Pertuzumab plus trastuzumab plus docetaxel for metastatic breast cancer

Overcoming treatment resistance in HER2-positive breast cancer: potential strategies

Human epidermal growth factor receptor (HER)-2 overexpression or amplification occurs in about 20% of all breast cancers and results in a worse prognosis. Nevertheless, anti-HER2 treatments have recently been developed, resulting in dramatic improvements in the clinical outcome of patients with HER2-positive breast cancer. Trastuzumab has shown efficacy in early and advanced breast cancer treatment and lapatinib is currently approved for the treatment of advanced disease. Other anti-HER2 agents are being investigated. Mechanisms of resistance to trastuzumab treatment include crosstalk with heterologous receptors and amplification of HER2 signalling; amplification of the phosphoinositide 3-kinase (PI3K)/AKT pathway; alteration in binding of trastuzumab to HER2; and loss of HER2 expression. Proposed mechanisms of resistance to lapatinib involve derepression and/or activation of compensatory survival pathways through increased PI3K/AKT or estrogen receptor (ER) signalling. Several strategies to overcome resistance to anti-HER2 treatment are in different phases of development and include treatment with pertuzumab, T-DM1 and mammalian target of rapamycin (mTOR) inhibitors.

Comprehensive molecular portraits of human breast tumours

We analysed primary breast cancers by genomic DNA copy number arrays, DNA methylation, exome sequencing, messenger RNA arrays, microRNA sequencing and reverse-phase protein arrays. Our ability to integrate information across platforms provided key insights into previously defined gene expression subtypes and demonstrated the existence of four main breast cancer classes when combining data from five platforms, each of which shows significant molecular heterogeneity. Somatic mutations in only three genes (TP53, PIK3CA and GATA3) occurred at >10% incidence across all breast cancers; however, there were numerous subtype-associated and novel gene mutations including the enrichment of specific mutations in GATA3, PIK3CA and MAP3K1 with the luminal A subtype. We identified two novel protein-expression-defined subgroups, possibly produced by stromal/microenvironmental elements, and integrated analyses identified specific signalling pathways dominant in each molecular subtype including a HER2/phosphorylated HER2/EGFR/phosphorylated EGFR signature within the HER2-enriched expression subtype. Comparison of basal-like breast tumours with high-grade serous ovarian tumours showed many molecular commonalities, indicating a related aetiology and similar therapeutic opportunities. The biological finding of the four main breast cancer subtypes caused by different subsets of genetic and epigenetic abnormalities raises the hypothesis that much of the clinically observable plasticity and heterogeneity occurs within, and not across, these major biological subtypes of breast cancer.

Pertuzumab in HER2-positive breast cancer

BACKGROUND

Lack of response in some patients and relapse during the course of therapy in the treatment of HER2-positive early breast cancer and metastatic breast cancer continue to challenge researchers and clinicians towards a better understanding of the fundamental mechanisms of trastuzumab action and new therapies for HER2. The aim of this review is to discuss current and future treatment options with pertuzumab in the light of new insights into HER2-positive breast cancer.

SCOPE

Pertuzumab showed positive results in clinical studies and agents in routine clinical usage are updated. The PubMed database, ASCO and San Antonio Breast Cancer Symposium Meeting abstracts were searched up to June 2012 by using the terms 'pertuzumab' and 'anti-HER2 treatment'; papers which were considered relevant for the aim of this review were selected by the authors.

FINDINGS

The presented trials of phase II and phase III randomized trials of CLEOPATRA, NEOSPHERE and TRYPHAENA have showed pertuzumab action to be complementary to trastuzumab without increasing adverse events. Adding pertuzumab to trastuzumab in the first line of HER2-positive metastatic breast cancer and in the neoadjuvant treatment of locally advanced HER2-positive breast cancer is usually well tolerated. The evaluation of health-related quality of life showed that combining pertuzumab with docetaxel and trastuzumab compared to placebo have no detrimental effect with adding pertuzumab.

CONCLUSION

Pertuzumab is the first HER dimerization inhibitor with a mechanism of action complementary to trastuzumab. Studies with anti-HER2 combination treatments indicate that the use of more than one HER2-targeted therapy was superior to one of these agents alone. Pertuzumab has produced impressive anti-tumor activity in combination with trastuzumab. There are ongoing studies with pertuzumab with an increasing tendency towards moving the study of these agents to earlier stages of the disease, namely in the adjuvant and neoadjuvant setting.

Targeting the human epidermal growth factor receptor 2 pathway in breast cancer

The discovery of amplification of human epidermal growth factor receptor 2 (HER2), a member of the epidermal growth factor receptor family, was an important milestone in our understanding of the biology of breast cancers. This heralded the discovery of trastuzumab, a humanized monoclonal antibody targeting HER2. Trastuzumab is the foundation of treatment of HER2-positive breast cancers, demonstrating dramatic responses in patients with metastatic disease. Unfortunately, most tumors will inevitably develop resistance to trastuzumab, necessitating the need for alternate HER2-directed therapeutic approaches. Recent advances in our understanding of the interaction between HER2 and other members of the epidermal growth factor receptor family have led to identification of newer agents, resulting in the expansion of the clinical armamentarium of available agents for the treatment of HER2-positive tumors. In this article, we review the molecular biology of the ERbb receptor family, the use of HER2-targeted agents in early and advanced breast cancer, and the next-generation anti-HER2 agents that are currently in clinical evaluation.

Improving treatment of HER2-positive cancers: opportunities and challenges

Amplification of the ERBB2 gene, which encodes human epidermal growth factor receptor 2 (HER2), causes the overexpression of a major proliferative driver for a subset of breast and gastric cancers. Treatments for patients with HER2-positive cancer include the monoclonal antibody trastuzumab and, in the case of metastatic breast cancer, the tyrosine kinase inhibitor lapatinib. Despite significant improvement in patient outcome as a result of these therapies, challenges remain. This Review focuses on proposed mechanisms of action and resistance in the context of potential new therapeutic options. Therapeutic approaches currently in development likely will yield additional clinically meaningful improvements for patients with HER2-positive cancer.

Molecular mechanisms of cardiotoxicity induced by ErbB receptor inhibitor cancer therapeutics

The introduction of the so-called “targeted therapies”, particularly those drugs that inhibit the activity of tyrosine kinases, has represented a remarkable progress in the treatment of cancer. Although these drugs improve survival rates in cancer, significant cardiotoxicity, manifesting as left vertricular dysfunction and/or heart failure, has emerged. The ErbB receptor tyrosine kinases are being pursued as therapeutic targets because of their important roles in normal physiology and in cancer. Besides the fact that the ErbB receptors are indispensable during development and in normal adult physiology, epidermal growth factor (EGFR) and ErbB2 in particular have been implicated in the development of many human cancers. This review focuses on the rationale for targeting members of ErbB receptor family and numerous agents that are in use for inhibiting the pathway. We summarize the current knowledge on the physiological role of ErbB signaling in the ventricle and on structural aspects of ErbB receptor activation in cancer and cardiac cells. We examine the underlying mechanisms that result in on-target or off-target cardiotoxicities of ErbB inhibitors, which can influence the design of future anticancer therapies.

The next generation of biologic agents: therapeutic role in relation to existing therapies in metastatic breast cancer

The use of more active cytotoxic agents (eg, anthracyclines and taxanes) in the adjuvant setting has impacted treatment options in metastatic breast cancer (MBC). Various new approaches to combination therapy are being investigated, including classic and novel cytotoxic agents and targeted therapies. The heterogeneous molecular pathways involved in the development of breast cancer provide numerous potential targets for therapeutic intervention. Molecular technologies have facilitated the development of various new therapies targeted at disrupting processes as diverse as angiogenesis and DNA repair. Targeted therapies have the potential to improve outcomes in MBC, and their use has increased dramatically over recent years after the introduction of human epidermal growth factor receptor 2 (EGFR2)-targeted therapy with trastuzumab. Lapatinib and bevacizumab have recently been approved for patients with MBC. Numerous other targeted agents are undergoing preclinical investigation or are being evaluated in clinical trials. The maximum benefit of targeted therapies has been realized by their combined use with cytotoxic agents. Overall, single-agent use of targeted therapies has failed to produce dramatic benefit in patients with advanced breast cancer. This article reviews the data from studies of established and emerging targeted therapies in the treatment of MBC and describes how best to incorporate these agents into current treatment paradigms.

Trichosanthin inhibits breast cancer cell proliferation in both cell lines and nude mice by promotion of apoptosis

Breast cancer ranks as a common and severe neoplasia in women with increasing incidence as well as high risk of metastasis and relapse. Translational and laboratory-based clinical investigations of new/novel drugs are in progress. Medicinal plants are rich sources of biologically active natural products for drug development. The 27-kDa trichosanthin (TCS) is a ribosome inactivating protein purified from tubers of the Chinese herbal plant Trichosanthes kirilowii Maximowicz (common name Tian Hua Fen). In this study, we extended the potential medicinal applications of TCS from HIV, ferticide, hydatidiform moles, invasive moles, to breast cancer. We found that TCS manifested anti-proliferative and apoptosis-inducing activities in both estrogen-dependent human MCF-7 cells and estrogen-independent MDA-MB-231 cells. Flow cytometric analysis disclosed that TCS induced cell cycle arrest. Further studies revealed that TCS-induced tumor cell apoptosis was attributed to activation of both caspase-8 and caspase-9 regulated pathways. The subsequent events including caspase-3 activation, and increased PARP cleavage. With regard to cell morphology, stereotypical apoptotic features were observed. Moreover, in comparison with control, TCS- treated nude mice bearing MDA-MB-231 xenograft tumors exhibited significantly reduced tumor volume and tumor weight, due to the potent effect of TCS on tumor cell apoptosis as determined by the increase of caspase-3 activation, PARP cleavage, and DNA fragmentation using immunohistochemistry. Considering the clinical efficacy and relative safety of TCS on other human diseases, this work opens up new therapeutic avenues for patients with estrogen-dependent and/or estrogen-independent breast cancers.

Critical issues on high-dose chemotherapy with autologous hematopoietic progenitor cell transplantation in breast cancer patients

INTRODUCTION

High-dose chemotherapy (HDC) with autologous hematopoietic progenitor cell transplantation (AHPCT) for high-risk (HR) or metastatic breast cancer (MBC) is no longer an option.

AREAS COVERED

An expert panel including medical oncologists and hematologists produce an opinion paper on the use of HDC and AHPCT in BC patients and they explain why they believe that; despite inconclusive results thus far, this treatment should have an ongoing role in breast cancer management under clinical trials.

EXPERT OPINION

HDC with AHPCT has become a safe treatment modality and an advantage in disease-free survival has been observed in most of the studies with HDC, with the caveat that today, even a limited relapse-free survival and progression-free survival benefit is sufficient for the approval of new antineoplastic agents. Moreover, in HRBC, an overall survival benefit by HDC could be achieved in the HER2-ve and triple-negative populations and, in this setting, HDC with AHPCT represents a therapeutic option that can be proposed to well-informed patients. In MBC, the HDC approach should be investigated further in selected patients with HER2-ve, chemosensitive disease. This paper is not intended to give any conclusion, but rather to open a debate on the value of HDC in HR and MBC.

2nd PEGS Annual Symposium on Antibodies for Cancer Therapy: April 30-May 1, 2012, Boston, USA

The 2nd Annual Antibodies for Cancer Therapy symposium, organized again by Cambridge Healthtech Institute as part of the Protein Engineering Summit, was held in Boston, USA from April 30th to May 1st, 2012. Since the approval of the first cancer antibody therapeutic, rituximab, fifteen years ago, eleven have been approved for cancer therapy, although one, gemtuzumab ozogamicin, was withdrawn from the market. The first day of the symposium started with a historical review of early work for lymphomas and leukemias and the evolution from murine to human antibodies. The symposium discussed the current status and future perspectives of therapeutic antibodies in the biology of immunoglobulin, emerging research on biosimilars and biobetters, and engineering bispecific antibodies and antibody-drug conjugates. The tumor penetration session was focused on the understanding of antibody therapy using ex vivo tumor spheroids and the development of novel agents targeting epithelial junctions in solid tumors. The second day of the symposium discussed the development of new generation recombinant immunotoxins with low immunogenicity, construction of chimeric antigen receptors, and the proof-of-concept of 'photoimmunotherapy'. The preclinical and clinical session presented antibodies targeting Notch signaling and chemokine receptors. Finally, the symposium discussed emerging technologies and platforms for therapeutic antibody discovery.

Targeted treatments of HER2-positive metastatic breast cancer: trastuzumab and beyond

SUMMARY HER2 positivity defines a molecular subtype of breast cancer with aggressive biological behavior. HER2 has been clinically validated as a prominent therapeutic target in breast cancer, and an abundance of data from clinical trials proving the efficacy of trastuzumab, a humanized anti-HER2 monoclonal antibody, has changed the natural history of this disease. Despite positive results from many trials, resistance to anti-HER2 agents inevitably occurs in both the metastatic and adjuvant settings. This clinical reality has led to the development of various other targeted agents designed to block the HER2 receptor. Similarly, attempts to elucidate the molecular mechanisms of resistance to the already established anti-HER2 agents have opened new therapeutic avenues with numerous promising agents. This review presents a comprehensive overview of the data available on anti-HER2-targeted agents other than trastuzumab, and describes both challenges and directions for the future.

Trastuzumab: a novel standard option for patients with HER-2-positive advanced gastric or gastro-oesophageal junction cancer

The human epidermal receptor-2 (HER-2) is amplified in up to 25% of patients with gastroesophageal adenocarcinomas. Although the presence of this amplification does not appear to confer a poor prognosis, it provides a valuable novel therapeutic target for this group of patients. Trastuzumab is a fully humanized monoclonal antibody directed at HER-2 which binds the external domain of the receptor and exerts its action via a combination of antibody-dependent cytotoxicity, reduced shedding of the extracellular domain, inhibition of dimerization and possibly receptor downregulation. The ToGA trial was an international multicentre randomized phase III study which evaluated the addition of trastuzumab to a cisplatin plus fluoropyrimidine chemotherapy doublet in 594 patients with HER-2-positive advanced gastric or oesophagogastric junction adenocarcinoma. The combination of the antibody with chemotherapy significantly improved response rate, median progression-free survival and median overall survival without additional toxicity or adversely affecting quality of life. Accordingly, trastuzumab plus chemotherapy is now a standard first-line treatment option for patients with advanced HER-2-positive gastroesophageal cancer. Unfortunately, many patients with HER-2-positive cancer exhibit primary resistance to trastuzumab and the remainder will acquire resistance to the antibody; therefore, urgent investigation into novel agents which may circumvent resistance mechanisms is warranted. Small molecule inhibitors of HER-2, which commonly also target other members of the HER family of receptors, such as EGFR and HER-3, are currently undergoing evaluation in gastroesophageal cancer as first-line alternatives to trastuzumab and second-line salvage treatments for trastuzumab-resistant disease. Extrapolating the successful use of trastuzumab in the advanced disease setting, clinical trials are underway to assess the role of this antibody in the perioperative and adjuvant settings, where it is hoped that it will have a meaningful impact upon the currently poor survival rates.

Novel targeted agents for the treatment of advanced breast cancer

The discovery of the molecular processes involved in cancer development has led to the design of an array of targeted agents. These agents, directed to specific proteins in the machinery of cancer cells, interfere with vital cascades involved in cell invasion, metastasis, apoptosis, cell-cycle control and angiogenesis. In breast cancer, the main pathways studied and targeted by drugs are the HER2 pathway, EGFR, VEGF, PI3K/Akt/mammalian target of rapamycin (PI3K-M-Tor), IGF/IGFR, poly(ADP ribose) polymerase 1, HDAC and many others. In this review, we present the most promising studies of these new targeted therapies and novel combination of targeted therapies with cytotoxic agents for the treatment of breast cancer patients.

Potential of afatinib in the treatment of patients with HER2-positive breast cancer

In the absence of treatment, overexpression of the human epidermal growth factor receptor 2 (HER2) predicts a poor prognosis in breast cancer. In the last decade, monoclonal antibodies and small molecule tyrosine kinase inhibitors have significantly improved the outcome of HER2-positive breast cancer patients. However, tumor resistance and toxicities often limit the use of these therapies. For this reason, there is a compelling need for further investigation of new targeted therapies, such as afatinib, an oral irreversible pan inhibitor of the epidermal growth factor receptor (EGFR) family. This compound covalently interacts with tyrosine kinase domains, which are deeply involved in signal transduction leading to cell proliferation and protection from apoptosis. Afatinib has been studied in several Phase I clinical trials in advanced solid tumors. These trials have shown encouraging clinical activity and manageable side effects when afatinib is used either as a single agent or in combination with chemotherapy, with cutaneous adverse events and diarrhea being the most frequently observed toxicities. This review will focus on afatinib's clinical activity and will discuss ongoing clinical studies in HER2-positive breast cancer patients. In the scenario of the different HER2-targeted therapies, it will be important to define the best specific clinical and "molecular" setting for afatinib use, trying to identify predictors of resistance and response. Moreover, afatinib, which has the ability to cross the blood-brain barrier, could play a role in patients with brain metastases from breast cancer.

Improving survival and limiting toxicity: latest advances in treating human epidermal growth factor receptor 2 overexpressing breast cancer

In recent years, new strategies for the treatment of breast cancer have focused on extensive target identification and understanding the expression, regulation and function of critical signaling pathways involved in breast cancer initiation and progression. This has led to significant progress in developing and understanding human epidermal growth factor receptor 2 (HER2)-targeted therapies, which in turn, has translated into significant increases in median survival for patients with HER2-overexpressing breast cancer. It is becoming increasingly difficult to make specific recommendations for the optimal treatment of HER2-overexpressing breast cancer since the field is evolving so rapidly. However, despite the many randomized trials that have been undertaken showing improvement in survival, the current standard treatment for HER2-overexpressing breast cancer continues to revolve around the addition of chemotherapy to a HER2-targeted agent, which in turn, carries substantial toxicities. This article reviews agents that have recently been investigated to treat HER2-overexpressing breast cancers. The goal is ultimately to increase the magnitude and duration of response to trastuzumab-based treatment while minimizing toxicity. Studies addressing length of therapy duration, the superiority and side-effect profile of the different biological drug combinations, and determination of biomarkers of resistance to HER2 therapy will be instrumental in decreasing morbidity and mortality for patients with HER2-overexpressing breast cancer.

[Tumor resistance to HER2 inhibitors: the drug sedimentation concept]

Twenty years have passed between the discovery of oncogene HER2, the description of its implication in mammary carcinogenesis, and the development of specific targeted therapies. To date, trastuzumab and lapatinib are the two anti-HER2 targeted therapies commonly used, demonstrating therapeutic effects. Although their clinical efficacy seems to be exclusively related to the amplification of the HER2 gene or to the overexpression of the protein, these factors are not sufficient since tumors can develop resistance. Because of a better knowledge in those mechanisms of resistance, novel therapeutic agents could help to bypass them. How should these be used with respect to current anti-HER2 targeted therapies? Recent notions such as oncogene addiction, tumor cell dormancy and residual disease led us to propose a new entity that we named the "sedimentation strategy", in which distinct targeted approaches are summed during the treatment of metastatic breast cancer patients.

Increased MET and HGF gene copy numbers are associated with trastuzumab failure in HER2-positive metastatic breast cancer

BACKGROUND

To investigate whether copy number gain of MET or hepatocyte growth factor (HGF) affect trastuzumab sensitivity in HER2-positive metastatic breast cancer (MBC).

METHODS

We analysed 130 HER2-positive MBC treated with trastuzumab-based therapy. MET and HGF gene copy numbers (GCN) were assessed by fluorescence in situ hybridisation (FISH) in primary breast cancer samples. Receiver operating characteristic analysis was applied to find the best cutoff point for both MET and HGF GCN.

RESULTS

MET FISH-positive cases (N=36, mean 3.72) had a significantly higher trastuzumab failure rate (44.4% vs 16.0%; P=0.001) and a significantly shorter time to progression (5.7 vs 9.9 months; HR 1.74; P=0.006) than MET FISH-negative cases (N=94, mean <3.72). Hepatocyte growth factor GCN was evaluated in 84 cases (64.6%). Receiver operating characteristic analysis identified 33 HGF FISH-positive patients (mean HGF GCN 3.01). HGF FISH-positive status was significantly associated with higher risk of failure (30.3% vs 7.8%; P=0.007) as compared with HGF FISH-negative cases (N=51, mean <3.01). MET and HGF FISH-positive status was highly correlated (P<0.001) and combination of both biomarkers did not increase predictive value of either considered separately.

CONCLUSION

High GCNs of MET and HGF associate with an increased risk of trastuzumab-based therapy failure in HER2-positive MBC.

Lapatinib, trastuzumab or the combination added to preoperative chemotherapy for breast cancer: a meta-analysis of randomized evidence

We compared the efficacy and safety of the addition of lapatinib versus trastuzumab or their combination to neoadjuvant chemotherapy in HER2-positive breast cancer. Potentially eligible trials were located through PubMed and Cochrane Library searches and abstracts of major international conferences. The endpoints that we assessed were pathologic complete response (pCR) rate, and toxicity. Pooled risk ratios (RR) were estimated for each endpoint with fixed or random effects models, depending on between studies heterogeneity. Six trials were identified with 1,494 eligible patients. The probability to achieve pCR was higher for the trastuzumab plus chemotherapy arm versus lapatinib plus chemotherapy (RR 1.25, 95 % confidence interval [CI] 1.08-1.43; p = 0.003) (6 trials; 1,494 patients). Probability to pCR was significantly higher in the group receiving lapatinib and trastuzumab than in the group with trastuzumab alone (RR 1.39, 95 % CI 1.20-1.63; p < 0.001) (4 trials; 779 patients). Grade III-IV diarrhea and dermatologic toxicities were statistically more frequent in patients receiving lapatinib. No differences were observed regarding cardiac adverse events among patients receiving trastuzumab, lapatinib, or their combination. These data supports the superiority of a dual-HER2 inhibition for the treatment of HER2-positive breast cancer in the neoadjuvant setting. The direct comparison of trastuzumab and lapatinib showed that lapatinib is inferior in terms of pCR and associated with a higher risk for toxicity.

Treating metastatic breast cancer with systemic chemotherapies: current trends and future perspectives

Treatment selection for metastatic breast cancer (MBC) is guided by multiple factors, most importantly hormone receptor (HR) or HER2 expression, treatment history, and prognostic factors such as short disease-free interval, presence of visceral metastases, performance status, and degree of symptoms. Chemotherapy is indicated as initial therapy for patients with HR-negative disease and following failure of hormonal therapies in HR-positive disease. Patients treated with an anthracycline or a taxane in early-stage settings may no longer be candidates for those drugs in MBC, thus underscoring the need for alternative options. Sequential single-agent therapy or combination therapy are viable strategies. Trials have shown that ixabepilone plus capecitabine significantly improves progression-free survival compared with capecitabine alone in anthracycline- or taxane-pretreated or -resistant patients, and single-agent eribulin improves survival compared with the physician's choice of treatment in patients treated previously with at least two regimens for MBC. Regardless of the regimen, proactive management to detect treatment-related adverse events in a timely manner remains important for ensuring effective delivery of treatment. Many promising investigational agents are in development, including T-DM1 (trastuzumab emtansine) and pertuzumab for HER2-positive disease, as well as PARP-1 (poly[adenosine diphosphate ribose] polymerase-1) inhibitors and cetuximab for triple-negative disease. In addition, new options for the treatment of MBC following failure of an anthracycline and a taxane promise to improve patient outcomes. Nurses should remain vigilant for adverse events and remember that the goal of treatment remains control of the disease and palliation.

Trifunctional antibody ertumaxomab: Non-immunological effects on Her2 receptor activity and downstream signaling

BACKGROUND

The trifunctional antibody ertumaxomab bivalently targets the human epidermal growth factor receptor 2 (Her2) on epithelial (tumor) cells and the T cell specific CD3 antigen, and its Fc region is selectively recognized by Fcγ type I/III receptor-positive immune cells. As a trifunctional immunoglobulin, ertumaxomab therefore not only targets Her2 on cancer cells, but also triggers immunological effector mechanisms mediated by T and accessory cells (e.g., macrophages, dendritic cells, natural killer cells). Whether molecular effects, however, might contribute to the cellular antitumor efficiency of ertumaxomab are largely unknown.

METHODS

Potential molecular effects of ertumaxomab on Her2-overexpressing BT474 and SK-BR-3 breast cancer cells were evaluated. The dissociation constant Kd of ertumaxomab was calculated from titration curves that were recorded by flow cytometry. Treatment-induced changes in Her2 homodimerization were determined by flow cytometric fluorescence resonance energy transfer measurements on a cell-by-cell basis. Potential activation / deactivation of Her2, ERK1/2, AKT and STAT3 were analyzed by western blotting, Immunochemistry and immunofluorescent cell staining.

RESULTS

The Kd of ertumaxomab for Her2-binding was determined at 265 nM and the ertumaxomab binding epitope was found to not overlap with that of the therapeutic anti-Her2 monoclonal antibodies trastuzumab and pertuzumab. Ertumaxomab caused an increase in Her2 phosphorylation at higher antibody concentrations, but changed neither the rate of Her2-homodimerization /-phosphorylation nor the activation state of key downstream signaling proteins analyzed.

CONCLUSIONS

The unique mode of action of ertumaxomab, which relies more on activation of immune-mediated mechanisms against tumor cells compared with currently available therapeutic antibodies for breast cancer treatment, suggests that modular or sequential treatment with the trifunctional bivalent antibody might complement the therapeutic activity of other anti-Her2/anti-ErbB receptor reagents.

Endocrine resistance in breast cancer: molecular pathways and rational development of targeted therapies

Endocrine resistance presents a major challenge in the management of estrogen receptor (ER)-positive breast cancer and is an area under intense investigation. Although the underlying mechanism is still poorly understood, many studies point towards the 'cross-talk' between ER and growth factor receptor signaling pathways as the key in the development of estrogen-independent growth in breast cancer. This review aims to provide the reader our current understanding of various molecular pathways that mediate endocrine resistance and that are being evaluated as therapeutic targets for ER-positive breast cancer. While most of the agents that target these pathways have only been tested in Phase I or small Phase II trials, some have shown encouraging results. A critical issue that remains is the development of research strategies and clinical trials that take into account the molecular heterogeneity of ER-positive breast cancer.

The ERBB network: at last, cancer therapy meets systems biology

Although it is broadly agreed that the improved treatment of patients with cancer will depend on a deeper molecular understanding of the underlying pathogenesis, only a few examples are already available. This Timeline article focuses on the ERBB (also known as HER) network of receptor tyrosine kinases (RTKs), which exemplifies how a constant dialogue between basic research and medical oncology can translate into both a sustained pipeline of novel drugs and ways to overcome acquired treatment resistance in patients. We track the key early discoveries that linked this RTK family to oncogenesis, the course of pioneering clinical research and their merger into a systems-biology framework that is likely to inspire further generations of effective therapeutic strategies.

Risk of rash with the anti-HER2 dimerization antibody pertuzumab: a meta-analysis

Pertuzumab is a novel humanized monoclonal antibody that blocks human epidermal growth factor receptor 2 (HER2) dimerization. It was recently approved by the US FDA for use in combination with trastuzumab and docetaxel for patients with HER2-positive metastatic breast cancer who have not received prior anti-HER2 therapy or chemotherapy for metastatic disease. Rash is inconsistently reported as a common adverse event in most clinical trials of pertuzumab, at varying incidences. In this study, we have investigated the overall incidence and risk of rash with pertuzumab. Relevant studies were identified from the PubMed database (1966-2012), abstracts presented at the American Society of Clinical Oncology annual conference (2004-2011), and Web of Science database (1998-2012). Eligible studies were prospective phase II-III clinical trials using pertuzumab in cancer patients. Incidence, relative risk (RR), and 95 % confidence intervals (CIs) were calculated using random-effects or fixed-effects models based on the heterogeneity of included studies. Data from a total of 1,726 patients (pertuzumab, n = 1,157; controls, n = 569) with breast, ovarian, and prostate cancers from eight clinical trials were included for analysis. The incidence of all-grade and high-grade rash with pertuzumab were 24.6 % (95 % CI 19.3-30.8 %) and 1.1 % (95 % CI 0.5-2.2 %), respectively. The risk varied with tumor types, as patients with prostate cancer had a lower incidence of rash (13.2 %; 95 % CI 8.0-21.1 %) than those with breast, ovarian, fallopian tube, and peritoneal cancer (P = 0.001). Overall, pertuzumab significantly increased the risk of rash in comparison with controls (RR 1.53; 95 % CI 1.12-2.09; P = 0.007). Pertuzumab is associated with a significant risk of rash, and the incidence varies among different tumor types. Prevention, early recognition, and appropriate treatment of this rash may lead to improvement in patient quality of life, adherence to therapy, and possibly optimize clinical outcomes.

Strong EGFR signaling in cell line models of ERBB2-amplified breast cancer attenuates response towards ERBB2-targeting drugs

Increasing the efficacy of targeted cancer therapies requires the identification of robust biomarkers suitable for patient stratification. This study focused on the identification of molecular mechanisms causing resistance against the anti-ERBB2-directed therapeutic antibodies trastuzumab and pertuzumab presently used to treat patients with ERBB2-amplified breast cancer. Immunohistochemistry and clinical data were evaluated and yielded evidence for the existence of ERBB2-amplified breast cancer with high-level epidermal growth-factor receptor (EGFR) expression as a separate tumor entity. Because the proto-oncogene EGFR tightly interacts with ERBB2 on the protein level, the hypothesis that high-level EGFR expression might contribute to resistance against ERBB2-directed therapies was experimentally validated. SKBR3 and HCC1954 cells were chosen as model systems of EGFR-high/ERBB2-amplified breast cancer and exposed to trastuzumab, pertuzumab and erlotinib, respectively, and in combination. Drug impact was quantified in cell viability assays and on the proteomic level using reverse-phase protein arrays. Phosphoprotein dynamics revealed a significant downregulation of AKT signaling after exposure to trastuzumab, pertuzumab or a coapplication of both antibodies in SKBR3 cells but no concomitant impact on ERK1/2, RB or RPS6 phosphorylation. On the other hand, signaling was fully downregulated in SKBR3 cells after coinhibition of EGFR and ERBB2. Inhibitory effects in HCC1954 cells were driven by erlotinib alone, and a significant upregulation of RPS6 and RB phosphorylation was observed after coincubation with pertuzumab and trastuzumab. In summary, proteomic data suggest that high-level expression of EGFR in ERBB2-amplified breast cancer cells attenuates the effect of anti-ERBB2-directed antibodies. In conclusion, EGFR expression may serve as diagnostic and predictive biomarker to advance personalized treatment concepts of patients with ERBB2-amplified breast cancer.

Revisiting the isobole and related quantitative methods for assessing drug synergism

The isobole is well established and commonly used in the quantitative study of agonist drug combinations. This article reviews the isobole, its derivation from the concept of dose equivalence, and its usefulness in providing the predicted effect of an agonist drug combination, a topic not discussed in pharmacology textbooks. This review addresses that topic and also shows that an alternate method, called "Bliss independence," is inconsistent with the isobolar approach and also has a less clear conceptual basis. In its simplest application the isobole is the familiar linear plot in cartesian coordinates with intercepts representing the individual drug potencies. It is also shown that the isobole can be nonlinear, a fact recognized by its founder (Loewe) but neglected or rejected by virtually all other users. Whether its shape is linear or nonlinear the isobole is equally useful in detecting synergism and antagonism for drug combinations, and its theoretical basis leads to calculations of the expected effect of a drug combination. Numerous applications of isoboles in preclinical testing have shown that synergism or antagonism is not only a property of the two agonist drugs; the dose ratio is also important, a fact of potential importance to the design and testing of drug combinations in clinical trials.

Breast Cancer 2012 - New Aspects

Treatment options as well as the characteristics for therapeutic decisions in patients with primary and advanced breast cancer are increasing in number and variety. New targeted therapies in combination with established chemotherapy schemes are broadening the spectrum, however potentially promising combinations do not always achieve a better result. New data from the field of pharmacogenomics point to prognostic and predictive factors that take not only the properties of the tumour but also inherited genetic properties of the patient into consideration. Current therapeutic decision-making is thus based on a combination of classical clinical and modern molecular biomarkers. Also health-economic aspects are more frequently being taken into consideration so that health-economic considerations may also play a part. This review is based on information from the recent annual congresses. The latest of these are the 34th San Antonio Breast Cancer Symposium 2011 and the ASCO Annual Meeting 2012. Among their highlights are the clinically significant results from the CLEOPATRA, BOLERO-2, EMILIA and SWOG S0226 trials on the therapy for metastatic breast cancer as well as further state-of-the-art data on the adjuvant use of bisphosphonates within the framework of the ABCSG-12, ZO-FAST, NSABP-B34 and GAIN trials.

Pertuzumab Increases 17-AAG-Induced Degradation of ErbB2, and This Effect Is Further Increased by Combining Pertuzumab with Trastuzumab

ErbB2 is an important oncogenic protein involved in carcinogenesis of, among others, breast, gastric, and ovarian carcinoma. Over-expression of ErbB2 is found in almost 20% of breast cancers, and this results in proliferative and anti-apoptotic signalling. ErbB2 is therefore an important treatment target. Antibodies recognizing full-length ErbB2 are clinically established, and drugs targeting the ErbB2 stabilizing heat shock protein 90 (Hsp90) are under clinical evaluation. We have investigated effects of the ErbB2-binding antibodies trastuzumab and pertuzumab alone and in combination, as well as the effect of the antibodies in combination with the Hsp90 inhibitor 17-AAG. Our results confirm the notion that combination of different ErbB2-binding antibodies more efficiently down-regulates ErbB2 than does one antibody in isolation. Additionally, our data demonstrate that ErbB2 is most efficiently down-regulated upon incubation with anti-ErbB2 antibodies in combination with Hsp90 inhibitors. The combination of anti-ErbB2 antibodies, and especially the combination of antibodies with 17-AAG, did also increase the inhibition of Akt activation of either agent, which could suggest an anti-proliferative effect. In such case, combining these agents could be beneficial in treatment of tumors not responding to trastuzumab only.

The evolving landscape of protein kinases in breast cancer: clinical implications

Dysfunction of protein kinases has been associated with the development of the various molecular subtypes of breast cancer. The best example is the known role of HER2 in the tumorigenesis of a proportion of breast tumors. In this article, we review the state of the art knowledge on protein kinases involved in breast cancer. Special attention is given to those that are potentially druggable and those for which targeted agents are currently under clinical evaluation. Options for targeted drug combinations will be discussed, as well as the optimal way to integrate new kinase inhibitors in the clinical armamentarium to fight breast cancer. We will review recent results from clinical studies with agents targeting different kinases involved in the pathophysiology of breast cancer. In addition, we will evaluate the clinical development of kinase inhibitors to identify areas of knowledge that could be explored in future preclinical and clinical studies.

The role of targeted therapy and biomarkers in breast cancer treatment

Breast cancer is the most prevalent life-threatening cancer in women and the second leading cause of cancer associated deaths. Consequently, optimizing breast cancer therapy to increase cure rates in early stage disease and improve life expectancy and palliation for patients with metastasis is a critical need and major area of research in medical oncology. This article focuses on the development of personalized therapy in breast cancer though the use of targeted therapies and their associated biomarkers. Topics reviewed include the historic advances in targeting the HER2 receptor and the current avenues being studied to circumvent resistance; new developments in the management of triple negative and metastatic breast cancer; and the challenges and pitfalls associated with targeting angiogenesis. Using these as examples, many of the innovations and challenges in the treatment of women with breast cancer are explored.

Role of pertuzumab in the treatment of HER2-positive breast cancer

Pertuzumab, a humanized monoclonal antibody to the HER2 receptor, represents a promising new anti-HER2 agent with a novel mechanism of action targeting the inhibition of HER2 dimerization. Nonclinical and clinical data to date indicate that pertuzumab provides a broader HER2 blockade through the inhibition of HER2 heterodimerization. In preclinical experiments, pertuzumab has demonstrated superior antitumor effects when combined with other anti-HER2 treatments such as trastuzumab, compared to when used as monotherapy. Trastuzumab and pertuzumab monoclonal antibodies bind to distinct epitopes on the HER2 receptor without competing with each other, resulting in distinctive mechanisms for disrupting HER2 signaling. These mechanisms are complementary and result in augmented therapeutic efficacy when pertuzumab and trastuzumab are given in combination. Clinically, pertuzumab may have optimal therapeutic effects when given to patients with HER2-positive cancers, in combination with trastuzumab. This observation is supported by recent clinical trials in the metastatic as well as neoadjuvant setting. Intravenous pertuzumab had an acceptable tolerability profile when added to trastuzumab and chemotherapy. This overview will review recent advances in the clinical development of this HER2-targeted therapy.

ErbB3 inhibitory surrobodies inhibit tumor cell proliferation in vitro and in vivo

ErbB3 is an important regulator of tumorigenesis and is implicated in development of resistance to several currently used oncology drugs. We have identified ErbB3 inhibitors based on a novel biologic scaffold termed a surrobody. Two of these inhibitors appear to work by a previously unrecognized mechanism of action. As a consequence, they not only inhibited cell proliferation and intracellular signaling driven by stimulation with the ErbB3 ligand neuregulin (NRG), but also inhibited signaling and proliferation that was driven by overexpression of ErbB2 in the absence of ligand stimulation. In addition, the surrobodies inhibited tumor growth in vivo in both ErbB2-overexpressing and nonoverexpressing cells. In ErbB2-overexpressing cells, both of the anti-ErbB3 surrobodies significantly augmented the activities of trastuzumab, lapatinib, and GDC-0941, agents that inhibit cell proliferation by different mechanisms. Moreover, although NRG diminished the efficacy of these agents, when they were combined with anti-ErbB3 surrobodies the affect of NRG was abrogated. In this capacity, the anti-ErbB3 surrobodies were more effective than the ErbB2/ErbB3 dimerization inhibitory antibody pertuzumab. Despite the fact that these surrobodies appear to engage ErbB3 differently than previously described anti-ErbB3 antibodies, they retain all of the beneficial characteristics of this class of agents, including the ability to augment drugs that inhibit EGF receptor. These anti-ErbB3 agents, therefore, show substantial promise for development as single agents or in combination with other ErbB-directed antibodies or small molecules and may provide for a broader range of therapeutic indications than previously described anti-ErbB3 antibodies.

Defining the molecular response to trastuzumab, pertuzumab and combination therapy in ovarian cancer

BACKGROUND

Trastuzumab and pertuzumab target the Human Epidermal growth factor Receptor 2 (HER2). Combination therapy has been shown to provide enhanced antitumour activity; however, the downstream signalling to explain how these drugs mediate their response is not clearly understood.

METHODS

Transcriptome profiling was performed after 4 days of trastuzumab, pertuzumab and combination treatment in human ovarian cancer in vivo. Signalling pathways identified were validated and investigated in primary ovarian xenografts at the protein level and across a timeseries.

RESULTS

A greater number and variety of genes were differentially expressed by the combination of antibody therapies compared with either treatment alone. Protein levels of cyclin-dependent kinase inhibitors p21 and p27 were increased in response to both agents and further by the combination; pERK signalling was inhibited by all treatments; but only pertuzumab inhibited pAkt signalling. The expression of proliferation, apoptosis, cell division and cell-cycle markers was distinct in a panel of primary ovarian cancer xenografts, suggesting the heterogeneity of response in ovarian cancer and a need to establish predictive biomarkers.

CONCLUSION

This first comprehensive study of the molecular response to trastuzumab, pertuzumab and combined therapy in vivo highlights both common and distinct downstream effects to agents used alone or in combination, suggesting that complementary pathways may be involved.

Cancer and innate immune system interactions: translational potentials for cancer immunotherapy

Passive immunotherapy, including adoptive T-cell therapy and antibody therapy, has shown encouraging results in cancer treatment lately. However, active immunotherapy of solid cancers remains an elusive goal. It is now known that the human innate immune system recognizes pathogen-associated molecular patterns conserved among microbes or damage-associated molecular patterns released from tissue injuries to initiate adaptive immune responses during infection and tissue inflammation, respectively. In contrast, how the innate immune system recognizes endogenously arising cancer remains poorly understood at the molecular level, which poses a significant roadblock to the development of active cancer immunotherapy. We hereby review the current knowledge of how solid cancers directly and indirectly interact with cells of the human innate immune system, with a focus on the potential effect of such interactions to the resultant adaptive immune responses against cancer. We believe that understanding cancer and innate immune system interactions may allow us to better manipulate the adaptive immune system at the molecular level to develop effective active immunotherapy against cancer. Current and future perspectives in clinical development that exploits these molecular interactions are discussed.