Kinetics of serum HER-2/neu changes in patients with HER-2-positive primary breast cancer after initiation of primary chemotherapy

Application of population physiologically based pharmacokinetic modelling to optimize target expression and clearance mechanisms of therapeutic monoclonal antibodies

AIMS

To use population physiologically based pharmacokinetic (PopPBPK) modelling to optimize target expression, kinetics and clearance of HER1/2 directed therapeutic monoclonal antibodies (mAbs). Thus, to propose a general workflow of PopPBPK modelling and its application in clinical pharmacology.

METHODS

Full PBPK model of pertuzumab (PTZ) was developed in patient population using Simcyp V21R1 incorporating mechanistic targeted-mediated drug disposition process by fitting known clinical PK and sparse receptor proteomics data to optimize target expression and kinetics of HER2 receptor. Trastuzumab (TTZ) PBPK modelling was used to validate the optimized HER2 target. Additionally, the simulator was also used to develop a full PBPK model for the HER1-directed mAb cetuximab (CTX) to assess the underlying targeted-mediated drug disposition-independent elimination mechanisms.

RESULTS

HER2 final parameterisation coming from the PBPK modelling of PTZ was successfully cross validated through PBPK modelling of TTZ with average fold error (AFE), absolute AFE and percent prediction error values for area under the concentration-time curve (AUC) and maximum plasma concentration (Cmax ) of 1.13, 1.16 and 16, and 1.01, 1.07 and 7, respectively. CTX PBPK model performance was validated after the incorporation of an additional systemic clearance of 0.033 L/h as AFE and absolute AFE showed an acceptable predictive power of AUC and Cmax with percent prediction error of 13% for AUC and 10% for Cmax .

CONCLUSIONS

Optimisation of both system and drug related parameters were performed through PBPK modelling to improve model performance of therapeutic mAbs (PTZ, TTZ and CTX). General workflow was proposed to develop and apply PopPBPK to support clinical development of mAbs targeting same receptor.

Challenges in Detection of Serum Oncoprotein: Relevance to Breast Cancer Diagnostics

Breast cancer is a highly prevalent malignancy that shows improved outcomes with earlier diagnosis. Current screening and monitoring methods have improved survival rates, but the limitations of these approaches have led to the investigation of biomarker evaluation to improve early diagnosis and treatment monitoring. The enzyme-linked immunosorbent assay (ELISA) is a specific and robust technique ideally suited for the quantification of protein biomarkers from blood or its constituents. The continued clinical relevancy of this assay format will require overcoming specific technical challenges, including the ultra-sensitive detection of trace biomarkers and the circumventing of potential assay interference due to the expanding use of monoclonal antibody (mAb) therapeutics. Approaches to increasing the sensitivity of ELISA have been numerous and include employing more sensitive substrates, combining ELISA with the polymerase chain reaction (PCR), and incorporating nanoparticles as shuttles for detection antibodies and enzymes. These modifications have resulted in substantial boosts in the ability to detect extremely low levels of protein biomarkers, with some systems reliably detecting antigen at sub-femtomolar concentrations. Extensive utilization of mAb therapies in oncology has presented an additional contemporary challenge for ELISA, particularly when both therapeutic and assay antibodies target the same protein antigen. Resolution of issues such as epitope overlap and steric hindrance requires a rational approach to the design of diagnostic antibodies that takes advantage of modern antibody generation pipelines, epitope binning techniques and computational methods to strategically target biomarker epitopes. This review discusses technical strategies in ELISA implemented to date and their feasibility to address current constraints on sensitivity and problems with interference in the clinical setting. The impact of these recent advancements will depend upon their transformation from research laboratory protocols into facile, reliable detection systems that can ideally be replicated in point-of-care devices to maximize utilization and transform both the diagnostic and therapeutic monitoring landscape.

Serum HER2 levels predict treatment efficacy and prognosis in patients with HER2-positive breast cancer undergoing neoadjuvant treatment

Background

Controversy remains regarding the predictive and prognostic value of serum human epidermal growth factor receptor 2 (HER2) in breast cancer. The purpose of this retrospective study was to determine the clinical utility and efficacy of serum HER2 (sHER2) in predicting treatment response and prognosis in patients with HER2-positive breast cancer undergoing neoadjuvant chemotherapy and trastuzumab treatment.

Methods

A total of 309 HER2-positive breast cancer patients diagnosed at Fudan University Shanghai Cancer Center from July 2015 to January 2019 were analyzed. Baseline sHER2 levels were obtained for all patients and sHER2 levels were collected after 2 cycles of treatment in 208 patients. A sHER2 level ≥15 ng/mL was regarded as "high expression" and sHER2 <15 ng/mL was regarded as "low expression". Outcome measures of treatment efficacy and prognosis were pathological complete response (pCR) and invasive disease-free survival (iDFS), respectively.

Results

In patients with high baseline sHER2, more were ER-negative (P=0.029), had larger tumor size (P=0.006), more advanced clinical stage (P=0.002), higher Miller-Payne grade (P=0.024) and higher likelihood of iDFS events (P=0.015). Patients with high sHER2 levels after 2 cycles of treatment had lower pCR rates (P=0.038), higher Miller-Payne grade (P=0.013) and higher likelihood of iDFS events (P=0.003). Kaplan-Meier analysis showed significant differences in iDFS between patients with high and low sHER2 levels at baseline (P=0.019) and after 2 cycles of treatment (P=0.000). Further analyses according to cancer subtypes found baseline sHER2 to be significantly correlated with the iDFS of Luminal B patients (p=0.002), while sHER2 levels after 2 cycles of treatment was significantly correlated with the iDFS of HER2-enriched patients (P=0.000). Univariate analysis showed significant association between iDFS and tumor size (P=0.026), lymph node status (P=0.008), clinical stage (P=0.031), baseline sHER2 (P=0.024), overall tumor response (P=0.011), pCR (P=0.043) and Miller-Payne grade (P=0.001). Multivariate analysis found Miller-Payne grade (P=0.037) to be significantly associated with iDFS.

Conclusions

Our results demonstrate the clinical value of sHER2 in a population of Chinese breast cancer patients, suggesting that sHER2 levels after 2 cycles of neoadjuvant therapy may be more predictive of treatment outcomes and that the prognostic value of sHER2 may be time point and subtype dependent.

Antigen Mass May Influence Trastuzumab Concentrations in Cerebrospinal Fluid After Intrathecal Administration

Intravenous administration of monoclonal antibodies leads to low concentrations in the central nervous system, which is a serious concern in neuro-oncology, especially in leptomeningeal carcinomatosis of HER2-overexpressing breast cancer. Case reports of i.t. administrations of trastuzumab have shown promising results in these patients but dosing regimens are empirical in absence of pharmacokinetic (PK) study. With a population PK approach, we described the fate of trastuzumab after i.t. administration in 21 women included in a phase I-II clinical trial. Trastuzumab was administered by i.t. route every week for 8 weeks and both cerebrospinal fluid (CSF) and serum were sampled to measure trough concentrations. Some patients showed noticeable CSF concentration fluctuations predicted using a target-mediated drug disposition. This target was latent and produced with a delayed feedback. Apparent volumes of distribution were close to physiological volumes (V₁  = 3.25 L, V₂  = 0.644 L, for serum and CSF, respectively). Estimated (constant) transfer from serum to CSF was very slow (k₁₂  = 0.264 mg/day) whereas estimated half-life of transfer from CSF to serum was rapid (2.2 days). From the individual parameters of patients, a single i.t. administration of 150 mg of trastuzumab corresponded to median mean residence times of 3.8 days and 15.6 days in CSF and serum, respectively. Survival without neurological relapse was not related to trastuzumab exposure. This study confirms that transfer of trastuzumab from serum to CSF is very limited and that this monoclonal antibody, when administered by i.t. route, is rapidly transferred to the serum.

The extracellular domain of Her2 in serum as a biomarker of breast cancer

Breast cancer is a major health problem worldwide. In ~15% of breast cancers, the epidermal growth factor receptor HER2, a transmembrane protein, is overexpressed. This HER2 overexpression is associated with an aggressive form of the disease and a poor clinical prognosis. The extracellular domain (ECD) of HER2 is released into the blood by a proteolytic mechanism known as "ECD shedding". This proteolytic shedding leaves a constitutively active truncated receptor in the membrane that is 10-100-fold more oncogenic than the full-length receptor and promotes the growth and survival of cancer cells. Shedding of the HER2 ECD is increased during metastasis: whereas 15% of primary breast cancer patients have elevated levels of serum HER2 ECD (sHER2 ECD), the levels reach 45% in patients with metastatic disease. Thus, sHER2 ECD has been proposed as a promising biomarker for cancer recurrence and for monitoring the disease status of patients overexpressing HER2. Nevertheless, in 2016, the American Society of Clinical Oncology advises clinicians not to use soluble HER2 levels to guide their choice of adjuvant therapy for patients with HER2-positive breast cancer, because the evidence was considered not strong enough. Currently, biomarkers such as carcinoembryonic antigen and cancer antigen 15-3 are widely used to monitor metastatic breast cancer disease even if the level of evidence of clinical impact of this monitoring is poor. In this article, we review the evidence that sHER2 ECD might be used in some situations as a biomarker for breast cancer. Although this serum biomarker will not replace the direct measurement of tumor HER2 status for diagnosis of early-stage tumors; it might be especially useful in metastatic disease for prognosis, as an indicator of cancer progression and of therapy response, particularly to anti-HER2 therapies. Owing to these data, sHER2 ECD should be considered as a promising biomarker to detect cancer recurrence and metastasis.

Circulating Tumor Cells in HER-2 Positive Metastatic Breast Cancer Patients Treated with Trastuzumab and Chemotherapy

The detection of circulating tumor cells (CTCs) in peripheral blood may have important prognostic and predictive implications in breast cancer treatment. A limitation in this field has been the lack of a validated method of accurately measuring CTCs. While sensitivity has improved using RT-PCR, specificity remains a major challenge. The goal of this paper is to present a sensitive and specific methodology of detecting CTCs in women with HER-2-positive metastatic breast cancer, and to examine its role as a marker that tracks disease response during treatment with trastuzumab-containing regimens.

The study included patients with HER-2-positive metastatic breast cancer enrolled on two different clinical protocols using a trastuzumab-containing regimen. Serial CTCs were measured at planned time points and clinical correlations were made. Immunomagnetic selection of circulating epithelial cells was used to address the specificity of tumor cell detection using cytokeratin 19 (CK19). In addition, the extracellular domain of the HER-2 protein (HER-2/ECD) was measured to determine if CTCs detected by CK19 accurately reflect tumor burden.

The presence of CTCs at first restaging was associated with disease progression. We observed an association between CK19 and HER-2/ECD. The association of HER-2/ECD with clinical response followed a similar pattern to that seen with CK19. Finally, the absence of HER-2/ECD at best overall response and a change of HER-2/ECD from positive at baseline to negative at best overall response was associated with favorable treatment response.

Our study supports the prognostic and predictive role of the detection of CTCs in treatment of HER-2-positive metastatic breast cancer patients. The association between CK19 and markers of disease burden is in line with the concept that CTCs may be a reliable measure of tumor cells in the peripheral blood of patients with metastatic breast cancer. The association of CTCs at first restaging with treatment failure indicates that CTCs may have a role as surrogate markers to monitor treatment response.

A prospective study to assess the clinical utility of serum HER2 extracellular domain in breast cancer with HER2 overexpression

Purpose

We explored the clinical utility of human epidermal growth factor receptor-2 extracellular domain (HER2/ECD) in patients treated for an invasive breast cancer with HER2 overexpression.

Methods

We prospectively studied HER2/ECD levels in the sera of 334 women included between 2007 and 2014, all treated with trastuzumab. HER2/ECD levels were measured at diagnosis, during treatments, and along the follow-up. We investigated the relationship of HER2/ECD with other clinicopathological parameters at diagnosis, its prognosis value, and its utility during the monitoring of a neoadjuvant treatment and the follow-up.

Results

Elevated HER2/ECD at diagnosis correlated positively with parameters associated with tumor aggressiveness. Disease-free survival of non-metastatic patients was significantly shorter in patients with high HER2/ECD at diagnosis (HR = 13.6, 95 % CI 1.6–113.6, P < 0.0001). Progression-free survival of metastatic patients was better for patients with low HER2/ECD (HR = 2.6, 95 % CI 1.2–5.3, P = 0.033). A multivariate analysis revealed that HER2/ECD level at diagnosis was an independent prognosis factor. During neoadjuvant therapy, a significant decrease in HER2/ECD was reported only for the complete histological response group (P = 0.031). During the follow-up, HER2/ECD helped predict relapse, disease progression, and metastases before imaging in 18.6 % cases of the studied cohort.

Conclusions

HER2/ECD is a prognosis factor that is valuable in evaluating the neoadjuvant treatment efficiency. HER2/ECD also appears to be a helpful surveillance biomarker for the early diagnosis of relapses and to predict the fate of metastases. This study brings evidences to support the use of HER2/ECD in the management of HER2-positive breast cancer.

Circulating oncoproteins HER2/neu, EGFR and CAIX (MN) as novel cancer biomarkers

Pharmaceutical companies have developed targeted therapies such as trastuzumab and lapatinib for human epidermal growth factor receptor (HER)2/neu-positive tumors, while others have developed antiepidermal growth factor receptor (EGFR) therapies, such as tarceva and erbitux for EGFR-positive tumors. A drug called rencarex is targeted to an oncoprotein designated carbonic anhydrase IX (CAIX), which is being evaluated in renal cell carcinoma patients. Based on these targeted therapeutic approaches, this review describes clinical research studies performed with enzyme-linked immunosorbent assays specific for the circulating oncoproteins, HER2/neu, EGFR and CAIX. These circulating biomarkers have the potential to be used in conjunction with the specific targeted therapies for patient selection, monitoring and management. With the variety of new therapeutic options, the major challenge ahead will be to select the appropriate therapy or combinations of therapies for each patient. Specific biomarker tests, either alone or in panels, will be needed at the appropriate time in the course of disease to ensure that patients receive the right drug at the right time. These tests will also be valuable in monitoring the efficacy of the targeted therapies. A circulating biomarker such as serum HER2/neu may be able to specifically identify patients with progressing HER2/neu-positive disease and provide the information needed by physicians to choose from the variety of HER2/neu-targeted therapies that will soon be available to cancer patients.

Serum thymidine kinase 1 levels predict cancer-free survival following neoadjuvant, surgical and adjuvant treatment of patients with locally advanced breast cancer

In this study, the use of serum thymidine kinase 1 protein (STK1p) concentration for the prognosis of the overall survival of patients with locally advanced breast cancer (n=51) following routine treatment (neoadjuvant treatment, surgery and chemotherapy) was investigated. The patients were followed up for 44 months and the STK1p values were determined by a high-sensitivity enhanced chemiluminescence (ECL) dot blot assay. The variables investigated in relation to metastasis and survival were STK1p, clinical stage, tumor size and age, by the Kaplan-Meier method, the log-rank test and Cox uni- and multivariate analyses. Patients with high STK1p values (≥2.0 pM) 3–6 months after surgery exhibited a positive correlation to clinical stage, tumor size, occurrence of metastasis and survival. The hazard risk for the development of metastatic disease and mortality among breast cancer patients was 11–12 times higher in patients with high compared to those with low STK1p values (<2.0 pM). Notably, patients with stage III/IV disease and low STK1p values exhibited statistically significantly improved survival compared to patients with high STK1p values. A multivariate Cox analysis demonstrated that the STK1p levels 6 months after surgery was the only independent prognostic factor for metastasis and survival. In conclusion, STK1p is a prognostic marker in patients with locally advanced breast cancer and it may help identify a subgroup of stage III/IV patients with improved cancer-free survival expectancy, enabling personalized treatment.

Predictive Factors of Response in HER2-Positive Breast Cancer Treated by Neoadjuvant Therapy

Since 2005, major progresses have been made in the neoadjuvant treatment of HER2-positive breast cancer. Trastuzumab introduction associated with chemotherapy has been the first major step leading to the improvement of the complete pathological response rate and, like in the adjuvant studies, better survivals. Dual HER2 blockade has been the next step and trastuzumab is associated now with other anti-HER2 therapies like lapatinib or pertuzumab, the latter being much more easy to use in combination with chemotherapy. Additional knowledge is necessary to better define within the HER2 tumor subgroup which patients could benefit more from targeted therapies. Different biomarkers have been studied to predict the response after anti-HER2 neoadjuvant therapies but until now none has been validated.

Effect of HER2 status on distant recurrence in early stage breast cancer

It has long been recognized in breast cancer that the effect of hormone receptor (HR) status on recurrence rates varies over time and with the site of recurrence. However, there is relatively little in the literature on the effect of human epidermal growth factor receptor 2 (HER2) on recurrence patterns. We wanted to assess whether the effect of HER2 status on the risk of distant recurrence changed over time and/or with HR status and whether these relationships varied with site of recurrence. We retrospectively studied 11,011 women diagnosed with stage I, II, or III breast cancer after 1997 who had data on HR status and HER2 status. 20 % were HR negative and HER2 negative (so-called "triple-negatives"), 7 % were HR negative and HER2 positive, 64 % were HR positive and HER2 negative, and 10 % were HR positive and HER2 positive. The estimated overall cumulative incidence of developing distant metastases is 20 % at 4 years, 30 % at 8 years, and 36 % at 12 years. The 12-year cumulative incidence was 23 % for bone, 16 % for liver, 14 % for lung, 13 % for distant lymph node, 10 % for brain, and 8 % for pleura. After adjusting for potential confounding factors, the nature of the effect of HER2 on recurrence rates was found to differ markedly across the sites of recurrence. For brain and pleura recurrences, the effect of HER2 depended on HR status in ways that significantly changed over time. For bone recurrences, the effect of HER2 did not depend on HR status, but did change significantly over time. For liver and distant lymph node recurrences, there was a significant effect of HER2 status that did not change with time or HR status. For lung recurrences, rates did not significantly vary with HER2 status.

Predictive value of HER2 serum levels in patients treated with lapatinib or trastuzumab -- a translational project in the neoadjuvant GeparQuinto trial

BACKGROUND

We were able to demonstrate a predictive value of serum HER2 (sHER2) in patients receiving trastuzumab in the neoadjuvant GeparQuattro trial. However, the role of sHER2 in patients receiving neoadjuvant therapy (NT) with lapatinib is still unclear.

METHODS

The neoadjuvant GeparQuinto trial compared trastuzumab vs lapatinib in addition to chemotherapy in HER2-positive primary breast cancer patients. The sHER2 levels were measured by enzyme-linked immunosorbant assay in 210 patients, of whom 109 (52%) patients received trastuzumab and 101 (48%) lapatinib at three different time points.

RESULTS

Twenty-two percent of patients had elevated baseline sHER2 levels (>15 ng ml⁻¹). A decrease of sHER2 levels (>20%) in the trastuzumab and lapatinib-treated group during NT was seen in 44% and 24% of the patients, an increase of sHER2 levels (>20%) was seen in 6% and 41% of patients, respectively. Higher pre-chemotherapy sHER2 levels were associated with higher pathological complete remission (pCR) rates in the entire study cohort (OR 1.8, 95% CI 1.02-3.2, P=0.043). A decline of sHER2 levels (>20%) during NT was a predictor for pCR in the lapatinib-treated patient group (OR: 11.7, 95% CI 1.3-110, P=0.031).

CONCLUSION

Results of this study demonstrate that sHER2 levels change differently during NT depending on the anti-HER2 treatment strategy. Elevated baseline sHER2 levels (>15 ng ml⁻¹) and a decrease of sHER2 levels (>20%) early after therapy initiation are both relevant criteria to predict response to lapatinib-based treatment.

The Predictive Value of Serum HER2/neu for Response to Anthracycline-Based and Trastuzumab-Based Neoadjuvant Chemotherapy

PURPOSE

Little information exists about the possible influence of serum HER2/neu on response to chemotherapy. We propose that the assessment of serum HER2/neu in a pretreatment serum sample may be useful in predicting response to neoadjuvant chemotherapy.

METHODS

All breast cancer patients were tested by immunohistochemical stain and fluorescent in situ hybridization for HER2/neu before treatment. Serum HER2/neu was twice measured by chemiluminescence immunoassay (ADVIA Centaur System) before neoadjuvant chemotherapy and before operation. The cut-off value was 10.2 mg/mL, according to the previous study. Pathologic complete response (pCR) was considered as no residual tumor or remnant ductal carcinoma in situ; partial response (PR) was a less than 50% decrease in maximal diameter in pathologic tumor size. The measurements for the changes of serum HER2/neu were defined as pretreatment HER2/neu-preoperation HER2/neu. We compared the change of serum HER2/neu between that from before chemotherapy and that after chemotherapy, the pathologic complete response and partial response, and the trastuzumab group and anthracycline group.

RESULTS

Serum HER2/neu was decreased after neoadjuvant chemotherapy. The mean of serum HER2/neu in prechemotherapy was 15.4±9.0 ng/mL, and that of postchemotherapy was 10.5±2.0 ng/mL (p=0.04). Pathologic response was correlated with the change of serum HER2/neu (PR, 11.7±2.2 ng/mL vs. pCR, 23.7±13.1 ng/mL; p=0.01). In the trastuzumab group, pCR was marginally correlated with the change of serum HER2/neu (PR, 0.8±0.84 ng/mL vs. pCR, 21.1±13.2 ng/mL; p=0.08).

CONCLUSION

Serum HER2/neu levels during treatment were associated with pathologic response in patients receiving neoadjuvant chemotherapy, particularly, in a trastuzumab-based regimen. The change of serum HER2/neu levels may serve in monitoring neoadjuvant therapy in HER2/neu-overexpressed breast cancer.

Challenges in the clinical utility of the serum test for HER2 ECD

Approximately 15-30% of breast cancers over-express the HER2/neu receptor. Historically, over-expression of HER2/neu has been identified using IHC or FISH, both of which are invasive approaches requiring tissue samples. Recent evidence has shown that some tumors identified as "negative" using these methods can respond to HER2/neu targeted therapy. Shedding of the extracellular domain (ECD) of the receptor into the circulation has led to the development of a serum test of HER2 ECD as an additional approach to probe HER2/neu overexpression. The serum test will be able to monitor the dynamic changes of HER2 status over the course of disease progression. Some studies further suggest that the serum HER2 ECD level and its change may serve as a biomarker to reflect patients' response to therapy. Yet more than 10years after the first serum HER2 ECD test was approved by the FDA, serum HER2 testing has yet to be widely used in clinical practice. In this article we will review the progress of the serum HER2 ECD test and discuss some obstacles impeding its incorporation into broad clinical practice. We will also discuss recent improvements in the sensitivity and specificity of the assay that offer some hope for the future of serum HER2 test.

High serum HER2 extracellular domain levels: correlation with a worse disease-free survival and overall survival in primary operable breast cancer patients

PURPOSE

High serum human epidermal growth factors receptor-2 (HER2) extracellular domain (ECD) has been identified as an independent prognostic indicator of poor prognosis in metastatic breast cancer. However, its prognostic value in primary operable breast cancer was still controversial. We aim to investigate the correlation between serum HER2 ECD levels and tissue HER2 status, the association between serum HER2 ECD levels and clinicopathological characteristics, and their impacts on disease-free survival (DFS) and overall survival (OS) in primary operable breast cancer.

METHODS

Two hundred and fifty-two primary operable breast cancer patients pretreated from 2002 to 2009 in Sun Yat-Sen University Cancer Center were enrolled in this study. Serum HER2 ECD was measured by chemiluminescent assay, and tissue HER2 status was accessed by immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH) assay.

RESULTS

There was a significant correlation between serum HER2 ECD levels and HER2 tissue status (P < 0.001, R = 0.36). High serum HER2 ECD levels (≥15 ng/mL) were significantly associated with age (≥35 years) (P = 0.028), postmenopausal status (P < 0.001), stage III (P < 0.001), tumor size (≥2 cm) (P < 0.001), lymph node involvement (P < 0.001), negative estrogen receptor (P = 0.005), and progesterone receptor status (P = 0.001). Multivariate analysis showed that high serum HER2 ECD level was an independent prognostic factor of worse DFS (P = 0.014) and OS (P = 0.014) in primary operable breast cancer patients.

CONCLUSION

Serum HER2 ECD level can reflect tissue HER2 status and can be an independent prognostic indicator for primary operable breast cancer patients.

Serum HER2 testing in patients with HER2-positive breast cancer: the death knell tolls

Determination of the human epidermal growth factor receptor 2 (HER2; also known as ERBB2) status of breast tumours is emphasised in various national guidelines as a necessary step for the diagnosis of breast cancer. As an alternative to tissue-based diagnostic methods, there has been substantial interest in the establishment of an easily accessible serum-based alternative that could be used for prognosis and diagnosis. Detection of serum-soluble-HER2 extracellular domain (ECD) and establishment of its potential clinical usefulness has created much debate. We assessed whether identification of circulating concentrations of HER2 ECD have clinical usefulness for management of patients with HER2-positive breast cancer. We examined data from 63 studies of patients with breast cancer. Prevalence of increased concentrations varied greatly between studies. Some studies showed significant associations between raised concentrations and poor prognosis, poor response to treatments including trastuzumab, or tumour characteristics associated with aggressive disease, whereas others did not. Examination of existing data showed that concentrations of HER2 ECD are not consistently related to patient outcomes; therefore, there is insufficient evidence to support the clinical use of serum HER2 ECD testing. Design and execution of future large-scale trials to investigate the clinical use of HER2 ECD testing, in view of the progressive non-supportive evidence, is not recommended. Oncologists should continue to adhere to national guidelines for determining HER2 status. Furthermore, oncologists should continue to use clinical parameters when making decisions about initiation, continuation, and discontinuation of HER2-targeted treatments.

Identifying responders to trastuzumab therapy in breast cancer

In breast cancer, HER2-targeted therapy with trastuzumab has gained significant attention, owing to the dramatic response observed in a subset of HER2-positive patients. The mechanisms of action are complex and not fully understood, and much effort has been spent in order to identify responders. Good patient management, side effects of the humanized monoclonal antibody and socioeconomics all demand that the drug should be administered only to the patients who will benefit from it. This has been a difficult task and contributions to solve it have been proposed from a variety of research. In this article we describe some of these contributions based on the literature and provide our viewpoint as to which identifiers will emerge in the following decade.

Evaluation of changes in serum protein profiles during neoadjuvant chemotherapy in HER2-positive breast cancer using an LC-MALDI-TOF/MS procedure

Comparison of protein profiles of sera acquired before and after preoperative chemotherapy for breast cancer may reveal tumor markers that could be used to monitor tumor response. In this study, we analyzed pre- and post-chemotherapy protein profiles of sera from 39 HER2-postive breast cancer patients (n=78 samples) who received 6 months of preoperative chemotherapy using LC-MALDI-TOF/MS technology. We detected qualitative and quantitative differences in pair-wise comparison of pre- and post chemotherapy samples that were different in patients who achieved pathological complete response (pCR, n=21) compared with those with residual disease (n=18). We identified 2329 and 3152 peaks as differentially expressed in the pre-chemotherapy samples of the responders and non-responders. Comparison of matching pre- and post-chemotherapy samples identified 34 (32 decreased, two increased) and 304 peaks (157 decreased, 147 increased) that significantly changed (p<0.01, false discovery rate ≤ 20%) after treatment in responders and non-responders, respectively. The top 11 most significantly altered peptide peaks with the greatest change in intensity were positively identified. These corresponded to eight proteins including α-2-macroglobulin, complement 3, hemopexin, and serum amyloid P in the responder group and chains C and A of apolipoprotein A-I, hemopexin precursor, complement C, and amyloid P component in the non-responding groups. All proteins decreased after therapy, except chain C apolipoprotein A and hemopexin precursor that increased. These results suggest that changes in serum protein levels occur in response to chemotherapy and these changes partly appear different in patients who are highly sensitive to chemotherapy compared with those with lesser response.

Lapatinib: new opportunities for management of breast cancer

Approximately 20% of new diagnosed breast cancers overexpress the human epidermal growth factor receptor 2 (EGFR2), also known as erythroblastic leukemia viral oncogene homolog 2 (ERBB2) protein, as a consequence of ERBB2 gene amplification, resulting in a poor prognosis. Clinical outcome can be substantially improved by ERBB2-targeted therapy. Lapatinib is a potent, orally bioavailable small molecule that reversibly and selectively inhibits epidermal growth factor receptor (EGFR1 or ERBB1) and ERBB2 tyrosine kinases. Lapatinib binds the adenosine triphosphate-binding site of the receptor's intracellular domain to inhibit tumor cell growth. This review summarizes the pharmacology, pharmacokinetics, efficacy, and tolerability of lapatinib, and reviews both Food and Drug Administration-approved and investigational uses of lapatinib in breast cancer therapy. The drug is generally well tolerated in patients, with diarrhea and rashes being the most common (usually mild or moderate) adverse effects. Unlike trastuzumab, lapatinib has infrequent adverse effects on cardiac function. Lapatinib has substantial activity for advanced ERBB2-positive breast cancer, particularly in combination with capecitabine, following progression after anthracyclines, taxanes, and trastuzumab. Lapatinib combined with capecitabine yielded significant improvements in time to progression and response rate compared with capecitabine alone. This drug can also be combined with letrozole for the treatment of postmenopausal women with ERBB2-positive breast cancer, for whom hormonal therapy is indicated. Lapatinib has shown early promise in treatment of central nervous system metastasis and is being further evaluated in various clinical settings.

Models for prevention and treatment of cancer: problems vs promises

Current estimates from the American Cancer Society and from the International Union Against Cancer indicate that 12 million cases of cancer were diagnosed last year, with 7 million deaths worldwide; these numbers are expected to double by 2030 (27 million cases with 17 million deaths). Despite tremendous technological developments in all areas, and President Richard Nixon's initiative in the 1974 "War against Cancer", the US cancer incidence is the highest in the world and the cancer death rate has not significantly changed in the last 50 years (193.9 per 100,000 in 1950 vs 193.4 per 100,000 in 2002). Extensive research during the same time, however, has revealed that cancer is a preventable disease that requires major changes in life style; with one third of all cancers assigned to Tobacco, one third to diet, and remaining one third to the environment. Approximately 20 billion dollars are spent annually to find a cure for cancer. We propose that our inability to find a cure to cancer lies in the models used. Whether cell culture or animal studies, no model has yet been found that can reproduce the pathogenesis of the disease in the laboratory. Mono-targeted therapies, till know in most cases, have done a little to make a difference in cancer treatment. Similarly, molecular signatures/predictors of the diagnosis of the disease and response are also lacking. This review discusses the pros and cons of current cancer models based on cancer genetics, cell culture, animal models, cancer biomarkers/signature, cancer stem cells, cancer cell signaling, targeted therapies, therapeutic targets, clinical trials, cancer prevention, personalized medicine, and off-label uses to find a cure for cancer and demonstrates an urgent need for "out of the box" approaches.

Value and Limitations of Measuring HER-2 Extracellular Domain in the Serum of Breast Cancer Patients

The human epidermal receptor-2 (HER-2) is overexpressed or amplified in 15% to 25% of breast cancers. Determination of HER-2 tumor status offers clinically useful information, as it selects patients who may benefit from treatment with trastuzumab, the monoclonal antibody against HER-2. Currently approved methods for HER-2 testing include immunohistochemistry or fluorescent in situ hybridization using tumor tissue. A fragment of HER-2 composed of its extracellular domain (ECD) can also be detected in the serum of some patients with breast cancer. As an easily accessible tumor marker, it could offer additional useful prognostic or predictive information. This review will briefly address the biology of the circulating HER-2 ECD and discuss the evidence to support the role, if any, for measuring HER-2 ECD levels in women with breast cancer. In particular, we focus on the value and limitations of serum ECD in both early and advanced breast cancer in the following clinical contexts: as a marker of HER-2 tumor tissue status; clinical implications of raised levels in women who have a tumor not overexpressing HER-2; as a prognostic indicator and as a predictor of response to treatment; and as a monitoring tool for early recurrence. On the basis of our review of the literature, we conclude that there is currently insufficient evidence to support the use of serum HER-2 ECD in the routine management of individual patients with breast cancer. This conclusion is in agreement with the 2007 American Society of Clinical Oncology guidelines on the use of biomarkers in breast cancer.

Her2-positive breast cancer: herceptin and beyond

Breast cancer accounts for approximately 30% of all new cancer cases each year, with an annual incidence of approximately 200,000. Additionally, almost 25% of breast cancers are noted to overexpress Her2, which is an epidermal growth factor receptor. Overexpression of Her2 has been associated with a more aggressive phenotype with decreased survival. Trastuzumab, a recombinant monoclonal antibody against the Her2 receptor, is the only FDA-approved targeted agent for treatment of Her2-overexpressing breast cancer. However, despite the great success achieved with trastuzumab, many women will either not respond or eventually progress despite trastuzumab treatment. As a result, significant efforts have been applied to finding other therapies besides trastuzumab for the treatment of Her2-positive breast cancer. Work has been directed at trying to elucidate the exact mechanism of resistance to trastuzumab and identifying ways to overcome them, at increasing the efficacy of trastuzumab by combining it with other therapeutic agents and at investigating other novel agents.

Collagen IV levels are elevated in the serum of patients with primary breast cancer compared to healthy volunteers

Collagen IV is a major component of the vascular basement membrane and may be a marker of angiogenesis. Serum levels of this protein are elevated in some human cancers. Our objectives were to compare collagen IV levels in the serum of breast cancer patients and healthy women and to examine changes during preoperative chemotherapy. Sera from 51 patients with stage II–III breast cancer and 55 healthy controls were analysed. Collagen IV level was measured by a commercially available sandwich enzyme link immunoassay. Baseline serum levels were compared between cancer patients and healthy women and paired pre- and post-chemotherapy measurements were also performed in 39 patients who received preoperative chemotherapy and were correlated with response to therapy. The median serum collagen IV concentration was significantly higher in cancer patients (166 μg l⁻¹) than in healthy women (115 μg l⁻¹), P<0.001. Chemotherapy induced a significant further increase in serum collagen IV (167 μg l⁻¹ prechemo vs 206 μg l⁻¹ postchemo, P=0.001). There were no correlations between baseline collagen IV levels and response to therapy, age, clinical stage or HER2 status. In conclusion, patients with breast cancer have elevated levels of collagen IV compared to healthy women and collagen IV levels increase further during chemotherapy.

Integrating trastuzumab in the neoadjuvant treatment of primary breast cancer: Accumulating evidence of efficacy, synergy and safety

Neoadjuvant chemotherapy is used in non-metastatic breast cancer in order to eradicate micrometastatic deposits early during disease course, as well as in order to decrease tumour bulk and render surgery feasible or breast-conserving. Moreover, it offers promise to serve as an in vivo chemosensitivity assay and as a powerful predictive factor for outcome. Trastuzumab, a monoclonal antibody targeting an epitope in the extracellular domain of the Human Epidermal Growth Factor Receptor-2 (HER2/erbB-2), was found to be active in HER2-overexpressing metastatic as well as in resected breast cancer when given post-operatively. In this review, we summarise the evidence on the activity and safety of trastuzumab-containing neoadjuvant chemotherapy for the management of women with localised, irresectable or resectable breast cancer. Twenty-three published studies enrolling a total of 585 patients reported pathologic complete responses (pCR) ranging from 7 to 78% with a favourable adverse event profile, data that are presented and discussed in this review. The impact of trastuzumab on long-term outcome, the identification of surrogate biomarkers for sensitivity or resistance to antineoplastic therapy, the optimal schedule of trastuzumab administration and the more active chemotherapeutic regimen for synergism are only a few of the key points needing elucidation so as to rationalise trastuzumab-based approaches.

Serum epidermal growth factor receptor and HER2 expression in primary and metastatic breast cancer patients

Background

Breast tissue expression of the ERBB proto-oncogene family has been extensively studied. It was recently shown that expression of epidermal growth factor receptor (EGFR; c-erbB-1) and epidermal growth factor receptor (HER)2 (c-erbB-2) can be detected in the serum of breast cancer patients. The clinical relevance of this has not been fully established.

Methods

EGFR and HER2 immunoassays were conducted in blood from 57 patients in whom paired serum samples were available (from the times of primary and metastatic diagnoses), from 96 primary breast cancer patients and from 49 normal individuals. Of the 57 patients with paired serum samples, paired tissue samples for HER2 expression were available for eight.

Results

Serum levels of EGFR serum levels were significantly higher in normal individuals (median 75.3 ng/ml, range 43.2 to 114.2 ng/ml) than in patients with primary breast cancer (median 59.3 ng/ml, range 21.3 to 94.1 ng/ml; P < 0.001). In the paired serum samples, EGFR levels decreased significantly between the time of primary diagnosis (median 56.3 ng/ml, range 29.1 to 142.7 ng/ml) and metastatic diagnosis (median 30.9 ng/ml, range 10.9 to 106.4 ng/ml; P < 0.001). In six (11%) a change occurred from over-expression (>78 ng/ml) to normal expression. In contrast, no significant difference was seen in HER2 serum levels in normal individuals (median 12.2 ng/ml, range 7.8 to 20.9 ng/ml) and primary breast cancer patients (median 12.5 ng/ml, range 6.9 to 122.2 ng/ml; P = 0.511). However, in the paired serum samples, HER2 levels increased significantly between the time of primary (median 12.2 ng/ml, range 5.7 to 85.0 ng/ml) and metastasis (median 17.7 ng/ml, range 6.3 to 3,337.4 ng/ml; P < 0.001). HER2 over-expression (>15 ng/ml) was observed in 16 out of 57 patients (28%) at primary breast cancer diagnosis and in 31 out of 57 (54%) at metastasis. In 18 patients (32%) HER2 expression changed from normal to over-expression.

Conclusion

Decisions regarding the use of targeted therapies in the metastatic setting are often based on the oncogene expression of the primary tumour. Our results suggest that serum oncogene assessments may be complementary to this and could potentially widen the indications for these beneficial therapies.

Predicting the efficacy of trastuzumab-based therapy in breast cancer: current standards and future strategies

Breast cancer is the most common female malignancy in many industrialized countries. Approximately one fourth of all women diagnosed with early breast cancer present with tumors that are characterized by erbB2 amplification. While the associated Her-2/neu receptor overexpression results in a high risk of relapse and poor prognosis, these tumors also represent a target for a selective monoclonal antibody therapy with trastuzumab (Herceptin). The combination of trastuzumab with chemotherapy has led to a considerable reduction of recurrences and to a significant reduction in breast cancer mortality both in the adjuvant and metastatic setting. Unfortunately, despite Her-2/neu overexpression, not all patients equally benefit from trastuzumab treatment, and almost all women with metastatic breast cancer eventually progress during antibody therapy. Moreover, trastuzumab is burdened with cardiotoxicity, thus increasing the risk of symptomatic congestive heart failure. In addition, the marginal costs for a 1 year therapy of trastuzumab-based therapy, which is currently considered to be the most effective treatment regimen in the adjuvant setting, may amount for up to US$ 40.000. Testing for erbB2 oncogene amplification by fluorescence in situ hybridization (FISH) and chromogenic in situ hybridization (CISH), respectively, and staining for Her-2/neu receptor overexpression by immunohistochemistry (IHC) represent the current standard for determining patient eligibility for trastuzumab-based therapy. However, while the negative predictive value of these assays for predicting the absence of benefit from trastuzumab-based therapy is sufficiently high, their positive predictive value remains insufficient, i.e. only a proportion of patients selected by these tests substantially benefit from trastuzumab-containing regimen. Accordingly, over the last years a number of biomarkers have been evaluated in their potential to predict response to trastuzumab-based therapies. These include markers auf activation of Her-2/neu (e.g., tyrosine phosphorylated Her-2/neu in tissue and cleaved Her-2/neu extracellular domain in serum) and its dimerization partners (e.g., EGFR), respectively, but also components of Her-2/neu-induced downstream signaling pathways that are crucial for the growth inhibitory effects of trastuzumab (e.g., PTEN and PI3K). Other parameters, such as topoisomerase-II alpha and c-myc co-amplifications, have also been identified as potentially useful predictors of response to trastuzumab-based chemotherapy regimen. While the benefit of these predictive biomarkers in the metastatic setting is currently explored, their usefulness in the adjuvant setting is still largely unknown. It is, however, undisputable that, within the group of Her-2/neu overexpressing tumors, further response predictors are needed in order to minimize trastuzumab-associated side effects, and to reduce the considerable societal costs that are associated with trastuzumab-based treatment regimen.

Elements related to heterogeneity of antibody-dependent cell cytotoxicity in patients under trastuzumab therapy for primary operable breast cancer overexpressing Her2

Preliminary results from a pilot trial on trastuzumab's mechanism of action against operable breast tumors overexpressing Her2 suggested a role for antibody-dependent cell cytotoxicity (ADCC). To examine factors affecting ADCC intensity and variability, we extended this study to the phenotypic and functional analysis of circulating mononuclear cells in 18 patients. ADCC was induced by trastuzumab therapy in 15 of 18 patients (83%). Inability to develop ADCC in three patients did not depend on inadequate levels of trastuzumab because further increase in its concentration in vitro was ineffective. Rather, susceptibility to develop ADCC was fairly predicted by test with trastuzumab before therapy and was correlated to the number of lymphocytes coexpressing CD16 and CD56. Phenotypic analysis at the end of ADCC evaluating down-regulation of CD16, and up-regulation of CD69 and CD107a, confirmed that natural killer (NK) cells and CD56(+) T cells were involved in productive engagement of trastuzumab. Also, the killing efficiency of CD16(+) lymphocytes was influenced by 158 V/F polymorphism of Fc gamma RIII (CD16), whereas variations of CD247 on NK cells were consistent with trends between ADCC before and after therapy. Complete pathologic response was observed in one patient showing ADCC of outstanding intensity, whereas four cases of partial response showed intermediate ADCC; none of the three patients unable to mount ADCC had significant tumor regression. These data indicate that quantity and lytic efficiency of CD16(+) lymphocytes are major factors for ADCC induction by trastuzumab, and confirm that breast cancer responses to short-term trastuzumab monotherapy may depend on involvement of the ADCC mechanism.

HER-2/neu diagnostics in breast cancer

HER-2/neu status of the primary breast cancer (PBC) is determined by immunohistochemistry and fluorescent in situ hybridization. Because of a variety of technical factors, however, the PBC may not accurately reflect the metastatic tumor in terms of HER-2/neu status. Recently published guidelines recommend that tumors be defined as HER-2/neu positive if 30% or more of the cells are 3+. Circulating levels of the HER-2 extracellular domain can be measured in serum using a test cleared by the US Food and Drug Administration, and increased serum HER-2/neu levels to above 15 ng/ml can reflect tumor progression. Studies comparing tissue HER-2/neu status of the PBC and HER-2/neu levels above 15 ng/ml in metastatic breast cancer patients are also reviewed.