Standardization of negative controls in diagnostic immunohistochemistry: recommendations from the international ad hoc expert panel

Review of immunohistochemistry techniques: Applications, current status, and future perspectives

The Hematoxylin and Eosin stain is a cornerstone in histopathology that facilitates the microscopic examination of tissue samples for identifying infections and tumors. However, challenges arise from the similar appearances of diseases and cells, prompting the emergence of Immunohistochemistry (IHC) as an important technique. This review summarizes the principles, procedures, and applications and future perspectives of IHC, a prevalent immunostaining method allowing the detection of specific proteins in tissue sections. The multistep IHC process involves fixation, embedding, sectioning, antigen retrieval, blocking, detection, counterstaining, mounting, and visualization, with interpretation relying on factors such as microanatomic distribution and staining intensity. Common errors in IHC such as non-specific staining, tissue artifacts, inadequately inactivation of endogenous peroxidase activity and cross-reactivity, can substantially affect the accuracy and reliability of results, thereby impacting the interpretation of biological findings. Serving diagnostic, prognostic, predictive, and therapeutic roles in various conditions, including tumors, infectious diseases, neurodegenerative disorders, and muscle diseases, IHC remains pivotal despite its intricate nature. The adoption of digital pathology emerges as a progressive enhancement, addressing limitations and ensuring more accurate analyses in histopathology.

Novel quantitative immunohistochemistry method using histone H3, family 3B as the internal reference standard for measuring human epidermal growth factor receptor 2 expression in breast cancer

BACKGROUND

Immunohistochemistry (IHC) is an essential technique in surgical and clinical pathology for detecting diagnostic, prognostic, and predictive biomarkers for personalized cancer therapy. However, the lack of standardization and reference controls results in poor reproducibility, and a reliable tool for IHC quantification is urgently required. The objective of this study was to describe a novel approach in which H3F3B (histone H3, family 3B) can be used as an internal reference standard to quantify protein expression levels using IHC.

METHODS

The authors enrolled 89 patients who had human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC). They used a novel IHC-based assay to measure protein expression using H3F3B as the internal reference standard. H3F3B was uniformly expressed at the protein level in all tumor regions in cancer tissues. HER2 expression levels were measured with the H-score using HALO software.

RESULTS

Kaplan-Meier analysis indicated that, among patients who had HER2-positive BC in The Cancer Genome Atlas data set and the authors' data set, the subgroup with low HER2 expression had a significantly better prognosis than the subgroup with high HER2 expression. Furthermore, the authors observed that HER2 expression levels were precisely evaluated using the proposed method, which can classify patients who are at higher risk of HER2-positive BC to receive trastuzumab-based adjuvant therapy. Dual-color IHC with H3F3B is an excellent tool for internal and external quality control of HER2 expression assays.

CONCLUSIONS

The proposed IHC-based quantification method accurately assesses HER2 expression levels and provides insights for predicting clinical prognosis in patients with HER2-positive BC who receive trastuzumab-based adjuvant therapy.

Multi-cohort validation of Ascore: an anoikis-based prognostic signature for predicting disease progression and immunotherapy response in bladder cancer

Bladder cancer ranks as the 10th most common cancer worldwide, with deteriorating prognosis as the disease advances. While immune checkpoint inhibitors (ICIs) have shown promise in clinical therapy in both operable and advanced bladder cancer, identifying patients who will respond is challenging. Anoikis, a specialized form of cell death that occurs when cells detach from the extracellular matrix, is closely linked to tumor progression. Here, we aimed to explore the anoikis-based biomarkers for bladder cancer prognosis and immunotherapeutic decisions. Through consensus clustering, we categorized patients from the TCGA-BLCA cohort into two clusters based on anoikis-related genes (ARGs). Significant differences in survival outcome, clinical features, tumor immune environment (TIME), and potential ICIs response were observed between clusters. We then formulated a four-gene signature, termed "Ascore", to encapsulate this gene expression pattern. The Ascore was found to be closely associated with survival outcome and served as an independent prognosticator in both the TCGA-BLCA cohort and the IMvigor210 cohort. It also demonstrated superior predictive capacity (AUC = 0.717) for bladder cancer immunotherapy response compared to biomarkers like TMB and PD-L1. Finally, we evaluated Ascore's independent prognostic performance as a non-invasive biomarker in our clinical cohort (Gulou-Cohort1) using circulating tumor cells detection, achieving an AUC of 0.803. Another clinical cohort (Gulou-Cohort2) consisted of 40 patients undergoing neoadjuvant anti-PD-1 treatment was also examined. Immunohistochemistry of Ascore in these patients revealed its correlation with the pathological response to bladder cancer immunotherapy (P = 0.004). Impressively, Ascore (AUC = 0.913) surpassed PD-L1 (AUC = 0.662) in forecasting immunotherapy response and indicated better net benefit. In conclusion, our study introduces Ascore as a novel, robust prognostic biomarker for bladder cancer, offering a new tool for enhancing immunotherapy decisions and contributing to the tailored treatment approaches in this field.

Belgian Recommendations for Analytical Verification and Validation of Immunohistochemical Tests in Laboratories of Anatomic Pathology

Analytical verification and validation of immunohistochemical (IHC) tests and their equipment are common practices for today's anatomic pathology laboratories. Few references or guidelines are available on how this should be performed. The study of Sciensano (the Belgian national competent authority regarding licensing of medical laboratories) performed in 2016, demonstrated a significant interlaboratory variation in validation procedures of IHC tests among Belgian laboratories. These results suggest the unavailability of practical information on the approach to the verification and validation of these tests. The existing Belgian Practice Guideline for the implementation of a quality management system in anatomic pathology laboratories has been reviewed to meet this demand and, in addition, to prepare the laboratories for the EU-IVD revised regulations (IVDR). This paper describes Belgian recommendations for the verification and validation of IHC tests before implementation, for ongoing validation, and for revalidation. For each type of test (according to the IVDR classification and the origin) and its intended use (purpose), it addresses how to perform analytical verification/validation by recommending: (1) the number of cases in the validation set, (2) the performance characteristics to be evaluated, (3) the objective acceptance criteria, (4) the evaluation method for the obtained results, and (5) how and when to revalidate. A literature study and a risk analysis taking into account the majority of variables regarding verification/validation of methods have been performed, resulting in an expert consensus recommendation that is a compromise among achievability, affordability, and patient safety. This new consensus recommendation has been incorporated in the aforementioned ISO 15189:2012-based Practice Guideline.

Clinical Proteomics for Solid Organ Tissues

The evaluation of biopsied solid organ tissue has long relied on visual examination using a microscope. Immunohistochemistry is critical in this process, labeling and detecting cell lineage markers and therapeutic targets. However, while the practice of immunohistochemistry has reshaped diagnostic pathology and facilitated improvements in cancer treatment, it has also been subject to pervasive challenges with respect to standardization and reproducibility. Efforts are ongoing to improve immunohistochemistry, but for some applications, the benefit of such initiatives could be impeded by its reliance on monospecific antibody-protein reagents and limited multiplexing capacity. This perspective surveys the relevant challenges facing traditional immunohistochemistry and describes how mass spectrometry, particularly liquid chromatography-tandem mass spectrometry, could help alleviate problems. In particular, targeted mass spectrometry assays could facilitate measurements of individual proteins or analyte panels, using internal standards for more robust quantification and improved interlaboratory reproducibility. Meanwhile, untargeted mass spectrometry, showcased to date clinically in the form of amyloid typing, is inherently multiplexed, facilitating the detection and crude quantification of 100s to 1000s of proteins in a single analysis. Further, data-independent acquisition has yet to be applied in clinical practice, but offers particular strengths that could appeal to clinical users. Finally, we discuss the guidance that is needed to facilitate broader utilization in clinical environments and achieve standardization.

Diagnostic performances of Schistosoma haematobium and Schistosoma mansoni recombinant proteins, peptides and chimeric proteins antibody based tests. Systematic scoping review

BACKGROUND

Traditional diagnostic tests for schistosome infections are suboptimal, particularly when the parasite burden is low. In the present review we sought to identify recombinant proteins, peptides, and chimeric proteins with potential to be used as sensitive and specific diagnostic tools for schistosomiasis.

METHODS

The review was guided by PRISMA-ScR guidelines, Arksey and O'Malley's framework, and guidelines from the Joanna Briggs Institute. Five databases were searched: Cochrane library, PubMed, EMBASE, PsycInfo and CINAHL, alongside preprints. Identified literature were assessed by two reviewers for inclusion. A narrative summary was used to interpret the tabulated results.

RESULTS

Diagnostic performances were reported as specificities, sensitivities, and AUC. The AUC for S. haematobium recombinant antigens ranged from 0.65 to 0.98, and 0.69 to 0.96 for urine IgG ELISA. S. mansoni recombinant antigens had sensitivities ranging from 65.3% to 100% and specificities ranging from 57.4% to 100%. Except for 4 peptides which had poor diagnostic performances, most peptides had sensitivities ranging from 67.71% to 96.15% and specificities ranging from 69.23% to 100%. S. mansoni chimeric protein was reported to have a sensitivity of 86.8% and a specificity of 94.2%.

CONCLUSION

The tetraspanin CD63 antigen had the best diagnostic performance for S. haematobium. The tetraspanin CD63 antigen Serum IgG POC-ICTs had a sensitivity of 89% and a specificity of 100%. Peptide Smp_150390.1 (216-230) serum based IgG ELISA had the best diagnostic performance for S. mansoni with a sensitivity of 96.15% and a specificity of 100%. Peptides were reported to demonstrate good to excellent diagnostic performances. S. mansoni multi-peptide chimeric protein further improved the diagnostic accuracy of synthetic peptides. Together with the advantages associated with urine sampling technique, we recommend development of multi-peptide chimeric proteins urine based point of care tools.

Companion diagnostic requirements for spatial biology using multiplex immunofluorescence and multispectral imaging

Immunohistochemistry has long been held as the gold standard for understanding the expression patterns of therapeutically relevant proteins to identify prognostic and predictive biomarkers. Patient selection for targeted therapy in oncology has successfully relied upon standard microscopy-based methodologies, such as single-marker brightfield chromogenic immunohistochemistry. As promising as these results are, the analysis of one protein, with few exceptions, no longer provides enough information to draw effective conclusions about the probability of treatment response. More multifaceted scientific queries have driven the development of high-throughput and high-order technologies to interrogate biomarker expression patterns and spatial interactions between cell phenotypes in the tumor microenvironment. Such multi-parameter data analysis has been historically reserved for technologies that lack the spatial context that is provided by immunohistochemistry. Over the past decade, technical developments in multiplex fluorescence immunohistochemistry and discoveries made with improving image data analysis platforms have highlighted the importance of spatial relationships between certain biomarkers in understanding a patient's likelihood to respond to, typically, immune checkpoint inhibitors. At the same time, personalized medicine has instigated changes in both clinical trial design and its conduct in a push to make drug development and cancer treatment more efficient, precise, and economical. Precision medicine in immuno-oncology is being steered by data-driven approaches to gain insight into the tumor and its dynamic interaction with the immune system. This is particularly necessary given the rapid growth in the number of trials involving more than one immune checkpoint drug, and/or using those in combination with conventional cancer treatments. As multiplex methods, like immunofluorescence, push the boundaries of immunohistochemistry, it becomes critical to understand the foundation of this technology and how it can be deployed for use as a regulated test to identify the prospect of response from mono- and combination therapies. To that end, this work will focus on: 1) the scientific, clinical, and economic requirements for developing clinical multiplex immunofluorescence assays; 2) the attributes of the Akoya Phenoptics workflow to support predictive tests, including design principles, verification, and validation needs; 3) regulatory, safety and quality considerations; 4) application of multiplex immunohistochemistry through lab-developed-tests and regulated in vitro diagnostic devices.

Angiopoietin-like protein 8 deficiency attenuates thoracic aortic aneurysm/dissection development in β-aminopropionitrile monofumarate-induced model mice

Thoracic aortic aneurysm/dissection (TAAD) is a life-threatening cardiovascular disorder. Endoplasmic reticulum stress (ERS) and vascular smooth muscle cell (VSMC) apoptosis are involved in TAAD progression. The Protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) pathway is associated with VSMC apoptosis. Serum Angiopoietin-Like Protein 8 (ANGPTL8) levels are associated with aortic diameter and rupture rate of TAAD. However, a direct role of ANGPTL8 in TAAD has not been determined. β-Aminopropionitrile monofumarate (BAPN) was used to induce TAAD in C57BL/6 mice. ANGPTL8 knockout mice were used to detect the effects of ANGPTL8 on TAAD development. ANGPTL8knockdown in vitro was used to analyze the role of ANGPTL8 in VSMCs and ERS. In addition, over-expression of ANGPTL8 in VSMCs and a PERK inhibitor were used to assess the effect of ANGPTL8 on the PERK pathway. ANGPTL8 levels were increased in the aortic wall and VSMCs of BAPN-induced TAAD mice. Compared with BAPN-treated wild-type mice, ANGPTL8 knockout significantly reduced the rupture rate of TAAD to 0 %. In addition, the protein levels of proinflammatory cytokines and matrix metalloproteinase 9 (MMP9) and ERS proteins were decreased in the aorta wall. Angptl8 shRNA decreased MMP9 and ERS protein levels in VSMCs in vitro. Overexpression of ANGPTL8 significantly increased the levels of ERS proteins and MMPs, while a PERK inhibitor significantly decreased the effects of ANGPTL8 in VSMCs. ANGPTL8 contributed to TAAD development by inducing ERS activation and degradation of extracellular matrix in the aorta wall. Inhibition of ANGPTL8 may therefore represent a new strategy for TAAD therapy.

Intra-uterine diazepam exposure decreases the number of catecholaminergic and serotoninergic neurons of neonate rats

Benzodiazepines, such as diazepam (DZP), are used to treat anxiety disorders, and are prescribed to pregnant woman for therapeutic purposes. Concerns regarding their consequences on postnatal development rise as they cross the placenta and interact with the embryo. Occurrence of malformation and behavioral syndromes have been reported for different ages, but little is known about their effects on the brain after exposure during intrauterine life. Thus, we sought to evaluate the effects of intrauterine exposure to DZP on the number of brainstem's catecholaminergic and serotonergic neurons, implicated in respiratory control, in male and female rats on postnatal (P) day 12-13, using immunofluorescence labeling for tyrosine-hydroxylase (TH) and serotonin (5-HT). We observed a reduction in the number of catecholaminergic neurons for males and females. Special attention is given to the reduction in the density of neurons in the A6 region, involved in ventilatory responses to CO₂. Interestingly, only males showed a reduction in the number of serotonergic neurons, while females were not affected. These findings suggest that in utero exposure to DZP results in deleterious neuroanatomical effects on P12-13 rats and raises a note of concern for women clinicians to make more informed choices about the use of anxiolytic treatments during gestation.

Neuronal internalization of immunoglobulin G injected into the mouse brain by a novel absorption strategy to avoid unwanted interaction with immune complex using centrifugal filtration

Monoclonal immunoglobulin-G (IgG) antibodies are now emerging as therapeutic tools to tackle various disorders, including those affecting the brain. However, little is known about how these IgG molecules behave in the brain. To better understand the potential behavior of IgG molecules in the brain, here we established a specific protocol to immunolocalize rat IgG injected into mouse striatum with an anti-rat IgG antibody. Using double immunolabeling, IgG-like immunoreactivity (IR) was mainly found in neurons but scarcely observed in glia 1 h after intrastriatal injection of IgG, whereas some surrounding glia contained IgG-like IR 24 h after injection. However, preabsorption with a large excess of rat IgG to confirm the authenticity of this labeling failed to eliminate this neuronal IgG-like IR but rather exhibited nuclear staining in glial cells. Because this unexpected nuclear staining escalated with increasing amount of absorbing IgG, we postulated that this nuclear staining is due to formation of immune complex IgG-anti-IgG, which can be removed by centrifugal filtration. As expected, this nuclear staining in glial cells was eliminated after centrifugal filtration of the IgG/anti-IgG mixture, and authentic IgG-like IR was chiefly detected in the cytoplasm of neurons around the injection channel. This study is the first demonstration of neuronal redistribution of injected IgG in the mouse brain. Neuronal internalization of exogenous IgG may be advantageous especially when the therapeutic targets of monoclonal IgG are intraneuronal such as neurofibrillary tangles or Lewy bodies.

A whole-slide image (WSI)-based immunohistochemical feature prediction system improves the subtyping of lung cancer

BACKGROUND

Clinically, accurate pathological diagnosis is often challenged by insufficient tissue amounts and the unaffordability of additional immunohistochemical or genetic tests; thus, there is an urgent need for a universal approach to improve the subtyping of lung cancer without the above limitations. Here we aimed to develop a deep learning system to predict the immunohistochemistry (IHC) phenotype directly from whole-slide images (WSIs) to improve the subtyping of lung cancer from surgical resection and biopsy specimens.

METHODS

A total of 1914 patients with lung cancer from three independent hospitals in China were enrolled for WSI-based immunohistochemical feature prediction system (WIFPS) development and validation.

RESULTS

The WIFPS could directly predict the IHC status of nine subtype-specific biomarkers, including CK7, TTF-1, Napsin A, CK5/6, P63, P40, CD56, Synaptophysin, and Chromogranin A, achieving average areas under the curve (AUCs) of 0.912, 0.906, and 0.888 and overall diagnostic accuracies of 0.925, 0.941, and 0.887 in the validation datasets of total, external surgical resection specimens and biopsy specimens, respectively. The histological subtyping performance of the WIFPS remained comparable with that of general pathologists (GPs), with Cohen's kappa values ranging from 0.7646 to 0.8282. Furthermore, the WIFPS could be trained to not only predict the IHC status of anaplastic lymphoma kinase (ALK), programmed death-1 (PD-1), and programmed death ligand 1 (PD-L1), but also predict EGFR and KRAS mutation status, with AUCs from 0.525 to 0.917, as detected in separate populations.

CONCLUSIONS

In this study, the WIFPS showed its proficiency as a useful complement to traditional histologic subtyping for integrated immunohistochemical spectrum prediction as well as potential in the detection of gene mutations.

Immunohistochemistry Use by Diagnostic Category and Pathologist in 4477 Prostate Core Biopsy Sets Assessed at Two Hospitals

BACKGROUND

Immunohistochemistry (IHC) use in prostate cores is not routinely determined and its value assessed.

METHODS

Pathology reports for cases accessioned 2011 to 2017 at two hospitals were retrieved. IHC orders by pathologist and hospital were extracted with a custom program and tabulated. The diagnostic category (and highest grade cancer if applicable) was obtained by a hierarchical (free text) string matching algorithm.

RESULTS

The study period contained 4477 biopsy sets. Categorized by worst pathology (% stained), the cohort was: benign: 1184 cases (42%); prostatic intraepithelial neoplasia: 168 (68%); suspicious: 323 (93%); grade group 1 cancer (WHO1): 900 (78%); grade group two (WHO2): 840 (60%); WHO3 cancer: 451 (54%); WHO4 cancer: 363 (46%); WHO5 cancer: 215 (56%); cancer grade not specified: 33 (52%). The hospital was a predictor; site A(2716 biopsies) and site B(1761) accounted for 10,183 and 14,852 IHC, respectively. The cases with IHC decreased in the last 4 years (site A: 57->45%, site B: 79->73%). Thirty-five pathologists read >20 cases each and together interpreted 4418 (range, 21 to 415; median, 88). In total 24,766 IHCs were done on the 4,418 cases (5.6/case). The mean/median/SD/max/min IHCs/case for the 35 pathologists was 5.6/4.1/3.9/15.2/0.9. High IHC users (1st and 2nd quintile pathologists) called more suspicious for malignancy but not significantly more WHO1 than low IHC users.

CONCLUSIONS

IHC use is most frequent at the benign/malignant interface, and dependent on the pathologist and hospital; however, it is independent of WHO1 cancer rate. Diagnostic rate information can inform and define appropriate and rational IHC use. We plan to follow IHC utilization retrospectively in relation to the diagnostic category going forward.

Angiopoietin-like proteins 8 knockout reduces intermittent hypoxia-induced vascular remodeling in a murine model of obstructive sleep apnea

OBJECTIVE

Obstructive sleep apnea (OSA) is a major risk factor for cardiovascular mortality. Apnea-induced chronic intermittent hypoxia (CIH) is a primary pathophysiological manifestation of OSA that promotes various cardiovascular alterations, such as aortic vascular remodeling. In this study, we investigated the association between angiopoietin-like proteins 8 (ANGPTL8) and CIH-induced aortic vascular remodeling in mice.

METHODS

C57BL/6J male mice were divided into four groups: Normoxia group, ANGPTL8^-/- group, CIH group, CIH + ANGPTL8^-/- group. Mice in the normoxia group and ANGPTL8^-/- group received no treatment, while mice in the CIH and CIH + ANGPTL8^-/- group were subjected to CIH (21%-5% O₂, 180 s/cycle, 10 h/day) for 6 weeks. At the end of the experiments, intima-media thickness (IMT), elastin disorganization, and aortic wall collagen abundance were assessed in vivo. Immunohistochemistry and Western-blot were used to detect endoplasmic reticulum stress (ERS) and aortic vascular smooth muscle cell proliferation. ANGPTL8 shRNA and ANGPL8 overexpression were used in aortic vascular smooth muscle cells to investigate the mechanism of ANGPTL8 in CIH.

RESULTS

Compared to the control group, CIH exposure significantly increased intima-media thickness (IMT), elastic fibers disorganization, and aortic wall collagen abundance. CIH also significantly increased blood pressure, induced hyperlipidemia, as well as the expression of ERS protein activating transcription factor-6 (ATF6) and aortic vascular smooth muscle cell proliferation. Contrary, ANGPTL8^-/- significantly mitigated the CIH-induced vascular remodeling; ANGPTL8^-/- decreased CIH-induced hypertension and hyperlipidemia, inhibited the protein expression of ATF6, and aortic vascular smooth muscle cell proliferation. Moreover, our in vitro study suggested that CIH could induce ANGPTL8 expression via hypoxia-inducible factor (HIF-1α); ANGPTL8 induced proliferation of aortic vascular smooth muscle cells via the ERS pathway.

CONCLUSION

ANGPTL8^-/- can prevent CIH-induced aortic vascular remodeling, probably through the inhibition of the ERS pathway. Therefore, ANGPTL8 might be a potential target in CIH-induced aortic vascular remodeling.

Cannabinoid Receptor 1 Inhibition in Chronic Kidney Disease: A New Therapeutic Toolbox

Chronic kidney disease (CKD) concerns millions of individuals worldwide, with few therapeutic strategies available to date. Recent evidence suggests that the endocannabinoid system (ECS) could be a new therapeutic target to prevent CKD. ECS combines receptors, cannabinoid receptor type 1 (CB1R) and type 2 (CB2R), and ligands. The most prominent receptor within the kidney is CB1R, its endogenous local ligands being anandamide and 2-arachidonoylglycerol. Therefore, the present review focuses on the therapeutic potential of CB1R and not CB2R. In the normal kidney, CB1R is expressed in many cell types, especially in the vasculature where it contributes to the regulation of renal hemodynamics. CB1R could also participate to water and sodium balance and to blood pressure regulation but its precise role remains to decipher. CB1R promotes renal fibrosis in both metabolic and non-metabolic nephropathies. In metabolic syndrome, obesity and diabetes, CB1R inhibition not only improves metabolic parameters, but also exerts a direct role in preventing renal fibrosis. In non-metabolic nephropathies, its inhibition reduces the development of renal fibrosis. There is a growing interest of the industry to develop new CB1R antagonists without central nervous side-effects. Experimental data on renal fibrosis are encouraging and some molecules are currently under early-stage clinical phases (phases I and IIa studies). In the present review, we will first describe the role of the endocannabinoid receptors, especially CB1R, in renal physiology. We will next explore the role of endocannabinoid receptors in both metabolic and non-metabolic CKD and renal fibrosis. Finally, we will discuss the therapeutic potential of CB1R inhibition using the new pharmacological approaches. Overall, the new pharmacological blockers of CB1R could provide an additional therapeutic toolbox in the management of CKD and renal fibrosis from both metabolic and non-metabolic origin.

Hyperinsulinaemia in cancer

Elevated circulating insulin levels are frequently observed in the setting of obesity and early type 2 diabetes, as a result of insensitivity of metabolic tissues to the effects of insulin. Higher levels of circulating insulin have been associated with increased cancer risk and progression in epidemiology studies. Elevated circulating insulin is believed to be a major factor linking obesity, diabetes and cancer. With the development of targeted cancer therapies, insulin signalling has emerged as a mechanism of therapeutic resistance. Although metabolic tissues become insensitive to insulin in the setting of obesity, a number of mechanisms allow cancer cells to maintain their ability to respond to insulin. Significant progress has been made in the past decade in understanding the insulin receptor and its signalling pathways in cancer, and a number of lessons have been learnt from therapeutic failures. These discoveries have led to numerous clinical trials that have aimed to reduce the levels of circulating insulin and to abrogate insulin signalling in cancer cells. With the rising prevalence of obesity and diabetes worldwide, and the realization that hyperinsulinaemia may contribute to therapeutic failures, it is essential to understand how insulin and insulin receptor signalling promote cancer progression.

Fit-For-Purpose PD-L1 Biomarker Testing For Patient Selection in Immuno-Oncology: Guidelines For Clinical Laboratories From the Canadian Association of Pathologists-Association Canadienne Des Pathologistes (CAP-ACP)

Supplemental Digital Content is available in the text.

Since 2014, programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) checkpoint inhibitors have been approved by various regulatory agencies for the treatment of multiple cancers including melanoma, lung cancer, urothelial carcinoma, renal cell carcinoma, head and neck cancer, classical Hodgkin lymphoma, colorectal cancer, gastroesophageal cancer, hepatocellular cancer, and other solid tumors. Of these approved drug/disease combinations, a subset also has regulatory agency-approved, commercially available companion/complementary diagnostic assays that were clinically validated using data from their corresponding clinical trials. The objective of this document is to provide evidence-based guidance to assist clinical laboratories in establishing fit-for-purpose PD-L1 biomarker assays that can accurately identify patients with specific tumor types who may respond to specific approved immuno-oncology therapies targeting the PD-1/PD-L1 checkpoint. These recommendations are issued as 38 Guideline Statements that address (i) assay development for surgical pathology and cytopathology specimens, (ii) reporting elements, and (iii) quality assurance (including validation/verification, internal quality assurance, and external quality assurance). The intent of this work is to provide recommendations that are relevant to any tumor type, are universally applicable and can be implemented by any clinical immunohistochemistry laboratory performing predictive PD-L1 immunohistochemistry testing.

3D Tissue Microarray Controls: A Potential Standardization Solution

The use of controls is a hallmark for quality control in anatomic pathology. However, standardization of controls between laboratories has been a significant issue. Differential processing techniques between institutions and a multitude of preanalytical difficulties can result in different immunostain intensities. So called histoid controls, xenografts or culture cell lines, have been discussed in the past but with no recent followup. Herein is presented a histoid termed a 3D tissue microarray control (3D TMAC) control to help alleviate the burgeoning need for control standardization. A breast and cervix 3D TMAC control were tested for staining quality for 11 different antibodies commonly tested in either breast or cervical cancer work ups. We additionally looked at a small run of 5 days of CK5 and HER2 for reproducibility of the 3DRSTMA. Staining quality of 9 of the antibodies stained appropriately and 2 stained inappropriately, mammoglobin and GCDFP. Two of the antibodies were not reported to have any staining properties in the 3D TMAC, p16 and mammoglobin. Of these, p16 had appropriate staining and mammoglobin did not. In the 5 runs of CK5 and HER2, there was good reproducibility between stains assessed by both visual and computer-assisted methods, with membrane intensity coefficients of variation of 3.58% and 3.18%, respectively. The 3D TMAC has the potential to markedly improve intralaboratory and interlaboratory standardization practices.

Crizotinib inhibition of ROS1-positive tumours in advanced non-small-cell lung cancer: a Canadian perspective

The ros1 kinase is an oncogenic driver in non-small-cell lung cancer (nsclc). Fusion events involving the ROS1 gene are found in 1%-2% of nsclc patients and lead to deregulation of a tyrosine kinase-mediated multi-use intracellular signalling pathway, which then promotes the growth, proliferation, and progression of tumour cells. ROS1 fusion is a distinct molecular subtype of nsclc, found independently of other recognized driver mutations, and it is predominantly identified in younger patients (<50 years of age), women, never-smokers, and patients with adenocarcinoma histology. Targeted inhibition of the aberrant ros1 kinase with crizotinib is associated with increased progression-free survival (pfs) and improved quality-of-life measures. As the sole approved treatment for ROS1-rearranged nsclc, crizotinib has been demonstrated, through a variety of clinical trials and retrospective analyses, to be a safe, effective, well-tolerated, and appropriate treatment for patients having the ROS1 rearrangement. Canadian physicians endorse current guidelines which recommend that all patients with nonsquamous advanced nsclc, regardless of clinical characteristics, be tested for ROS1 rearrangement. Future integration of multigene testing panels into the standard of care could allow for efficient and cost-effective comprehensive testing of all patients with advanced nsclc. If a ROS1 rearrangement is found, treatment with crizotinib, preferably in the first-line setting, constitutes the standard of care, with other treatment options being investigated, as appropriate, should resistance to crizotinib develop.

High-Quality Immunohistochemical Stains Through Computational Assay Parameter Optimization

Accurate profiling of tumors using immunohistochemistry (IHC) is essential in cancer diagnosis. The inferences drawn from IHC-stained images depend to a great extent on the quality of immunostaining, which is in turn affected strongly by assay parameters. To optimize assay parameters, the available tissue sample is often limited. Moreover, with current practices in pathology, exploring the entire assay parameter space is not feasible. Thus, the evaluation of IHC stained slides is conventionally a subjective task, in which diagnoses are commonly drawn on images that are suboptimal. In this work, we introduce a framework to analyze IHC staining quality and its sensitivity to process parameters. To that extent, first histopathological sections are segmented automatically. Then, machine learning techniques are employed to extract disease-specific staining quality metrics (SQMs) targeting a quantitative assessment of staining quality. Finally, an approach to efficiently analyze the parameter space is introduced to infer sensitivity to process parameters. We present results on microscale IHC tissue samples of five breast tumor classes, based on disease state and protein expression. A disease-type classification F1-score of 0.82 and a contrast-level classification F1-score of 0.95 were achieved. With the proposed SQMs, an area under the curve of 0.85 was achieved on average over different disease types. Our methodology provides a promising step in automatically evaluating and quantifying staining quality of IHC stained tissue sections, and it can potentially standardize immunostaining across diagnostic laboratories.

NordiQC Assessments of Chromogranin A Immunoassays

This paper is number 6 in a series developed through a partnership between ISIMM and Nordic IHC Quality Control with the purpose of reporting research assessing the performance characteristics of immunoassays in an external proficiency testing program.

NordiQC Assessments of CD117 Immunoassays

This paper is the number 5 in a series developed through a partnership between ISIMM and NordiQC for the purpose of reporting research assessing the performance characteristics of immunoassays in an external proficiency-testing program.

Comparative Pathologists: Ultimate Control Freaks Seeking Validation!

Definable, reproducible, and meaningful are elemental features of grading/scoring systems, while thoroughness, accuracy, and consistency are quality indicators of pathology reports. The expertise of pathologists is significantly underutilized when it is limited to rendering diagnoses. The opportunity to provide guidance on animal model development, experimental design, optimal sample collection, and data interpretation not only contributes to job satisfaction but also, more importantly, promotes validation of the pathology data. Keys to validation include standard operating procedures, experimental controls, and standardized nomenclature applied throughout the experimental design and execution, tissue sampling, and slide preparation, as well as the creation or adaptation and application of semiquantitative grading/scoring systems. Diagnostic drift, thresholds, mental noise, and various diurnal fluctuations strongly influence the repeatability of grading/scoring systems used by the same or different pathologists. Quantitative image analyses are not plagued by the visual and cognitive traps that affect manual semiquantitative grading schemes but may still be affected by technical variables associated with necropsy, tissue sampling, and slide preparation. The validity of a grading scheme is ultimately assessed by its repeatability and biologic relevance, so it is important to correlate scores with comprehensive pathobiology data such as results of antemortem imaging, clinical pathology data, body and organ weights, and histopathologic evaluation of full tissue sets.

Immunohistochemistry in Investigative and Toxicologic Pathology

Immunohistochemistry (IHC) is a valuable tool in pathology. This review provides a brief description of the technical aspects of IHC and a detailed discussion on the variables that affect the results, interpretation, and reproducibility of IHC results. Lists of antibodies that have and have not worked in IHC on various mouse and rat tissues in our laboratory are provided as a guidance for selection of antibodies. An approach to IHC method optimization is presented. Finally, the critical information that should be included as a part of peer-reviewed manuscript is also discussed.

Whole tumor section quantitative image analysis maximizes between-pathologists' reproducibility for clinical immunohistochemistry-based biomarkers

Pathologists have had increasing responsibility for quantitating immunohistochemistry (IHC) biomarkers with the expectation of high between-reader reproducibility due to clinical decision-making especially for patient therapy. Digital imaging-based quantitation of IHC clinical slides offers a potential aid for improvement; however, its clinical adoption is limited potentially due to a conventional field-of-view annotation approach. In this study, we implemented a novel solely morphology-based whole tumor section annotation strategy to maximize image analysis quantitation results between readers. We first compare the field-of-view image analysis annotation approach to digital and manual-based modalities across multiple clinical studies (~120 cases per study) and biomarkers (ER, PR, HER2, Ki-67, and p53 IHC) and then compare a subset of the same cases (~40 cases each from the ER, PR, HER2, and Ki-67 studies) using whole tumor section annotation approach to understand incremental value of all modalities. Between-reader results for each biomarker in relation to conventional scoring modalities showed similar concordance as manual read: ER field-of-view image analysis: 95.3% (95% CI 92.0-98.2%) vs digital read: 92.0% (87.8-95.8%) vs manual read: 94.9% (91.4-97.8%); PR field-of-view image analysis: 94.1% (90.3-97.2%) vs digital read: 94.0% (90.2-97.1%) vs manual read: 94.4% (90.9-97.2%); Ki-67 field-of-view image analysis: 86.8% (82.1-91.4%) vs digital read: 76.6% (70.9-82.2%) vs manual read: 85.6% (80.4-90.4%); p53 field-of-view image analysis: 81.7% (76.4-86.8%) vs digital read: 80.6% (75.0-86.0%) vs manual read: 78.8% (72.2-83.3%); and HER2 field-of-view image analysis: 93.8% (90.0-97.2%) vs digital read: 91.0 (86.6-94.9%) vs manual read: 87.2% (82.1-91.9%). Subset implementation and analysis on the same cases using whole tumor section image analysis approach showed significant improvement between pathologists over field-of-view image analysis and manual read (HER2 100% (97-100%), P=0.013 field-of-view image analysis and 0.013 manual read; Ki-67 100% (96.9-100%), P=0.040 and 0.012; ER 98.3% (94.1-99.5%), p=0.232 and 0.181; and PR 96.6% (91.5-98.7%), p=0.012 and 0.257). Overall, whole tumor section image analysis significantly improves between-pathologist's reproducibility and is the optimal approach for clinical-based image analysis algorithms.

Comparison of protein-based cell-of-origin classification to the Lymph2Cx RNA assay in a cohort of diffuse large B-cell lymphomas in Malaysia

Aims

The cell of origin (COO) based molecular characterisation into germinal centre B-cell-like (GCB) and activated B-cell-like (ABC) subtypes are central to the pathogenesis and clinical course in diffuse large B-cell lymphoma (DLBCL). Globally, clinical laboratories employ pragmatic but less than ideal immunohistochemical (IHC) assay for COO classification. Novel RNA-based platforms using routine pathology samples are emerging as new gold standard and offer unique opportunities for assay standardisation for laboratories across the world. We evaluated our IHC protocols against RNA-based technologies to determine concordance; additionally, we gauged the impact of preanalytical variation on the performance of Lymph2Cx assay.

Methods

Diagnostic biopsies (n=104) were examined for COO classification, employing automated RNA digital quantification assay (Lymph2Cx). Results were equated against IHC-based COO categorisation. Assay performance was assessed through its impact on overall survival (OS).

Results

96 (92%) informative samples were labelled as GCB (38/96; 40%) and non-GCB (58/96; 60%) by IHC evaluation. Lymph2Cx catalogued 36/96 (37%) samples as GCB, 45/96 (47%) as ABC and 15/96 (16%) as unclassified. Lymph2Cx being reference, IHC protocol revealed sensitivity of 81% for ABC and 75% for GCB categorisation and positive predictive value of 81% versus 82%, respectively. Lymph2Cx-based COO classification performed superior to Hans algorithm in predicting OS (log rank test, p=0.017 vs p=0.212).

Conclusions

Our report show that current IHC-based protocols for COO classification of DLBCL at UKM Malaysia are in line with previously reported results and marked variation in preanalytical factors do not critically impact Lymph2Cx assay quality.

A Novel Technique for the Generation of Multitissue Blocks Using a Carrier

Paraffin blocks containing several tissues have become a major tool in surgical pathology. As multitissue blocks, they usually consist of few rather large samples and as tissue microarrays (TMAs) they may contain up to several hundred small-sized tissue cores. We developed a novel approach to generate multitissue blocks using a carrier in which tissue samples are inserted. Normal tissues with homogenous consistency such as liver, spleen, and lung seem to be ideal carriers. Carrier tissue size can be freely chosen to accommodate number and size of sample tissues as desired. As the carrier tissue serves as a scaffold for the inserted tissue, even small-sized tissues will stay exactly as placed in the carrier. This makes carrier-based multitissue blocks (CBMTBs) an ideal approach when exact orientation of layers is important, for example in normal GIT tissues. The carrier tissue approach can also be used for few large-sized sample tissues or to generate classical TMAs with sample cores of <1 mm. As the newly generated CBMTB or carrier-based tissue microarray is completely reembedded after assembling, sectioning of CBMTBs is comparable with sectioning a normal solid tissue block producing virtually no sample loss and requiring minimal trimming and consequently vastly increasing yield.

Quality control in diagnostic immunohistochemistry: integrated on-slide positive controls

Standardization in immunohistochemistry is a priority in modern pathology and requires strict quality control. Cost containment has also become fundamental and auditing of all procedures must take into account both these principles. Positive controls must be routinely performed so that their positivity guarantees the appropriateness of the immunohistochemical procedure. The aim of this study is to develop a low cost (utilizing a punch biopsy-PB-tool) procedure to construct positive controls which can be integrated in the patient's tissue slide. Sixteen frequently used control blocks were selected and multiple cylindrical samples were obtained using a 5-mm diameter punch biopsy tool, separately re-embedding them in single blocks. For each diagnostic immunoreaction requiring a positive control, an integrated PB-control section (cut from the appropriate PB-control block) was added to the top right corner of the diagnostic slide before immunostaining. This integrated control technique permitted a saving of 4.75% in total direct lab costs and proved to be technically feasible and reliable. Our proposal is easy to perform and within the reach of all pathology labs, requires easily available tools, its application costs is less than using external paired controls and ensures that a specific control for each slide is always available.

Immunohistochemistry of Pulmonary Biomarkers: A Perspective From Members of the Pulmonary Pathology Society

The use of immunohistochemistry for the determination of pulmonary carcinoma biomarkers is a well-established and powerful technique. Immunohistochemisty is readily available in pathology laboratories, is relatively easy to perform and assess, can provide clinically meaningful results very quickly, and is relatively inexpensive. Pulmonary predictive biomarkers provide results essential for timely and accurate therapeutic decision making; for patients with metastatic non-small cell lung cancer, predictive immunohistochemistry includes ALK and programmed death ligand-1 (PD-L1) (ROS1, EGFR in Europe) testing. Handling along proper methodologic lines is needed to ensure patients receive the most accurate and representative test outcomes.

The Detection Techniques for Autophagy-Associated Cell Death-Related Genes and Proteins: Gene Expression Assay and Immunohistochemistry

Autophagy is important in cellular homeostasis for the cell survival mechanism. Deficiency or excess of autophagy is generally related to some of diseases such as cancer and neurodegeneration. Although autophagy is a cell survival mechanism, it can mediate programmed cell death in several conditions. Autophagy-related genes (ATGs) regulate the autophagy and also control the crosstalk with autophagy-associated cell death and apoptosis in some condition. Various methods have been used to detect the marker genes and the proteins involved in these processes. Quantitative real-time PCR (qRT-PCR) method for monitoring the expression of genes involved in autophagy or autophagic cell death is often preferred because of its sensitivity, high efficiency potential, accurate quantification, and high-grade potential automation. The detection of the markers for autophagy-related process by immunohistochemistry in paraffin sections of various patient tissues has become a reliable method for monitoring autophagy. Here, we introduce protocols for detecting autophagy and autophagy-associated cell death in HeLa cells by using gene expression assays qRT-PCR, and also in paraffin-embedded tissue section from human biopsy material by using immunohistochemistry.

An iOS App to Expedite the Evaluation of Immunohistochemistry Control Tissue

Control tissues play a vital role in diagnostic immunohistochemistry. They serve to document that the appropriate antibody was used, on the correct control tissue, and run on optimized conditions. As part of the evolving process of standardization in diagnostic immunohistochemistry, specific tissues have been identified based on agreement by experts in this field capable of serving as the benchmark(s) for several antibodies. These tissues are recommended based on known and predictable levels of strong, weak, and no expression of the antigen being queried. These tissues can be used for positive and negative control purposes, respectively, and are regarded as primary positive and/or negative external control tissue. If some of these tissues are not present in sufficient numbers in a laboratory's archive for daily use, they can still be used as the basis to evaluate other tissues that are not as well characterized and chosen to serve as secondary and external positive controls. In this manner, either the former or latter can function as external positive and negative control tissue for the quality assurance of immunohistochemistry done in a laboratory. The use of the selected tissues may be applicable to the detection of several different antigens by a number of separate antibodies, with differences in the staining of specific cells or the localization in staining within those cells. However, the amount of information needed to be familiar with to render a correct interpretation of the control tissue may prove daunting. One means of dealing with this problem would be to create a document capable of serving as a reference guide. Traditional types of references, however, may suffer from issues related to convenience, updating, and mobility. Herein we describe a mobile device application (app) created to serve as a reference for control block tissues. This app can capably house and easily retrieve all the relevant information on all the antibodies and their respective control tissues in a laboratories test menu, thus enabling the use of standardized tissues as control material and spreading the ability to perform immunohistochemical quality control to individual pathologists.

Proficiency testing in immunohistochemistry--experiences from Nordic Immunohistochemical Quality Control (NordiQC)

Despite extensive use of immunohistochemistry (IHC) for decades, lack of standardization remains a major problem, even aggravated in the era of targeted therapy. Nordic Immunohistochemical Quality Control (NordiQC) is an international academic proficiency testing (PT) program established in 2003 primarily aimed at assessing the analytical phases of the laboratory IHC quality. About 700 laboratories from 80 countries are currently participating. More than 30,000 IHC slides have been evaluated during 2003-2015. Overall, about 20 % of the staining results in the breast cancer IHC module and about 30 % in the general module have been assessed as insufficient for diagnostic use. The most common causes for insufficient results are less successful antibodies (poor and less robust antibodies, poorly calibrated ready-to-use (RTU) products, and stainer platform-dependent antibodies; 17 %), insufficiently calibrated antibody dilutions (20 %), insufficient or erroneous epitope retrieval (27 %), less sensitive visualization systems (19 %), and other (heat- and proteolysis-induced impaired morphology, endogenous biotin reaction, drying out phenomena, stainer platform-dependant protocol issues; 17 %). Approximately, 90 % of the insufficient results are characterized by either a too weak or false negative staining, whereas in the remaining 10 %, a poor signal-to-noise ratio or false positive staining is seen. Individually tailored recommendations for protocol optimization and identification of best tissue controls to ensure appropriate calibration of the IHC assay have for many markers improved IHC staining as well as inter-laboratory consistency of the IHC results. RTUs will not always provide an optimal result and data sheets frequently misguide the laboratories hampering the improvement in IHC quality. The overall data generated by NordiQC during 12 years indicates that continuous PT is valuable and necessary. Detailed description of the results of the NordiQC programme is available on www.nordiqc.org and summarized in this paper.

Getting controls under control: the time is now for immunohistochemistry

For several decades, immunohistochemistry (IHC), more specifically diagnostic IHC (dIHC), has been considered an art rather than a laboratory test. There was no clarity about what test performance characteristics are relevant to dIHC, test performance characteristics were not fully defined for dIHC and partly as a consequence of that, there were no standardised controls or reference standards. Herein, we discuss the role of standardisation of external controls for test performance characteristics and the role of standardised controls and reference standards for overall standardisation of IHC.

Quantitative in situ proteomics; a proposed pathway for quantification of immunohistochemistry at the light-microscopic level

Companion diagnostics, tests that purport to classify patients into "responders" and "non-responders" for a specified targeted therapy, demand methods that quantify the actual amount of the corresponding target molecule in tumors from these patients. Various methods are employed depending upon the nature of the target. Many of the candidate therapeutic agents target the abnormal expression of a protein, the detection of which lends itself to an immunohistochemistry (IHC) approach. This review focuses on IHC with formalin-fixed paraffin-embedded (FFPE) tissues for purely pragmatic reasons; first, the morphologic information pertaining to the tumor is of value and should not be discarded as in extraction type assays; second, FFPE tissues are mostly what we have to hand at the time that the diagnostic question is posed. During the four decades of employment of IHC involving the production of a variety of special stains used in the diagnosis or classification of tumors, we have acquired some bad habits, essentially when judging the IHC result via the perception of a "good" stain that "pleases the eye" of the user pathologist, and nothing more. This review takes, as its basic premise, the notion that IHC can be upgraded from its use as a qualitative special staining method to an accurate and reliable quantitative "tissue-based immunologic assay". If accomplished, this enhanced IHC assay would serve accurately to quantify proteins in tissue sections, analogous to the use of the ELISA (enzyme-linked immunosorbent assay) method in the clinical laboratory. The necessary steps for converting IHC to a tissue-based ELISA-like immunoassay of immediate practical use are reviewed with constructive suggestions for steps that can be (must be) taken to achieve the practical reality of quantitative in situ proteomics.

Predictive biomarkers and companion diagnostics. The future of immunohistochemistry: "in situ proteomics," or just a "stain"?

A ‘companion diagnostic’ is a test for a predictive biomarker, that classifies patients (tumors) into responders and non-responders, for a specified therapeutic agent. Companion diagnostics are designated as Class III medical devices by the FDA, because the test result equates directly to administration of a drug.

Testing for HER2 expression was approved by the FDA in 1998, and served as the prototype for using immunohistochemistry (IHC) as the basis for a companion diagnostic. However, over four decades IHC has primarily been employed in a broad range of ‘special stains’, for identification and classification cells and tumors in FFPE (formalin fixed paraffin embedded) tissues. During the long use of IHC as a ‘special stain’ we have acquired some very bad habits, changing protocols, concentrations, incubation times, retrieval methods, or reagents, to achieve the perception of a ‘good’ stain, that ‘pleases the eye’ of the user pathologist. While this approach may be acceptable for IHC stains, it is a recipe for disaster when transferred to companion diagnostics, where quantification and absolute reproducibility are required. In the context of companion diagnostics the IHC method should be regarded as an assay, not simply a stain. Elevating IHC to a true immunoassay will necessitate a much more rigorous approach to performance, reproducibility and control. The ultimate goal is to supplement morphologic judgment with precise measurement of proteins in tissues and in individual cells, ‘in situ proteomics’ as it were.