Herceptin: increasing survival in metastatic breast cancer

Ethical Concerns of the Veterinarian in Relation to Experimental Animals and In Vivo Research

Animal experiments, despite their controversial nature, play an indispensable role in scientific advancement and led to numerous significant discoveries. The supervision of veterinarians in the realm of in vivo research holds immense importance. However, this particular aspect of veterinary medicine, distinct from their other activities, can pose ethical challenges. Veterinarians are entrusted with the prevention of diseases, healing, and pain elimination, yet in the case of animal experiments, they witness intentional suffering and death. This article evaluates the ethical and professional deontological aspects of this issue. It explores the historical evolution of human-animal (including experimental) relationships and discusses how deontology stems from the definition of ethics. The article also examines codes of ethics for veterinarians, providing illustrative examples. It highlights that the actions of veterinarians in this domain align with their deontology and emphasises the role of veterinarians in in vivo research as viewed within current legal frameworks. In conclusion, the veterinarian's participation in animal research is both ethically and deontologically justified, and it is also a legal requirement.

Confirmatory prediction-driven RCTs in comparative effectiveness settings for cancer treatment

BACKGROUND

Medical advances in the treatment of cancer have allowed the development of multiple approved treatments and prognostic and predictive biomarkers for many types of cancer. Identifying improved treatment strategies among approved treatment options, the study of which is termed comparative effectiveness, using predictive biomarkers is becoming more common. RCTs that incorporate predictive biomarkers into the study design, called prediction-driven RCTs, are needed to rigorously evaluate these treatment strategies. Although researched extensively in the experimental treatment setting, literature is lacking in providing guidance about prediction-driven RCTs in the comparative effectiveness setting.

METHODS

Realistic simulations with time-to-event endpoints are used to compare contrasts of clinical utility and provide examples of simulated prediction-driven RCTs in the comparative effectiveness setting.

RESULTS

Our proposed contrast for clinical utility accurately estimates the true clinical utility in the comparative effectiveness setting while in some scenarios, the contrast used in current literature does not.

DISCUSSION

It is important to properly define contrasts of interest according to the treatment setting. Realistic simulations should be used to choose and evaluate the RCT design(s) able to directly estimate that contrast. In the comparative effectiveness setting, our proposed contrast for clinical utility should be used.

Engineering nanosystems to overcome barriers to cancer diagnosis and treatment

Over the past two decades, multidisciplinary investigations into the development of nanoparticles for medical applications have continually increased. However, nanoparticles are still subject to biological barriers and biodistribution challenges, which limit their overall clinical potential. This has motivated the implementation of innovational modifications to a range of nanoparticle formulations designed for cancer imaging and/or cancer treatment to overcome specific barriers and shift the accumulation of payloads toward the diseased tissues. In recent years, novel technological and chemical approaches have been employed to modify or functionalize the surface of nanoparticles or manipulate the characteristics of nanoparticles. Combining these approaches with the identification of critical biomarkers provides new strategies for enhancing nanoparticle specificity for both cancer diagnostic and therapeutic applications. This review discusses the most recent advances in the design and engineering of nanoparticles as well as future directions for developing the next generation of nanomedicines.

Regulation of Signaling from the Epidermal Growth Factor Family

The epidermal growth factor (EGF) system has allowed chemists, biologists, and clinicians to improve our understanding of cell production and cancer therapy. The discovery of EGF led to the recognition of cell surface receptors capable of controlling the proliferation and survival of cells. The detailed structures of the EGF-like ligand and the responses of their receptors (EGFR-family) has revealed the conformational and aggregation changes whereby ligands activate the intracellular kinase domains. Biophysical analysis has revealed the preformed clustering of different EGFR-family members and the processes which occur on ligand binding. Understanding these receptor activation processes and the consequential cytoplasmic signaling has allowed the development of inhibitors which are revolutionizing cancer therapy. This Review describes the recent progress in our understanding of the activation of the EGFR-family, the effects of signaling from the EGFR-family on cell proliferation, and the targeting of the EGFR-family in cancer treatment.

Targeting of EGFR and HER2 with therapeutic antibodies and siRNA: a comparative study in glioblastoma cells

BACKGROUND

The epidermal growth factor receptors, EGFR (HER1) and HER2, have proven prognostic relevance in a variety of human malignancies and both are functionally involved in the molecular pathogenesis of malignant gliomas.

MATERIAL AND METHODS

We selectively inhibited EGFR and HER2 in glioblastoma cell lines via EGFR- and HER2-specific siRNAs and through the binding of the therapeutic antibodies cetuximab and trastuzumab. The expression of EGFR and HER2 was verified by real-time PCR and western blot analyses. We examined the growth rate, cell cycle distribution, cell migration, clonogenic survival, and radiosensitivity of U251MG and LN-229 glioblastoma cell lines to determine the physiological and cell biological effects of EGFR and HER2 targeting.

RESULTS

EGFR and HER2 targeting using the therapeutic antibodies cetuximab and trastuzumab had no effect on cellular growth rate, cell cycle distribution, cell migration, clonogenic survival, and radiosensitivity in the cell lines U251 and LN-229. In contrast, siRNA knock-down of EGFR and HER2, reduced the growth rate by 40-65 %. The knock-down of EGFR did not change the cell migration rate in the cell lines U251 and LN-229. However, knock-down of HER2 reduced the cell migration rate by 50 %. Radiobiological analysis revealed that EGFR knock-down induced no radiosensitization in U251MG and LN-229 cells. However, the knock-down of HER2 induced radiosensitization in U251MG cells.

CONCLUSION

The epidermal growth factor receptor HER2 is a promising anti-tumor target for the therapy of glioblastoma. HER2 targeting may represent a promising strategy to induce cell physiological and radiobiological anti-tumor effects in glioblastoma.

HER4 expression status correlates with improved outcome in both neoadjuvant and adjuvant Trastuzumab treated invasive breast carcinoma

Prognostic and predictive markers utilized in invasive breast carcinoma are limited and include ER, PR, Ki67, and ERBB2 (HER2). In the case of HER2, over-expression or amplification serves as eligibility for anti-HER2 based therapy, including trastuzumab (Herceptin®, Genentech). While clinical trials have shown trastuzumab improves overall survival and time to progression, an individual's response to anti-HER2 based therapy is highly variable. This suggests that, in a “uniform” HER2 positive population, additional markers could help in predicting patient outcome to therapy. Here we utilized a recently validated high-specificity HER4 antibody (E200) and generated a standard clinical HER4 scoring algorithm (HER4 H-Score) utilizing two breast carcinoma cohorts: 1) patients receiving neoadjuvant trastuzumab (n=47) and 2) patients receiving trastuzumab for metastatic disease (n=33). Our HER4 H-Score showed significant correlation with high sensitivity RT-qPCR performed on matched patients (p=<0.0001). In addition, patients with HER2/HER4 co-over-expression status showed a significant delay in development of metastasis after neo-adjuvant trastuzumab therapy (p= 0.04) and showed a significant improvement in progression free survival after adjuvant trastuzumab therapy (p=0.03). These findings suggest HER4 IHC, used in conjunction with a standard HER2 testing algorithm, could aid in predicting clinical outcome and help identify patients likely to show improved response to trastuzumab therapy.

Clinical trial designs for predictive biomarker validation: theoretical considerations and practical challenges

PURPOSE

Biomarkers can add substantial value to current medical practice by providing an integrated approach to prediction using the genetic makeup of the tumor and the genotype of the patient to guide patient-specific treatment selection. We discuss and evaluate various clinical trial designs for the validation of biomarker-guided therapy.

METHODS

Designs for predictive marker validation are broadly classified as retrospective (ie, using data from previously well-conducted randomized controlled trials [RCTs]) versus prospective (enrichment, unselected, hybrid, or adaptive analysis). We discuss the salient features of each design in the context of real trials.

RESULTS

Well-designed retrospective analysis from well-conducted prospective RCTs can bring forward effective treatments to marker-defined subgroups of patients in a timely manner (eg, KRAS and colorectal cancer). Enrichment designs are appropriate when preliminary evidence suggest that patients with or without that marker profile do not benefit from the treatments in question; however, this may sometimes leave questions unanswered (eg, trastuzumab and breast cancer). An unselected design is optimal where preliminary evidence regarding treatment benefit and assay reproducibility is uncertain (eg, epidermal growth factor receptor and lung cancer). Hybrid designs are appropriate when preliminary evidence demonstrate the efficacy of certain treatments for a marker-defined subgroup, making it unethical to randomly assign patients with that marker status to other treatments (eg, multigene assay and breast cancer). Adaptive analysis designs allow for prespecified marker-defined subgroup analyses of data from an RCT.

CONCLUSION

The implementation of these design strategies will lead to a more rapid clinical validation of biomarker-guided therapy.

Presence of HER4 associates with increased sensitivity to Herceptin in patients with metastatic breast cancer

INTRODUCTION

HER2 overexpression, or rather HER2 gene amplification, is indicative for Herceptin therapy in both metastatic and pre-metastatic breast cancer patients. Patient's individual sensitivity to Herceptin treatment, however, varies enormously and spans from effectual responsiveness over acquired insensitivity to complete resistance from the outset. Thus no predictive information can be deduced from HER2 determination so that molecular biomarkers indicative for Herceptin sensitivity or resistance need to be identified. Both ErbB receptor-dependent signalling molecules as well as HER2-related ErbB receptor tyrosine kinases, known to mutually interact and to cross-regulate each other are prime candidates to be involved in cellular susceptibility to Herceptin.

METHODS

Using immunohistochemistry and fluorescence in situ hybridisation, we retrospectively investigated primary breast cancer tissues from 48 patients who were under Herceptin treatment. We quantified the gene copy numbers of all HER receptors and evaluated their coexpression profile. Moreover the HER2 phosphorylation state, the ratio of native to truncated HER2, p27(kip1) and PTEN expression were objects of this study.

RESULTS

Above all markers investigated in this study Kaplan-Meier and Cox regression analysis revealed a significant positive impact of HER4 (co-)expression on overall survival from beginning of antibody therapy. Both HER4 expression and HER4 gene amplification emerged as independent prognostic markers in Herceptin-treated breast cancer patients and responsiveness to Herceptin turned out to be more efficient if tumour cells show HER4 expression.

CONCLUSIONS

Although HER4 is known to potentially exert a tumour cell killing activity and in turn to have a favourable impact in breast cancer patients we demonstrate here the first time that HER4 expression prolongs overall survival in Herceptin-treated patients. Elucidating HER4 receptor function in the context of Herceptin treatment will advance the design of highly efficient receptor targeting. By then we need to extend the analysis of breast cancer by allowing for HER2/HER4 coexpression by which valuable additional prognostic and predictive information might possibly be revealed.

Genomic advances and their impact on clinical trial design

Medical treatment for patients has historically been based on two primary elements: the expected outcome for the patient, and the ability of treatment to improve the expected outcome. The advance in genomic technologies has the potential to change this paradigm and add substantial value to current medical practice by providing an integrated approach to guide patient-specific treatment selection using the genetic make-up of the disease and the genotype of the patient. Specifically, genomic signatures can aid in patient stratification (risk assessment), treatment response identification (surrogate markers), and/or in differential diagnosis (identifying who is likely to respond to which drug(s)). Several critical issues, including scientific rationale, clinical trial design, marker assessment methods, cost and feasibility have to be carefully considered in the validation of biomarkers through clinical research before they can be routinely integrated into clinical practice. Here, we highlight the impact of genomic advances on various aspects of clinical trial design.

Clinical trial designs for predictive biomarker validation: one size does not fit all

Traditionally, anatomic staging systems have been used to provide predictions of individual patient outcome and, to a lesser extent, guide the choice of treatment in cancer patients. With targeted therapies, biomarkers have the potential for providing added value through an integrated approach to prediction using the genetic makeup of the tumor and the genotype of the patient for treatment selection and patient management. Specifically, biomarkers can aid in patient stratification (risk assessment), treatment response identification (surrogate markers), or differential diagnosis (identifying individuals who are likely to respond to specific drugs). In this study, we explore two major topics in relation to the design of clinical trials for predictive marker validation. First, we discuss the appropriateness of an enrichment (i.e., targeted) vs. an unselected design through case studies focusing on the clinical question(s) at hand, the strength of the preliminary evidence, and assay reproducibility. Second, we evaluate the efficiency (total number of events and sample size) of two unselected predictive marker designs for validation of a marker under a wide range of clinically relevant scenarios, exploring the impact of the prevalence of the marker and the hazard ratios for the treatment comparisons. The review and evaluation of these designs represents an essential step toward the goal of personalized medicine because we explicitly seek to explore and evaluate the methodology for the clinical validation of biomarker guided therapy.

EGFR family: structure physiology signalling and therapeutic targets

There are four members of the EGFR family: EGFR, erbB2, erbB3 and erbB4. These receptors form ligand-activated oligomers which regulate intracellular processes via an oligomeric tyrosine kinase scaffold. The receptors are activated when the extracellular domain undergoes a conformational change which facilitates either homo- or hetero-oligomerization with other family members. The absence of one EGFR family member leads to embryonic or early post-natal death due to implantation, central nervous system or cardiac defects. Many mouse models of defective or deficient EGFR family members are available for studying physiology and/or pathology of EGFR family members. Sophisticated antibody and kinase inhibitors which target different family members have been designed, produced. EGFR and erbB2 are frequently activated, over expressed or mutated in many common cancers and the antagonists and/or inhibitors of EGFR and/or erbB2 signalling have already been shown to have therapeutic benefits for cancer patients.

Cytogenetic analysis of HER1/EGFR, HER2, HER3 and HER4 in 278 breast cancer patients

INTRODUCTION

The HER (human EGFR related) family of receptor tyrosine kinases (HER1/EGFR (epidermal growth factor receptor)/c-erbB1, HER2/c-erbB2, HER3/c-erbB3 and HER4/c-erbB4) shares a high degree of structural and functional homology. It constitutes a complex network, coupling various extracellular ligands to intracellular signal transduction pathways resulting in receptor interaction and cross-activation. The most famous family member is HER2, which is a target in Herceptin therapy in metastatic status and also in adjuvant therapy of breast cancer in the event of dysregulation as a result of gene amplification and resulting protein overexpression. The HER2-related HER receptors have been shown to interact directly with HER2 receptors and thereby mutually affect their activity and subsequent malignant growth potential. However, the clinical outcome with regard to total HER receptor state remains largely unknown.

METHODS

We investigated HER1-HER4, at both the DNA and the protein level, using fluorescence in situ hybridisation (FISH) probes targeted to all four receptor loci and also immunohistochemistry in tissue microarrays derived from 278 breast cancer patients.

RESULTS

We retrospectively found HER3 gene amplification with a univariate negative impact on disease-free survival (hazard ratio 2.35, 95% confidence interval 1.08 to 5.11, p = 0.031), whereas HER4 amplification showed a positive trend in overall and disease-free survival. Protein expression revealed no additional information.

CONCLUSION

Overall, the simultaneous quantification of HER3 and HER4 receptor genes by means of FISH might enable the rendering of a more precise stratification of breast cancer patients by providing additional prognostic information. The continuation of explorative and prospective studies on all HER receptors will be required for an evaluation of their potential use for specific therapeutic targeting with respect to individualised therapy.

Cytoplasmic expression of c-erb-B2 in endometrial carcinomas

BACKGROUND

The aim of this study was to investigate the expression of c-erb-B2 in endometrial cancer with attention to both membranous and cytoplasmic staining, and to elucidate the significance of cytoplasmic signaling.

MATERIALS AND METHODS

c-erb-B2 reactivity was assessed by immunohistochemistry in 110 patients using a polyclonal antibody, and evaluated semiquantitatively according to the percentage of cells demonstrating membranous or diffuse cytoplasmic staining. Correlation was made with tumor stage, grade, myometrial invasion, histologic type, and disease outcome.

RESULTS

c-erb-B2 overexpression, indicated by membranous and cytoplasmic staining of at least 10% of the tumor cells, was found in 47 (42.7%) cases. Cytoplasmic expression of c-erb-B2 was observed more frequently than membranous (69.1 vs. 5.5%). Synchronous cytoplasmic and membranous signaling was noticed in 7.9% of cases. Interestingly, patients with cytoplasmic c-erb-B2-positive tumors had a significantly shorter survival (p = 0.047).

CONCLUSIONS

These results indicate that c-erb-B2 is a specific marker of endometrial cancer. It is also an independent prognostic indicator of poor outcome. Cytoplasmic staining is as important as membranous staining, and is also a specific finding.

Brain metastases: old problem, new strategies

Brain metastases from breast cancer are a common complication of the disease and alter the management of patients more than any other site of distant progression. Certain subgroups of patients are at high risk for developing CNS disease, warranting targeted research and perhaps screening for occult disease. Data from studies that include other solid tumor histologies provide the bulk of supporting evidence for the use of therapies, such as steroids, antiepileptic drugs, surgery, and radiation. However, there are several issues specific to brain metastases from breast cancer illustrating that this disease should be considered pathophysiologically distinct, and future research should be tailored accordingly.

Preparation and evaluation of paclitaxel-loaded PEGylated immunoliposome

A sterically stabilized paclitaxel-loaded liposome tailored to target human breast cancer cells was developed, thereby promoting the efficiency of intracellular delivery of paclitaxel through receptor-mediated endocytosis. Results indicated that the targeting moiety (thiolated Herceptin) was successfully coupled to the distal reactive maleimide terminus of the poly (ethylene glycol)-phospholipid conjugate as well as being incorporated in the liposomal bilayers. The particle size of the PEGylated immunoliposome was maintained at about 200 nm. Confocal microscopy studies showed that the PEGylated immunoliposome was uptaken into the interior of the tumor cell through the receptor-mediated endocytosis pathway. The PEGylated immunoliposome showed substantially higher cellular uptake than the PEGylated liposome in cancer cells (BT-474 and SK-BR-3) over-expressing human epidermal growth factor receptor 2 (HER2) at 37 degrees C, while no difference was found in low HER2 expressing cells (MDA-MB-231) nor at low temperature (4 degrees C). Pharmacokinetics of paclitaxel in the PEGylated immunoliposome was compared with that in Taxol and in the PEGylated liposome in rats. The circulating time of paclitaxel in the PEGylated immunoliposome was prolonged compared to Taxol while slightly shortened than that in the PEGylated liposome. Therefore, the paclitaxel-loaded PEGylated immunoliposome using Herceptin could serve as a promising model for future tumor specific cancer therapy of HER2 over-expressing breast cancers.

Prolonged Survival of Patients Receiving Trastuzumab beyond Disease Progression for HER2 Overexpressing Metastatic Breast Cancer (MBC)

BACKGROUND

The aim of this retrospective analysis was to evaluate the impact of trastuzumab-based regimens on the survival of patients with HER2-overexpressing metastatic breast cancer (MBC). The study specifically focussed on the influence of the continuation of trastuzumab-based treatment despite tumor progression on survival.

PATIENTS AND METHODS

Patients with HER2 overexpressing MBC were included in this retrospective analysis. HER2 overexpression was determined by the immunohistochemical staining score (DAKO Hercep Test). Trastuzumab was applied at a loading dose of 4 mg/kg and a maintenance dose of 2 mg/kg.

RESULTS

Among 136 HER2 overexpressing patients (DAKO score 3+), 66 patients received first-line trastuzumab, 47 patients received trastuzumab as second-line therapy and 23 patients received trastuzumab beyond disease progression. There was no significant difference regarding the duration of trastuzumab-based treatment (first-line: 29.5 weeks vs. second-line: 25 weeks). Moreover, there was no difference in the response rate (first-line: 37.9% vs. second-line: 35.7%) or the median survival (p = 0.47 log rank). Patients who received = 2 trastuzumab-based regimens for MBC survived significantly longer compared to those who had received only 1 regimen (= 2 regimens: 62.4 months vs. 1 regimen: 38.5 months; p = 0.01 log rank).

CONCLUSIONS

Trastuzumab is highly effective in the treatment of HER2 overexpressing MBC. Compared to historical controls, overall survival appears to be markedly prolonged, particularly in patients who received sequential trastuzumab-based treatment beyond disease progression.

Characteristics of patients with brain metastases receiving trastuzumab for HER2 overexpressing metastatic breast cancer

The intention of this retrospective analysis was to describe the characteristics of patients with brain metastasis (BM) receiving trastuzumab for HER2 overexpressing metastatic breast cancer (MBC). A specific focus was the relation of BM occurrence to remission status of visceral disease during trastuzumab treatment. Patients with MBC presenting between March 2000 and May 2004 were included in this retrospective analysis. HER2 overexpression was determined by immunohistochemistry (IHC; DAKO Hercep Test). Trastuzumab was applied at a loading dose of 4 mg/kg and a maintenance dose of 2 mg/kg. Among 136 HER2 overexpressing patients (DAKO score 3+), 42 patients with BM were identified during follow-up (30.9%). Negative hormone receptor expression (estrogen receptor (ER) and progesterone receptor (PgR)) correlated with incidence of BM (42.8% vs. 23.4%; P=0.01). There was no correlation of the development of BM with regard to tumor grading and patient age. In patients who developed BM, the median interval between visceral and brain metastasis was 14 months (range 0-69 months). At the time BM was diagnosed, 14 out of 42 patients responded to trastuzumab-based treatment schedules (OR: 33.3%, 95% CI 18.5-48.2%). Median survival from diagnosis of BM was 13 months (range 0-60 months). The median overall survival calculated from first diagnosis of metastasis was not significantly shorter in patients with BM than in patients without BM (37 vs. 47 months; P=0.07 log rank). Trastuzumab is highly effective for the treatment of liver and lung metastasis in HER2 overexpressing patients, while it is apparently ineffective for treating or preventing BM. Since one third of HER2 overexpressing patients with MBC developed BM despite effective trastuzumab treatment, new treatment strategies and closer surveillance may be warranted for these patients.