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Amplification of human epidermal growth factor 2 receptor (HER2) and overexpression of estrogen receptor (ER) and/or progesterone receptor (PR) are key determinants in the treatment planning for human breast cancer (BC). Currently, targeted therapies for BC are focused mainly on these biomarkers. However, development of resistance to targeted drugs is almost unavoidable, emphasizing the importance of biochemical and pharmaceutical advances to improve treatment outcomes. To the best of our knowledge, the present study is the first to show functional crosstalk in vitro between HER2 and epithelial membrane protein 3 (EMP3), a tetraspan membrane protein, in human BC. EMP3 overexpression significantly promoted BC cell proliferation, invasion and migration by Transwell assays via epithelial-mesenchymal transition and transactivated the HER family, resulting in increased ER and PR expression in vitro . Knocking down EMP3 notably suppressed cell proliferation and migration and was accompanied by decreased expression of HER1‑HER3 and p‑SRC proteins. Suppression of EMP3 expression enhanced sensitivity of BC cells to trastuzumab in vitro . Xenograft experiments revealed decreased expression of HER1 and HER2 in stable EMP3‑knockdown cells, resulting in decreased tumor weight and size. In patients with BC, EMP3 overexpression was detected in 72 of 166 cases (43.4%), with 18 of 43 (41.9%) HER2‑amplified BC samples co‑expressing EMP3. Co‑expression of EMP3 and HER2 was positively associated with ER expression (P=0.028) and tended to be associated with nodal metastasis (P=0.085), however this was not significant. Taken together, the present results supported the potential of targeting EMP3 as a novel therapeutic strategy for human BC via co‑expression of HER2 and EMP3.

The aberrant expression of HER family members and cancer stem cells (CSCs) have been associated with tumour progression and resistance to therapy. At present, several HER inhibitors have been approved for the treatment of patients with a range of cancers but not for the treatment of patients with hepatocellular carcinoma (HCC). The present study investigated the co‑expression and prognostic significance of HER family members, type‑III deletion mutant EGFR (EGFRvIII), and the putative CSC biomarkers CD44 and epithelial cell adhesion molecule (EpCAM) in 43 patients with HCC. The relative expression of these biomarkers was determined using immunohistochemistry. At a cut off value of >5% of tumour cells stained for these biomarkers, 35% [wild‑type (wt)EGFR], 58% (HER‑2), 0% (HER‑3), 19% (HER‑4), 26% (EGFRvIII), 40% (CD44) and 33% (EpCAM) of patients were positive. In 23, 14 and 9% of the patients, wtEGFR expression was accompanied by co‑expression with HER‑2, EGFRvIII and HER‑2/EGFRvIII, respectively. EGFRvIII expression, membranous expression of CD44 and co‑expression of wtEGFR/EGFRvIII were associated with poor overall survival (OS). By contrast, cytoplasmic CD44 expression was associated with a longer OS time. The present study also investigated the effect of several agents targeting one or more members of the HER family, other growth factor receptors and cell signalling proteins on the proliferation of HCC cell lines. Among agents targeting one or more members of the HER family, the pan‑HER family blocker afatinib was the most effective, inhibiting the proliferation of three out of seven human liver cancer cell lines (LCCLs), while the CDK inhibitor dinacicilib was the most effective agent, inhibiting the proliferation of all human LCCLs tested. Taken together, the present results suggested that EGFRvIII expression and its co‑expression with wtEGFR or CD44 was of prognostic significance. These results also support further investigations of the therapeutic potential of drugs targeting EGFRvIII and other members of the HER family in patients with HCC.

Receptors of the large HER family play an important role in breast cancer, which is undergoing a gradual development in connection with biological development, both in the field of diagnostics and therapy. Dimerization of HER-2 with other HER members, such as HER-3, is the biggest driver of tumor cell growth and survival. Numerous studies show that HER-3 gene overexpression correlates with poor prognosis. However, other studies have shown HER-3 overexpression to be a positive prognostic factor. HER-3 may confer resistance to certain EGFR or HER-2 receptor therapeutics. An interesting fact, however, is that HER-3 expression can serve as a marker in immunotherapy for triple-negative breast cancer (TNBC). It is thought to be involved not only in cell survival and proliferation, but also in the regulation of PD-L1 expression. In breast cancer, PD-L1 expression is heterogeneous and is generally associated with the presence of tumor-infiltrating lymphocytes and a number of factors with poor prognosis such as young age, hormone receptor negativity, and high HER-2 expression and proliferation index. Our results showed amplification of HER-3 (CERB3) in 2 out of a sample of 20 patients with TNBC, and 13 of 20 HER-2-positive patients. PD-L1 expression was demonstrated in 3 out of 13 HER-3-positive patients and 2 out of 2 HER-3-positive TNBC patients. There was a strong correlation between positive HER-3 and PD-L1 TNBC expression (p = < 0.001). Thus, the view of the HER-3 receptor will be much more complex, and the overexpression of this receptor appears to have both negative and positive prognostic and clinical impacts (Tab. 1, Ref. 17). Text in PDF www.elis.sk [ABSTRACT FROM AUTHOR]

Abstract Background The human epidermal growth factor receptor (HER) family, notably EGFR, is overexpressed in most triple-negative breast cancer (TNBC) cases and provides cancer cells with compensatory signals that greatly contribute to the survival and development of resistance in response to therapy. This study investigated the effects of Pan-HER (Symphogen, Ballerup, Denmark), a novel mixture of six monoclonal antibodies directed against members of the HER family EGFR, HER2, and HER3, in a preclinical trial of TNBC patient-derived xenografts (PDXs). Methods Fifteen low passage TNBC PDX tumor samples were transferred into the right mammary fat pad of mice for engraftment. When tumors reached an average size of 100–200 mm3, mice were randomized (n ≥ 6 per group) and treated following three 1-week cycles consisting of three times/week intraperitoneal (IP) injection of either formulation buffer (vehicle control) or Pan-HER (50 mg/kg). At the end of treatment, tumors were collected for Western blot, RNA, and immunohistochemistry analyses. Results All 15 TNBC PDXs were responsive to Pan-HER treatment, showing significant reductions in tumor growth consistent with Pan-HER-mediated tumor downmodulation of EGFR and HER3 protein levels and significantly decreased activation of associated HER family signaling pathways AKT and ERK. Tumor regression was observed in five of the models, which corresponded to those PDX tumor models with the highest level of HER family activation. Conclusions The marked effect of Pan-HER in numerous HER family-dependent TNBC PDX models justifies further studies of Pan-HER in TNBC clinical trials as a potential therapeutic option.

Members of the human epidermal growth factor receptor (HER) family, which includes HER1 (also known as EGFR), HER2, HER3 and HER4, have played a central role in regulating cell proliferation, survival, differentiation and migration. The overexpression of the HER family has been recognized as one of the most common cellular dysregulation associated with a wide variety of tumor types. Antibody-drug conjugates (ADCs) represent a new and promising class of anticancer therapeutics that combine the cancer specificity of antibodies with cytotoxicity of chemotherapeutic drugs. Two HER2-directed ADCs, trastuzumane-emtansine (T-DM1) and trastuzumab-deruxtecan (DS-8201a), have been approved for HER2-positive metastatic breast cancer by the U.S. Food and Drug Administration (FDA) in 2013 and 2019, respectively. A third HER2-directed ADC, disitamab vedotin (RC48), has been approved for locally advanced or metastatic gastric or gastroesophageal junction cancer by the NMPA (National Medical Products Administration) of China in 2021. A total of 11 ADCs that target HER family receptors (EGFR, HER2 or HER3) are currently under clinical trials. In this review article, we summarize the three approved ADCs (T-DM1, DS-8201a and RC48), together with the investigational EGFR-directed ADCs (ABT-414, MRG003 and M1231), HER2-directed ADCs (SYD985, ARX-788, A166, MRG002, ALT-P7, GQ1001 and SBT6050) and HER3-directed ADC (U3-1402). Lastly, we discuss the major challenges associated with the development of ADCs, and highlight the possible future directions to tackle these challenges.

HER family members are interdependent and functionally compensatory. Simultaneously targeting EGFR/HER2/HER3 by antibody combinations has demonstrated superior treatment efficacy over targeting one HER receptor. However, antibody combinations have their limitations, with high immunogenicity and high cost. In this study, we have developed a three-in-one nucleic acid aptamer-small interfering RNA (siRNA) chimera, which targets EGFR/HER2/HER3 in one molecule. This inhibitory molecule was constructed such that a single EGFR siRNA is positioned between the HER2 and HER3 aptamers to create a HER2 aptamer-EGFR siRNA-HER3 aptamer chimera (H2EH3). EGFR siRNA was delivered into HER2-expressing cells by HER2/HER3 aptamer-induced internalization. HER2/HER3 aptamers act as antagonist molecules for blocking HER2 and HER3 signaling pathways and also as tumor-targeting agents for siRNA delivery. H2EH3 enables down-modulation of the expression of all three receptors, thereby triggering cell apoptosis. In breast cancer xenograft models, H2EH3 is able to bind to breast tumors with high specificity and significantly inhibits tumor growth via either systemic or intratumoral administration. Owing to low immunogenicity, ease of production, and high thermostability, H2EH3 is a promising therapeutic to supplement current single HER inhibitors and may act as a treatment for HER2+ breast cancer with intrinsic or acquired resistance to current drugs.

Background: The human epidermal growth factor receptor (HER) family, notably EGFR, is overexpressed in most triple-negative breast cancer (TNBC) cases and provides cancer cells with compensatory signals that greatly contribute to the survival and development of resistance in response to therapy. This study investigated the effects of Pan-HER (Symphogen, Ballerup, Denmark), a novel mixture of six monoclonal antibodies directed against members of the HER family EGFR, HER2, and HER3, in a preclinical trial of TNBC patient-derived xenografts (PDXs).Methods: Fifteen low passage TNBC PDX tumor samples were transferred into the right mammary fat pad of mice for engraftment. When tumors reached an average size of 100-200 mm3, mice were randomized (n ≥ 6 per group) and treated following three 1-week cycles consisting of three times/week intraperitoneal (IP) injection of either formulation buffer (vehicle control) or Pan-HER (50 mg/kg). At the end of treatment, tumors were collected for Western blot, RNA, and immunohistochemistry analyses.Results: All 15 TNBC PDXs were responsive to Pan-HER treatment, showing significant reductions in tumor growth consistent with Pan-HER-mediated tumor downmodulation of EGFR and HER3 protein levels and significantly decreased activation of associated HER family signaling pathways AKT and ERK. Tumor regression was observed in five of the models, which corresponded to those PDX tumor models with the highest level of HER family activation.Conclusions: The marked effect of Pan-HER in numerous HER family-dependent TNBC PDX models justifies further studies of Pan-HER in TNBC clinical trials as a potential therapeutic option. [ABSTRACT FROM AUTHOR]

Abstract Cancer immunotherapy is the most exciting advancement in cancer therapy. Similar to immune checkpoint blockade and chimeric antigen receptor T cell (CAR-T), bispecific antibody (BsAb) is attracting more and more attention as a novel strategy of antitumor immunotherapy. BsAb not only offers an effective linkage between therapeutics (e.g., immune effector cells, radionuclides) and targets (e.g., tumor cells) but also simultaneously blocks two different oncogenic mediators. In recent decades, a variety of BsAb formats have been generated. According to the structure of Fc domain, BsAb can be classified into two types: IgG-like format and Fc-free format. Among these formats, bispecific T cell engagers (BiTEs) and triomabs are commonly investigated. BsAb has achieved an exciting breakthrough in hematological malignancies and promising outcome in solid tumor as showed in various clinical trials. In this review, we focus on the preclinical experiments and clinical studies of epithelial cell adhesion molecule (EpCAM), human epidermal growth factor receptor (HER) family, carcinoembryonic antigen (CEA), and prostate-specific membrane antigen (PSMA) related BsAbs in solid tumors, as well as discuss the challenges and corresponding approaches in clinical application.

Introduction: NRG1 gene fusions are clinically actionable alterations identified in NSCLC and other tumors. Previous studies have reported that NRG1 fusions signal through HER2 and HER3 but, thus far, strategies targeting HER3 specifically or HER2-HER3 signaling have exhibited modest activity in patients with NSCLC bearing NRG1 fusions. Although NRG1 fusion proteins can bind HER4 in addition to HER3, the contribution of HER4 and other HER family members in NRG1 fusion-positive cancers is not fully understood., Methods: We investigated the role of HER4 and EGFR-HER3 signaling in NRG1 fusion-positive cancers using Ba/F3 models engineered to express various HER family members in combination with NRG1 fusions and in vitro and in vivo models of NRG1 fusion-positive cancer., Results: We determined that NRG1 fusions can stimulate downstream signaling and tumor cell growth through HER4, independent of other HER family members. Moreover, EGFR-HER3 signaling is also activated in cells expressing NRG1 fusions, and inhibition of these receptors is also necessary to effectively inhibit tumor cell growth. We observed that cetuximab, an anti-EGFR antibody, in combination with anti-HER2 antibodies, trastuzumab and pertuzumab, yielded a synergistic effect. Furthermore, pan-HER tyrosine kinase inhibitors were more effective than tyrosine kinase inhibitors with greater specificity for EGFR, EGFR-HER2, or HER2-HER4, although the relative degree of dependence on EGFR or HER4 signaling varied between different NRG1 fusion-positive cancers., Conclusions: Our findings indicate that pan-HER inhibition including HER4 and EGFR blockade is more effective than selectively targeting HER3 or HER2-HER3 in NRG1 fusion-positive cancers., (Copyright © 2023. Published by Elsevier Inc.)

Targeting ErbB family of receptors is an important therapeutic option, because of its essential role in the broad spectrum of human cancers, including non-small cell lung cancer (NSCLC). Therefore, in the present work, considerable effort has been made to develop an inhibitor against HER family proteins, by combining the use of pharmacophore modelling, docking scoring functions, and ADME property analysis. Initially, a five-point pharmacophore model was developed using known HER family inhibitors. The generated model was then used as a query to screen a total of 468,880 compounds of three databases namely ZINC, ASINEX, and DrugBank. Subsequently, docking analysis was carried out to obtain hit molecules that could inhibit the HER receptors. Further, analysis of GLIDE scores and ADME properties resulted in one hit namely BAS01025917 with higher glide scores, increased CNS involvement, and good pharmaceutically relevant properties than reference ligand, afatinib. Furthermore, the inhibitory activity of the lead compounds was validated by performing molecular dynamic simulations. Of note, BAS01025917 was found to possess scaffolds with a broad spectrum of antitumor activity. We believe that this novel hit molecule can be further exploited for the development of a pan-HER inhibitor with low toxicity and greater potential. [ABSTRACT FROM AUTHOR]

Metformin has effects beyond its antihyperglycemic properties, including altering the localization of membrane receptors in cancer cells. Metformin decreases human epidermal growth factor receptor (HER) membrane density. Depletion of cell-surface HER decreases antibody-tumor binding for imaging and therapeutic approaches. Here, we used HER-targeted PET to annotate antibody-tumor binding in mice treated with metformin. Methods: Small-animal PET annotated antibody binding in HER-expressing xenografts on administration of an acute versus a daily dose schedule of metformin. Analyses at the protein level in the total, membrane, and internalized cell extracts were performed to determine receptor endocytosis, HER surface and internalized protein levels, and HER phosphorylation. Results: At 24 h after injection of radiolabeled anti-HER antibodies, control tumors had higher antibody accumulation than tumors treated with an acute dose of metformin. These differences were temporal, and by 72 h, tumor uptake in acute cohorts was similar to uptake in control. Additional PET imaging revealed a sustained decrease in tumor uptake on daily metformin treatment compared with control and acute metformin cohorts. The effects of metformin on membrane HER were reversible, and after its removal, antibody-tumor binding was restored. The time- and dose-dependent effects of metformin-induced HER depletion observed preclinically were validated with immunofluorescence, fractionation, and protein analysis cell assays. Conclusion: The findings that metformin decreases cell-surface HER receptors and reduces antibody-tumor binding may have significant implications for the use of antibodies targeting these receptors in cancer treatment and molecular imaging., (© 2023 by the Society of Nuclear Medicine and Molecular Imaging.)

Background: The aim of the study was to evaluate the prognostic ability of the transcriptional profiling of the HER family genes in early breast cancer, as a validation analysis of another previously published HeCOG study. Methods: RNA was extracted from 663 formalin-fixed paraffin-embedded (FFPE) tumor tissue samples of high-risk early breast cancer patients enrolled in the randomized HE10/00 trial. Relative mRNA expression of all four HER family members was assessed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Results: In compliance with our previous study, the overall agreement between qRT-PCR and IHC/FISH for HER2 status determination was good (69%). Likewise, the overall concordance between qRT-PCR and IHC for EGFR status was high (81%). In line with our previously reported data, we demonstrated a positive association between HER2 and HER3 mRNA expression. Similarly, mRNA expression of HER3 and HER4 was positively associated with each other and negatively associated with EGFR. Regarding relationships with clinico-pathological parameters, our findings are also in agreement with our previous results. Generally, increased EGFR and HER2 mRNA expression was related to unfavorable, whereas high HER3 and HER4 mRNA expression was associated with favorable clinico-pathological parameters. In univariate analysis, no significant association between EGFR, HER2 and HER3 mRNA expression and overall survival (OS) or disease-free survival (DFS) was demonstrated. However, high EGFR protein expression was associated with significantly shorter OS (log-rank, p = 0.015). In compliance with our previously published data, increased HER4 mRNA expression had a significantly favorable prognostic value in terms of OS (p = 0.044) and DFS (p = 0.047). In multivariate analysis, among all HER receptors, only EGFR protein expression was found to affect OS (Wald's p = 0.028) and DFS (p = 0.015) independently. Concerning the combined expression of all four HER family receptors, the combination of high EGFR, high HER2, low HER3 and low HER4 mRNA expression was associated with a trend for shorter OS (log-rank, p = 0.065) and significantly worse DFS (p = 0.033), compared with all other co-expression profiles. Conclusions: These data indicate that qRT-PCR may represent a valid alternative method for evaluating the expression of HER family members in FFPE breast carcinoma tissue samples. [ABSTRACT FROM AUTHOR]

Recent progress in molecular biology and translational research has initiated an era of personalized medicine in head and neck clinical oncology. The genetic information defined by biomarker analysis in tumors and individuals is indispensable for the administration of molecular targeting agents. The epidermal growth factor receptor (EGFR) signaling pathway is an important therapeutic target in head and neck squamous cell carcinoma (HNSCC). The use of an anti-EGFR monoclonal antibody (mAb), cetuximab (Cmab), has been approved for the treatment of patients with head and neck cancer. Although KRAS mutation has been established as a potential biomarker for predicting the efficacy of anti-EGFR mAb in colorectal cancer, little is known about predictive markers for Cmab in head and neck cancer. Optimal predictive and prognostic markers as well as safety markers are required to promote the appropriate clinical use of Cmab and to determine malignant phenotypes in head and neck cancer. This article first reviews the role of EGFR signaling in HNSCC. The article then focuses on Ras/Raf/Mek/Erk and PTEN/PI3K/Akt signaling pathways as predictive markers for Cmab. Subsequently, the molecular basis and clinical outcome of human papillomavirus (HPV)-positive cancer is highlighted, and the potential role of anti-EGFR target therapy for HPV-positive HNSCC is discussed. Finally, the possible mechanism for resistance to anti-EGFR target therapy is reviewed, and I discuss approaches to overcome the resistance with reference to an ongoing clinical trial. [ABSTRACT FROM AUTHOR]

HER family receptors play a critical role in lung carcinogenesis. There is a growing body of evidence showing that cooperation between them contributes to a more aggressive tumor phenotype and impacts on their response to targeted therapy. We explored immunohistochemical co-expression of HER family receptors (HER1, HER2, HER3, HER4) and its potential role as prognostic factor in resected non-small cell lung cancer (NSCLC). Expression of HER family receptors was assessed by immunohistochemistry on 125 surgically resected NSCLC. Kaplan–Meier estimates of overall survival (OS), disease-free survival (DFS), and time to recurrence were calculated for clinical variables and HER expression, using the Cox model for multivariate analysis. HER1 and HER3 expression was detected more frequently in squamous cell carcinoma ( p = 0.002 and p = <0.001, respectively). HER4 was more often expressed in patients older than 60 years ( p = 0.02) and in tumors of low histological grade ( p = 0.04). Cases which expressed only HER1 had a worse DFS ( p = 0.01) and OS ( p = 0.01) compared to cases expressing HER1 and one or more of the other family members and to cases which did not express HER1 but one of the other HERs. By multivariate analysis, stage was an independent prognostic factor for DFS and OS. Furthermore, different patterns of co-expression of HER family receptors showed a statistically significant correlation with a shorter DFS ( p = 0.03) and OS ( p = 0.02). Our findings suggest that expression of HER1 only is correlated with worse DFS and OS. A better understanding of the functional relationships between these receptors may lead to a useful predictive indicator of response to targeted therapy. [ABSTRACT FROM AUTHOR]

Background To evaluate roles of human epidermal growth factor receptor ( HER) family molecules in ameloblastomas, protein expression and gene status were analyzed in odontogenic tissues. Methods Sixty five ameloblastomas, 10 dental follicles, and 11 dentigerous cysts were immunohistochemically examined with antibodies against epidermal growth factor receptor ( EGFR) and HER2, HER3, and HER4. Amplification of EGFR and HER2 was evaluated by chromogenic in situ hybridization ( CISH). In 18 ameloblastomas, EGFR exons 19 and 21 were analyzed by direct DNA sequencing. Results Immunohistochemical reactivity for EGFR and HER2, HER3, and HER4 was detected in odontogenic epithelium. Expression of EGFR and HER4 was remarkable in these odontogenic tissues, as compared with that of HER2 and HER3. The level of HER2 immunoreactivity was significantly lower in ameloblastomas than in dental follicles and dentigerous cysts. Follicular ameloblastomas showed significantly higher expression of HER2 and HER4 than plexiform ameloblastomas. Reactivity for EGFR and HER3 was slightly stronger in recurrent ameloblastomas than in primary ameloblastomas. CISH did not reveal obvious amplification of EGFR or HER2 in ameloblastomas; however, EGFR and HER2 gene signals were significantly higher in follicular ameloblastomas than in plexiform ameloblastomas. Direct DNA sequencing of EGFR did not show any gene alteration in ameloblastomas. Conclusion Expression of HER family molecules, especially EGFR and HER4, in odontogenic tissues suggests that growth signals mediated by these receptor molecules contribute to cell proliferation, survival, and differentiation in both normal and neoplastic odontogenic epithelial tissues. Some of these molecules might be useful for predicting outcomes in patients with ameloblastomas. [ABSTRACT FROM AUTHOR]

HER2-positive tumors account for approximately 18–20% of all breast cancers. These tumors tend to be more aggressive than HER2-negative tumors and are associated with a poorer prognosis. HER2 overexpression, as determined by either 3+ immunohistochemical staining for HER2 protein or HER2 gene amplification by fluorescence in situ hybridization, should be used to select patients for anti-HER2 therapy. Trastuzumab-containing regimens as first-line therapy should be recommended to women with HER2-positive metastatic breast cancer. The continuation of trastuzumab plus capecitabine provided a significant clinical benefit compared with capecitabine alone in women who experienced progression during trastuzumab treatment. An adjuvant trastuzumab-containing regimen should be also recommended to all intermediate- or high-risk women with HER2-positive early breast cancer. Cardiac function should be serially monitored during this treatment. Many anti-HER2 drugs against breast cancer are being developed. The basic mechanisms of their action and resistance emergence are being clarified step by step. Over the mid- or long term, clinical trials comparing these drugs will be conducted until drugs that are clinically effective and easy to use in the true sense survive. Biomarkers are being aggressively searched for concerning individual drugs under development. A position of the “proper drug for the proper patient” will be more firmly established. [ABSTRACT FROM AUTHOR]

Abstract: The epidermal growth factor (EGF) family of receptor tyrosine kinases consists of four members: EGFR (HER1/ErbB1), HER2/neu (ErbB2), HER3 (ErbB3) and HER4 (ErbB4). Receptor activation via ligand binding leads to downstream signaling that influence cell proliferation, angiogenesis, invasion and metastasis. Aberrant expression or activity of EGFR and HER2 have been strongly linked to the etiology of several human epithelial cancers including but not limited to head and neck squamous cell carcinoma (HNSCC), non-small cell lung cancer (NSCLC), colorectal cancer (CRC), and breast cancer. With this, intense efforts have been made to inhibit the activity of the EGFR and HER2 by designing antibodies against the ligand binding domains (cetuximab, panitumumab and trastuzumab) or small molecules against the tyrosine kinase domains (erlotinib, gefitinib, and lapatinib). Both approaches have shown considerable clinical promise. However, increasing evidence suggests that the majority of patients do not respond to these therapies, and those who show initial response ultimately become refractory to treatment. While mechanisms of resistance to tyrosine kinase inhibitors have been extensively studied, resistance to monoclonal antibodies is less well understood, both in the laboratory and in the clinical setting. In this review, we discuss resistance to antibody-based therapies against the EGFR and HER2, similarities between these resistance profiles, and strategies to overcome resistance to HER family targeting monoclonal antibody therapy. [Copyright &y& Elsevier]

J Oral Pathol Med (2010) 39: 79–86 Objectives: The squamous cell carcinoma of the tongue (SCCT) is biologically and epidemiologically distinct from other oral cavity cancers and is associated with lower overall survival rates. The role of HER family members (HER-1, HER-2/ neu, HER-3 and HER-4) in the pathogenesis and progression of head and neck squamous cell carcinomas has been demonstrated but no report have focused on SCCT. This study investigated, the expression of all members of the HER family, in a series of SCCT and studied the possible prognostic value and correlation with various clinico-pathological parameters. Methods: HER-1, HER-2/ neu, HER-3 and HER-4 expression was analysed by semi-quantitative immunohistochemical staining on paraffin embedded tissue specimens from 40 patients who underwent surgery for SCCT between 1996 and 2006. Results: HER-1 was overexpressed in 26 cases (65%), HER-2/ neu in two (5%), HER-3 in 19 (48%) and HER-4 in three cases (8%). No significant correlation was found between clinicopathological variables and expression of HER-1 and HER-2/ neu. HER-3 overexpression was significantly related to nodal stage, age (≥64 years) and decreased overall survival ( P ≤ 0.05). HER-4 overexpression was significantly associated with low histological grade including when it was coexpressed with HER-3 but in this case the prognosis was worse ( P < 0.05). Conclusions: These results suggest that HER-1 and HER-2/ neu when determined with stringent criteria are not useful indicators of prognosis in SCCT. Only HER-3 overexpression may help in identifying SCCT with greater malignant potential also when it is coexpressed with HER-4. Instead, as in other malignancies, HER-4 could play a protective role in SCCT. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate the prognostic ability of the transcriptional profiling of the HER family genes in early breast cancer, as well as to investigate the predictive value of HER2 mRNA expression for adjuvant treatment with paclitaxel. RNA was extracted from 268 formalin-fixed paraffin-embedded (FFPE) tumour tissue samples of high-risk breast cancer patients enrolled in the randomised HE10/97 trial, evaluating the effect of dose-dense anthracycline-based sequential adjuvant chemotherapy with or without paclitaxel. The mRNA expression of all four HER family members was assessed by kinetic reverse transcription-polymerase chain reaction (kRT–PCR). The overall concordance between kRT–PCR and IHC/FISH for HER2 status determination was 74%. At a median follow-up of 8 years, multivariate analysis showed that EGFR and HER2 mRNA expression was associated with reduced overall survival (OS). HER3 and HER4 mRNA level had a favourable prognostic value in terms of OS and disease-free survival (DFS), respectively. Adjusting for HER2 mRNA expression, OS and DFS did not differ between treatment groups. These data indicate that EGFR as well as HER2 are prognostic factors of worse clinical outcomes, whereas HER3 and HER4 gene transcription is associated with better prognosis in high-risk early breast cancer. However, HER2 mRNA expression did not predict clinical benefit from paclitaxel. Kinetic RT–PCR represents an alternative method for evaluating the expression of HER family members in FFPE breast carcinomas.British Journal of Cancer (2008) 99, 1775–1785. doi:10.1038/sj.bjc.6604769 www.bjcancer.com Published online 4 November 2008 [ABSTRACT FROM AUTHOR]

Abstract: The ERBB or EGF receptor (EGFR) proto-oncogene family, which consists of four structurally-related transmembrane receptors (i.e., EGFR, ErbB2, ErbB3, and ErbB4), plays an etiological role in the molecular pathogenesis of cancer and is a key therapeutic target in many types of cancer, including ovarian cancer. These ErbB/EGF receptor tyrosine kinases play important physiologic roles in cell proliferation, survival, adhesion, motility, invasion, and angiogenesis. It is, therefore, not surprising that gene amplification, genetic mutation, and altered transcription/translation result in aberrant ErbB/EGF receptor expression and/or signal transduction, contributing to the development of malignant transformation. Clinically, the diagnostic, prognostic, and theragnostic significance of any single ErbB receptor and/or ErbB ligand is controversial, but generally, ErbB receptor overexpression has been correlated with poor prognosis and decreased therapeutic responsiveness in ovarian cancer patients. Thus, anticancer agents targeting ErbB/EGF receptors hold great promise for personalized cancer treatment. Yet, challenges remain in designing prospective clinical trials to assess the clinical utility of ErbB receptors and their ligands to diagnose cancer; to predict progression-free and overall survival, therapeutic responsiveness, and disease recurrence; and to monitor treatment responsiveness. Here, we review the tissue expression and serum biomarker studies that have evaluated the diagnostic, prognostic, and theragnostic utility of ErbB/EGF receptors, their circulating soluble isoforms (sEGFR/sErbBs), and their cognate ligands in ovarian cancer patients. [Copyright &y& Elsevier]

Purpose: The aims of this study were twofold: (1) to examine the effects of dual inhibition of 2 members of the HER family, the epidermoid growth factor receptor (EGFR) and HER2/neu, by gefitinib (ZD1839) and trastuzumab on radiosensitivity; and (2) to explore the molecular mechanism of radiosensitization especially focusing on the survival signal transduction pathways by using A431 human vulvar squamous carcinoma cells expressing EGFR and HER2/neu. Methods and Materials: The effects of inhibitors on the radiation-induced activation of EGFR and/or HER2/neu, and the intracellular proteins that are involved in their downstream signaling, were quantified by the Western blot. Radiosensitizing effects by the blockage of EGFR and/or HER2/neu were determined by a clonogenic assay. Results: Radiation-induced activation of the EGFR and HER2/neu was inhibited with ZD1839 and/or trastuzumab. ZD1839 also inhibited the radiation-induced phosphorylation of HER2/neu. Radiation in combination with the HER family inhibitors inhibited the activation of Akt and MEK1/2, the downstream survival signaling of the HER family. ZD1839 enhanced radiosensitivity with a dose-modifying factor (DMF) (SF3) of 1.45 and trastuzumab did so with a DMF (SF3) of 1.11. Simultaneous blockade of EGFR and HER2/neu induced a synergistic radiosensitizing effect with a DMF (SF3) of 2.29. Conclusions: The present data suggest that a dual EGFR and HER2/neu targeting may have potential for radiosensitization in tumors in which both of these pathways are active. [Copyright &y& Elsevier]

Both homo- and hetero-dimers of ErbB receptor tyrosine kinases mediate signaling by a large group of epidermal growth factor (EGF)-like ligands. However, some ligands are more potent than others, although they bind to the same direct receptor. In addition, signaling by receptor heterodimers is superior to homodimers. We addressed the mechanism underlying these two features of signal tuning by using three ligands: EGF; transforming growth factor a (TGFα); and their chimera, denoted E4T, which act on cells singly expressing ErbB-1 as a weak, a strong, and a very strong agonist, respectively. Co-expression of ErbB-2, a developmentally important co-receptor whose expression is frequently elevated in human cancers, specifically potentiated EGF signaling to the level achieved by TGFα, an effect that was partially mimicked by ErbB-3. Analysis of the mechanism underlying this trans-potentiation implied that EGF-driven homodimers of ErbB-1 are destined for intracellular degradation, whereas the corresponding heterodimers with ErbB-2 or with ErbB-3, dissociate in the early endosome. As a consequence, in the presence of either co-receptor, ErbB-1 is recycled to the cell surface and its signaling is enhanced. This latter route is followed by TGFα-driven homodimers of ErbB-1, and also by E4T-bound receptors, whose signaling is further enhanced by repeated cycles of binding and dissociation from the receptors. We conclude that alternative endocytic routes of homo- and hetero-dimeric receptor complexes may contribute to tuning and diversification of signal transduction. In addition, the ability of ErbB-2 to shunt ligand-activated receptors to recycling may explain, in part, its oncogenic potential. [ABSTRACT FROM AUTHOR]

In recent years, HER2 amplification has been evaluated as a potential prognostic biomarker and therapeutic target in urothelial carcinoma (UC). In this retrospective study, we aimed at exploring the prognostic role of HER2 amplification in UC, measured by chromogenic in situ hybridization (CISH). We retrospectively evaluated the presence of HER2 amplification by using CISH in 31 UC patients followed at a single institution between 2018 and 2020. The primary objective was to assess the frequency of HER2 amplification and to compare clinical outcomes of HER2-amplified patients with non-amplified UCs. HER2 amplification was identified in 4 out of 31 patients (12.9 %). After a median follow-up of 28.1 months (95 % Confidence Intervals [CI] 11.2–45.1), median overall survival (OS) in the whole population was 10.9 months (95 % CI 3.5–22.1). Despite not reaching statistical significance, median OS was shorter in HER2-amplified patients (6.8 months, 95 % CI 3.9–9.7) compared to HER2-negative UCs (15.4 months, 95 % CI 7.5–23.3) (p = 0.45). Although limited by the small sample size, the results of our study suggest that HER2 amplifications by CISH could represent a prognostic factor for shorter survival in UC patients. [ABSTRACT FROM AUTHOR]

• Heregulin-1β (HRG) decreased ERα and inversely increased HER -family mRNA expression in ERα-positive breast cancer cells. • HRG expression increased cancer stem cell-like characteristics in ERα-positive breast cancer cells. • HRG attenuated the reduction in cell growth of ERα-positive breast cancer cells following mTOR inhibitor treatment. Estrogen receptor (ER)α and the human epidermal growth factor receptor (HER) family are inversely expressed in ERα-positive cancer in association with resistance to hormonal therapy, but the mechanism underlying their relationship remains unknown. We analyzed the effect of HER family ligands on the expression of ER and the HER family in ERα-positive MCF-7 and T47D breast cancer cell lines in 3D spheroid culture. Here, we demonstrated for the first time that heregulin-1β (HRG), a HER3 and HER4 ligand, most effectively regulated ER/HER family expression by decreasing ERα mRNA expression and increasing HER family mRNA expression. HRG treatment attenuated fulvestrant-mediated growth inhibition, and promoted the migration of MCF-7 cells. Moreover, HRG increased the CD44+/CD24− cell fraction and side population cells, both of which are recognized as prospective breast cancer stem cell markers. HRG activated both phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin (PI3K/AKT/mTOR) and mitogen-activated protein kinase (MAPK) pathways. Inhibitors of these pathways reduced the growth of MCF-7 cells, but the addition of HRG has different effects on these pathways. HRG blocked the inhibitory effect of mTOR inhibitors, such as rapamycin and everolimus, on cell growth but not that of a PI3K inhibitor. Furthermore, HRG slightly decreased the inhibitory effect of an AKT inhibitor on cell growth. In contrast, HRG enhanced the MEK inhibitor-induced inhibition of cell growth. These findings suggest that HRG-stimulated signaling pathways allow ERα-positive breast cancer cells to escape from growth inhibition caused by everolimus, via MAPK signaling and/or other signaling pathways. Everolimus improves progression-free survival in combination with exemestane as second-line therapy for metastatic hormone receptor-positive breast cancer. Our study suggests that HRG is a novel target for ERα-positive breast cancer therapy. [ABSTRACT FROM AUTHOR]

Gastric adenocarcinoma (GAC), the most common malignancy of the stomach, is the fourth most common and the second cause of cancer-related death worldwide. Although HER family plays a cardinal role in tumorigenesis of GAC, trastuzumab is the only approved anti-HER drug for this malignancy and development of resistance to trastuzumab is inevitable. Additionally, single-targeted HER inhibitors have demonstrated limited activity in GAC. Hence, there is a pressing need to devise more efficacious anti-HER therapeutic strategies. Here, we examined the anti-tumor activity of neratinb, a pan-HER inhibitor, on GAC cells. Anti-proliferative effects of neratinib were determined using a cell proliferation assay and crystal violet staining. Annexin V/PI staining, radiation therapy and anoikis resistance and wound healing assays were carried out to examine the effects of neratinib on apoptosis, radio-sensitivity and cell motility, respectively. Quantitative reverse transcription-PCR (qRT-PCR) analyses were applied to further investigate the anti-tumor activity of neratinib. We found that neratinib sensitized GAC cells to 5FU, carboplatin and oxaliplatin. Moreover, we found that neratinib was synergistic with trametinib (an approved MEK inhibitor) and foretinib (a c-MET inhibitor) and potentiated radio-sensitivity of GAC cells. Furthermore, we found that neratinib diminished GAC cell proliferation along with downregulation of FOXM1 and its targets. Additionally, neratinib induced apoptosis along with upregulation of pro-apoptotic and downregulation of anti-apoptotic genes. Treatment with neratinib attenuated invasive ability of GAC cells as shown by reduced anoikis resistance, downregulation of EMT markers, and reduced width in scratch assay. Our findings indicate that neratinib provides the therapeutic potential in the treatment of GAC. [ABSTRACT FROM AUTHOR]