Targeting the human epidermal growth factor receptor 2 (HER2) oncogene in colorectal cancer

Human epidermal growth factor receptor 2 (HER2) is an oncogenic driver, and a well-established therapeutic target in breast and gastric cancers. Using functional and genomic analyses of patient-derived xenografts, we previously showed that a subset (approximately 5%) of metastatic colorectal cancer (CRC) tumors is driven by amplification or mutation of HER2. This paper reviews the role of HER2 amplification as an oncogenic driver, a prognostic and predictive biomarker, and a clinically actionable target in CRC, considering the specifics of HER2 testing in this tumor type. While the role of HER2 as a biomarker for prognosis in CRC remains uncertain, its relevance as a therapeutic target has been established. Indeed, independent studies documented substantial clinical benefit in patients treated with biomarker-driven HER2-targeted therapies, with an impact on response rates and duration of response that compared favorably with immunotherapy and other examples of precision oncology. HER2-targeted therapeutic strategies have the potential to change the treatment paradigm for a clinically relevant subgroup of metastatic CRC patients.

High concordance of a closed-system, RT-qPCR breast cancer assay for HER2 mRNA, compared to clinically determined immunohistochemistry, fluorescence in situ hybridization, and quantitative immunofluorescence

Historically, mRNA measurements have been tested on several commercially available platforms, but none have gained broad acceptance for assessment of HER2. An mRNA measurement, as a continuous value, has the potential for use in adjudication of the equivocal category. Here we use a real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) assay in a closed, single-use cartridge, automated system. Multiple cores (1 mm in diameter) were retrospectively collected from 80 formalin-fixed paraffin-embedded (FFPE) tissue blocks with invasive breast cancer seen by Yale Pathology Labs between 1998 and 2011. Tissue cores were processed with a FFPE lysis kit to create lysates that were tested with the automated RT-qPCR assay. Results for IHC and FISH were extracted from the pathology reports and quantitative immunofluorescence (QIF) for each case was measured as previously described. Quality control testing showed that the GX platform RT-qPCR shows no case to case cross contamination on material from routine histology practices. Concordance between RT-qPCR and IHC/FISH was 91.25% (sensitivity=0.87; specificity=0.94; PPV=0.89; NPV=0.92) using a pre-defined delta Ct cut-off (dCt≥-1) for HER2. Concordance (OPA) between RT-qPCR and QIF was 94% (sensitivity=0.90; specificity=0.96; PPV=0.93; NPV=0.94) using dCt≥-1 and a previously defined cut-point for positivity by QIF. In conclusion, the closed system RT-qPCR assay shows >90% concordance with the ASCO/CAP HER2 IHC/FISH scoring. Additionally, the RT-qPCR assay is highly concordant (94%) with the continuous variable HER2 QIF assay, and may better reflect the true continuum of HER2 receptor status in invasive breast cancer. These initial results suggest that fast, closed system molecular assays may have future value for the adjudication of the ASCO/CAP HER2 equivocal category or possibly routine usage in time constrained or low resource settings.

Activating HER2 mutations as emerging targets in multiple solid cancers

The epidermal growth factor receptor (EGFR) family of transmembrane receptor tyrosine kinases activates signalling pathways regulating cellular proliferation and survival. HER2 is a non-ligand-binding member of this family and exerts its activity through heterodimerisation with other EGFR family members. HER2 functional activation promotes oncogenesis, leading to the investigation of HER2-directed agents in cancers with HER2 alterations. This has been best characterised in the context of HER2 gene amplification in breast and gastro-oesophageal cancers, for which HER2-directed drugs form part of standard treatment regimens. More recently, somatic HER2 gene mutations have been detected in a range of human cancer types. Preclinical data suggest that functionally activating HER2 mutations may drive and maintain cancers in a manner analogous to HER2 gene amplification and that HER2 mutations may similarly confer sensitivity to HER2-directed drugs. Here, we critically review the emerging roles for HER2-directed drugs in HER2 mutant cancers. We review data from experimental models, where our knowledge of the underlying biology of HER2 mutational activation remains incomplete. We discuss clinical data from Phase I and II clinical trials which evaluate HER2-directed agents (tyrosine kinase inhibitors and antibody-based drugs) in several cancer types. We highlight the heterogeneity of HER2 mutations in human cancers, differences in the clinical efficacy of HER2-directed drugs between cancer types and possible mechanisms of primary and acquired resistance, in order to guide clinical practice and future drug development.

Clinicopathological factors associated with HER2-positive gastric cancer: A meta-analysis

BACKGROUND

The treatment of patients with advanced gastric cancer remains a most challenging task in the clinical practice. Recently, targeted therapies have significantly impacted the treatment strategy for many common malignancies. The use of trastuzumab, a monoclonal antibody against human epidermal growth factor receptor 2 (HER2; also known as ERBB2), plus chemotherapy proved to improve median overall survival in patients with advanced gastric cancer, compared with chemotherapy alone in Trastuzumab for Gastric Cancer (ToGA) trial. However, the prognostic value of HER2 status in gastric cancer remains controversial. Therefore, the aim of this study was to investigate the clinical pathology significance of HER2 overexpression in resectable gastric cancer for selecting the right patients with gastric cancer who may benefit from trastuzumab treatment.

METHODS

Publications reported the clinicopathological factors associated with HER2 status in gastric cancer from 2012 to 2017 were collected. The literature databases, such as "Cochrane Library", "Sciencedirect", "Springer", "PubMed", "Embase", were extensively searched to retrieve the clinical studies of HER2 expression in gastric cancer. The major outcomes measures were odds ratios (ORs) and their 95% CIs. Statistical analysis was carried out by Revman software 5.3. The Newcastle-Ottawa scale was used to assess the quality of evidence.

RESULT

Fifteen studies met our inclusion criteria. This study demonstrated that the pooled OR for HER2 positivity was associated with being male (OR: 1.42; 95% CI: 1.23-1.64), well/moderately differentiated tumor (OR: 2.76; 95% CI: 1.72-4.45), and for intestinal-type tumor (OR: 0.31; 95% CI: 0.25-0.38). However, it had no correlation with depth of tumor (P = .07), venous invasion (P = .82), and lymphovascular invasion (P = .24).

CONCLUSION

HER2-positive expression was associated with male gender, intestinal type, and well/moderate cell differentiation. We recommend that those gastric cancer patients who may benefit from trastuzumab treatment should be subjected to targeted therapies. However, detecting HER2 status may contribute to the target therapy for gastric carcinoma using trastuzumab. This would be strengthened by further studies incorporating comorbidity data, and outcomes from centralized programs.

The Framingham risk score underestimates the risk of cardiovascular events in the HER2-positive breast cancer population

INTRODUCTION

Patients with breast cancer (bca) who overexpress her2 (the human epidermal growth factor receptor 2) are at risk for cardiotoxicity when treated with anthracycline-based chemotherapy and her2-targeted agents. The Framingham risk score (frs) is a validated tool that stratifies patients into high-, intermediate-, or low-risk groups and calculates their 10-year risk of developing cardiovascular disease (cvd) based on past medical history, systolic blood pressure, and measurement of serum lipids. We retrospectively analyzed patients with her2-positive bca to determine whether the frs predicts adverse cardiovascular (CV) events or cardiotoxicity in patients treated using anthracyclines or her2-targeted therapy, or both.

METHODS

The frs was determined for patients with bca referred to The Ottawa Hospital Cardiology-Oncology Clinic from October 2008 to August 2014. The patients were stratified into high (≥20%), intermediate (10%-20%), and low (<10%) 10-year cv risk groups. Primary outcomes included cvd-related hospitalizations and deaths, and cardiotoxicity [drop in left ventricular ejection fraction (lvef) of >10% to a lvef ≤50%].

RESULTS

Of the 152 patients included in the analysis (median follow-up: 40.7 months; range: 3.5-263 months), 47 (31%) were classified as high risk; 36 (24%), as intermediate risk; and 69 (45%), as low-risk. The number of cvd-related hospitalizations and deaths was 22, for an overall prevalence of 14%, with significantly more events occurring in high-risk than in low-risk patients (odds ratio: 4.18; 95% confidence limits: 1.47, 11.89). The frs predicted a 10-year risk of any cv event of 11.2% and underestimated the actual rate of cv events in the entire cohort. High frs was not associated with cardiotoxicity (p = 0.82).

CONCLUSIONS

In a population of patients with her2-positive bca referred to a cardiology-oncology clinic, the frs does not accurately predict the risk of cv events or cardiotoxicity.

Metastatic HER2+ Breast Cancer: A Potentially Curable Disease?

The advent of trastuzumab and other human epidermal growth factor receptor 2 (HER2)-directed therapies has revolutionized the treatment of metastatic HER2-positive breast cancer, leading to prolonged survival and appreciable clinical benefit for a substantial subset of patients. Previously, in a retrospective study at our institution, we observed that nearly 10% of patients achieved a durable complete remission (DCR) following a combination of HER2-directed therapy and cytotoxic chemotherapy. We are currently expanding this study to include patients who were treated since the initial introduction of trastuzumab. From our ongoing study, we present a selected case series of three patients with metastatic HER2-positive breast cancer who achieved a DCR. It is theorized that metastatic HER2-positive breast cancer may be potentially curable in certain patients with favorable clinicopathological and molecular factors, which the patients within our case series mostly demonstrate. These include de novo presentation, estrogen receptor (ER)-negative status, limited disease burden, and absence of deleterious gene or pathway mutations. More research is needed in order to incorporate these findings into clinical practice.

Role of tyrosine kinase inhibitors in the treatment of pituitary tumours: from bench to bedside

PURPOSE OF REVIEW

Treatment of aggressive pituitary tumours often yields suboptimal control of the tumour and confers significant morbidity. Lactotroph and corticotroph-derived tumours express ErbB receptors and ligands, and mutations in ubiquitin-specific protease 8 (USP8), which alters epidermal growth factor receptor (EGFR) degradation, have been implicated in Cushing disease pathogenesis. EGFR tyrosine kinase inhibitor (TKI) therapy has emerged as a potential new therapeutic approach for patients with aggressive prolactinomas and Cushing disease.

RECENT FINDINGS

Using EGFR or human epidermal growth factor receptor 2-driven prolactin (PRL) promoters, transgenic mice develop large tumours that respond to TKI inhibition. In human corticotroph primary cultures, treatment with the pan-ErbB TKI canertinib as well as the EGFR TKI gefitinib suppresses proopiomelanocortin mRNA. USP8 mutations, detected in up to two-thirds of Cushing disease, may underlie the increase in EGFR signalling in these tumours. Human prolactinomas have differential ErbB receptor expression associated with aggressive behaviour and data from an ongoing clinical trial suggest that resistant prolactinomas may respond to the EGFR TKI lapatinib.

SUMMARY

Preclinical and clinical models substantiate the role of the EGFR pathway in corticotroph and lactotroph adenomas. Although further study is needed, results to date suggest that targeting the ErbB pathway may be an effective therapeutic approach for patients with aggressive pituitary tumours.

Synergy between Androgen Receptor Antagonism and Inhibition of mTOR and HER2 in Breast Cancer

The androgen receptor (AR) is widely expressed in breast cancer, and evidence suggests dependence on AR signaling for growth and survival. AR antagonists such as enzalutamide and seviteronel have shown success in preclinical models and clinical trials of prostate cancer and are currently being evaluated in breast cancer. Reciprocal regulation between AR and the HER2/PI3K/mTOR pathway may contribute to resistance to HER2- and mTOR-targeted therapies; thus, dual inhibition of these pathways may synergistically inhibit breast cancer growth. HER2+ and triple-negative breast cancer cell lines were treated with AR antagonist plus anti-HER2 mAb trastuzumab or mTOR inhibitor everolimus. Apoptosis, cell proliferation, and drug synergy were measured in vitro Pathway component genes and proteins were measured by qRT-PCR, Western blot, and reverse phase protein array. In vivo, HER2+ breast cancer xenografts were treated with enzalutamide, everolimus, trastuzumab, and combinations of these drugs. AR antagonists inhibited proliferation of both HER2+ and TNBC cell lines. Combining AR antagonist and either everolimus or trastuzumab resulted in synergistic inhibition of proliferation. Dihydrotestosterone caused increased phosphorylation of HER2 and/or HER3 that was attenuated by AR inhibition. Everolimus caused an increase in total AR, phosphorylation of HER2 and/or HER3, and these effects were abrogated by enzalutamide. Growth of trastuzumab-resistant HER2+ xenograft tumors was inhibited by enzalutamide, and combining enzalutamide with everolimus decreased tumor viability more than either single agent. AR antagonists synergize with FDA-approved breast cancer therapies such as everolimus and trastuzumab through distinct mechanisms. Treatment combinations are effective in trastuzumab-resistant HER2+ breast cancer cells in vivoMol Cancer Ther; 16(7); 1389-400. ©2017 AACR.

Amplification of HER2 and TOP2A and deletion of TOP2A genes in a series of Taiwanese breast cancer

BACKGROUND

The prognostic relevance of topoisomerase II alpha (TOP2A) copy number change remains not well established. This study is aimed to investigate the frequency and pattern of TOP2A aberrations; to correlate TOP2A alterations with human epidermal growth factor receptor 2 (HER2) status and clinicopathological parameters, and further to explore prognostic value of TOP2A and HER2 status in breast cancer in Taiwan.

METHODS

We analyzed tissue samples from 311 invasive carcinomas in tissue microarrays for TOP2A and HER2 status by fluorescent in situ hybridization.

RESULTS

TOP2A copy number change is an infrequent genetic event (9.8% amplification and 2.7% deletion) and is present in both HER2-amplified and nonamplified tumors. TOP2A amplification is statistically associated with age >50 at diagnosis (P = 0.016) and HER2 amplification (P < 0.001). HER2 amplification, but not TOP2A amplification, is a predictor of unfavorable prognosis (P = 0.002). Univariate and multivariate analysis showed that higher histologic grading, positive nodal involvement, and HER2 positivity were associated with poorer overall survival. Cytogenetically, double minutes-type amplification is the predominant pattern for both genes (HER2: 64% and TOP2A: 93.1%). Homogeneous staining region-type signals of both genes are resistant to RNase digestion, supporting that these were not nuclear accumulation of mRNA transcripts.

CONCLUSION

Our results demonstrate the prognostic value of tumor grading, nodal involvement, and HER2 status in Taiwanese breast cancer. TOP2A aberrations are an infrequent event independent of HER2 status, and TOP2A amplification carries no prognostic value. The predictive value of TOP2A aberrations in patients of breast cancer taking athracycline-containing treatment in Taiwan remains to be determined in prospectively well-designed clinical trials.

Developmental therapeutics for patients with breast cancer and central nervous system metastasis: current landscape and future perspectives

Breast cancer is the second-leading cause of metastatic disease in the central nervous system (CNS). Recent advances in the biological understanding of breast cancer have facilitated an unprecedented increase of survival in a subset of patients presenting with metastatic breast cancer. Patients with HER2 positive (HER2+) or triple negative breast cancer are at highest risk of developing CNS metastasis, and typically experience a poor prognosis despite treatment with local and systemic therapies. Among the obstacles ahead in the realm of developmental therapeutics for breast cancer CNS metastasis is the improvement of our knowledge on its biological nuances and on the interaction of the blood–brain barrier with new compounds. This article reviews recent discoveries related to the underlying biology of breast cancer brain metastases, clinical progress to date and suggests rational approaches for investigational therapies.

Melatonin Represses Metastasis in Her2-Postive Human Breast Cancer Cells by Suppressing RSK2 Expression

The importance of the circadian/melatonin signal in suppressing the metastatic progression of breast and other cancers has been reported by numerous laboratories including our own. Currently, the mechanisms underlying the antimetastatic actions of melatonin have not been well established. In the present study, the antimetastatic actions of melatonin were evaluated and compared on the ERα-negative, Her2-positive SKBR-3 breast tumor cell line and ERα-positive MCF-7 cells overexpressing a constitutively active HER2.1 construct (MCF-7Her2.1 cells). Activation of Her2 is reported to induce the expression and/or phosphorylation-dependent activation of numerous kinases and transcription factors that drive drug resistance and metastasis in breast cancer. A key signaling node activated by the Her2/Mapk/Erk pathway is Rsk2, which has been shown to induce numerous signaling pathways associated with the development of epithelial-to-mesenchymal transition (EMT) and metastasis including: Creb, Stat3, cSrc, Fak, Pax, Fascin, and actin polymerization. The data demonstrate that melatonin (both endogenous and exogenous) significantly represses this invasive/metastatic phenotype through a mechanism that involves the suppression of EMT, either by promoting mesenchymal-to-epithelial transition, and/or by inhibiting key signaling pathways involved in later stages of metastasis. These data, combined with our earlier in vitro studies, support the concept that maintenance of elevated and extended duration of nocturnal melatonin levels plays a critical role in repressing the metastatic progression of breast cancer.

IMPLICATIONS

Melatonin inhibition of Rsk2 represses the metastatic phenotype in breast cancer cells suppressing EMT or inhibiting other mechanisms that promote metastasis; disruption of the melatonin signal may promote metastatic progression in breast cancer. Mol Cancer Res; 14(11); 1159-69. ©2016 AACR.

Loss of N-acetylgalactosaminyltransferase 3 in poorly differentiated pancreatic cancer: augmented aggressiveness and aberrant ErbB family glycosylation

BACKGROUND

Aberrant glycosylation of several proteins underlie pancreatic ductal adenocarcinoma (PDAC) progression and metastasis. O-glycosylation is initiated by a family of enzymes known as polypeptide N-acetylgalactosaminyl transferases (GalNAc-Ts/GALNTs). In this study, we investigated the role of the O-glycosyltransferase GALNT3 in PDAC.

METHODS

Immunohistochemistry staining of GALNT3 was performed on normal, inflammatory and neoplastic pancreatic tissues. Several in vitro functional assays such as proliferation, colony formation, migration and tumour-endothelium adhesion assay were conducted in GALNT3 knockdown PDAC cells to investigate its role in disease aggressiveness. Expression of signalling molecules involved in growth and motility was evaluated using western blotting. Effect of GALNT3 knockdown on glycosylation was examined by lectin pull-down assay.

RESULTS

N-acetylgalactosaminyl transferase 3 expression is significantly decreased in poorly differentiated PDAC cells and tissues as compared with well/moderately differentiated PDAC. Further, knockdown of GALNT3 resulted in increased expression of poorly differentiated PDAC markers, augmented growth, motility and tumour-endothelium adhesion. Pull-down assay revealed that O-glycans (Tn and T) on EGFR and Her2 were altered in PDAC cells, which was accompanied by their increased phosphorylation.

CONCLUSIONS

Our study indicates that loss of GALNT3 occurs in poorly differentiated PDAC, which is associated with the increased aggressiveness and altered glycosylation of ErbB family proteins.

HER2 Signaling Drives DNA Anabolism and Proliferation through SRC-3 Phosphorylation and E2F1-Regulated Genes

Approximately 20% of early-stage breast cancers display amplification or overexpression of the ErbB2/HER2 oncogene, conferring poor prognosis and resistance to endocrine therapy. Targeting HER2(+) tumors with trastuzumab or the receptor tyrosine kinase (RTK) inhibitor lapatinib significantly improves survival, yet tumor resistance and progression of metastatic disease still develop over time. Although the mechanisms of cytosolic HER2 signaling are well studied, nuclear signaling components and gene regulatory networks that bestow therapeutic resistance and limitless proliferative potential are incompletely understood. Here, we use biochemical and bioinformatic approaches to identify effectors and targets of HER2 transcriptional signaling in human breast cancer. Phosphorylation and activity of the Steroid Receptor Coactivator-3 (SRC-3) is reduced upon HER2 inhibition, and recruitment of SRC-3 to regulatory elements of endogenous genes is impaired. Transcripts regulated by HER2 signaling are highly enriched with E2F1 binding sites and define a gene signature associated with proliferative breast tumor subtypes, cell-cycle progression, and DNA replication. We show that HER2 signaling promotes breast cancer cell proliferation through regulation of E2F1-driven DNA metabolism and replication genes together with phosphorylation and activity of the transcriptional coactivator SRC-3. Furthermore, our analyses identified a cyclin-dependent kinase (CDK) signaling node that, when targeted using the CDK4/6 inhibitor palbociclib, defines overlap and divergence of adjuvant pharmacologic targeting. Importantly, lapatinib and palbociclib strictly block de novo synthesis of DNA, mostly through disruption of E2F1 and its target genes. These results have implications for rational discovery of pharmacologic combinations in preclinical models of adjuvant treatment and therapeutic resistance.

Trastuzumab-Based Photoimmunotherapy Integrated with Viral HER2 Transduction Inhibits Peritoneally Disseminated HER2-Negative Cancer

Peritoneal dissemination is the most frequent metastasis in gastric cancer and is associated with poor prognosis. The lack of particular target antigens in gastric cancer other than HER2 has hampered the development of treatments for peritoneal dissemination of gastric cancer. We hypothesized that HER2-extracellular domain (HER2-ECD) gene transduction combined with trastuzumab-based photoimmunotherapy (PIT) might provide excellent and selective antitumor effects for peritoneal dissemination of gastric cancer. In vitro, adenovirus/HER2-ECD (Ad/HER2-ECD) efficiently transduced HER2-ECD into HER2-negative gastric cancer cells. Trastuzumab-IR700 (Tra-IR700)-mediated PIT induced selective cell death of HER2-ECD-transduced tumor cells. Ad/HER2-ECD also induced homogenous expression of HER2 in heterogeneous gastric cancer cells, resulting in uniform sensitivity of the cells to Tra-IR700-mediated PIT. Anti-HER2 PIT integrated with adenoviral HER2-ECD gene transfer was applied in mice bearing peritoneal dissemination of HER2-negative gastric cancer. Intraperitoneal administration of Ad/HER2-ECD and Tra-IR700 with PIT inhibited peritoneal metastasis and prolonged the survival of mice bearing MKN45. Furthermore, minimal side effects allowed the integrated therapy to be used repeatedly, providing better control of peritoneal dissemination. In conclusion, the novel therapy of molecular-targeted PIT integrated with gene transfer technology is a promising approach for the treatment of peritoneal dissemination in gastric cancer.

Molecular targeted photoimmunotherapy for HER2-positive human gastric cancer in combination with chemotherapy results in improved treatment outcomes through different cytotoxic mechanisms

BACKGROUND

Photoimmunotherapy (PIT) is a novel type of molecular optical imaging-guided cancer phototherapy based on a monoclonal antibody conjugated to a photosensitizer, IR700, in combination with near-infrared (NIR) light. PIT rapidly causes target-specific cell death by inducing cell membrane damages and appears to be highly effective; however, we have previously demonstrated that tumor recurrences were eventually seen in PIT-treated mice, likely owing to inhomogeneous mAb-IR700 conjugate distribution in the tumor, thus limiting the effectiveness of PIT as a monotherapy. Here, we examined the effects of human epidermal growth factor-2 (HER2)-targeted PIT in combination with 5-fluorouracil (5-FU) compared to PIT alone for HER2-expressing human gastric cancer cells.

METHODS

NCI-N87 cells, HER2-positive human gastric cancer cells, were used for the experiments. Trastuzumab, a monoclonal antibody directed against HER2, was conjugated to IR700. To assess the short-term cytotoxicity and examine the apoptotic effects upon addition of 5-FU in vitro, we performed LIVE/DEAD and caspase-3 activity assays. Additionally, to explore the effects on long-term growth inhibition, trypan blue dye exclusion assay was performed. NCI-N87 tumor xenograft models were prepared for in vivo treatment studies and the tumor-bearing mice were randomized into various treatment groups.

RESULTS

Compared to PIT alone, the combination of HER2-targeted PIT and 5-FU rapidly induced significant cytotoxicity in both the short-term and long-term cytotoxicity assays. While both 5-FU and/or trastuzumab-IR700 conjugate treatment induced an increase in caspase-3 activity, there was no additional increase in caspase-3 activity upon NIR light irradiation after incubation with 5-FU and/or trastuzumab-IR700. The combination of HER2-targeted PIT and 5-FU resulted in greater and longer tumor growth inhibition than PIT monotherapy in vivo. This combined effect of PIT and 5-FU is likely owing to their different mechanisms of inducing tumor cell death, namely necrotic membrane damage by PIT and apoptotic cell death by 5-FU and trastuzumab.

CONCLUSIONS

PIT in combination with 5-FU resulted in enhanced antitumor effects compared to PIT alone for HER2-expressing human gastric cancer in vitro and in vivo. This combination photoimmunochemotherapy represents a practical method for treating human gastric cancer and should be investigated further in the clinical setting.

Exceptional Response to Systemic Therapy in Advanced Metastatic Gastric Cancer: A Case Report

Gastroesophageal adenocarcinomas represent one of the top five most common types of cancer worldwide. Despite significant advancement, it is still not known which first-line chemotherapy option is best matched to an individual patient. The vast advances in molecular biology have led to the discovery of many potential predictive biomarkers, such as HER-2 neu, thymidylate synthase (TS), excision repair cross-complementation group 1 (ERCC1), and topoisomerase-1 (TOPO1). These markers could allow us to select treatment based on an individual’s tumor profile, resulting in an improvement of outcome. Our report highlights two patients with metastatic gastric cancer that achieved an exceptional response with traditional therapy and provides insights into the future perspectives of molecular profile-directed chemotherapy.

A TORC2-Akt Feed-Forward Topology Underlies HER3 Resiliency in HER2-Amplified Cancers

The requisite role of HER3 in HER2-amplified cancers is beyond what would be expected as a dimerization partner or effector substrate and it exhibits a substantial degree of resiliency that mitigates the effects of HER2-inhibitor therapies. To better understand the roots of this resiliency, we conducted an in-depth chemical-genetic interrogation of the signaling network downstream of HER3. A unique attribute of these tumors is the deregulation of TORC2. The upstream signals that ordinarily maintain TORC2 signaling are lost in these tumors, and instead TORC2 is driven by Akt. We find that in these cancers HER3 functions as a buffering arm of an Akt-TORC2 feed-forward loop that functions as a self-perpetuating module. This network topology alters the role of HER3 from a conditionally engaged ligand-driven upstream physiologic signaling input to an essential component of a concentric signaling throughput highly competent at preservation of homeostasis. The competence of this signaling topology is evident in its response to perturbation at any of its nodes. Thus, a critical pathophysiologic event in the evolution of HER2-amplified cancers is the loss of the input signals that normally drive TORC2 signaling, repositioning it under Akt dependency, and fundamentally altering the role of HER3. This reprogramming of the downstream network topology is a key aspect in the pathogenesis of HER2-amplified cancers and constitutes a formidable barrier in the targeted therapy of these cancers.

Association between HER2 status in gastric cancer and clinicopathological features: a retrospective study using whole-tissue sections

BACKGROUND

Gastric cancer is usually diagnosed in an advanced stage of disease and treatment options are sparse. Trastuzumab was recently approved for metastatic or locally advanced carcinomas arising in the stomach or in the gastroesophageal junction in patients with HER2-positive tumors. However, data on the frequency of HER2-positive cases among Brazilian patients are limited. Our aim was to characterize HER2 protein and gene status in a series of Brazilian patients with gastric cancer and to evaluate its association with clinicopathological data.

METHODS

Histological slides from 124 primary gastrectomies were reviewed and their pathological reports were retrieved from the files at a Brazilian university hospital. Automated immunohistochemistry for HER2 was performed on whole-tissue sections from each tumor. HER2-equivocal cases by immunohistochemistry were submitted to automated dual in situ hybridization for gene amplification evaluation. HER2 status was confronted with clinicopathological parameters in order to assess statistically significant associations.

RESULTS

Immunohistochemistry analysis revealed that 13/124 cases (10.5 %) were HER2 positive (3+), 10/124 cases (8.1 %) were equivocal (2+) and 101/124 cases (81.4 %) were negative, being 7 cases 1+. None of the equivocal cases showed gene amplification. The overall HER2 positivity rate was 10.5 %. There was an association between HER2 expression and Laurén's intestinal histological subtype (P = 0.048), well to moderately differentiated tumors (P = 0.004) and presence of lymphovascular invasion (P = 0.031). No association was found between HER2 status and tumor topography.

CONCLUSIONS

Confronted with data published by other authors, the lower percentage of HER2-positive cases found in our series might be partially explained by the lower frequency of tumors arising at the gastroesophageal junction in comparison with distal gastric carcinomas in Brazilian patients. This could also account for the lack of statistically significant association between HER2 status and tumor topography in our study.

Relevance of tumor-infiltrating lymphocytes in breast cancer

While breast cancer has not been considered a cancer amenable to immunotherapeutic approaches, recent studies have demonstrated evidence of significant immune cell infiltration via tumor-infiltrating lymphocytes in a subset of patient tumors. In this review we present the current evidence highlighting the clinical relevance and utility of tumor-infiltrating lymphocytes in breast cancer. Retrospective and prospective studies have shown that the presence of tumor-infiltrating lymphocytes is a prognostic marker for higher responses to neoadjuvant chemotherapy and better survival, particularly in triple negative and HER2-positive early breast cancer. Further work is required to determine the immune subsets important in this response and to discover ways of encouraging immune infiltrate in tumor-infiltrating lymphocytes-negative patients.

Constitutive phosphorylated STAT3-associated gene signature is predictive for trastuzumab resistance in primary HER2-positive breast cancer

BACKGROUND

The likelihood of recurrence in patients with breast cancer who have HER2-positive tumors is relatively high, although trastuzumab is a remarkably effective drug in this setting. Signal transducer and activator of transcription 3 protein (STAT3), a transcription factor that is persistently tyrosine-705 phosphorylated (pSTAT3) in response to numerous oncogenic signaling pathways, activates downstream proliferative and anti-apoptotic pathways. We hypothesized that pSTAT3 expression in HER2-positive breast cancer will confer trastuzumab resistance.

METHODS

We integrated reverse phase protein array (RPPA) and gene expression data from patients with HER2-positive breast cancer treated with trastuzumab in the adjuvant setting.

RESULTS

We show that a pSTAT3-associated gene signature (pSTAT3-GS) is able to predict pSTAT3 status in an independent dataset (TCGA; AUC = 0.77, P = 0.02). This suggests that STAT3 induces a characteristic set of gene expression changes in HER2-positive cancers. Tumors characterized as high pSTAT3-GS were associated with trastuzumab resistance (log rank P = 0.049). These results were confirmed using data from the prospective, randomized controlled FinHer study, where the effect was especially prominent in HER2-positive estrogen receptor (ER)-negative tumors (interaction test P = 0.02). Of interest, constitutively activated pSTAT3 tumors were associated with loss of PTEN, elevated IL6, and stromal reactivation.

CONCLUSIONS

This study provides compelling evidence for a link between pSTAT3 and trastuzumab resistance in HER2-positive primary breast cancers. Our results suggest that it may be valuable to add agents targeting the STAT3 pathway to trastuzumab for treatment of HER2-positive breast cancer.

HER2 activating mutations are targets for colorectal cancer treatment

The Cancer Genome Atlas project identified HER2 somatic mutations and gene amplification in 7% of patients with colorectal cancer. Introduction of the HER2 mutations S310F, L755S, V777L, V842I, and L866M into colon epithelial cells increased signaling pathways and anchorage-independent cell growth, indicating that they are activating mutations. Introduction of these HER2 activating mutations into colorectal cancer cell lines produced resistance to cetuximab and panitumumab by sustaining MAPK phosphorylation. HER2 mutants are potently inhibited by low nanomolar doses of the irreversible tyrosine kinase inhibitors neratinib and afatinib. HER2 gene sequencing of 48 cetuximab-resistant, quadruple (KRAS, NRAS, BRAF, and PIK3CA) wild-type (WT) colorectal cancer patient-derived xenografts (PDX) identified 4 PDXs with HER2 mutations. HER2-targeted therapies were tested on two PDXs. Treatment with a single HER2-targeted drug (trastuzumab, neratinib, or lapatinib) delayed tumor growth, but dual HER2-targeted therapy with trastuzumab plus tyrosine kinase inhibitors produced regression of these HER2-mutated PDXs.

SIGNIFICANCE

HER2 activating mutations cause EGFR antibody resistance in colorectal cell lines, and PDXs with HER2 mutations show durable tumor regression when treated with dual HER2-targeted therapy. These data provide a strong preclinical rationale for clinical trials targeting HER2 activating mutations in metastatic colorectal cancer.

Systemic targeted therapy for her2-positive early female breast cancer: a systematic review of the evidence for the 2014 Cancer Care Ontario systemic therapy guideline

BACKGROUND

This systematic review addresses the question "What is the optimal targeted therapy for female patients with early-stage human epidermal growth factor receptor 2 (her2)-positive breast cancer?"

METHODS

The medline and embase databases were searched for the period January 2008 to May 2014. The Standards and Guidelines Evidence directory of cancer guidelines and the Web sites of major guideline organizations were also searched.

RESULTS

Sixty publications relevant to the targeted therapy portion of the systematic review were identified. In four major trials (hera, National Surgical Adjuvant Breast and Bowel Project B-31, North Central Cancer Treatment Group N9831, and Breast Cancer International Research Group 006), adjuvant trastuzumab for 1 year was superior in disease-free survival (dfs) and overall survival (os) to no trastuzumab; trastuzumab showed no benefit in one trial (pacs 04). A shorter duration of trastuzumab (less than 1 year compared with 1 year) was evaluated, with mixed results for dfs: one trial showed superiority (finher), one trial could not demonstrate noninferiority (phare), another trial showed equivalent results (E 2198), and one trial is still ongoing (persephone). Longer trastuzumab duration (hera: 2 years vs. 1 year) showed no improvement in dfs or os and a higher rate of cardiac events. Newer her2-targeted agents (lapatinib, pertuzumab, T-DM1, neratinib) have been or are still being evaluated in both adjuvant and neoadjuvant trials, either by direct comparison with trastuzumab alone or combined with trastuzumab. In the neoadjuvant setting (neoaltto, GeparQuinto, Neosphere), trastuzumab alone or in combination with another anti-her2 agent (lapatinib, pertuzumab) was compared with either lapatinib or pertuzumab alone and showed superior or equivalent rates of pathologic complete response. In the adjuvant setting, lapatinib alone or in combination with trastuzumab, compared with trastuzumab alone (altto) or with placebo (teach), was not superior in dfs. The results of the completed aphinity trial, evaluating the role of dual her2 blockade with trastuzumab and pertuzumab, are highly anticipated. Ongoing trials are evaluating trastuzumab as a single agent without adjuvant chemotherapy (respect) and in patients with low her2 expression (National Surgical Adjuvant Breast and Bowel Project B-47).

CONCLUSIONS

Taking into consideration disease characteristics and patient preference, 1 year of trastuzumab should be offered to all patients with her2-positive breast cancer who are receiving adjuvant chemotherapy. Cardiac function should be regularly assessed in this patient population.

Targeted therapy in her2-positive metastatic breast cancer: a review of the literature

Breast tumours positive for her2 (human epidermal growth factor receptor 2) represent approximately 20% of all breast cancer cases and are associated with an aggressive natural history. The advent of targeted anti-her2 therapies has dramatically improved disease control and survival in patients with metastatic her2-positive breast cancer. Targeted agents are now considered the standard of care in the first-line setting and beyond. The present review summarizes the currently available data on targeted anti-her2 therapies from completed randomized phase iii clinical trials and briefly discusses emerging advances that will address unmet needs in metastatic her2-positive breast cancer.

A new prodrug form of Affibody molecules (pro-Affibody) is selectively activated by cancer-associated proteases

Affinity proteins have advanced the field of targeted therapeutics due to their generally higher specificity compared to small molecular compounds. However, side effects caused by on-target binding in healthy tissues are still an issue. Here, we design and investigate a prodrug strategy for improving tissue specificity of Affibody molecules in future in vivo studies. The prodrug Affibody (pro-Affibody) against the HER2 receptor was constructed by fusing a HER2-specific Affibody (ZHER2) to an anti-idiotypic Affibody (anti-ZHER2). The linker was engineered to comprise a substrate peptide for the cancer-associated matrix metalloprotease 1 (MMP-1). The hypothesis was that the binding surface of ZHER2 would thereby be blocked from interacting with HER2 until the substrate peptide was specifically hydrolyzed by MMP-1. Binding should thereby only occur where MMP-1 is overexpressed, potentially decreasing on-target toxicities in normal tissues. The pro-Affibody was engineered to find a suitable linker and substrate peptide, and the different constructs were evaluated with a new bacterial display assay. HER2-binding of the pro-Affibody was efficiently masked and proteolytic activation of the best variant yielded over 1,000-fold increase in apparent binding affinity. Biosensor analysis revealed that blocking of the pro-Affibody primarily affected the association phase. In a cell-binding assay, the activated pro-Affibody targeted native HER2 on cancer cells as opposed to the non-activated pro-Affibody. We believe this prodrug approach with proteolytic activation is promising for improving tissue specificity in future in vivo targeting applications and can hopefully be extended to other Affibody molecules and similar affinity proteins as well.

An evaluation of the prognostic model PREDICT using the POSH cohort of women aged ⩽40 years at breast cancer diagnosis

BACKGROUND

Breast cancer is the most common cancer in younger women (aged ⩽40 years) in the United Kingdom. PREDICT (http://www.predict.nhs.uk) is an online prognostic tool developed to help determine the best available treatment and outcome for early breast cancer. This study was conducted to establish how well PREDICT performs in estimating survival in a large cohort of younger women recruited to the UK POSH study.

METHODS

The POSH cohort includes data from 3000 women aged ⩽40 years at breast cancer diagnosis. Study end points were overall and breast cancer-specific survival at 5, 8, and 10 years. Evaluation of PREDICT included model discrimination and comparison of the number of predicted versus observed events.

RESULTS

PREDICT provided accurate long-term (8- and 10-year) survival estimates for younger women. Five-year estimates were less accurate, with the tool overestimating survival by 25% overall, and by 56% for patients with oestrogen receptor (ER)-positive tumours. PREDICT underestimated survival at 5 years among patients with ER-negative tumours.

CONCLUSIONS

PREDICT is a useful tool for providing reliable long-term (10-year) survival estimates for younger patients. However, for more accurate short-term estimates, the model requires further calibration using more data from young onset cases. Short-term prediction may be most relevant for the increasing number of women considering risk-reducing bilateral mastectomy.