Prognostic value of phosphorylated HER2 in HER2-positive breast cancer patients treated with adjuvant trastuzumab

Clinicopathological significance of concurrent ErbB receptor expression in human meningioma

In general, human meningiomas grow slowly and have a favourable prognosis; however, some are prone to recur despite their benign histology. Therefore, knowledge of their tumour biology is essential to determine objective biomarkers that can identify cases with an increased risk for recurrence and to generate effective treatment options. Thus, studies on the epidermal growth factor receptor (EGFR) family, comprising ErbB1/EGFR, ErbB2/HER2, ErbB3/HER3 and ErbB4/HER4, are important. We have recently published papers on the expression of each of these receptor proteins in human meningiomas. The present study aimed to assess the clinicopathological significance of their concurrent expression. A total of 185 grade 1 and 2 meningiomas with robust clinical data underwent immunohistochemical analyses with antibodies against the aforementioned receptors. All meningiomas exhibited upregulation of these receptor proteins relative to normal meninges. In addition, the expression of phosphorylated/activated ErbB1/EGFR1 and phosphorylated/activated ErbB2/HER2 was significantly associated with histological malignancy grade and prognosis, respectively. The concurrent upregulation of ErbB receptors in human meningioma supports their fundamental role in the tumourigenesis of these tumours, and they could thus be exploited in diagnostics, prognosis, and ultimately, in targeted clinical interventions.

Extensive conformational and physical plasticity protects HER2-HER3 tumorigenic signaling

Surface-targeting biotherapeutic agents have been successful in treating HER2-amplified cancers through immunostimulation or chemodelivery but have failed to produce effective inhibitors of constitutive HER2-HER3 signaling. We report an extensive structure-function analysis of this tumor driver, revealing complete uncoupling of intracellular signaling and tumorigenic function from regulation or constraints from their extracellular domains (ECDs). The canonical HER3 ECD conformational changes and exposure of the dimerization interface are nonessential, and the entire ECDs of HER2 and HER3 are redundant for tumorigenic signaling. Restricting the proximation of partner ECDs with bulk and steric clash through extremely disruptive receptor engineering leaves tumorigenic signaling unperturbed. This is likely due to considerable conformational flexibilities across the span of these receptor molecules and substantial undulations in the plane of the plasma membrane, none of which had been foreseen as impediments to targeting strategies. The massive overexpression of HER2 functionally and physically uncouples intracellular signaling from extracellular constraints.

New HER2-negative breast cancer subtype responsive to anti-HER2 therapy identified

Purpose

HER2 signaling functional activity may be important to measure in addition to HER2 protein quantification when identifying patients eligible for HER2 therapies. A HER2 Signaling Function (CELx HSF) Test for HER2-negative patients uses patient’s live tumor cells on a biosensor to identify patients with abnormally high HER2-related signaling (HSFs+) likely to respond to anti-HER2 therapies.

Methods

The CELx HSF test was employed to: (1) characterize the sensitivity and specificity of the test to detect abnormal levels of HER2 signaling; (2) evaluate the inhibitory effectiveness of five different anti-HER2 therapies; (3) assess the correlation between CELx HSF test detection of abnormal HER2 signaling and response to HER2 therapy using xenograft models; and (4) confirm the prevalence of abnormal HER2 signaling amongst HER2-negative breast cancer patients (HER2−/HSFs+).

Results

HER2−/HSFs+ breast cancer patient samples were identified and showed sensitivity to five approved anti-HER2 therapies. Xenograft studies using both HER2+ and HER2− cell lines confirmed that CELx HER2 signaling status better predicts HER2 inhibitor efficacy than HER2 receptor status. In a study of 114 HER2-negative breast tumor patient samples, 27 (23.7%; 95% CI = 17–32%) had abnormal HER2 signaling (HSFs+). A ROC curve constructed with this dataset projects the CELx HSF Test would have greater than 90% sensitivity and specificity to detect the HER2−/HSFs+ patient population.

Conclusions

The CELx HSF test is a well-characterized functional biomarker assay capable of identifying dynamic HER2-driven signaling dysfunction in tumor cells from HER2-negative breast cancer patients. This test has demonstrated efficacy of various HER2 targeted therapies in live tumor cells from the HSFs+ population and correlated the test result to HER2 drug response in mouse xenograft studies. The proportion of HER2-negative breast cancer patients found to have abnormal HER2 signaling in a 114 patient sample study, 20–25%, is significant. A clinical trial to evaluate the efficacy of anti-HER2 therapies in this patient population is warranted.

Electronic supplementary material

The online version of this article (10.1007/s00432-020-03144-7) contains supplementary material, which is available to authorized users.

Phosphorylated HER3 and FITC-labeled trastuzumab immunohistochemistry in patients with HER2-positive breast cancer treated with adjuvant trastuzumab

The development of trastuzumab has significantly improved the prognosis of HER2-positive breast cancer. However, disease recurs in some patients with HER2-positive breast cancer. A new strategy for treating HER2-positive breast cancer is necessary. Although several studies have reported that HER3 is a prognostic factor for HER2-positive breast cancers, phosphorylated HER3 (pHER3) has not been well studied. There has been no survival analysis including immunohistochemistry with trastuzumab as the primary antibody. We analyzed immunohistochemistry using anti-pHER3 antibody and FITC-labeled trastuzumab (FITC-tra). Of 78 patients enrolled in the study, we could evaluate the immunohistochemistry for pHER3 in 71 cases and that for FITC-tra in 72 cases. Sixteen cases were positive for pHER3 (16/71, 22.5%), and 19 positive for FITC-tra (19/72, 26.4%). Kaplan-Meier analysis showed a significant association of pHER3 positivity (p = 0.011) but not HER3 positivity or FITC-tra positivity with disease-free survival. Therefore, immunohistochemical evaluation of pHER3 in HER2-positive breast cancer may provide a useful biomarker. An expanded study of pHER3 involving standardization of the pHER3 test to be encouraged.

Extended Adjuvant Therapy with Neratinib Plus Fulvestrant Blocks ER/HER2 Crosstalk and Maintains Complete Responses of ER+/HER2+ Breast Cancers: Implications to the ExteNET Trial

PURPOSE

The phase III ExteNET trial showed improved invasive disease-free survival in patients with HER2⁺ breast cancer treated with neratinib versus placebo after trastuzumab-based adjuvant therapy. The benefit from neratinib appeared to be greater in patients with ER⁺/HER2⁺ tumors. We thus sought to discover mechanisms that may explain the benefit from extended adjuvant therapy with neratinib.Experimental Design: Mice with established ER⁺/HER2⁺ MDA-MB-361 tumors were treated with paclitaxel plus trastuzumab ± pertuzumab for 4 weeks, and then randomized to fulvestrant ± neratinib treatment. The benefit from neratinib was evaluated by performing gene expression analysis for 196 ER targets, ER transcriptional reporter assays, and cell-cycle analyses.

RESULTS

Mice receiving "extended adjuvant" therapy with fulvestrant/neratinib maintained a complete response, whereas those treated with fulvestrant relapsed rapidly. In three ER⁺/HER2⁺ cell lines (MDA-MB-361, BT-474, UACC-893) but not in ER⁺/HER2^- MCF7 cells, treatment with neratinib induced ER reporter transcriptional activity, whereas treatment with fulvestrant resulted in increased HER2 and EGFR phosphorylation, suggesting compensatory reciprocal crosstalk between the ER and ERBB RTK pathways. ER transcriptional reporter assays, gene expression, and immunoblot analyses showed that treatment with neratinib/fulvestrant, but not fulvestrant, potently inhibited growth and downregulated ER reporter activity, P-AKT, P-ERK, and cyclin D1 levels. Finally, similar to neratinib, genetic and pharmacologic inactivation of cyclin D1 enhanced fulvestrant action against ER⁺/HER2⁺ breast cancer cells.

CONCLUSIONS

These data suggest that ER blockade leads to reactivation of ERBB RTKs and thus extended ERBB blockade is necessary to achieve durable clinical outcomes in patients with ER⁺/HER2⁺ breast cancer.

Comprehensive immunohistochemical analyses on expression levels of hedgehog signaling molecules in breast cancers

BACKGROUND

The hedgehog (Hh) signaling pathway plays important roles in cell proliferation, malignant progression, invasion and metastasis, and the expansion of cancer stem cells (CSCs). Comprehensive immunohistochemical (IHC) analyses have not yet been conducted on the expression levels of Hh signaling molecules in breast cancer tissues.

METHODS

A total of 204 patients with invasive breast cancer treated in our institute were study subjects. IHC analyses on the expression levels of the Hh signaling molecules, sonic Hh (SHH), PTCH1, GLI1, GLI2, and GLI3 and the CSC-related factor, SOX2, were investigated.

RESULTS

Positive correlations were observed among all of the Hh signaling molecules tested. SOX2 expression correlated with the expression levels of all Hh signaling molecules. SHH expression positively correlated with tumor size, the Ki-67 labeling index, histological grade, estrogen receptor negativity, progesterone receptor negativity, and HER2 positivity. GLI1 expression positively correlated with the histological grade. GLI2 expression positively correlated with the histological grade, Ki-67 labeling index, and HER2 positivity. Univariate analyses revealed that a younger age, larger tumor size, positive lymph node metastasis, higher histological grade, positive lymphatic invasion, and higher Ki-67 labeling index were related to poor relapse-free survival (RFS). The positivity of all Hh signaling molecules and SOX2 did not correlate with poor RFS. A multivariate analysis revealed that positive lymphatic invasion and a younger age were independent worse prognostic factors for RFS.

CONCLUSIONS

This comprehensive analysis demonstrated for the first time that SHH, GLI1, and GLI2 expression levels positively correlated with the malignant phenotypes of tumor cells.

Human epidermal growth factor receptor 4 (HER4) is a favorable prognostic marker of breast cancer: a systematic review and meta-analysis

Based on a large cohort of clinical studies involving a total of 8024 patients and reporting the effects of HER4 on breast cancer prognosis, we conducted the first meta-analysis and review of this type. We identified 26 studies published between 1985 and 2016 and assessed the prognostic value of HER4 in breast cancer by either real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR, for mRNA levels) or immunohistochemistry (IHC, for protein levels). Elevated expression of HER4 was significantly associated with longer relapse-free survival (RFS) (HR = 0.63; CI: 0.48-0.83; P = 0.001, random effects). Further subgroup analysis showed that our results were stable irrespective of subtype [Luminal: HR = 0.40, CI: 0.30-0.53, P < 0.001, fixed effects; triple negative breast cancer (TNBC): HR = 0.49, CI: 0.26-0.90, P = 0.02, fixed effects; and HER2-positive: HR = 0.53, CI: 0.40-0.71, P < 0.001, fixed effects]. Cytoplasmic HER4 was more effective than nuclear HER4 (HR = 0.74, CI: 0.60-0.92, P = 0.007, fixed effects) for predicting RFS. HER4 was also found to be a favorable prognostic marker for overall survival (OS) among patients with non-TNBC in the subgroup analysis (Luminal: HR = 0.71, CI: 0.52-0.95, P = 0.023, fixed effects; HER2-positive: HR = 0.48, CI: 0.26-0.89, P = 0.020, fixed effects).

Cell-specific biomarkers and targeted biopharmaceuticals for breast cancer treatment

Breast cancer is the second leading cause of cancer death among women, and its related treatment has been attracting significant attention over the past decades. Among the various treatments, targeted therapy has shown great promise as a precision treatment, by binding to cancer cell-specific biomarkers. So far, great achievements have been made in targeted therapy of breast cancer. In this review, we first discuss cell-specific biomarkers, which are not only useful for classification of breast cancer subtyping but also can be utilized as goals for targeted therapy. Then, the innovative and generic-targeted biopharmaceuticals for breast cancer, including monoclonal antibodies, non-antibody proteins and small molecule drugs, are reviewed. Finally, we provide our outlook on future developments of biopharmaceuticals, and provide solutions to problems in this field.

Non-HER2 signaling pathways activated in resistance to anti-HER2 therapy in breast cancer

HER2 receptor is overexpressed approximately in 20 % of human breast cancer (BC) and is a poor prognostic factor. Although therapies targeting this receptor have improved the prognosis of this cancer, up to 62 % patients treated with these drugs experiment progression during the first year of treatment. Some molecular mechanisms have been proposed to be responsible for this resistance, such as activation of alternative signaling pathways (through ERBB receptors and non-ERBB receptors or increased expression of ligands and alterations in HER2 signaling components). In this article, we will review the influence of genetic markers in non-HER2 signaling pathways investigated to date as cause of resistance to HER2-targeted drugs in HER2-positive BC patients. GRB7, included in the 17q12 amplicon, has been associated to poor prognosis in BC patients. Biomarkers like EPHAR and SRC, have demonstrated clinical relevance and prognostic value in HER2-positive BC patients. Non-invasive biomarkers, such as elevated IGF1 serum levels have been revealed as interesting biomarkers to be considered as predictors of trastuzumab clinical outcomes in BC patients. However, the prognostic value of most of the biomarkers investigated to date, such as HER3, IGF1R, PIK3CA, or AKT1 cannot be fully established yet, since results have not been conclusive.

Efficacy of vinorelbine-based neoadjuvant chemotherapy in breast cancer: A systematic review and meta-analysis of randomized controlled trials

The present study aimed to compare the effects of vinorelbine-based neoadjuvant chemotherapy and vinorelbine-free regimens. A meta-analysis of all the relevant randomized controlled trials was performed to investigate the improvement in pathological complete response (pCR), overall response rate (ORR) and breast-conserving surgery (BCS). The PubMed and Embase databases were searched for relevant studies reporting randomized controlled trials comparing vinorelbine-based neoadjuvant chemotherapy with vinorelbine-free regimens until July 2013. Risk ratios/odds ratio and 95% confidence intervals (CIs) were used to estimate the association between vinorelbine in neoadjuvant chemotherapy and various efficacy outcomes. Fixed- or random-effect models were adopted to pool the data. Five eligible studies with a total of 1,495 patients were included in the meta-analysis. Compared to vinorelbine-free chemotherapy, vinorelbine-based regimens demonstrated no significant improvement in clinical outcomes including: pCR [relative risk (RR)=1.016; 95% CI, 0.738-1.399; P=0.922], ORR (RR=1.048; 95% CI, 0.969-1.133; P=0.239) and BCS (RR=1.764; 95% CI, 0.734-4.239; P=0.205). However, vinorelbine-based regimens were associated with a lower incidence of grade 3-4 alopecia (OR, 0.617; 95% CI, 0.448-0.848; P=0.003). In a hierarchical analysis for patients who received neoadjuvant chemotherapy, the proportion of subjects achieving pCR was significantly increased when HER2-amplified (RR=2.31; 95% CI, 1.20-4.43; P=0.01) and hormone receptor negative (RR=0.488; 95% CI, 0.263-0.908; P=0.023). The present review confirms that neoadjuvant chemotherapy vinorelbine-based regimens are unlikely to emerge as superior to pCR, ORR and BCS. Hierarchical analysis indicated that the HER2-amplified and hormone receptor-negative patients were significantly associated with a pathological response rate.

Phosphoprotein secretome of tumor cells as a source of candidates for breast cancer biomarkers in plasma

Breast cancer is a heterogeneous disease whose molecular diversity is not well reflected in clinical and pathological markers used for prognosis and treatment selection. As tumor cells secrete proteins into the extracellular environment, some of these proteins reach circulation and could become suitable biomarkers for improving diagnosis or monitoring response to treatment. As many signaling pathways and interaction networks are altered in cancerous tissues by protein phosphorylation, changes in the secretory phosphoproteome of cancer tissues could reflect both disease progression and subtype. To test this hypothesis, we compared the phosphopeptide-enriched fractions obtained from proteins secreted into conditioned media (CM) derived from five luminal and five basal type breast cancer cell lines using label-free quantitative mass spectrometry. Altogether over 5000 phosphosites derived from 1756 phosphoproteins were identified, several of which have the potential to qualify as phosphopeptide plasma biomarker candidates for the more aggressive basal and also the luminal-type breast cancers. The analysis of phosphopeptides from breast cancer patient plasma and controls allowed us to construct a discovery list of phosphosites under rigorous collection conditions, and second to qualify discovery candidates generated from the CM studies. Indeed, a set of basal-specific phosphorylation CM site candidates derived from IBP3, CD44, OPN, FSTL3, LAMB1, and STC2, and luminal-specific candidates derived from CYTC and IBP5 were selected and, based on their presence in plasma, quantified across all cell line CM samples using Skyline MS1 intensity data. Together, this approach allowed us to assemble a set of novel cancer subtype specific phosphopeptide candidates for subsequent biomarker verification and clinical validation.

The changing paradigm in EUS-guided tissue acquisition

The diagnostic performance of endoscopic ultrasound-guided fine-needle aspiration is strongly dependent on the availability of an onsite cytopathologist. The diagnosis of some rare tumors may require ancillary testing for which a histologic core biopsy is required. There is increasing interest in evaluating core tissue for molecular markers that may serve as prognostic predictors and targets for focused chemotherapy in patients with cancer. If core tissue can be procured efficiently and reliably at endoscopic ultrasound, this will eliminate the need for an onsite cytopathologist, accurately diagnose tumors that are occasionally missed by fine-needle aspiration cytology, and enable the assessment for molecular markers.