The role of HER3, the unpretentious member of the HER family, in cancer biology and cancer therapeutics

A prospective study of HER3 expression pre and post neoadjuvant therapy of different breast cancer subtypes: implications for HER3 imaging therapy guidance

PURPOSE

HER3, a member of the EGFR receptor family, plays a central role in driving oncogenic cell proliferation in breast cancer. Novel HER3 therapeutics are showing promising results while recently developed HER3 PET imaging modalities aid in predicting and assessing early treatment response. However, baseline HER3 expression, as well as changes in expression while on neoadjuvant therapy, have not been well-characterized. We conducted a prospective clinical study, pre- and post-neoadjuvant/systemic therapy, in patients with newly diagnosed breast cancer to determine HER3 expression, and to identify possible resistance mechanisms maintained through the HER3 receptor.

EXPERIMENTAL DESIGN

The study was conducted between May 25, 2018 and October 12, 2019. Thirty-four patients with newly diagnosed breast cancer of any subtype (ER ± , PR ± , HER2 ±) were enrolled in the study. Two core biopsy specimens were obtained from each patient at the time of diagnosis. Four patients underwent a second research biopsy following initiation of neoadjuvant/systemic therapy or systemic therapy which we define as neoadjuvant therapy. Molecular characterization of HER3 and downstream signaling nodes of the PI3K/AKT and MAPK pathways pre- and post-initiation of therapy was performed. Transcriptional validation of finings was performed in an external dataset (GSE122630).

RESULTS

Variable baseline HER3 expression was found in newly diagnosed breast cancer and correlated positively with pAKT across subtypes (r = 0.45). In patients receiving neoadjuvant/systemic therapy, changes in HER3 expression were variable. In a hormone receptor-positive (ER +/PR +/HER2-) patient, there was a statistically significant increase in HER3 expression post neoadjuvant therapy, while there was no significant change in HER3 expression in a ER +/PR +/HER2+ patient. However, both of these patients showed increased downstream signaling in the PI3K/AKT pathway. One subject with ER +/PR -/HER2- breast cancer and another subject with ER +/PR +/HER2 + breast cancer showed decreased HER3 expression. Transcriptomic findings, revealed an immune suppressive environment in patients with decreased HER3 expression post therapy.

CONCLUSION

This study demonstrates variable HER3 expression across breast cancer subtypes. HER3 expression can be assessed early, post-neoadjuvant therapy, providing valuable insight into cancer biology and potentially serving as a prognostic biomarker. Clinical translation of neoadjuvant therapy assessment can be achieved using HER3 PET imaging, offering real-time information on tumor biology and guiding personalized treatment for breast cancer patients.

Long road towards effective HER3 targeting in breast cancer

Breast cancer is a heterogeneous disease, encompassing multiple different subtypes. Thanks to the increasing knowledge of the diverse biological features of each subtype, most patients receive personalized treatment based on known biomarkers. However, the role of some biomarkers in breast cancer evolution is still unknown, and their potential use as a therapeutic target is still underexplored. HER3 is a member of the human epidermal growth factors receptor family, overexpressed in 50%-70% of breast cancers. HER3 plays a key role in cancer progression, metastasis development, and drug resistance across all the breast cancer subtypes. Owing to its critical role in cancer progression, many HER3-targeting therapies have been developed over the past decade with conflicting findings. Next-generation antibody-drug conjugates have recently shown promising results in solid tumors expressing HER3, including breast cancer. In this review, we discuss the HER3 role in the pathogenesis of breast cancer and its relevance across all subtypes. We also explore the new anti-HER3 treatment strategies, calling into question the significance of HER3 detection as crucial information in breast cancer treatment.

Targeting HER2/HER3 co-mutations in metastatic breast cancer: Case reports of exceptional responders to trastuzumab and pertuzumab therapy

BACKGROUND

Overexpression of HER2 plays an important role in cancer progression and is the target of multiple therapies in HER2-positive breast cancer. Recent studies have also highlighted the presence of activating mutations in HER2, and HER3 that are predicted to enhance HER2 downstream pathway activation in a HER2-dependent manner.

METHODS

In this report, we present two exceptional responses in hormone receptor-positive, HER2-nonamplified, HER2/HER3 co-mutated metastatic breast cancer patients who were treated with the anti-HER2-directed monoclonal antibodies, trastuzumab and pertuzumab.

RESULTS

Both patients acheived exceptional responses to treatment, suggesting that combined trastuzumab, pertuzumab, and endocrine therapy could be a highly effective therapy for these patients and our observations could help prioritize trastuzumab deruxtecan as an early therapeutic choice for patients whose cancers have activating mutations in HER2.

ImmunoPET Targeting Receptor Tyrosine Kinase: Clinical Applications

Receptor tyrosine kinases, or RTKs, are one large family of cell surface receptors involved in signal transduction, which represent an integral part of the signaling pathways. They play a crucial role in most important cellular processes, starting with the cell cycle, proliferation and differentiation, as well as cell migration, metabolism and survival. The introduction of ImmunoPET evaluating the expression of RTKs by specific monoclonal antibodies (mAbs) or antibody fragments is regarded as a promising tool for imaging treatment efficacy and developing anticancer therapeutics. Our review focuses mainly on the current clinical research regarding ImmunoPET targeting RTKs, with particular interest in the epidermal growth factor family, or HER family, and vascular endothelial-derived growth factor/receptor.

Inhibiting HER3 Hyperphosphorylation in HER2-Overexpressing Breast Cancer through Multimodal Therapy with Branched Gold Nanoshells

Treatment failure in breast cancers overexpressing human epidermal growth factor receptor 2 (HER2) is associated mainly to the upregulation of human epidermal growth factor receptor 3 (HER3) oncoprotein linked to chemoresitence. Therefore, to increase patient survival, here a multimodal theranostic nanoplatform targeting both HER2 and HER3 is developed. This consists of doxorubicin-loaded branched gold nanoshells functionalized with the near-infrared (NIR) fluorescent dye indocyanine green, a small interfering RNA (siRNA) against HER3, and the HER2-specific antibody Transtuzumab, able to provide a combined therapeutic outcome (chemo- and photothermal activities, RNA silencing, and immune response). In vitro assays in HER2+ /HER3+ SKBR-3 breast cancer cells have shown an effective silencing of HER3 by the released siRNA and an inhibition of HER2 oncoproteins provided by Trastuzumab, along with a decrease of the serine/threonine protein kinase Akt (p-AKT) typically associated with cell survival and proliferation, which helps to overcome doxorubicin chemoresistance. Conversely, adding the NIR light therapy, an increment in p-AKT concentration is observed, although HER2/HER3 inhibitions are maintained for 72 h. Finally, in vivo studies in a tumor-bearing mice model display a significant progressively decrease of the tumor volume after nanoparticle administration and subsequent NIR light irradiation, confirming the potential efficacy of the hybrid nanocarrier.

HER2 in uterine serous carcinoma: Current state and clinical perspectives

OBJECTIVES

Uterine cancer has the highest incidence and the second-highest mortality rate among gynecologic malignancies in the United States. Although uterine serous carcinoma (USC) represents less than 10% of endometrial carcinomas, it accounts for a disproportionate 50% of tumor relapses and 40% of endometrial cancer deaths. Over the past decade, clinical trials have focused on finding better treatments for this aggressive subtype of endometrial cancer, especially HER2-targeted therapy.

METHODS

We conducted a literature search in PubMed to expand the understanding of HER2 in USC.

RESULTS

HER2 has been established as an important biomarker with prognostic and therapeutic implications in USC. Intratumoral heterogeneity and lateral/basolateral membranous staining of HER2 as well as high discordance between HER2 immunohistochemistry and in situ hybridization are more common in USC than in breast carcinoma. Therefore, a universal HER2 testing and scoring system more suitable to endometrial cancer is needed and currently under investigation.

CONCLUSIONS

This review discusses the clinical perspective of HER2 overexpression/gene amplification in USC, the distinct HER2 staining pattern and the evaluation of HER2 in USC, the resistance mechanisms of HER2-targeted therapy in HER2-positive cancers, and likely areas of future investigation.

HER3 functions as an effective therapeutic target in triple negative breast cancer to potentiate the antitumor activity of gefitinib and paclitaxel

BACKGROUND

Triple negative breast cancer (TNBC) represents a significant clinical challenge. Chemotherapy remains the mainstay for a large part of TNBC patients, whereas drug resistance and tumor recurrence frequently occur. It is in urgent need to identify novel molecular targets for TNBC and develop effective therapy against the aggressive disease.

METHODS

Immunohistochemistry was performed to examine the expression of HER3 in TNBC samples. Western blots were used to assess protein expression and activation. Cell proliferation and viability were determined by cell growth (MTS) assays. TCGA databases were analyzed to correlate HER3 mRNA expression with the clinical outcomes of TNBC patients. Specific shRNA was used to knockdown HER3 expression. IncuCyte system was utilized to monitor cell growth and migration. LIVE/DEAD Cell Imaging was to detect live and dead cells. HER3 recognition by our anti-HER3 monoclonal antibody (mAb) 4A7 was verified by ELISA, flow cytometry, and co-immunoprecipitation assays. Orthotopic tumor models were established in nude mice to determine the capability of TNBC cells forming tumors and to test if our mAb 4A7 could potentiate the antitumor activity of paclitaxel in vivo.

RESULTS

Elevated expression of HER3 was observed in approximately half of the TNBC specimens and cell lines tested. Analyses of TCGA databases found that the TNBC patients with high HER3 mRNA expression in the tumors showed significantly worse overall survival (OS) and relapse-free survival (RFS) than those with low HER3 expression. Specific knockdown of HER3 markedly inhibited TNBC cell proliferation and mammosphere formation in vitro and tumor growth in vivo. Our mAb 4A7 abrogated heregulin (a ligand for HER3), but not SDF-1 (a ligand for CXCR4)-induced enhancement of TNBC cell migration. Combinations of 4A7 and the EGFR-tyrosine kinase inhibitor (TKI) gefitinib dramatically decreased the levels of phosphorylated HER3, EGFR, Akt, and ERK1/2 in TNBC cells and potently induced growth inhibition and cell death. Moreover, 4A7 in combination with paclitaxel exerted significant antitumor activity against TNBC in vitro and in vivo.

CONCLUSIONS

Our data demonstrate that increased HER3 is an effective therapeutic target for TNBC and our anti-HER3 mAb (4A7) may enhance the efficacy of gefitinib or paclitaxel in TNBC.

Desmocollin-1 is associated with pro-metastatic phenotype of luminal A breast cancer cells and is modulated by parthenolide

BACKGROUND

Desmocollin-1 (DSC1) is a desmosomal transmembrane glycoprotein that maintains cell-to-cell adhesion. DSC1 was previously associated with lymph node metastasis of luminal A breast tumors and was found to increase migration and invasion of MCF7 cells in vitro. Therefore, we focused on DSC1 role in cellular and molecular mechanisms in luminal A breast cancer and its possible therapeutic modulation.

METHODS

Western blotting was used to select potential inhibitor decreasing DSC1 protein level in MCF7 cell line. Using atomic force microscopy we evaluated effect of DSC1 overexpression and modulation on cell morphology. The LC-MS/MS analysis of total proteome on Orbitrap Lumos and RNA-Seq analysis of total transcriptome on Illumina NextSeq 500 were performed to study the molecular mechanisms associated with DSC1. Pull-down analysis with LC-MS/MS detection was carried out to uncover DSC1 protein interactome in MCF7 cells.

RESULTS

Analysis of DSC1 protein levels in response to selected inhibitors displays significant DSC1 downregulation (p-value ≤ 0.01) in MCF7 cells treated with NF-κB inhibitor parthenolide. Analysis of mechanic cell properties in response to DSC1 overexpression and parthenolide treatment using atomic force microscopy reveals that DSC1 overexpression reduces height of MCF7 cells and conversely, parthenolide decreases cell stiffness of MCF7 cells overexpressing DSC1. The LC-MS/MS total proteome analysis in data-independent acquisition mode shows a strong connection between DSC1 overexpression and increased levels of proteins LACRT and IGFBP5, increased expression of IGFBP5 is confirmed by RNA-Seq. Pathway analysis of proteomics data uncovers enrichment of proliferative MCM_BIOCARTA pathway including CDK2 and MCM2-7 after DSC1 overexpression. Parthenolide decreases expression of LACRT, IGFBP5 and MCM_BIOCARTA pathway specifically in DSC1 overexpressing cells. Pull-down assay identifies DSC1 interactions with cadherin family proteins including DSG2, CDH1, CDH3 and tyrosine kinase receptors HER2 and HER3; parthenolide modulates DSC1-HER3 interaction.

CONCLUSIONS

Our systems biology data indicate that DSC1 is connected to mechanisms of cell cycle regulation in luminal A breast cancer cells, and can be effectively modulated by parthenolide.

Programmed death receptor ligand-2 (PD-L2) bearing extracellular vesicles as a new biomarker to identify early triple-negative breast cancer patients at high risk for relapse

PURPOSE

Based on the tumor-promoting features of extracellular vesicles (EV) and PD-L1/2-bearing EV subpopulations (PD-L1/2_EV), we evaluated their potential as surrogate markers for disease progression or eligibility criteria for PD-1 immune checkpoint inhibition (ICI) approaches in early triple-negative breast cancer (TNBC).

METHODS

After enrichment of EV from plasma samples of 56 patients before and 50 after chemotherapy (CT), we determined levels of EV particle number and PD-L1/2_EV by nanoparticle tracking analysis or ELISA and associated the results with clinical status/outcome and the presence of distinct circulating tumor cells (CTC) subpopulations.

RESULTS

Compared to healthy controls, patients had a tenfold higher EV concentration and significantly elevated PD L2_EV but not PD L1_EV levels. The most important clinical implications were found for PD-L2_EV. High PD-L2_EV levels were associated with a significantly reduced 3-year progression-free and overall survival (PFS and OS). A loss of PD-L2_EV after CT was significantly more prominent in patients achieving pathological complete response (pCR). Increased pre-CT PD-L2_EV levels were found in patients having NOTCH1-positive or ERBB3-positive CTC. The presence of ERBB3-positive CTC combined with high pre-CT PD-L2_EV resulted in a shorter PFS.

CONCLUSION

This study highlights PD L2_EV as a promising biomarker for risk assessment of TNBC patients and represents the basic for additional studies introducing PD-L2_EV as an eligibility criterion for PD-1 ICI approaches.

Mathematical modeling of regulatory networks of intracellular processes - Aims and selected methods

Regulatory networks structure and signaling pathways dynamics are uncovered in time- and resource consuming experimental work. However, it is increasingly supported by modeling, analytical and computational techniques as well as discrete mathematics and artificial intelligence applied to to extract knowledge from existing databases. This review is focused on mathematical modeling used to analyze dynamics and robustness of these networks. This paper presents a review of selected modeling methods that facilitate advances in molecular biology.

MicroRNA-592 Inhibits the Growth of Ovarian Cancer Cells by Targeting ERBB3

Objectives: Ovarian cancer is the most lethal gynecologic malignancy, and targeted therapy for different pathological types and molecular phenotypes is urgent to be studied. Studies have shown that MicroRNA-592 (miR-592) plays an important negative regulatory role in the occurrence of gastrointestinal malignancies, breast cancer, non-small cell lung cancer, and glioma, but the expression of miR-592 in ovarian cancer and the mechanism of action are still unclear. Methods: The expressions of miR-592 were examined by RT-PCR and Western Blot. Cell viability and migratory capacity were detected by CCK-8 and transwell assay. TargetScan (http://www.targetscan.org) was analyzed to predict potential targets of miR-592. Then Dual-luciferase reporter gene assay was performed to verify the targeting relationship between miR-592 and ERBB3. A mouse xenograft model was applied to confirm the effect of miR-592. Results: In our study, we found that the expression of miR-592 is reduced in epithelial ovarian cancer tissues. The exogenous expression of miR-592 inhibits the proliferation, migration, and invasion in epithelial ovarian cancer tumor cells. Furthermore, the exogenous expression of miR-592 inhibits tumor growth in the nude mouse xenograft model. Therefore, miR-592 may play a role of tumor suppressor miRNA in the occurrence and development of ovarian cancer. Further experiments demonstrated that tumor-related ERBB3 is a target gene mediated by miRNA-592. The dual-luciferase reporter system was used to identify miRNA-592 target genes; qPCR and Western Blot were used to detect the expression of ERBB3. Mechanical experiments confirmed that miRNA-592 negatively regulated ERBB3.Conclusion: Together, these findings identify a heretofore unrecognized link between miR-592 and ERBB3 and suggest that targeting on miR-592 warrants attention as a novel and potential therapeutic strategy for ovarian cancer.

Efficacy evaluation of neoadjuvant chemotherapy in patients with HER2-low expression breast cancer: A real-world retrospective study

Background

To characterize the clinicopathological features and evaluate the neoadjuvant chemotherapy (NACT) efficacy of patients with human epidermal growth factor receptor 2 (HER2)-low breast cancer.

Methods

A total of 905 breast cancer patients who received 4 cycles of thrice-weekly standard NACT in the First Affiliated Hospital of Chongqing Medical University were retrospectively enrolled, including 685 cases with HER2-low expression and 220 cases with HER2-negative expression. Clinicopathological features were compared between patients with HER2-negative and HER2-low expression. Univariate and multivariate logistic regression analyses were used to find the independent factors of achieving a pathological complete response (pCR) after NACT.

Results

There were significant differences in stage_N (P = 0.014), histological grade (P = 0.001), estrogen receptor (ER) status (P < 0.001), progesterone receptor (PgR) status (P < 0.001), NACT regimens (P = 0.032) and NACT efficacy (P = 0.037) between patients with HER2-negative and HER2-low expression breast cancer. In subgroup analysis, histological grade (P = 0.032), ER (P = 0.002), Ki-67 (P < 0.001) and HER2 status (P = 0.025) were independent predictors of achieving a pCR in ER-positive breast cancer. And the nomogram for pCR in ER-positive breast cancer showed great discriminatory ability with an AUC of 0.795. The calibration curve also showed that the predictive ability of the nomogram was a good fit to actual observations. Then, in the analysis of ER-negative breast cancer, only stage_N (P = 0.001) and Ki-67 (P = 0.018) were independent influencing factors of achieving a pCR in ER-negative breast cancer.

Conclusion

HER2-low breast cancer was a different disease from HER2-negative breast cancer in clinicopathological features. Moreover, the NACT efficacy of HER2-low breast cancer patients was poorer.

HER3 in cancer: from the bench to the bedside

The HER3 protein, that belongs to the ErbB/HER receptor tyrosine kinase (RTK) family, is expressed in several types of tumors. That fact, together with the role of HER3 in promoting cell proliferation, implicate that targeting HER3 may have therapeutic relevance. Furthermore, expression and activation of HER3 has been linked to resistance to drugs that target other HER receptors such as agents that act on EGFR or HER2. In addition, HER3 has been associated to resistance to some chemotherapeutic drugs. Because of those circumstances, efforts to develop and test agents targeting HER3 have been carried out. Two types of agents targeting HER3 have been developed. The most abundant are antibodies or engineered antibody derivatives that specifically recognize the extracellular region of HER3. In addition, the use of aptamers specifically interacting with HER3, vaccines or HER3-targeting siRNAs have also been developed. Here we discuss the state of the art of the preclinical and clinical development of drugs aimed at targeting HER3 with therapeutic purposes.

Ampk Activation Attenuates Her3 Upregulation And Neuregulin-Mediated Rescue of Cell Proliferation in Her2-Overexpressing Breast Cancer Cell Lines Exposed to Lapatinib

Lapatinib is a highly selective reversible inhibitor of the tyrosine kinase domains of HER2 and EGFR, approved for the treatment of advanced stage HER2-overexpressing breast cancers. Although targeted therapy with lapatinib provides initial clinical advantage, cancer cells' adaptive responses can overcome the inhibitory effects of lapatinib. HER3 upregulation and autocrine induction of HER3 ligand neuregulin-1 (NRG), have been implicated in the restoration of AKT and ERK1/2 activity and rescue of cell proliferation. In this study we evaluated the effects of lapatinib alone and in combination with AMPK activator GSK-621 in HER2-overexpressing breast cancer cell lines SKBR3 and BT474. Our results show that in cells exposed to lapatinib and GSK-621 in combination, lapatinib-mediated HER3 upregulation was reduced and reactivation of AKT and ERK1/2 kinases was prevented. The two drugs in combination decreased cell viability in a synergistic manner and greatly reduced the ability of NRG to rescue cell proliferation. Finally, we provide evidence that in cells exposed to lapatinib and GSK-621 in combination the establishment of a transcriptionally permissive chromatin structure at the HER3 promoter is hampered. The results of this study highlight a potential role for AMPK activation in counteracting lapatinib-induced adaptive responses of HER2-overexpressing breast cancer cells.

Integrated driver mutations profile of chinese gastrointestinal-natural killer/T-cell lymphoma

Background

One of the most common nasal external sites in extranodal Natural Killer/T-cell lymphoma (NKTCL) is in the gastrointestinal (GI) system. Despite this, reports on gastrointestinal-Natural Killer/T-cell lymphoma (GI-NKTCL) are very few. To obtain a better understanding of this manifestation of NKTCL, we conducted a retrospective study on GI-NKTCL to analyze its clinical features, genomic changes and immune infiltration.

Methods

We retrospectively collected patients diagnosed with GI-NKTCL in the Sixth Affiliated Hospital of Sun Yat-sen University from 2010 to 2020. From this cohort we obtained mutation data via whole exome sequencing.

Results

Genomic analysis from 15 patients with GI-NKTCL showed that the most common driving mutations were ARID1B(14%, 2/15), ERBB3(14%, 2/15), POT1(14%, 2/15), and TP53(14%, 2/15). In addition, we found the most common gene mutation in patients with GI-NKTCL to be RETSAT(29%, 4/15) and SNRNP70(21%, 3/15), and the most common hallmark pathway mutations to be G2M checkpoint pathway (10/15, 66.7%), E2F targets (8/15, 53.3%), estrogen response late (7/15, 46.7%), estrogen response early (7/15, 46.7%), apoptosis (7/15, 46.7%) and TNFA signaling via NFKB (7/15, 46.7%). In the ICIs-Miao cohort, SNRNP7-wild-type (WT) melanoma patients had significantly prolonged overall survival (OS) time compared with SNRNP7 mutant type (MT) melanoma patients. In the TCGA-UCEC cohort, the patients with RETSAT-MT or SNRNP7-MT had significantly increased expression of immune checkpoint molecules and upregulation of inflammatory immune cells.

Conclusions

In this study, we explored GI-NKTCL by means of genomic analysis, and identified the most common mutant genes (RETSAT and SNRNP70), pathway mutations (G2M checkpoint and E2F targets) in GI-NKTCL patients. Also, we explored the association between the common mutant genes and immune infiltration. Our aim is that our exploration of these genomic changes will aid in the discovery of new biomarkers and therapeutic targets for those with GI-NKTCL, and finally provide a theoretical basis for improving the treatment and prognosis of patients with GI-NKTCL.

Improved prediction of gene expression through integrating cell signalling models with machine learning

Background

A key problem in bioinformatics is that of predicting gene expression levels. There are two broad approaches: use of mechanistic models that aim to directly simulate the underlying biology, and use of machine learning (ML) to empirically predict expression levels from descriptors of the experiments. There are advantages and disadvantages to both approaches: mechanistic models more directly reflect the underlying biological causation, but do not directly utilize the available empirical data; while ML methods do not fully utilize existing biological knowledge.

Results

Here, we investigate overcoming these disadvantages by integrating mechanistic cell signalling models with ML. Our approach to integration is to augment ML with similarity features (attributes) computed from cell signalling models. Seven sets of different similarity feature were generated using graph theory. Each set of features was in turn used to learn multi-target regression models. All the features have significantly improved accuracy over the baseline model - without the similarity features. Finally, the seven multi-target regression models were stacked together to form an overall prediction model that was significantly better than the baseline on 95% of genes on an independent test set. The similarity features enable this stacking model to provide interpretable knowledge about cancer, e.g. the role of ERBB3 in the MCF7 breast cancer cell line.

Conclusion

Integrating mechanistic models as graphs helps to both improve the predictive results of machine learning models, and to provide biological knowledge about genes that can help in building state-of-the-art mechanistic models.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12859-022-04787-8.

Recent advances in targeting protein kinases and pseudokinases in cancer biology

Kinases still remain the most favorable members of the druggable genome, and there are an increasing number of kinase inhibitors approved by the FDA to treat a variety of cancers. Here, we summarize recent developments in targeting kinases and pseudokinases with some examples. Targeting the cell cycle machinery garnered significant clinical success, however, a large section of the kinome remains understudied. We also review recent developments in the understanding of pseudokinases and discuss approaches on how to effectively target in cancer.

Molecular Assessment of HER2 to Identify Signatures Associated with Therapy Response in HER2-Positive Breast Cancer

Simple Summary

The HER2 status of breast cancers is accurately determined by measuring HER2 protein overexpression and gene amplification. However, these clinical diagnostic tests cannot predict the response to therapy. Single molecule imaging approaches can quantify molecular features of HER2, such as receptor nano-organization, with exquisite spatial resolution and sensitivity. The aim of our study was to assess how the molecular features of HER2 varied with the therapy response. According to our results in cultured cell lines and six patient specimens, the therapy response was associated with high detected HER2 densities and clustering. This advanced imaging approach can thus provide key data to complement the current diagnostic standards.

Abstract

Trastuzumab, the prototype HER2-directed therapy, has markedly improved survival for women with HER2-positive breast cancers. However, only 40–60% of women with HER2-positive breast cancers achieve a complete pathological response to chemotherapy combined with HER2-directed therapy. The current diagnostic assays have poor positive-predictive accuracy in identifying therapy-responsive breast cancers. Here, we deployed quantitative single molecule localization microscopy to assess the molecular features of HER2 in a therapy-responsive setting. Using fluorescently labeled trastuzumab as a probe, we first compared the molecular features of HER2 in trastuzumab-sensitive (BT-474 and SK-BR-3) and trastuzumab-resistant (BT-474^R and JIMT-1) cultured cell lines. Trastuzumab-sensitive cells had significantly higher detected HER2 densities and clustering. We then evaluated HER2 in pre-treatment core biopsies from women with breast cancer undergoing neoadjuvant therapy. A complete pathological response was associated with a high detected HER2 density and significant HER2 clustering. These results established the nano-organization of HER2 as a potential signature of therapy-responsive disease.

Patritumab deruxtecan (HER3-DXd), a novel HER3 directed antibody drug conjugate, exhibits in vitro activity against breast cancer cells expressing HER3 mutations with and without HER2 overexpression

ErbB3 (HER3), a member of the HER family, is overexpressed in various cancers and plays an important role in cell proliferation and survival. Certain HER3 mutations have also been identified as oncogenic drivers, making them potential therapeutic targets. In the current study, antitumor activity of patritumab deruxtecan (HER3-DXd), a HER3 directed antibody drug conjugate, was evaluated in tumor models with clinically reported HER3 mutations. MDA-MB-231, a HER3-negative human triple-negative breast cancer cell line, was transduced with lentiviral vectors encoding HER3 wild type (HER3^WT), one of 11 HER3 mutations, or HER3 empty vector (HER3^EV), in the presence/absence of HER2 overexpression. Targeted delivery of HER3-DXd was assessed using cell-surface binding, lysosomal trafficking, and cell-growth inhibition assays. HER3-DXd bound to the surface of HER3^WT and mutant cells in a similar, concentration-dependent manner but not to HER3^EV. HER3-DXd was translocated to the lysosome, where time- and concentration-dependent signals were observed in the HER3 mutant and HER3^WT cells. HER3-DXd inhibited the growth of HER3^WT and HER3 mutant cells. HER3-DXd activity was observed in the presence and absence of HER2 overexpression. These data suggest that HER3-DXd may have activity against tumors expressing wild type HER3 or clinically observed HER3 mutations, supporting further clinical evaluation.

CAN017, a novel anti-HER3 antibody, exerted great potency in mouse avatars of esophageal squamous cell carcinoma with NRG1 as a biomarker

CAN017 (AV-203), a novel anti-HER3 antibody, exerts very promising anti-tumor activities in several human tumor models. The aim of this study was to further investigated the efficacy and possible responsive biomarkers of CAN017 in esophageal squamous cell carcinoma (ESCC) with Chinese characteristics. Two separate cohorts of ESCC patient-derived xenograft (PDX) models including 24 (cohort 1 as training models, from Crown Bioscience Inc.) and 22 (cohort 2 as validating models, from Peking University Cancer Hospital) models, respectively, were used to study the efficacy and safety of CAN017, as well as the correlation of NRG1 expression to the response of CAN017. In cohort 1, all PDX models showed good tolerance to CAN017 and 8 out of 24 (33.3%) PDX models responded to CAN017 with tumor growth inhibition (TGI) ≥70% compared to controls. Furthermore, the efficacy of CAN017 was positively correlated with NRG1 expression and the response rates in cohort 1 were 73% (8/11) versus 0% (0/13) in NRG1 high and low expression models, respectively. These results were also validated in PDX models of cohort 2 indicated as the powerful anti-tumor activity of CAN017 in PDX models with NRG1 high expression. In our study, HER3-targeting therapy was first demonstrated to have potency in inhibiting ESCC tumor growth, and NRG1 served as a predictive biomarker to screen patients in future clinical trials.

A bivalent, bispecific Dab-Fc antibody molecule for dual targeting of HER2 and HER3

Dual targeting of surface receptors with bispecific antibodies is attracting increasing interest in cancer therapy. Here, we present a novel bivalent and bispecific antagonistic molecule (Dab-Fc) targeting human epidermal growth factors 2 and 3 (HER2 and HER3) derived from the Db-Ig platform, which was developed for the generation of multivalent and multispecific antibody molecules. Dab-Fc comprises the variable domains of the anti-HER2 antibody trastuzumab and the anti-HER3 antibody 3-43 assembled into a diabody-like structure stabilized by CH1 and CL domains and further fused to a human γ1 Fc region. The resulting Dab-Fc 2 × 3 molecule retained unhindered binding to both antigens and was able to bind both antigens sequentially. In cellular experiments, the Dab-Fc 2 × 3 molecule strongly bound to different tumor cell lines expressing HER2 and HER3 and was efficiently internalized. This was associated with potent inhibition of the proliferation and migration of these tumor cell lines. Furthermore, IgG-like pharmacokinetics and anti-tumoral activity were demonstrated in a xenograft tumor model of the gastric cancer cell-line NCI-N87. These results illustrate the suitability of our versatile Db-Ig platform technology for the generation of bivalent bispecific molecules, which has been successfully used here for the dual targeting of HER2 and HER3.

Neoadjuvant chemotherapy promotes the expression of HER3 in patients with ovarian cancer

HER3 (erbB3) signaling serves an important role in the development and chemoresistance of ovarian cancer, and is activated by chemotherapy. To evaluate the influence of neoadjuvant chemotherapy and other clinical factors on the expression of HER3, as well as to examine its role as a prognostic marker, the present study evaluated archived tissues from patients who underwent surgery for ovarian cancer between 2011 and 2018 at our hospital. Immunohistochemical staining for HER3 was performed using formalin-fixed paraffin-embedded surgical specimens and biopsy samples. In total, data from 111 patients with sufficient surgically resected tumor samples were extracted. A total of 28 patients with histology type high-grade serous carcinoma (HGSC) had specimens available from both pre-chemotherapy biopsies and post-chemotherapy surgery. High HER3 expression (HER3-high) was observed in 64 patients (58%), whereas low HER3 expression (HER3-low) was observed in 47 patients (42%). Multivariate logistic regression analysis identified neoadjuvant chemotherapy [odds ratio (OR), 7.49; 95% confidence interval (CI), 2.48–22.64; P<0.001) and non-HGSC histology (OR, 5.42; 95% CI, 1.99–14.78; P<0.001) as significant predictive factors for HER3-high. In pre-chemotherapy biopsy specimens, 15 patients were HER3-high and 13 were HER3-low. After chemotherapy, eight of 13 patients with HER3-low exhibited a change in status to HER3-high, with a trend toward poorer progression-free survival compared to that of patients whose status remained HER3-low. In conclusion, HER3 overexpression was revealed to be common among patients with ovarian cancer, especially in those with non-HGSC histology. In addition, HER3 expression may be promoted by chemotherapy. These findings suggested that patients with ovarian cancer are good candidates for emerging HER3-targeting therapies.

HER3 protein expression as a risk factor for post-operative recurrence in patients with early-stage adenocarcinoma and adenosquamous carcinoma of the cervix

Patients with cervical adenocarcinoma (AC) and adenosquamous carcinoma (ASC) have a poorer prognosis than those with squamous cell carcinoma (SCC). Erb-b2 receptor tyrosine kinase 3 (HER3) is a member of the epidermal growth factor receptor family and its expression is associated with unfavorable prognosis in several cancer types, including SCC of the cervix. As there is limited information on the prognostic value of HER3 for AC and ASC of the cervix, the present study aimed to evaluate the expression of HER3 and its impact on post-operative recurrence in patients with AC and ASC of the cervix. This retrospective study included 39 patients with early-stage AC and ASC who underwent primary surgery between January 1997 and December 2017. Immunohistochemical staining for HER3 was performed on formalin-fixed paraffin-embedded surgical specimens. The possible influence of HER3 expression on disease-free survival (DFS) was studied by using multivariate Cox regression with adjustment for established risk factors of post-operative recurrence. High expression of HER3 (HER3-high) was detected in 85.1% of cases of AC (23/27) and in 58.3% of cases of ASC (7/12). The median follow-up duration was 63.1 months and Kaplan-Meier analysis indicated that the 5-year DFS rates of patients with AC and ASC of the cervix were 56.7% in patients with HER3-high and 77.8% in patients with HER3-low (log rank, P=0.20). On multivariate analysis, HER3-high [hazard ratio (HR)=6.32, 95% CI: 1.10–36.26, P=0.039), pelvic lymph node metastasis (HR=7.61, 95% CI: 2.07–28.00, P=0.002) and vascular invasion (HR=4.28, 95% CI: 1.12–16.31, P=0.033) were indicated to be independent predictors of DFS. To date, the present study is the most comprehensive analysis to evaluate the expression of HER3 in patients with early-stage AC and ASC of the cervix. The results suggested that HER3 overexpression may be an independent risk factor for post-operative recurrence. However, these results and the prognostic value of HER3 should be confirmed in a larger sample.

Structural Insights into Pseudokinase Domains of Receptor Tyrosine Kinases

Despite their apparent lack of catalytic activity, pseudokinases are essential signaling molecules. Here, we describe the structural and dynamic properties of pseudokinase domains from the Wnt-binding receptor tyrosine kinases (PTK7, ROR1, ROR2, and RYK), which play important roles in development. We determined structures of all pseudokinase domains in this family and found that they share a conserved inactive conformation in their activation loop that resembles the autoinhibited insulin receptor kinase (IRK). They also have inaccessible ATP-binding pockets, occluded by aromatic residues that mimic a cofactor-bound state. Structural comparisons revealed significant domain plasticity and alternative interactions that substitute for absent conserved motifs. The pseudokinases also showed dynamic properties that were strikingly similar to those of IRK. Despite the inaccessible ATP site, screening identified ATP-competitive type-II inhibitors for ROR1. Our results set the stage for an emerging therapeutic modality of "conformational disruptors" to inhibit or modulate non-catalytic functions of pseudokinases deregulated in disease.

Benefit of Later-Time-Point PET Imaging of HER3 Expression Using Optimized Radiocobalt-Labeled Affibody Molecules

HER3-binding affibody molecules are a promising format for visualization of HER3 expression. Cobalt-55, a positron-emitting isotope, with a half-life of 17.5 h, allows for next-day imaging. We investigated the influence of the charge of the radiocobalt–chelator complex on the biodistribution of anti-HER3 affibody molecule (HE)₃-Z_HER3 and compared the best radiocobalt-labeled variant with a recently optimized gallium-labeled variant. Affibody conjugates (HE)₃-Z_HER3-X (X = NOTA, NODAGA, DOTA, DOTAGA) were labeled with [⁵⁷Co]Co (surrogate for ⁵⁵Co). Affinity measurements, binding specificity and cellular processing were studied in two HER3-expressing cancer cell lines. Biodistribution was studied 3 and 24 h post-injection (pi) in mice with HER3-expressing BxPC-3 xenografts and compared to [⁶⁸Ga]Ga-(HE)₃-Z_HER3-NODAGA. Micro-single-photon emission tomography/computed tomography (microSPECT/CT) and micro-positron emission tomography/computed tomography (microPET/CT) imaging was performed 3 and 24 h pi. Stably labeled conjugates bound to HER3 with subnanomolar affinity. [⁵⁷Co]Co-(HE)₃-Z_HER3-DOTA had the best tumor retention and a significantly lower concentration in blood than other conjugates, leading to superior tumor-to-blood and tumor-to-liver ratios 24 h pi. Compared to [⁶⁸Ga]Ga-(HE)₃-Z_HER3-NODAGA 3 h pi, [⁵⁷Co]Co-(HE)₃-Z_HER3-DOTA provided superior imaging contrast in liver 24 h pi. Concluding, the composition and charge of the [⁵⁷Co]Co–chelator complex influenced the uptake in tumors and normal tissue. [⁵⁷Co]Co-(HE)₃-Z_HER3-DOTA provided the best imaging properties among the cobalt-labeled conjugates. Delayed imaging of HER3 expression with [⁵⁷Co]Co-(HE)₃-Z_HER3-DOTA improved imaging contrast compared to early-time-point imaging with [⁶⁸Ga]Ga-(HE)₃-Z_HER3-NODAGA.

Inhibitory Effect of Polyclonal Antibodies Against HER3 Extracellular Subdomains on Breast Cancer Cell Lines

Objective:

Human epidermal growth factor receptor 3 (HER3) is a unique member of the tyrosine kinase receptors with an inactive kinase domain and is the preferable dimerization partner for HER2 which lead to potent tumorigenic signaling.

Methods:

In this study, the expression plasmids coding for the human HER3 subdomains were transfected into CHO-K1 cells. Produced proteins were characterized by ELISA and SDS-PAGE. Rabbits were immunized and produced polyclonal antibodies (pAbs) that were characterized by ELISA, Immunoblotting and flowcytometry and their inhibitory effects were assessed by XTT on BT-474 and JIMT-1 breast cancer cell lines.

Result:

The recombinant subdomains were highly immunogenic in rabbits. The pAbs reacted with the recombinant subdomains as well as commercial HER3 and the native receptor on tumor cell membranes and could significantly inhibit growth of Trastuzumab sensitive (BT-474) and resistant (JIMT-1) breast cancer cell lines in vitro.

Conclusion:

It seems that HER3 extra cellular domains (ECD) induce a strong anti-tumor antibody response and may prove to be potentially useful for immunotherapeutic applications.

Novel functional anti-HER3 monoclonal antibodies with potent anti-cancer effects on various human epithelial cancers

Resistance of progressive cancers against chemotherapy is a serious clinical problem. In this context, human epidermal growth factor receptor 3 (HER3) can play important roles in drug resistance to HER1- and HER2- targeted therapies. Since clinical testing of anti-HER3 monoclonal antibodies (mAbs) such as patritumab could not show remarkable effect compared with existing drugs, we generated novel mAbs against anti-HER3. Novel rat mAbs reacted with HEK293 cells expressing HER3, but not with cells expressing HER1, HER2 or HER4. Specificity of mAbs was substantiated by the loss of mAb binding with knockdown by siRNA and knockout of CRISPR/Cas9-based genome-editing. Analyses of CDR sequence and germline segment have revealed that seven mAbs are classified to four groups, and the binding of patritumab was inhibited by one of seven mAbs. Seven mAbs have shown reactivity with various human epithelial cancer cells, strong internalization activity of cell-surface HER3, and inhibition of NRG1 binding, NRG1-dependent HER3 phosphorylation and cell growth. Anti-HER3 mAbs were also reactive with in vivo tumor tissues and cancer tissue-originated spheroid. Ab4 inhibited in vivo tumor growth of human colon cancer cells in nude mice. Present mAbs may be superior to existing anti-HER3 mAbs and support existing anti-cancer therapeutic mAbs.

The emerging treatment landscape of targeted therapy in non-small-cell lung cancer

Lung cancer is one of the most common cancer in the world. In 2018, there were over 2 million new cases of lung cancer and over 1.7 million deaths were attributed to lung cancer. Targeted therapy has emerged as an important mean of the disease management for patients with non-small-cell lung cancer (NSCLC). Herein, we review and analyze recent literature, discuss the targeting pathways and ongoing clinical trials in lung cancer. Chemotherapy is no longer the best available treatment for all patients. Therapeutic decisions should be guided by an understanding of the molecular features of patient's tumor tissues. The future gains will likely emerge from finding optimal ways of combining targeted therapy, immunotherapy, and chemotherapy.

Increase in negative charge of 68Ga/chelator complex reduces unspecific hepatic uptake but does not improve imaging properties of HER3-targeting affibody molecules

Upregulation of the human epidermal growth factor receptor type 3 (HER3) is a common mechanism to bypass HER-targeted cancer therapy. Affibody-based molecular imaging has the potential for detecting and monitoring HER3 expression during treatment. In this study, we compared the imaging properties of newly generated ⁶⁸Ga-labeled anti-HER3 affibody molecules (HE)₃-Z_HER3-DOTA and (HE)₃-Z_HER3-DOTAGA with previously reported [⁶⁸Ga]Ga-(HE)₃-Z_HER3-NODAGA. We hypothesized that increasing the negative charge of the gallium-68/chelator complex would reduce hepatic uptake, which could lead to improved contrast of anti-HER3 affibody-based PET-imaging of HER3 expression. (HE)₃-Z_HER3-X (X = DOTA, DOTAGA) were produced and labeled with gallium-68. Binding of the new conjugates was specific in HER3 expressing BxPC-3 and DU145 human cancer cells. Biodistribution and in vivo specificity was studied in BxPC-3 xenograft bearing Balb/c nu/nu mice 3 h pi. DOTA- and DOTAGA-containing conjugates had significantly higher concentration in blood than [⁶⁸Ga]Ga-(HE)₃-Z_HER3-NODAGA. Presence of the negatively charged ⁶⁸Ga-DOTAGA complex reduced the unspecific hepatic uptake, but did not improve overall biodistribution of the conjugate. [⁶⁸Ga]Ga-(HE)₃-Z_HER3-DOTAGA and [⁶⁸Ga]Ga-(HE)₃-Z_HER3-NODAGA had similar tumor-to-liver ratios, but [⁶⁸Ga]Ga-(HE)₃-Z_HER3-NODAGA had the highest tumor uptake and tumor-to-blood ratio among the tested conjugates. In conclusion, [⁶⁸Ga]Ga-(HE)₃-Z_HER3-NODAGA remains the favorable variant for PET imaging of HER3 expression.

A Novel HER3-Targeting Antibody-Drug Conjugate, U3-1402, Exhibits Potent Therapeutic Efficacy through the Delivery of Cytotoxic Payload by Efficient Internalization

PURPOSE

HER3 is a compelling target for cancer treatment; however, no HER3-targeted therapy is currently clinically available. Here, we produced U3-1402, an anti-HER3 antibody-drug conjugate with a topoisomerase I inhibitor exatecan derivative (DXd), and systematically investigated its targeted drug delivery potential and antitumor activity in preclinical models.

EXPERIMENTAL DESIGN

In vitro pharmacologic activities and the mechanisms of action of U3-1402 were assessed in several human cancer cell lines. Antitumor activity of U3-1402 was evaluated in xenograft mouse models, including patient-derived xenograft (PDX) models. Safety assessments were also conducted in rats and monkeys.

RESULTS

U3-1402 showed HER3-specific binding followed by highly efficient cancer cell internalization. Subsequently, U3-1402 was translocated to the lysosome and released its payload DXd. While U3-1402 was able to inhibit HER3-activated signaling similar to its naked antibody patritumab, the cytotoxic activity of U3-1402 in HER3-expressing cells was predominantly mediated by released DXd through DNA damage and apoptosis induction. In xenograft mouse models, U3-1402 exhibited dose-dependent and HER3-dependent antitumor activity. Furthermore, U3-1402 exerted potent antitumor activity against PDX tumors with HER3 expression. Acceptable toxicity was noted in both rats and monkeys.

CONCLUSIONS

U3-1402 demonstrated promising antitumor activity against HER3-expressing tumors with tolerable safety profiles. The activity of U3-1402 was driven by HER3-mediated payload delivery via high internalization into tumor cells.

HER3 and HER4 are highly expressed in human meningiomas

HER3 and HER4 are tyrosine kinase receptors of the ErbB family that have been detected in several cancers but lack substantial investigation in human meningiomas. In this study, HER3 and -4 expression levels were evaluated as potential biomarkers by immunohistochemistry and explored for association to clinical features in a large series of human meningiomas. 186 primary intracranial meningiomas from adult patients were investigated with antibodies against HER3 and -4 intracellular domains. Tumors were scored with a staining index (SI) based on cytoplasmic/membranous staining intensity and on the percentage of positive cells. SIs were tested for associations with WHO malignancy grade, tumor subtype, localization, and prognosis. HER3 and HER4 were highly expressed in most tumors. Both cytoplasmic and membranous immunoreactivity occurred, and for HER4 nuclear immunoreactivity was observed as well. Non-neoplastic meningeal tissue was not immunoreactive. HER3 and -4 immunoreactivity was not associated with WHO malignancy grade, nor with recurrence or survival in adjusted analyses. Meningiomas of all grades were shown to widely express both HER3 and HER4 receptors. This feature may have diagnostic value since non-neoplastic meninges were not immunoreactive. There was no prognostic significance in adjusted survival analyses.

A Comprehensive Review of Non-Covalent Radiofluorination Approaches Using Aluminum [18F]fluoride: Will [18F]AlF Replace 68Ga for Metal Chelate Labeling?

Due to its ideal physical properties, fluorine-18 turns out to be a key radionuclide for positron emission tomography (PET) imaging, for both preclinical and clinical applications. However, usual biomolecules radiofluorination procedures require the formation of covalent bonds with fluorinated prosthetic groups. This drawback makes radiofluorination impractical for routine radiolabeling, gallium-68 appearing to be much more convenient for the labeling of chelator-bearing PET probes. In response to this limitation, a recent expansion of the 18F chemical toolbox gave aluminum [18F]fluoride chemistry a real prominence since the late 2000s. This approach is based on the formation of an [18F][AlF]2+ cation, complexed with a 9-membered cyclic chelator such as NOTA, NODA or their analogs. Allowing a one-step radiofluorination in an aqueous medium, this technique combines fluorine-18 and non-covalent radiolabeling with the advantage of being very easy to implement. Since its first reports, [18F]AlF radiolabeling approach has been applied to a wide variety of potential PET imaging vectors, whether of peptidic, proteic, or small molecule structure. Most of these [18F]AlF-labeled tracers showed promising preclinical results and have reached the clinical evaluation stage for some of them. The aim of this report is to provide a comprehensive overview of [18F]AlF labeling applications through a description of the various [18F]AlF-labeled conjugates, from their radiosynthesis to their evaluation as PET imaging agents.

Development of Effective Therapeutics Targeting HER3 for Cancer Treatment

HER3 is the third member of the human epidermal growth factor receptor (HER/EGFR) family, and unlike its other family members, is unique due to its minimal intrinsic kinase activity. As a result, HER3 has to interact with another receptor tyrosine kinase (RTK), such as EGFR or HER2, in order to activate the PI-3 K/Akt, MEK/MAPK, Jak/Stat pathways, as well as Src kinase. Over-expression of HER3 in various human cancers promotes tumor progression by increasing metastatic potential and acting as a major cause of treatment failure. Effective inhibition of HER3, and/or the key downstream mediators of HER3 signaling, is thought to be required to overcome resistance and enhance therapeutic efficacy. To date, there is no known HER3-targeted therapy that is approved for breast cancer, with a number of anti-HER3 antibodies current in various stages of development and clinical testing. Recent data suggests that the epigenetic strategy of using a histone deacetylase (HDAC) inhibitor, or functional cooperative miRNAs, may be an effective way to abrogate HER3 signaling. Here, we summarize the latest advances in our understanding of the mechanism of HER3 signaling in tumor progression, with continuing research towards the identification of therapeutic anti-HER3 antibodies. We will also examine the potential to develop novel epigenetic approaches that specifically target the HER3 receptor, along with important key downstream mediators that are involved in cancer treatment.

Optimization of HER3 expression imaging using affibody molecules: Influence of chelator for labeling with indium-111

Radionuclide molecular imaging of human epidermal growth factor receptor 3 (HER3) expression using affibody molecules could be used for patient stratification for HER3-targeted cancer therapeutics. We hypothesized that the properties of HER3-targeting affibody molecules might be improved through modification of the radiometal-chelator complex. Macrocyclic chelators NOTA (1,4,7-triazacyclononane-N,N',N''-triacetic acid), NODAGA (1-(1,3-carboxypropyl)-4,7-carboxymethyl-1,4,7-triazacyclononane), DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), and DOTAGA (1,4,7,10-tetraazacyclododececane,1-(glutaric acid)-4,7,10-triacetic acid) were conjugated to the C-terminus of anti-HER3 affibody molecule Z08698 and conjugates were labeled with indium-111. All conjugates bound specifically and with picomolar affinity to HER3 in vitro. In mice bearing HER3-expressing xenografts, no significant difference in tumor uptake between the conjugates was observed. Presence of the negatively charged 111In-DOTAGA-complex resulted in the lowest hepatic uptake and the highest tumor-to-liver ratio. In conclusion, the choice of chelator influences the biodistribution of indium-111 labeled anti-HER3 affibody molecules. Hepatic uptake of anti-HER3 affibody molecules could be reduced by the increase of negative charge of the radiometal-chelator complex on the C-terminus without significantly influencing the tumor uptake.

Polyfunctional anti-human epidermal growth factor receptor 3 (anti-HER3) antibodies induced by HER3 vaccines have multiple mechanisms of antitumor activity against therapy resistant and triple negative breast cancers

BACKGROUND

Upregulation of human epidermal growth factor receptor 3 (HER3) is a major mechanism of acquired resistance to therapies targeting its heterodimerization partners epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2), but also exposes HER3 as a target for immune attack. We generated an adenovirus encoding full length human HER3 (Ad-HER3) to serve as a cancer vaccine. Previously we reported the anti-tumor efficacy and function of the T cell response to this vaccine. We now provide a detailed assessment of the antitumor efficacy and functional mechanisms of the HER3 vaccine-induced antibodies (HER3-VIAs) in serum from mice immunized with Ad-HER3.

METHODS

Serum containing HER3-VIA was tested in complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC) assays and for its effect on HER3 internalization and degradation, downstream signaling of HER3 heterodimers and growth of metastatic HER2+ (BT474M1), HER2 therapy-resistant (rBT474), and triple negative (MDA-MB-468) breast cancers.

RESULTS

HER3-VIAs mediated CDC and ADCC, HER3 internalization, interruption of HER3 heterodimer-driven tumor signaling pathways, and anti-proliferative effects against HER2+ tumor cells in vitro and significant antitumor effects against metastatic HER2+ BT474M1, treatment refractory HER2+ rBT474 and triple negative MDA-MB-468 in vivo.

CONCLUSIONS

In addition to the T cell anti-tumor response induced by Ad-HER3, the HER3-VIAs provide additional functions to eliminate tumors in which HER3 signaling mediates aggressive behavior or acquired resistance to HER2-targeted therapy. These data support clinical studies of vaccination against HER3 prior to or concomitantly with other therapies to prevent outgrowth of therapy-resistant HER2+ and triple negative clones.

Targeting of HER3 with Functional Cooperative miRNAs Enhances Therapeutic Activity in HER2-Overexpressing Breast Cancer Cells

Background

The HER3 receptor functions as a major cause of drug resistance in cancer treatment. It is believed that therapeutic targeting of HER3 is required to improve patient outcomes. It is not clear whether a novel strategy with two functional cooperative miRNAs would effectively inhibit erbB3 expression and potentiate the anti-proliferative/anti-survival effects of a HER2-targeted therapy (trastuzumab) and chemotherapy (paclitaxel) on HER2-overexpressing breast cancer cells.

Results

Combination of miR-125a and miR-205, as compared to either miRNA alone, potently inhibited expression of HER3 in HER2-overexpressing breast cancer BT474 cells. Co-expression of the two miRNAs not only reduced the levels of phosphorylated erbB3 (P-erbB3), Akt (P-Akt), and Src (P-Src), it also inhibited cell proliferation and increased cells at G1 phase. A multi-miRNA lentiviral vector - the cluster of miR-125a and miR-205 - was constructed to simultaneously express the two miRNAs in HER2-overexpressing breast cancer cells. Concurrent expression of miR-125a and miR-205 via the miRNA cluster transfection significantly enhanced trastuzumab-mediated growth inhibition and cell cycle G1 arrest in BT474 cells and markedly increased paclitaxel-induced apoptosis in another HER2-overexpressing breast cancer cell line HCC1954.

Conclusions

Here, we showed that functional cooperative miRNAs effectively suppressed erbB3 expression. This novel approach targeting of HER3 was able to enhance the therapeutic efficacy of trastuzumab and paclitaxel against HER2-overexpressing breast cancer.

The role of ErbB3 binding protein 1 in cancer: Friend or foe?

ErbB3, a member of the epidermal growth factor receptor family, reportedly plays an essential role in the regulation of cancer progression and therapeutic resistance. Numerous studies have indicated that ErbB3 binding protein 1 (Ebp1), a binding partner for ErbB3, plays an important regulatory role in the expression and function of ErbB3, but there is no agreement as to whether Ebp1 also has an ErbB3-independent function in cancer and how it might contribute to tumorigenesis. In this review, we will discuss the different functions of the two Ebp1 isoforms, p48 and p42, that may be responsible for the potentially dual role of Ebp1 in cancer growth.

Understanding the biology of HER3 receptor as a therapeutic target in human cancer

HER3 belongs to the human epidermal growth factor receptor (HER) family which also includes HER1/EGFR/erbB1, HER2/erbB2, and HER4/erbB4. As a unique member of the HER family, HER3 lacks or has little intrinsic tyrosine kinase activity. It frequently co-expresses and forms heterodimers with other receptor tyrosine kinases (RTKs) in cancer cells to activate oncogenic signaling, especially the PI-3K/Akt pathway and Src kinase. Elevated expression of HER3 has been observed in a wide variety of human cancers and associates with a worse survival in cancer patients with solid tumors. Studies on the underlying mechanism implicate HER3 expression as a major cause of treatment failure in cancer therapy. Activation of HER3 signaling has also been shown to promote cancer metastasis. These data strongly support the notion that therapeutic inactivation of HER3 and/or its downstream signaling is required to overcome treatment resistance and improve the outcomes of cancer patients.

HER3 signaling and targeted therapy in cancer

ERBB family members including epidermal growth factor receptor (EGFR) also known as HER1, ERBB2/HER2/Neu, ERBB3/HER3 and ERBB4/HER4 are aberrantly activated in multiple cancers and hence serve as drug targets and biomarkers in modern precision therapy. The therapeutic potential of HER3 has long been underappreciated, due to impaired kinase activity and relatively low expression in tumors. However, HER3 has received attention in recent years as it is a crucial heterodimeric partner for other EGFR family members and has the potential to regulate EGFR/HER2-mediated resistance. Upregulation of HER3 is associated with several malignancies where it fosters tumor progression via interaction with different receptor tyrosine kinases (RTKs). Studies also implicate HER3 contributing significantly to treatment failure, mostly through the activation of PI3K/AKT, MAPK/ERK and JAK/STAT pathways. Moreover, activating mutations in HER3 have highlighted the role of HER3 as a direct therapeutic target. Therapeutic targeting of HER3 includes abrogating its dimerization partners’ kinase activity using small molecule inhibitors (lapatinib, erlotinib, gefitinib, afatinib, neratinib) or direct targeting of its extracellular domain. In this review, we focus on HER3-mediated signaling, its role in drug resistance and discuss the latest advances to overcome resistance by targeting HER3 using mono- and bispecific antibodies and small molecule inhibitors.

HER3-Mediated Resistance to Hsp90 Inhibition Detected in Breast Cancer Xenografts by Affibody-Based PET Imaging

Purpose: Recent studies have highlighted a role of HER3 in HER2-driven cancers (e.g., breast cancer), implicating the upregulation of the receptor in resistance to HER-targeted therapies and Hsp90 inhibitors (e.g., AUY922). Therefore, we have developed an affibody-based PET radioconjugate that quantitatively assesses HER3 changes induced by Hsp90 inhibition in vivoExperimental Design: ZHER3:8698 affibody molecules were conjugated via the C-terminus cysteine to DFO-maleimide for 89Zr radiolabeling. The probe was characterized in vitro and in vivo in a panel of human breast cell lines and xenograft models with varying HER3 receptor levels. In addition, the radioconjugate was investigated as a tool to monitor the outcome of AUY922, an Hsp90 inhibitor, in an MCF-7 xenograft model.Results: We demonstrated that 89Zr-DFO-ZHER3:8698 can track changes in receptor expression in HER3-positive xenograft models and monitor the outcome of AUY922 treatment. Our in vitro findings showed that MCF-7 cells, which are phenotypically different from BT474, develop resistance to treatment with AUY922 through HER3/IGF-1Rβ-mediated signaling. Of note, the lack of response in vitro due to HER3 recovery was confirmed in vivo using 89Zr-DFO-ZHER3:8698-based imaging. Upon AUY922 treatment, higher radioconjugate uptake was detected in treated MCF-7 xenografts, correlating with an AUY922-induced HER3 upregulation concomitant with an increase in IGF-1Rβ expression.Conclusions: These data underline the potential of HER3-based PET imaging to noninvasively provide information about HER3 expression and to identify patients not responding to targeted therapies due to HER3 recovery. Clin Cancer Res; 24(8); 1853-65. ©2018 AACR.

Targeting and suppression of HER3-positive breast cancer by T lymphocytes expressing a heregulin chimeric antigen receptor

Chimeric antigen receptor-modulated T lymphocytes (CAR-T) have emerged as a powerful tool for arousing anticancer immunity. Endogenous ligands for tumor antigen may outperform single-chain variable fragments to serve as a component of CARs with high cancer recognition efficacy and minimized immunogenicity. As heterodimerization and signaling partners for human epidermal growth factor receptor 2 (HER2), HER3/HER4 has been implicated in tumorigenic signaling and therapeutic resistance of breast cancer. In this study, we engineered T cells with a CAR consisting of the extracellular domain of heregulin-1β (HRG1β) that is a natural ligand for HER3/HER4, and evaluated the specific cytotoxicity of these CAR-T cells in cultured HER3 positive breast cancer cells and xenograft tumors. Our results showed that HRG1β-CAR was successfully constructed, and T cells were transduced at a rate of 50%. The CAR-T cells specifically recognized and killed HER3-overexpressing breast cancer cells SK-BR-3 and BT-474 in vitro, and displayed potent tumoricidal effect on SK-BR-3 xenograft tumor models. Our results suggest that HRG1β-based CAR-T cells effectively suppress breast cancer driven by HER family receptors, and may provide a novel strategy to overcome cancer resistance to HER2-targeted therapy.

Evaluation of patritumab with or without erlotinib in combination with standard cytotoxic agents against pediatric sarcoma xenograft models

BACKGROUND

Integrating molecularly targeted agents with cytotoxic drugs used in curative treatment of pediatric cancers is complex. An evaluation was undertaken with the ERBB3/Her3-specific antibody patritumab (P) either alone or with the ERBB1/epidermal growth factor receptor inhibitor erlotinib (E) in combination with standard cytotoxic agents, cisplatin, vincristine, and cyclophosphamide, in pediatric sarcoma xenograft models that express receptors and ligands targeted by these agents.

PROCEDURES

Tumor models were selected based upon ERBB3 expression and phosphorylation, and ligand (heregulin) expression. Patritumab, E, or these agents combined was evaluated without or with concomitant cytotoxic agents using procedures developed by the Pediatric Preclinical Testing Program.

RESULTS

Full doses of cytotoxic agents were tolerated when combined with P, whereas dose reductions of 25% (vincristine, cisplatin) or 50% (cyclophosphamide) were required when combined with P + E. Patritumab, E alone, or in combination did not significantly inhibit growth of any tumor model, except for Rh18 xenografts (E alone). Patritumab had no single-agent activity and marginally enhanced the activity of vincristine and cisplatin only in Ewing sarcoma ES-4. P + E did not increase the antitumor activity of vincristine or cisplatin, whereas dose-reduced cyclophosphamide was significantly less active than cyclophosphamide administered at its maximum tolerated dose when combined with P + E.

CONCLUSIONS

P had no single-agent activity, although it marginally potentiated the activity of vincristine and cisplatin in one of three models studied. However, the addition of E necessitated dose reduction of each cytotoxic agent, abrogating the enhancement observed with P alone.

Survivin-targeting miR-542-3p overcomes HER3 signaling-induced chemoresistance and enhances the antitumor activity of paclitaxel against HER2-overexpressing breast cancer

Elevated expression of HER3, which interacts with HER2 in breast cancer cells, confers chemoresistance via phosphoinositide 3-kinase (PI-3K)/Akt-dependent upregulation of Survivin. However, the underlying mechanism is not clear. Ectopic expression or specific knockdown of HER3 in HER2-overexpressing breast cancer cells did not alter Survivin mRNA levels and Survivin protein stability, supporting the notion that HER3 signaling may regulate specific miRNAs that target Survivin to alter its protein translation. Here we showed that overexpression and specific knockdown of HER3 reduced and enhanced expression of two Survivin-targeting miRNAs, miR-203 and miR-542-3p, in breast cancer cells, respectively. While the specific inhibitor of either miR-203 or miR-542-3p attenuated an anti-HER3 antibody-induced downregulation of Survivin, inhibition of miR-542-3p exhibited a better efficacy than miR-203 inhibition did. Consistently, miR-542-3p mimic was much more effective than miR-203 mimic not only in inhibition of Survivin, but also in enhancement of paclitaxel-induced apoptosis in HER2-overexpressing breast cancer cells. Moreover, the combination of miR-542-3p mimic and paclitaxel, as compared with either agent alone, significantly inhibited in vivo tumor growth of HER2-overexpressing breast cancer cells. Collectively, our data indicated that the HER3/PI-3K/Akt signaling upregulates Survivin via suppression of miR-203 and miR-542-3p. Because miR-542-3p has three binding sites on the 3'-UTR of Survivin mRNA, its mimic was able to effectively downregulate Survivin in vitro and in vivo. Thus, miR-542-3p-replacement therapy is an excellent approach to overcome HER3-mediated paclitaxel resistance and significantly enhances the antitumor activity of paclitaxel against HER2-overexpressing breast cancer.

Oncogenic Ras triggers hyperproliferation and impairs polarized colonic morphogenesis by autocrine ErbB3 signaling

Here we study the effects of inducible oncogenic K-Ras (G12V) expression on the polarized morphogenesis of colonic epithelial cells. We provide evidence that the autocrine production of heregulins, ligands for the ErbB3 receptor tyrosine kinase, is responsible for the hyperproliferation and aberrant 3D morphogenesis upon oncogenic K-Ras expression. This is in line with results obtained in primary intestinal organoid cultures, in which exogenous heregulin is shown to interfere with normal tissue architecture. Importantly, ErbB3 inhibition and heregulin gene silencing rescued K-RasG12V-induced features of cell transformation. Together with the increased ErbB3 positivity detected in human high-grade primary colorectal cancers, our findings provide support for an autocrine signaling loop engaged by oncogenic K-Ras involving ErbB3 that contributes to the dedifferentiation of the intestinal epithelium during tumor initiation and progression.

Positive prognostic value of HER2-HER3 co-expression and p-mTOR in gastric cancer patients

Background

The HER2-HER3 heterodimer significantly decreases survival in breast cancer patients. However, the prognostic value of HER2-HER3 overexpression remains unknown in gastric cancer (GC).

Methods

The expression levels of HER2, HER3, Akt, p-Akt, mTOR and p-mTOR were examined in specimens from 120 GC patients by immunohistochemistry and quantitative reverse transcription-PCR. The associations of HER proteins, PI3K/Akt/mTOR pathway-related proteins, clinicopathological features of GC, and overall survival (OS) were assessed. To comprehensively evaluate the prognostic values of pathway-related proteins, meta-analyses were conducted with STATA 11.0.

Results

HER2 overexpression was significantly associated with HER3 levels (P = 0.02). HER3 was highly expressed in gastric cancer tissues. High HER2 and HER3 levels were associated with elevated p-Akt and p-mTOR amounts (P < 0.05). Furthermore, HER2-HER3 co-expression was associated with high p-Akt and p-mTOR (P < 0.05) levels. Meanwhile, p-mTOR overexpression was tightly associated with differentiation, depth of invasion, lymph node metastasis, TNM stage and OS (P < 0.05). By meta-analyses, Akt, p-Akt, and mTOR levels were unrelated to clinicopathological characters. HER3 overexpression was associated with depth of invasion (OR = 2.39, 95%CI 1.62–3.54, P < 0.001) and lymph node metastasis (OR = 2.35, 95%CI 1.34–4.11, P = 0.003). Further, p-mTOR overexpression was associated with patient age, tumor location, depth of invasion (OR = 1.63, 95%CI 1.08–2.45, P = 0.02) and TNM stage (OR = 1.73, 95%CI 1.29–2.32, P < 0.001). In addition, HER2-HER3 overexpression corresponded to gradually shortened 5-year OS (P < 0.05), and significant relationships were shown among HER3, p-mTOR overexpression, and 1-, 3-, 5-year OS (P < 0.05).

Conclusions

HER2-HER3 co-expression may potentially enhance mTOR phosphorylation. HER2-HER3 co-expression and p-mTOR are both related to the prognosis of GC patients.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3851-y) contains supplementary material, which is available to authorized users.

Expression and prognostic significance of human epidermal growth factor receptors 1, 2 and 3 in oesophageal and gastric adenocarcinomas preneoadjuvant and postneoadjuvant treatment

AIMS

Neoadjuvant treatment has now become the standard of care for oesophageal and gastric cancer. The aim of this study was to investigate the influence of neoadjuvant therapy on the expression of human epidermal growth factor receptor 1 (HER1/EGFR), HER2 and HER3, in oesophageal and gastric adenocarcinoma.

METHODS

Immunohistochemical expression of EGFR, HER2 and HER3 was examined and compared in pretreatment biopsies, post-treatment surgical resection specimens and metastases in a retrospective cohort of 166 patients with adenocarcinoma of the oesophagus or stomach. The relationship between expression of the investigative markers and histopathological response to neoadjuvant treatment, overall survival (OS) and recurrence free survival (RFS) was analysed.

RESULTS

Conversion of protein expression between pretreatment biopsy and post-treatment surgical resection was seen in 4.6% of the cases for EGFR, 5.9% for HER2% and 19.4% for HER3. Histopathological response to neoadjuvant treatment was significantly and stepwise associated with OS and RFS . High HER3 protein expression in post-treatment surgical resection specimens was significantly associated with a prolonged OS in univariable analysis (HR=0.39; 95% CI 0.17 to 0.93), but did not remain significant in multivariable analysis. Expression of EGFR and HER2 in post-treatment surgical resection specimens was not prognostic. No correlation between pretreatment HER-protein expression and histopathological response was seen.

CONCLUSIONS

The results from this study underscore the need for further studies on the influence of neoadjuvant treatment on biomarker expression, as this may influence treatment strategy as well as prognosis. Histopathological response is validated as a useful prognostic factor.

Evaluation of a radiocobalt-labelled affibody molecule for imaging of human epidermal growth factor receptor 3 expression

The human epidermal growth factor receptor 3 (HER3) is involved in the development of cancer resistance towards tyrosine kinase-targeted therapies. Several HER3‑targeting therapeutics are currently under clinical evaluation. Non-invasive imaging of HER3 expression could improve patient management. Affibody molecules are small engineered scaffold proteins demonstrating superior properties as targeting probes for molecular imaging compared with monoclonal antibodies. Feasibility of in vivo HER3 imaging using affibody molecules has been previously demonstrated. Preclinical studies have shown that the contrast when imaging using anti-HER3 affibody molecules can be improved over time. We aim to develop an agent for PET imaging of HER3 expression using the long-lived positron-emitting radionuclide cobalt-55 (55Co) (T1/2=17.5 h). A long-lived cobalt isotope 57Co was used as a surrogate for 55Co in this study. The anti-HER3 affibody molecule HEHEHE-ZHER3-NOTA was labelled with radiocobalt with high yield, purity and stability. Biodistribution of 57Co-HEHEHE-ZHER3-NOTA was measured in mice bearing DU145 (prostate carcinoma) and LS174T (colorectal carcinoma) xenografts at 3 and 24 h post injection (p.i.). Tumour-to-blood ratios significantly increased between 3 and 24 h p.i. (p<0.05). At 24 h p.i., tumour-to-blood ratios were 6 for DU145 and 8 for LS174T xenografts, respectively. HER3‑expressing xenografts were clearly visualized in a preclinical imaging setting already 3 h p.i., and contrast further improved at 24 h p.i. In conclusion, the radiocobalt-labelled anti-HER3 affibody molecule, HEHEHE-ZHER3-NOTA, is a promising tracer for imaging of HER3 expression in tumours.