Pertuzumab plus trastuzumab plus docetaxel for metastatic breast cancer

New developments in the treatment of HER2-positive breast cancer

Approximately 20%-30% of metastatic breast cancers show increased expression of the human epidermal growth factor receptor-2 (HER2) tyrosine kinase. Two HER2-specific therapies are currently approved for clinical treatment of patients with HER2-overexpressing metastatic breast cancer. Trastuzumab is a monoclonal antibody against HER2 and is approved for first-line treatment of HER2-positive metastatic breast cancer. Lapatinib is a small molecule dual inhibitor of epidermal growth factor receptor and HER2 tyrosine kinases, and is approved for trastuzumab-refractory disease. Although trastuzumab is a highly effective therapy for patients with HER2-overexpressing metastatic breast cancer, a significant number of patients in the initial clinical trials of trastuzumab monotherapy showed resistance to trastuzumab-based therapy. Further, among those who did respond, the initial trials indicated that the median time to progression was less than 1 year. Similarly, lapatinib is effective in a subset of trastuzumab-refractory cases, but the majority of patients display resistance. This review discusses the multiple molecular mechanisms of resistance that have been proposed in the literature. In addition, novel agents that are being tested for efficacy against HER2-positive breast cancer, including the antibodies pertuzumab and trastuzumab-DM1 and the immunotoxin affitoxin, are reviewed. The introduction of trastuzumab has revolutionized the clinical care of patients with HER2-positive metastatic breast cancer and has resulted in dramatic reductions in recurrences of early-stage HER2-positive breast cancer. The development and implementation of gene- and protein-based assays that measure potential molecular predictors of trastuzumab resistance will allow individualization of HER2-targeted therapeutic approaches, and may ultimately improve treatment of HER2-positive breast cancer.

Adjuvant treatment of HER2-positive breast cancer: winning efforts continue to improve HER2-positive patient outcome long-term

Randomized adjuvant trials continue to show significant reductions in distant recurrence and death for early-stage women treated with adjuvant trastuzumab. BCIRG-006 showed superior disease-free and overall survival of two trastuzumab-containing regimens in comparison to a non-trastuzumab-containing regimen. The rates of disease-free and overall survival were not statistically different for the two trastuzumab-containing arms. Ongoing study is needed to identify markers of resistance to trastuzumab and incorporate newer agents in the adjuvant setting in order to further decrease rates of distant recurrence and death from HER2-positive breast cancer.

Advances in first-line treatment for patients with HER-2+ metastatic breast cancer

BACKGROUND

The prognosis for breast cancer patients overexpressing human epidermal growth factor receptor (HER)-2 has changed with anti-HER-2-targeted therapy. Although anti-HER-2 therapy with trastuzumab and chemotherapy is the standard first-line treatment, the best therapeutic regimen has yet to be defined, and new strategies are evolving.

METHODS

A literature review of well-established and recently published trials, reviews, and ongoing clinical trials addressing first-line treatment for HER-2(+) metastatic breast cancer patients was performed.

RESULTS

Taxanes are the agents most commonly used in combination with trastuzumab, but other chemotherapy drugs, such as anthracyclines, vinorelbine, and gemcitabine and triple-combination therapies including platinum compounds, capecitabine, and taxanes have been studied. The combination of aromatase inhibitors with anti-HER-2 therapies is a new therapeutic option for some patients who coexpress HER-2 and hormone receptors, although its activity observed in randomized clinical trials seems to be inferior to that of chemotherapy plus anti-HER-2 therapies. In addition, new anti-HER-2 therapies have shown activity in HER-2(+) tumors, both alone and in combination with trastuzumab.

CONCLUSIONS

Trastuzumab plus chemotherapy is the current standard of care for the upfront treatment of HER-2(+) breast cancer patients, though other anti-HER-2-targeting agents may appear as new standards in the upcoming years.

Trastuzumab for HER2-Positive Metastatic Breast Cancer: Clinical and Economic Considerations

Trastuzumab is a recombinant humanized monoclonal antibody that selectively targets the extra-cellular domain of the HER2 receptor. It was approved by the FDA in September 1998 as the first targeted therapy for HER2-positive metastatic breast cancer, and has since led to significant improvements in the overall prognosis for patients with HER2-positive metastatic disease. The favourable benefit/risk profile associated with palliative trastuzumab has been demonstrated in a number of clinical trials that examined trastusumab as monotherapy or in combination with chemotherapy, endocrine therapy and other HER2 targeted agents. The clinical benefits of trastuzumab, however should also be examined within the context of its significant drug acquisition costs. This review highlights the significant findings from the landmark clinical trials of trastuzumab for metastatic HER2-positive breast cancer, and the potential “value for money” associated with its use in clinical practice.

Toward individualized breast cancer therapy: translating biological concepts to the bedside

The management of breast cancer has changed dramatically over the past 20 years. Based on gene expression profiles, or proteomics of three or four biomarkers, it is apparent that there are multiple subtypes with different clinical characteristics, clinical courses, and sensitivities to existing therapies. This manuscript reviews the management of hormone receptor-positive, human epidermal growth factor receptor 2-positive, and triple-negative breast cancers, emphasizing changes that have occurred in recent years and focusing on potential mechanisms of drug resistance. I also highlight strategies to prevent or overcome resistance to specific therapeutic agents. As a result of enhanced biological understanding of the molecular anomalies that drive the development, progression, and dissemination of breast cancer, a number of novel, molecularly targeted agents have been added to standard therapies. Chemotherapy, endocrine therapy, and targeted treatments have markedly reduced the risk for recurrence and mortality after primary treatment of breast cancer and have increased the 5- and 10-year survival rates. The challenges with novel therapeutics include the absence of accurate predictive biomarkers to identify those patient who will derive substantial benefit and those patients whose tumors are resistant to specific antitumor agents. As we move forward with increasing molecular segmentation of breast cancer and develop new, highly targeted agents, molecular diagnostics must accompany molecular therapeutics to implement the concept of personalized cancer therapy.

HER3 is required for HER2-induced preneoplastic changes to the breast epithelium and tumor formation

Increasing evidence suggests that HER2-amplified breast cancer cells use HER3/ErbB3 to drive therapeutic resistance to HER2 inhibitors. However, the role of ErbB3 in the earliest events of breast epithelial transformation remains unknown. Using mouse mammary specific models of Cre-mediated ErbB3 ablation, we show that ErbB3 loss prevents the progressive transformation of HER2-overexpressing mammary epithelium. Decreased proliferation and increased apoptosis were seen in MMTV-HER2 and MMTV-Neu mammary glands lacking ErbB3, thus inhibiting premalignant HER2-induced hyperplasia. Using a transgenic model in which HER2 and Cre are expressed from a single polycistronic transcript, we showed that palpable tumor penetrance decreased from 93.3% to 6.7% upon ErbB3 ablation. Penetrance of ductal carcinomas in situ was also decreased. In addition, loss of ErbB3 impaired Akt and p44/42 phosphorylation in preneoplastic HER2-overexpressing mammary glands and in tumors, decreased growth of preexisting HER2-overexpressing tumors, and improved tumor response to the HER2 tyrosine kinase inhibitor lapatinib. These events were rescued by reexpression of ErbB3, but were only partially rescued by ErbB36F, an ErbB3 mutant harboring six tyrosine-to-phenylalanine mutations that block its interaction with phosphatidyl inositol 3-kinase. Taken together, our findings suggest that ErbB3 promotes HER2-induced changes in the breast epithelium before, during, and after tumor formation. These results may have important translational implications for the treatment and prevention of HER2-amplified breast tumors through ErbB3 inhibition.

Targeting insulin-like growth factor in breast cancer therapeutics

The insulin-like growth factor (IGF) pathway holds crucial role in cell growth, differentiation and proliferation. Aberrant regulation of the IGF system has been attributed to the pathogenesis of breast cancer and has been shown to contribute to various stages of breast carcinogenesis. Therefore, targeting the IGF-related axis represents a promising strategy, mainly aiming to bypass the resistance of currently employed treatment options in breast cancer patients. Nevertheless, major limitations have aroused despite the early stage of clinical development of various IGF-system modulators. The present review highlights the current status and considers the future perspectives of IGF-system targeting in breast cancer therapeutics.

Trastuzumab for treatment of refractory/relapsed HER2-positive adult B-ALL: results of a phase 2 GRAALL study

The aim of this phase 2 study was to evaluate the efficacy and safety of trastuzumab, a humanized monoclonal antibody targeted against the human epidermal growth factor receptor 2 (HER2), for adult patients with relapsed/refractory HER2-positive B-ALL. Fifteen patients, with a median age of 62 years, received trastuzumab according to the schedule approved for breast cancer patients (ie, 4 mg/kg intravenous loading dose followed by 2 mg/kg weekly). The overall response rate was 13% with 2 patients achieving partial response and partial remission cytolytic response, respectively. Two other patients were documented with blast clearance. Only 1 reversible grade 3 cardiac toxic event occurred. This phase 2 study showed that trastuzumab monotherapy can allow for some responses in a very high-risk refractory/relapsed HER2-positive adult B-ALL population. Combination of trastuzumab with chemotherapy or other therapeutic monoclonal antibodies should be tested in the future. This trial was registered at www.clinicaltrials.gov/ct as NCT00724360.

Taxane resistance in breast cancer: a closed HER2 circuit?

Microtubule inhibitors, such as the taxanes docetaxel and paclitaxel, are commonly used drugs for the treatment of breast cancer. Although highly active in a large fraction of individuals a considerable number of patients show poor response due to either intrinsic or acquired drug resistance. Extensive research in the past identified several taxane resistance-related mechanisms being activated by pathologically altered single gene function. To date, however, a clinically relevant predictive biomarker for taxanes has not been derived yet from this knowledge, most likely due to the manifold of resistance mechanisms that may combine in one tumor, thereby fostering escape from taxane cytotoxicity. Here, we aimed to comprehensively review the current literature on taxane resistance mechanisms in breast cancer. Interestingly, besides altered microtubule physiology we identified the HER2 signaling cascade as a major dominator influencing several routes of cytotoxicity escape, such as cell survival, apoptosis, drug efflux, and drug metabolism. Furthermore, the transcription factor YBX-1, activated by HER2, facilitates a sustaining HER2 signaling feedback loop contributing to the establishment of cellular survival detours. In conclusion, taxane resistance in breast cancer follows a multiplex establishment of drug cytotoxicity escape routes, which may be most efficiently therapeutically targeted by interference with their mutually governing signaling nodes.

Therapeutic application of monoclonal antibodies in cancer: advances and challenges

INTRODUCTION

Monoclonal antibody (mAb)-based products are highly specific for a particular antigen. This characteristic feature of the molecules makes them an ideal tool for many applications including cancer diagnosis and therapy.

SOURCES OF DATA

We performed comprehensive searches of PubMed, Medline and the Food and Drug Administration website using keywords such as 'therapeutic antibodies' and 'anti-cancer antibodies'.

AREAS OF AGREEMENT

Treatment of cancer patients with antibodies when used alone or in combination with chemotherapy and radiotherapy, or conjugated to drugs or radioisotopes, prolongs overall survival in cancer patients. Currently, there are 14 mAb-based drugs that have been approved for the treatment of cancer patients.

AREAS OF CONTROVERSY

The response of cancer patients to antibody therapy can be of short duration. Therapeutic antibodies are expensive and may have side effects. There are no reliable predictive biomarkers for sensitivity or resistance to certain therapeutic antibodies. FUTURE FOCUS: There should be additional studies to discover novel therapeutic targets, to develop more effective antibody-based drugs with fewer side effects, to identify more reliable predictive biomarker(s) for response to therapy with antibody-based drugs and to develop alternative strategies (e.g. transgenic plants, transgenic farm animals) for production of large quantities and more affordable batches of therapeutic antibodies.

AREAS TIMELY FOR DEVELOPING RESEARCH

A better understanding of cancer biology, the hallmarks of human cancers and the immune system would lead to identification of additional cell surface biomarkers. These in turn would facilitate the development of novel and biosimilar antibody-based drugs and their routine use as 'magic bullets' for the targeted therapy of human cancers.

A dickens tale of the treatment of advanced breast cancer: the past, the present, and the future

Metastatic breast cancer (MBC), a usually incurable disease, continues to vex physicians and patients. Recent decades have seen great improvements in the treatment of MBC, based on the availability of novel targeted therapeutics and more standard chemotherapeutic agents. This article describes the goals of therapy for MBC, the progress made against MBC in recent decades, the current standard of care, and the ongoing efforts of basic and translational researchers to transfer the fruits of modern scientific discovery to patients in the clinic.

Core elements of the patient protection and affordable care act and their relevance to the delivery of high-quality cancer care

The Affordable Care Act (ACA) contains many provisions that affect cancer care. The provisions of health care reform aim to improve access to quality cancer care, particularly among the most vulnerable Americans. However, health care reform also offers many challenges and opportunities that affect every stakeholder in oncology. This article summarizes the ACA provisions relevant to oncology, discusses the ethical implications for the oncology caregiver, and describes the effects on specific oncology stakeholders.