Breast cancer: updated guideline recommendations for HER2 testing

Emerging Targets for Systemic Treatment of Gastric Cancer: HER2 and Beyond

In recent years, remarkable progress has been made in the molecular profiling of gastric cancer. This progress has led to the development of various molecular classifications to uncover subtype-specific dependencies that can be targeted for therapeutic interventions. Human epidermal growth factor receptor 2 (HER2) is a crucial biomarker for advanced gastric cancer. The recent promising results of novel approaches, including combination therapies or newer potent agents such as antibody-drug conjugates, have once again brought attention to anti-HER2 targeted treatments. In HER2-negative diseases, the combination of cytotoxic chemotherapy and programmed cell death-1/programmed cell death ligand-1 (PD-1/PD-L1) inhibitors has become the established standard of care in first-line settings. In the context of gastric cancer, potential biomarkers such as PD-L1 expression, Epstein-Barr virus, microsatellite instability, and tumor mutational burden are being considered for immunotherapy. Recently, promising results have been reported in studies on anti-Claudin18.2 and fibroblast growth factor receptor 2 treatments. Currently, many ongoing trials are aimed at identifying potential targets using novel approaches. Further investigations will be conducted to enhance the progress of these therapies, addressing challenges such as primary and acquired resistance, tumor heterogeneity, and clonal evolution. We believe that these efforts will improve patient prognoses. Herein, we discuss the current evidence of potential targets for systemic treatment, clinical considerations, and future perspectives.

Molecular features and clinical implications of the heterogeneity in Chinese patients with HER2-low breast cancer

The molecular heterogeneity and distinct features of HER2-low breast cancers, particularly in the Chinese population, are not well understood, limiting its precise management in the era of antibody‒drug conjugates. To address this issue, we established a cohort of 434 Chinese patients with HER2-low breast cancer (433 female and one male) and integrated genomic, transcriptomic, proteomic, and metabolomic profiling data. In this cohort, HER2-low tumors are more distinguished from HER2-0 tumors in the hormone receptor-negative subgroup. Within HER2-low tumors, significant interpatient heterogeneity also exists in the hormone receptor-negative subgroup: basal-like tumors resemble HER2-0 disease, and non-basal-like HER2-low tumors mimic HER2-positive disease. These non-basal-like HER2-low tumors are enriched in the HER2-enriched subtype and the luminal androgen receptor subtype and feature PIK3CA mutation, FGFR4/PTK6/ERBB4 overexpression and lipid metabolism activation. Among hormone receptor-positive tumors, HER2-low tumors show less loss/deletion in 17q peaks than HER2-0 tumors. In this work, we reveal the heterogeneity of HER2-low breast cancers and emphasize the need for more precise stratification regarding hormone receptor status and molecular subtype.

Mechanisms of Therapeutic Antitumor Monoclonal Antibodies

Monoclonal antibodies (mAb) are a major component of cancer therapy. In this review, we summarize the different therapeutic mAbs that have been successfully developed against various tumor-expressed antigens and examine our current understanding of their different mechanisms of antitumor action. These mechanisms of action (MOA) largely center on the stimulation of different innate immune effector processes, which appear to be principally responsible for the efficacy of most unconjugated mAb therapies against cancer. This is evident in studies of mAbs targeting antigens for hematologic cancers, with emerging data also demonstrating the critical nature of innate immune-mediated mechanisms in the efficacy of anti-HER2 mAbs against solid HER2+ cancers. Although HER2-targeted mAbs were originally described as inhibitors of HER2-mediated signaling, multiple studies have since demonstrated these mAbs function largely through their engagement with Fc receptors to activate innate immune effector functions as well as complement activity. Next-generation mAbs are capitalizing on these MOAs through improvements to enhance Fc-activity, although regulation of these mechanisms may vary in different tumor microenvironments. In addition, novel antibody-drug conjugates have emerged as an important means to activate different MOAs. Although many unknowns remain, an improved understanding of these immunologic MOAs will be essential for the future of mAb therapy and cancer immunotherapy.

Quality Management of the Immunohistochemistry Laboratory: A Practical Guide

Governmental regulations and most published guidelines do not provide specific guidance on implementation of quality management (QM) programs for immunohistochemistry (IHC) assays in Anatomic Pathology. QM of IHC consists of 3 main components: quality control, quality assurance, and quality improvement initiatives, each entailing distinctive but interrelated objectives. Discussion of the principles and some specific practices involved in these phases of QM of the IHC laboratory are therefore offered in this review, with an admitted emphasis on pragmatism.

New ASCO/CAP guideline recommendations for HER2 testing increase the proportion of reflex in situ hybridization tests and of HER2 positive breast cancers

Accurate determination of tumour human epidermal growth factor receptor type 2 (HER2) status is critical for optimal treatment of breast cancer. In October 2013, the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) issued joint updated guideline recommendations for HER2 testing in breast cancer, with a revised algorithm for interpretation of immunohistochemistry (IHC) and in situ hybridisation (ISH) results. This study investigates the impact on HER2 IHC categorisation, implication for reflex ISH testing and potential for identification of false negative IHC. HER2 IHC preparations on 251 invasive breast tumours, originally reported according to 2007 guidelines, were re-scored using 2013 guidelines and the diagnostic categories compared. The results of ISH testing on a separate cohort of 32 breast tumours reported as HER2 IHC 2+ following the introduction of the 2013 guidelines, that would have been designated 1+ according to 2007, were reviewed. Application of 2013 guidelines resulted in a decrease in tumours classified as HER2 negative (83/251 vs 144/251) and a comparable increase in those classified as equivocal (2+) (139/251 vs 80/251). Relatively few tumours were re-classified as positive (29/251 vs 27/251). Furthermore, 3/32 breast cancer cases (HER2 IHC 2+ as per 2013 guidelines, 1+ using 2007 guidelines) were HER2 ISH positive. Application of the 2013 guidelines increases the HER2 IHC equivocal (2+) category and requirement for reflex ISH testing. The reduced threshold for ISH testing identifies some patients with HER2 positive breast cancer whose tumours would have been categorised as HER2 negative according to the 2007 guidelines.

Impact of Modified 2013 ASCO/CAP Guidelines on HER2 Testing in Breast Cancer. One Year Experience

Introduction

The latest guidelines of the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) to test Human Epidermal Growth Factor Receptor 2 (HER2) in breast cancer after being revised in 2008 underwent a second modification in October 2013. The modification includes changes in cut-offs: 10% strong membranous staining for score 3+ on immunohistochemistry (IHC) (previously 30%) and using the ratio of >2 or absolute gene-copy-number (6 or more) alone or in combination with each other by in-situ-hybridisation technology (previously >2.2 and average copy-number of 6 or more). Hereby we addressed the question, which impact the modified cut-offs had on overall HER2-positivity in a single institution.

Methods

We prospectively analysed 617 consecutive diagnostic breast-cancer cases which underwent double HER2 testing by immunohistochemistry and fluorescent in-situ hybridisation (FISH), using the modified 2013 ASCO/CAP-guidelines for one year (October 2013–October 2014). Results were compared with HER2-test results on 1,528 consecutive diagnostic breast-cancer cases from two previous years (2011–2012), using the 2008 ASCO/CAP guidelines, also tested with IHC and FISH in each case.

Results

Between October 2013 and October 2014, overall HER2-positivity was 15.8% (98 of 617 cases were either IHC 3+ or FISH amplified). 79 of 617 cases (13%) were IHC 3+, 96 of 617 cases (15.5%) were FISH amplified. Equivocal cases were seen in 25 of 617 cases (4.1%). 22 of 25 equivocal cases (88%) in 2013–2014 were IHC 1+ or 2+. In 13 equivocal cases, there was a repeated IHC/FISH testing: 2 of 13 cases (15%) became FISH amplified, 1 of 13 cases (7.5%) became IHC 3+. In 2011–2012, overall HER2-positivity (IHC/FISH) was 13.8% (211 of 1,528 cases). 185 of 1,528 cases (12%) were 3+ on IHC, 181 of 1,522 cases (12%) were amplified by FISH. Six of 1,528 cases were equivocal by FISH, and interpreted as non-amplified (0.3%).

Conclusions

Applying the modified ASCO/CAP guidelines from 2013 resulted in an increase (2%) in overall HER2-positivity rate compared to overall-HER2-positivity rate using the 2008 ASCO/CAP guidelines. The increased positivity rate was mainly due to more FISH-positive cases (3.5% more than until 2013). The high rate of equivocal cases (4.1%) did not contribute to increase in overall HER2-positivity, but resulted in delay in definitive HER2-status.

A microfluidic platform with digital readout and ultra-low detection limit for quantitative point-of-care diagnostics

Quantitative assays are of great importance for point-of-care (POC) diagnostics because they can offer accurate information on the analytes. However, current POC devices often require an accessory instrument to give quantitative readouts for protein biomarkers, especially for those at very low concentration levels. Here, we report a microfluidic platform, the digital volumetric bar-chart chip (DV-chip), for quantitative POC diagnostics with ultra-low detection limits that are readable with the naked eye. Requiring no calibration, the DV-chip presents a digital ink bar chart (representing multiple bits composed of 0 and 1) for the target biomarker based on direct competition between O2 generated by the experimental and control samples. The bar chart clearly and accurately defines target concentration, allowing identification of disease status. For the standard PtNP solutions, the detection limit of the platform is approximately 0.1 pM and the dynamic range covers four orders of magnitude from 0.1 to 1000 pM. CEA samples with concentrations of 1 ng mL(-1) and 1.5 ng mL(-1) could be differentiated by the device. We also performed the ELISA assay for B-type natriuretic peptide (BNP) in 20 plasma samples from heart failure patients and the obtained on-chip data were in agreement with the clinical results. In addition, BNP was detectable at concentrations of less than 5 pM, which is three orders of magnitude lower than the detection limit of the previously reported readerless digital methods. By the integration of gas competition, volumetric bar chart, and digital readout, the DV-chip possesses merits of portability, visible readout, and ultra-low detection limit, which should offer a powerful platform for quantitative POC diagnostics in clinical settings and personalized detection.

Subclonal diversification of primary breast cancer revealed by multiregion sequencing

The sequencing of cancer genomes may enable tailoring of therapeutics to the underlying biological abnormalities driving a particular patient's tumor. However, sequencing-based strategies rely heavily on representative sampling of tumors. To understand the subclonal structure of primary breast cancer, we applied whole-genome and targeted sequencing to multiple samples from each of 50 patients' tumors (303 samples in total). The extent of subclonal diversification varied among cases and followed spatial patterns. No strict temporal order was evident, with point mutations and rearrangements affecting the most common breast cancer genes, including PIK3CA, TP53, PTEN, BRCA2 and MYC, occurring early in some tumors and late in others. In 13 out of 50 cancers, potentially targetable mutations were subclonal. Landmarks of disease progression, such as resistance to chemotherapy and the acquisition of invasive or metastatic potential, arose within detectable subclones of antecedent lesions. These findings highlight the importance of including analyses of subclonal structure and tumor evolution in clinical trials of primary breast cancer.

Human equilibrative nucleoside transporter 1 expression analysed by the clone SP 120 rabbit antibody is not predictive in patients with pancreatic cancer treated with adjuvant gemcitabine - Results from the CONKO-001 trial

BACKGROUND

High expression of human equilibrative nucleoside transporter 1 (hENT1) is considered to predict survival in patients treated with adjuvant gemcitabine for pancreatic cancer. A standard evaluation system for immunohistochemical analysis (antibody, scoring system) has not yet been established.

METHODS

CONKO-001, a prospective randomised phase III study investigated the role of adjuvant gemcitabine (gem) as compared to observation (obs). Tumour samples of 156 patients were analysed by immunohistochemistry with the rabbit monoclonal antibody SP120 (Ventana Medical Systems) for expression of hENT1. Kaplan-Meier analyses for median disease-free survival (DFS) and overall survival (OS) were performed in dependence of hENT1 expression measured analogously to Farrell et al. 2009 and Poplin et al. 2013.

RESULTS

For the 88 gem and 68 obs patients, median DFS/OS was 12.9/22.7 months and 6.2/19.1 months. High hENT1 expression was not associated with improved median DFS (Farrell: no hENT1 22.2 months, low hENT1 13.7 months, high hENT1 12.1 months, p=0.248; Poplin: low hENT1 13.2 months versus high hENT1 11.5 months, p=0.5) or median OS (Farrell: no hENT1 21.7 months, low hENT1 24.7 months, high hENT1 19.5, p=0.571; Poplin: low hENT1 24.4 months versus high hENT1 19.7 months, p=0.92;) in the gem group or in the obs group (median DFS Farrell: no hENT1 5.1 months, low hENT1 6.2 months, high hENT1 7.5 months, p=0.375; Poplin: low hENT1 6.2 months versus high hENT1 5.9 months, p=0.83; median OS Farrell: no hENT1 20.2months, low hENT1 17.7 months, high HENT1 19.1 months, p=0.738; Poplin: low hENT1 17.7 months versus high hENT1 20.4 months, p=0.65) measured by the Farrell or Poplin Score.

CONCLUSIONS

We cannot confirm a predictive role of hENT1 measured by the clone SP120 rabbit antibody in our study population. Reproducible standard procedures are urgently needed prior to the implementation or exclusion of hENT1 as a predictive biomarker in the treatment of pancreatic cancer.

TRIAL REGISTRATION

ISRCTN34802808.