of human tumor cells that overexpressed HER2 and to be a mediator of antibody-dependent cellular toxicity. Clinical trials have demonstrated that it is effective as both single and combination with chemotherapeutic agent in recurrent and metastatic breast cancer patients who's tumor tissue are overexpressed HER2. The incidence of severe adverse events were low but the occurrence of cardiac toxicity was unexpectedly high if trastuzumab was combined with anthracycline containing chemotherapy. The further studies are underway to assess the role of trastuzumab in combination chemotherapy, adjuvant chemotherapy and other type of tumors.     

Clinical development of CT-P6 in HER2 positive breast cancer

ABSTRACT

Introduction: CT-P6 (trastuzumab-pkrb, Herzuma) is a trastuzumab biosimilar approved for use in HER2 positive breast cancer and HER2 positive gastric cancer. CT-P6 has been shown to exhibit similar safety and efficacy profiles to its reference product, trastuzumab. Preclinical and clinical studies have been performed to prove equivalence between CT-P6 and the trastuzumab originator.

Areas Covered: In this review, we examine the evidence comparing CT-P6 with its reference product, trastuzumab. Both monoclonal antibodies function to target cells that overexpress HER2 on the cell surface. Preclinical pharmacologic modeling of CT-P6 shows a similar mechanism of action to trastuzumab, similar pharmacologic properties and a phase I trial in healthy volunteers showed similar pharmacokinetics. A multicenter phase III randomized clinical trial in patients with early breast cancer showed equivalent safety and efficacy between CT-P6 and trastuzumab. One-year follow-up of patients showed identical rates of cardiotoxicity.

Expert Opinion: Preclinical and clinical studies showed CT-P6 pharmacologic profile, safety and efficacy are equivalent to trastuzumab. As such, it is a safe and effective alternative for use in patients with HER2 positive breast cancer and gastric cancer. Its implementation into clinical practice can potentially increase patient access and help financially alleviate overburdened health-care systems.     

不同阶段HER2阳性乳腺癌分层治疗的要点解析

近年来抗HER2药物临床研究不断取得突破性进展，显著改善了HER2阳性乳腺癌患者的预后，改变了乳腺癌的诊疗模式。2020版《中国临床肿瘤学会（CSCO）乳腺癌诊疗指南》在HER2阳性乳腺癌的术前新辅助治疗、术后辅助治疗以及复发转移治疗部分做出重要更新，针对不同阶段患者特征分层给予治疗推荐，规范乳腺癌临床诊疗，提高患者生存率，改善患者生存质量。