A review of preanalytical factors affecting molecular, protein, and morphological analysis of formalin-fixed, paraffin-embedded (FFPE) tissue: how well do you know your FFPE specimen?

BRCA Mutation Testing in Men with Metastatic Castration-Resistant Prostate Cancer: Practical Guidance for Australian Clinical Practice

Some patients with metastatic castration-resistant prostate cancer (mCRPC) possess germline or acquired defects in the DNA damage repair (DDR) genes BRCA1 and BRCA2. Tumors with BRCA mutations exhibit sensitivity to poly-ADP ribose polymerase inhibitors (PARPi) such as olaparib and rucaparib. As a result, molecular diagnostic testing to identify patients with BRCA mutations eligible for the PARPi therapy has become an integral component of managing patients with mCRPC. There are practical challenges in the current molecular testing pathway in Australia that can compromise testing success. Testing success is often contingent on quality of tissue handling and laboratory processing techniques to minimize DNA degradation and suboptimal sequencing data quality. Greater adoption of best testing practices in Australia can be facilitated with education and greater awareness of expert recommendations. Here, we provide expert recommendations on how to optimize BRCA molecular diagnostic testing in patients with mCRPC. Optimization and standardization of molecular diagnostic testing will support health care providers and institutes in establishing more efficient testing pathways, enabling access to targeted therapies such as PARPi, and improving patient outcomes.

Resolving the bone - optimizing decalcification in spatial transcriptomics and molecular pathology

Bone tissue poses critical roadblocks for spatial transcriptomics and molecular pathology due to a combination of its dense, calcified matrix and inadequate preservation of biomolecules in conventional decalcification. Decalcification is a complex and nuanced histological process to concomitantly preserve nucleic acids, proteins, and tissue architecture, ensuring molecular integrity for downstream assays. However, commonly used agents like formic and hydrochloric acids, while efficient, can degrade biomolecules to varying extents, complicating assays such as PCR, sequencing, immunohistochemistry, and in situ hybridization. Advances in spatial transcriptomics, both sequencing- and imaging-based, emphasize the importance of optimizing decalcification protocols to improve research outcomes. This synoptic and perspective article explores traditional and modern decalcification methods, offering recommendations on technical and methodological refinements for achieving molecularly robust processing of bone and calcified tissues in spatial transcriptomics and molecular pathology.

Be bold, start cold! cold formalin fixation of colorectal cancer specimens granted superior DNA and RNA quality for downstream molecular analysis

The use of cold formalin fixation (CFF; i.e., fixating tissue samples with 4 °C precooled formalin) recently attracted further attention owing to its putative improved ability to preserve nucleic acid compared with standard room temperature formalin (SFF). In this study, we aimed to assess the effect of four formalin-based fixation protocols (SFF, CFF, delayed formalin fixation-DFF, and cold formalin hyperfixation; CFH) on both DNA and RNA quality. We collected 97 colorectal cancer (CRC) and analyzed 23 metrics of nucleic acid quantity and quality yield using a multiplatform approach by combining spectrophotometric, fluorimetric, electrophoretic, and polymerase chain reaction (PCR) assays. Following confirmation of fixation-protocol-related different effects via clustering analysis, CFF presented best metrics compared with all protocols, specifically positive coefficients of DV1000-60000, DV2/DV1, DNA λ ratio 260/230, and ABL gene expression absolute copies, and negative coefficient of DV150-1000. The SFF subgroup presented a positive coefficient of DV150-1000 and negative coefficients for DV1000-60000, DV2/DV1, RNA λ ratio 260/230, RNA QuBit concentration, DV100/200, RNA electrophoresis concentration and absolute quantity, and ABL copies. Overall, we confirmed the superior yield performances of CFF preservation for both DNA and RNA compared with the other protocols in our series of CRC samples. Pending further validations and clarification of the specific mechanisms behind these findings, our study supports the implementation of CFF in the pathology unit routine specimen management for tumor tissue molecular profiling.

Infrared Laser Ablation and Capture of Formalin-Fixed Paraffin-Embedded Tissue

Formalin-fixed paraffin-embedded (FFPE) tissue is a ubiquitous and invaluable resource for biomedical research and clinical applications. However, FFPE tissue proteomics is challenging due to protein cross-linking and chemical modification. Laser ablation sampling allows precise removal of material from tissue sections with high spatial control and reproducibility for offline proteomics by liquid chromatography coupled with tandem mass spectrometry. In this work, we used a pulsed mid-infrared laser for microsampling of rat liver tissue for subsequent identification and quantification of proteins. It was found that more proteins were identified by FFPE tissue laser ablation sampling compared to fresh frozen (FF) tissue laser ablation sampling and that more proteins were identified by laser ablation than by manual dissection of FFPE tissue. In contrast to previous studies, no loss of hydrophilic proteins due to residual cross-linking was observed. The efficient capture of proteins by laser ablation microsampling is attributed to efficient laser breakup of the tissue which facilitates downstream processing of the proteins.

Evaluation of a multiplex real-time PCR targeting the β-tubulin gene for the detection and differentiation of Sporothrix schenckii and Sporothrix brasiliensis

Sporothrix sp. is a thermally dimorphic genus of fungi known to cause subacute or chronic subcutaneous lesions in humans and animals and is the cause of increasing public health concern due to spread of feline-associated cases. Here, we adapted and evaluated a recently described real-time PCR assay targeting the β-tubulin gene to rapidly detect and differentiate two related species, S. schenckii and S. brasiliensis. The assay was tested with 55 S. brasiliensis, 19 S. schenckii, and 85 isolates from other clinically relevant fungi, and showed 100% concordance with reference identification methods. The assay showed high analytical sensitivity with a limit of detection of 1 pg of DNA per microliter of sample for both targets. The assay was further evaluated with 11 fresh and 17 formalin-fixed, paraffin-embedded (FFPE) tissues. This multiplex real-time PCR assay successfully detected the DNA from both S. brasiliensis and S. schenckii isolates as well as S. schenckii from fresh and FFPE tissues. Our results demonstrate this assay performs well and could be a helpful molecular tool to support rapid species identification in cultures and primary specimens.IMPORTANCEHaving available molecular tools to identify and differentiate closely related species will allow clinical, veterinarians, and public health labs to provide diagnostic results with accuracy and short turnaround time for the routine and outbreak response activities.

Optimized biomarker evaluation and molecular testing in the era of breast cancer precision medicine

Ground breaking advances in medicine, driven in part by major technologic developments in molecular biology have led us to a new model for cancer care that has been termed personalized, or precision medicine. Precision medicine is a model for making medical decisions that employs an innovative clinical approach and advanced tumor testing methods that are tailored to understanding an individual patient's tumor biology and the molecular drivers of their disease. This medical model includes a combination of diagnostic testing and specific treatment options that can be offered to patients at presentation and in theory throughout the course of their disease as new mutations arise with the development of disease recurrence. Although the precision medicine model offers incredible potential to transform cancer care, these advances are only meaningful when they reach the correct patients. The evolving paradigm of precision medicine is changing the practice of pathology, and the pathology community needs to be mindful of these changes because every tissue specimen represents a patient's life, and those patients are depending on the pathology community to handle their tissue correctly. The diagnostic tests performed in the pathology laboratory for precision medicine are increasingly complex, and pathologists along with the entire laboratory and clinical communities need to take steps to ensure that the right diagnosis is given to the right patient to inform the right treatment options, at the right time, along every step of the continuum of care for cancer patients. While hormone receptors and human epidermal growth factor receptor 2 (HER2) overexpression and/or amplification have been the mainstay for risk-stratification, and treatment decision making in breast cancer since the early 2000's, the seminal work on gene expression by Perou and colleagues in the early 2000's opened the door for molecular testing in the prognostic and predictive assessment of breast cancer. Molecular testing is now part of the standard of care in the precision medicine model for breast cancer care. In this article, the reader will gain a better understanding of how the lack of standardization of pre-analytic factors has the potential to negatively impact the quality of the tissue specimen for downstream biomarker and molecular testing, which ultimately can negatively affect patient care. The reader will also gain insight into the current climate surrounding molecular testing in breast cancer.

A best practices framework for spatial biology studies in drug discovery and development: enabling successful cohort studies using digital spatial profiling

The discovery of biomarkers, essential for successful drug development, is often hindered by the limited availability of tissue samples, typically obtained through core needle biopsies. Standard 'omics platforms can consume significant amounts of tissue, forcing scientist to trade off spatial context for high-plex assays, such as genome-wide assays. While bulk gene expression approaches and standard single-cell transcriptomics have been valuable in defining various molecular and cellular mechanisms, they do not retain spatial context. As such, they have limited power in resolving tissue heterogeneity and cell-cell interactions. Current spatial transcriptomics platforms offer limited transcriptome coverage and have low throughput, restricting the number of samples that can be analyzed daily or even weekly. While the Digital Spatial Profiling (DSP) method does not provide single-cell resolution, it presents a significant advancement by enabling scalable whole transcriptome and ultrahigh-plex protein analysis from distinct tissue compartments and structures using a single tissue slide. These capabilities overcome significant constraints in biomarker analysis in solid tissue specimens. These advancements in tissue profiling play a crucial role in deepening our understanding of disease biology and in identifying potential therapeutic targets and biomarkers. To enhance the use of spatial biology tools in drug discovery and development, the DSP Scientific Consortium has created best practices guidelines. These guidelines, built on digital spatial profiling data and expertise, offer a practical framework for designing spatial studies and using current and future spatial biology platforms. The aim is to improve tissue analysis in all research areas supporting drug discovery and development.

Guidelines of the Brazilian Society of Surgical Oncology for anatomopathological, immunohistochemical, and molecular testing in female tumors

INTRODUCTION

Precision medicine has revolutionized oncology, providing more personalized diagnosis, treatment, and monitoring for patients with cancer. In the context of female-specific tumors, such as breast, ovarian, endometrial, and cervical cancer, proper tissue collection and handling are essential for obtaining tissue, immunohistochemical (IHC), and molecular data to guide therapeutic decisions.

OBJECTIVES

To establish guidelines for the collection and handling of tumor tissue, to enhance the quality of samples for histopathological, IHC, genomic, and molecular analyses. These guidelines are fundamental in informing therapeutic decisions in cancer treatment.

METHOD

The guidelines were developed by a multidisciplinary panel of renowned specialists between June 12, 2013 and February 12, 2024. Initially, the panel deliberated on critical and controversial topics related to conducting precision medicine studies focusing on female tumors. Subsequently, 22 pivotal topics were identified within the framework and assigned to groups. These groups reviewed relevant literature and drafted preliminary recommendations. Following this, the recommendations were reviewed by the coordinators and received unanimous approval. Finally, the groups made the final adjustments, classified the level of evidence, and ranked the recommendations.

CONCLUSION

The collection of surgical samples requires minimum quality standards to enable histopathological, IHC, genomic, and molecular analyses. These analyses provide crucial data for informing therapeutic decisions, significantly impacting potential survival gains for patients with female tumors.

Systematic review and feasibility study on pre-analytical factors and genomic analyses on archival formalin-fixed paraffin-embedded breast cancer tissue

Formalin-fixed paraffin-embedded (FFPE) tissue represents a valuable source for translational cancer research. However, the widespread application of various downstream methods remains challenging. Here, we aimed to assess the feasibility of a genomic and gene expression analysis workflow using FFPE breast cancer (BC) tissue. We conducted a systematic literature review for the assessment of concordance between FFPE and fresh-frozen matched tissue samples derived from patients with BC for DNA and RNA downstream applications. The analytical performance of three different nucleic acid extraction kits on FFPE BC clinical samples was compared. We also applied a newly developed targeted DNA Next-Generation Sequencing (NGS) 370-gene panel and the nCounter BC360® platform on simultaneously extracted DNA and RNA, respectively, using FFPE tissue from a phase II clinical trial. Of the 3701 initial search results, 40 articles were included in the systematic review. High degree of concordance was observed in various downstream application platforms. Moreover, the performance of simultaneous DNA/RNA extraction kit was demonstrated with targeted DNA NGS and gene expression profiling. Exclusion of variants below 5% variant allele frequency was essential to overcome FFPE-induced artefacts. Targeted genomic analyses were feasible in simultaneously extracted DNA/RNA from FFPE material, providing insights for their implementation in clinical trials/cohorts.

Age-Related Clusters and Favorable Immune Phenotypes in Young Breast Cancer Patients

Breast cancer (BC) patients aged <40 years at diagnosis experience aggressive disease and poorer survival compared with women diagnosed with BC at 40 to 49 years, but the age-related biology is described to little extent. Here, we explored transcriptional alterations in BC to gain better understanding of age-related tumor biology. We studied a subset of the Bergen in-house cohort (n = 127; age range, 26-49 years) and used the NanoString Breast Cancer 360 expression panel on formalin-fixed paraffin-embedded BC tissue, and publicly available global BC messenger RNA expression data (n = 204; age range, 22-49 years), to explore differentially expressed genes between the young (age <40 years) and older (age 40-49 years) patients. Unsupervised hierarchical clustering was applied to identify gene expression-based patient clusters. We applied established computational approaches to define the PAM50 subtypes, risk of recurrence scores (ROR), and risk groups and to infer the proportions of 22 immune cell types from bulk gene expression profiles of patients aged <50 years at BC diagnosis. Differentially expressed genes and gene sets were investigated using OncoEnrichR and g:Profiler to describe functional profiles and pathway enrichment. We identified 4 age-related patient clusters presenting distinct characteristics of PAM50 subtypes and ROR profiles, which demonstrated independent prognostic value when adjusted for traditional clinicopathologic variables and the known molecular subtypes. Our findings showed better survival than expected in the basal-enriched cluster 2 and in triple-negative and basal-like BC. Deconvolution analyses of immunophenotypes indicated higher levels of M0 and M1 macrophages than M2 macrophages in subsets of young BC. Our approach identifies age-based patient clusters with distinct clinicopathologic profiles, to a large extent overlapping with the PAM50 subtypes, although with independent prognostic values in multivariate survival analyses. The patient clusters provided new insight in the immune cell distribution across tumor subtypes, potentially contributing to survival differences between the clusters and the molecular subtypes and indicating age-related mechanisms improving outcome. Our study confirms the applicability of ROR as a valid prognosticator also in a young BC cohort.

Heart proteomic profiling discovers MYH6 and COX5B as biomarkers for sudden unexplained death

Sudden unexplained death (SUD) is not uncommon in forensic pathology. Yet, diagnosis of SUD remains challenging due to lack of specific biomarkers. This study aimed to screen differentially expressed proteins (DEPs) and validate their usefulness as diagnostic biomarkers for SUD cases. We designed a three-phase investigation, where in the discovery phase, formalin-fixed paraffin-embedded (FFPE) heart specimens were screened through label-free proteomic analysis of cases dying from SUD, mechanical injury and carbon monoxide (CO) intoxication. A total of 26 proteins were identified to be DEPs for the SUD cases after rigorous criterion. Bioinformatics and Adaboost-recursive feature elimination (RFE) analysis further revealed that three of the 26 proteins (MYH6, COX5B and TNNT2) were potential discriminative biomarkers. In the training phase, MYH6 and COX5B were verified to be true DEPs in cardiac tissues from 29 independent SUD cases as compared with a serial of control cases (n = 42). Receiver operating characteristic (ROC) analysis illustrated that combination of MYH6 and COX5B achieved optimal diagnostic sensitivity (89.7 %) and specificity (84.4 %), with area under the curve (AUC) being 0.91. A diagnostic software based on the logistic regression formula derived from the training phase was then constructed. In the validation phase, the diagnostic software was applied to eight authentic SUD cases, seven (87.5 %) of which were accurately recognized. Our study provides a valid strategy towards practical diagnosis of SUD by integrating cardiac MYH6 and COX5B as dual diagnostic biomarkers.

Genome-scale mutational signature analysis in archived fixed tissues

Mutation spectra and mutational signatures in cancerous and non-cancerous tissues can be identified by various established techniques of massively parallel sequencing (or next-generation sequencing) including whole-exome or whole-genome sequencing, and more recently by error-corrected/duplex sequencing. One rather underexplored area has been the genome-scale analysis of mutational signatures as markers of mutagenic exposures, and their impact on cancer driver events applied to formalin-fixed or alcohol-fixed paraffin embedded archived biospecimens. This review showcases successful applications of the next-generation sequencing methodologies in archived fixed tissues, including the delineation of the specific tissue fixation-related DNA damage manifesting as artifactual signatures, distinguishable from the true signatures that arise from biological mutagenic processes. Overall, we discuss and demonstrate how next-generation sequencing techniques applied to archived fixed biospecimens can enhance our understanding of cancer causes including mutagenic effects of extrinsic cancer risk agents, and the implications for prevention efforts aimed at reducing avoidable cancer-causing exposures.

Consensus Guidelines on Human Epidermal Growth Factor Receptor 2 (HER2)-Low Testing in Breast Cancer in Malaysia

Breast cancer is one of the most common cancers in Malaysia. Recently, a new nomenclature was introduced for breast cancers with human epidermal growth factor receptor 2 (HER2) immunohistochemistry (IHC) 1+, or 2+ with negative in situ hybridization (ISH), i.e., HER2-low breast cancer. In current clinical practice, these breast cancers are reported as HER2-negative. Clinical trials have shown that HER2-low breast cancer benefits from targeted therapy with anti-HER2 antibody-drug conjugates. Unfortunately, various challenges and obstacles are faced by local pathologists in HER2 testing, which may jeopardize the standard of care for patients with HER2-low breast cancer. This consensus guideline aims to elucidate standard practices pertaining to HER2 testing and HER2-low interpretation in Malaysia. Topics discussed among a panel of local experts include tissue sampling and handling, assay and antibody selection, result interpretation and reporting, and quality assurance. Practice recommendations made in this consensus guideline reflect current international guidelines and, where appropriate, adapted to the Malaysian landscape.

Predictive molecular pathology after prolonged fixation: A study on tissue from anatomical body donors

Histopathological assessment of tissue samples after prolonged formalin fixation has been described previously, but currently there is only limited knowledge regarding the feasibility of molecular pathology on such tissue. In this pilot study, we tested routine molecular pathology methods (DNA isolation, DNA pyrosequencing/next-generation sequencing, DNA methylation analysis, RT-PCR, clonality analysis and fluorescence in situ hybridization) on tissue samples from 11 tumor entities as well as non-neoplastic brain tissue from 43 body donors during the gross anatomy course at Ulm University (winter semester 2019/20 and 2020/21). The mean post mortem interval until fixation was 2.5 ± 1.6 days (range, 1-6 days). Fixation was performed with aqueous formaldehyde solution (formalin, 1.5-2%). The mean storage time of body donors was 12.8 ± 5.6 months (range, 7-25 months). While most diagnostic methods were successful, samples showed significant variability in DNA quality and evaluability. DNA pyrosequencing as well as next-generation sequencing was successful in all investigated samples. Methylation analyses were partially not successful in some extend due to limited intact DNA yield for these analyses. Taken together, the use of prolonged formalin-fixed tissue samples from body donors offers new avenues in research and education, as these samples could be used for morpho-molecular studies and the establishment of biobanks, especially for tissue types that cannot be preserved and studied in vivo. Pathological ward rounds, sample collection, and histopathological and molecular workup have been integrated in the gross anatomy course in Ulm as an integral part of the curriculum, linking anatomy and pathology and providing medical students early insight into the broad field of (molecular) pathology.

Molecular Methods: Clinical Utilization and Designing a Test Menu

Pre-analytical factors in molecular oncology diagnostics are reviewed. Issues around sample collection, storage, and transport that might affect the stability of nucleic acids and the ability to perform molecular testing are addressed. In addition, molecular methods used commonly in clinical diagnostic laboratories, including newer technologies such as next-generation sequencing and digital droplet polymerase chain reaction, as well as their applications, are reviewed. Finally, we discuss considerations in designing a molecular test menu to deliver accurate and timely results in an efficient and cost-effective manner.

Double Chromogen-based Immunohistochemical Staining: An Efficient Approach for Utilizing Long-term Formalin-fixed Tissue in Biobanks

The New South Wales Brain Tissue Resource Centre is a human brain bank that provides top-quality brain tissue for cutting-edge neuroscience research spanning various conditions from alcohol use disorder to neurodegenerative diseases. However, the conventional practice of preserving brain tissue in formalin poses challenges for immunofluorescent staining primarily due to the formalin's tendency, over time, to create cross-links between antigens, which can obscure epitopes of interest. In addition, researchers can encounter issues such as spectral bleeding, limitations in using multiple colors, autofluorescence, and cross-reactivity when working with long-term formalin-fixed brain tissue. The purpose of the study was to test chromogen-based double immunolabeling to negate the issues with immunofluorescent staining. Colocalization of antigens was explored using chromogens 3-amino-9-ethylcarbazole (AEC) and 3,3,-diaminobenzidine in a sequential staining procedure where the AEC signal was eliminated by alcohol treatment. Combinations of 2 or 3 primary antibodies from the same or different species were trialed successfully with this protocol. The colocalization of antigens was also demonstrated with pseudocoloring that mimicked immunofluorescence staining. This staining technique increases the utility of archival formalin-fixed tissue samples.

Optimized whole-genome sequencing workflow for tumor diagnostics in routine pathology practice

Two decades after the genomics revolution, oncology is rapidly transforming into a genome-driven discipline, yet routine cancer diagnostics is still mainly microscopy based, except for tumor type-specific predictive molecular tests. Pathology laboratories struggle to quickly validate and adopt biomarkers identified by genomics studies of new targeted therapies. Consequently, clinical implementation of newly approved biomarkers suffers substantial delays, leading to unequal patient access to these therapies. Whole-genome sequencing (WGS) can successfully address these challenges by providing a stable molecular diagnostic platform that allows detection of a multitude of genomic alterations in a single cost-efficient assay and facilitating rapid implementation, as well as by the development of new genomic biomarkers. Recently, the Whole-genome sequencing Implementation in standard Diagnostics for Every cancer patient (WIDE) study demonstrated that WGS is a feasible and clinically valid technique in routine clinical practice with a turnaround time of 11 workdays. As a result, WGS was successfully implemented at the Netherlands Cancer Institute as part of routine diagnostics in January 2021. The success of implementing WGS has relied on adhering to a comprehensive protocol including recording patient information, sample collection, shipment and storage logistics, sequencing data interpretation and reporting, integration into clinical decision-making and data usage. This protocol describes the use of fresh-frozen samples that are necessary for WGS but can be challenging to implement in pathology laboratories accustomed to using formalin-fixed paraffin-embedded samples. In addition, the protocol outlines key considerations to guide uptake of WGS in routine clinical care in hospitals worldwide.

Quantitative assessment of H&E staining for pathology: development and clinical evaluation of a novel system

BACKGROUND

Staining tissue samples to visualise cellular detail and tissue structure is at the core of pathology diagnosis, but variations in staining can result in significantly different appearances of the tissue sample. While the human visual system is adept at compensating for stain variation, with the growth of digital imaging in pathology, the impact of this variation can be more profound. Despite the ubiquity of haematoxylin and eosin staining in clinical practice worldwide, objective quantification is not yet available. We propose a method for quantitative haematoxylin and eosin stain assessment to facilitate quality assurance of histopathology staining, enabling truly quantitative quality control and improved standardisation.

METHODS

The stain quantification method comprises conventional microscope slides with a stain-responsive biopolymer film affixed to one side, called stain assessment slides. The stain assessment slides were characterised with haematoxylin and eosin, and implemented in one clinical laboratory to quantify variation levels.

RESULTS

Stain assessment slide stain uptake increased linearly with duration of haematoxylin and eosin staining (r = 0.99), and demonstrated linearly comparable staining to samples of human liver tissue (r values 0.98-0.99). Laboratory implementation of this technique quantified intra- and inter-instrument variation of staining instruments at one point in time and across a five-day period.

CONCLUSION

The proposed method has been shown to reliably quantify stain uptake, providing an effective laboratory quality control method for stain variation. This is especially important for whole slide imaging and the future development of artificial intelligence in digital pathology.

P53 loss of heterozygosity (LOH) in formalin-fixed paraffin-embedded leiomyosarcoma (LMS): a novel report

BACKGROUND

The occurrence of p53 loss of heterozygosity (LOH) is a common genetic event in malignancy. LOH occurs when a heterozygous locus loses one of its two parental alleles, becoming homozygous at that locus, by either copy number loss (CNL-LOH) or by becoming copy number neutral (CNN-LOH). A role for CNL-LOH (cnLOH) has been postulated in cancer aetiology. Loss of heterozygosity (LOH) results in irreversible genetic loss.

AIMS

LOH was determined in DNA extracted from formalin-fixed paraffin-embedded (FFPE) leiomyosarcoma (LMS) specimens in a retrospective study from 30 patients, to assess the prognostic significance of LOH. The findings were analysed and their validity assessed. LOH was an adverse prognostic factor in LMS. Prospective uniform standardisation of formalin-fixation techniques is required.

METHODS

DNA was extracted from 169 formalin-fixed paraffin blocks of 30 patients with LMS, following extensive tissue microdissection. Genomic DNA was amplified using the polymerase chain reaction (PCR) technique. Fluorescence-based microsatellite PCR was used to detect and quantitate heterozygosity loss.

RESULTS

LOH was detected at gene locus 17p13 in 16 LMS (Four grade 2 and 12 grade 3 LMS). LOH was not detected in 14 LMS cases (one grade 1, five grade 2 and eight grade 3 LMS). LOH was associated with shorter patient survival.

CONCLUSIONS

The results reported herein endorse the value of utilizing FFPE DNA in identifying LOH as a prognostic factor in LMS. The results have implications for tumour biobanking and precision medicine in patients with sarcomas.

Optimizing tissue stewardship in non-small cell lung cancer to support molecular characterization and treatment selection: statement from a working group of thoracic pathologists

Many patients with non-small cell lung cancer do not receive guideline-recommended, biomarker-directed therapy, despite the potential for improved clinical outcomes. Access to timely, accurate, and comprehensive molecular profiling, including targetable protein overexpression, is essential to allow fully informed treatment decisions to be taken. In turn, this requires optimal tissue management to protect and maximize the use of this precious finite resource. Here, a group of leading thoracic pathologists recommend factors to consider for optimal tissue management. Starting from when lung cancer is first suspected, keeping predictive biomarker testing in the front of the mind should drive the development of practices and procedures that conserve tissue appropriately to support molecular characterization and treatment selection.

Colocalization of β-Sheets and Carotenoids in Aβ Plaques Revealed with Multimodal Spatially Resolved Vibrational Spectroscopy

The aggregation of amyloid β(Aβ) peptides is at the heart of Alzheimer's disease development and progression. As a result, amyloid aggregates have been studied extensively in vitro, and detailed structural information on fibrillar amyloid aggregates is available. However, forwarding these structural models to amyloid plaques in the human brain is still a major challenge. The chemistry of amyloid plaques, particularly in terms of the protein secondary structure and associated chemical moieties, remains poorly understood. In this report, we use Raman microspectroscopy to identify the presence of carotenoids in amyloid plaques and demonstrate that the abundance of carotenoids is correlated with the overall protein secondary structure of plaques, specifically to the population of β-sheets. While the association of carotenoids with plaques has been previously identified, their correlation with the β structure has never been identified. To further validate these findings, we have used optical photothermal infrared (O-PTIR) spectroscopy, which is a spatially resolved technique that yields complementary infrared contrast to Raman. O-PTIR unequivocally demonstrates the presence of elevated β-sheets in carotenoid-containing plaques and the lack of β structure in noncarotenoid plaques. Our findings underscore the potential link between anti-inflammatory species as carotenoids to specific secondary structural motifs within Aβ plaques and highlight the possible role of chemically distinct plaques in neuroinflammation, which can uncover new mechanistic insights and lead to new therapeutic strategies for AD.

ApoER2-Dab1 disruption as the origin of pTau-associated neurodegeneration in sporadic Alzheimer's disease

In sporadic Alzheimer's disease (sAD) specific regions, layers and neurons accumulate hyperphosphorylated Tau (pTau) and degenerate early while others remain unaffected even in advanced disease. ApoER2-Dab1 signaling suppresses Tau phosphorylation as part of a four-arm pathway that regulates lipoprotein internalization and the integrity of actin, microtubules, and synapses; however, the role of this pathway in sAD pathogenesis is not fully understood. We previously showed that multiple ApoER2-Dab1 pathway components including ApoE, Reelin, ApoER2, Dab1, pP85αTyr607, pLIMK1Thr508, pTauSer202/Thr205 and pPSD95Thr19 accumulate together within entorhinal-hippocampal terminal zones in sAD, and proposed a unifying hypothesis wherein disruption of this pathway underlies multiple aspects of sAD pathogenesis. However, it is not yet known whether ApoER2-Dab1 disruption can help explain the origin(s) and early progression of pTau pathology in sAD. In the present study, we applied in situ hybridization and immunohistochemistry (IHC) to characterize ApoER2 expression and accumulation of ApoER2-Dab1 pathway components in five regions known to develop early pTau pathology in 64 rapidly autopsied cases spanning the clinicopathological spectrum of sAD. We found that (1) these selectively vulnerable neuron populations strongly express ApoER2; and (2) multiple ApoER2-Dab1 components representing all four arms of this pathway accumulate in abnormal neurons and neuritic plaques in mild cognitive impairment (MCI) and sAD cases and correlate with histological progression and cognitive deficits. Multiplex-IHC revealed that Dab1, pP85αTyr607, pLIMK1Thr508, pTauSer202/Thr205 and pPSD95Thr19 accumulate together within many of the same ApoER2-expressing neurons and in the immediate vicinity of ApoE/ApoJ-enriched extracellular plaques. Collective findings reveal that pTau is only one of many ApoER2-Dab1 pathway components that accumulate in multiple neuroanatomical sites in the earliest stages of sAD and provide support for the concept that ApoER2-Dab1 disruption drives pTau-associated neurodegeneration in human sAD.

Utility of Retrospective Molecular Analysis in Diagnostically Challenging Mesenchymal Neoplasms

Introduction: Molecular analysis plays a growing role in the diagnosis of mesenchymal neoplasms. The aim of this study was to retrospectively apply broad, multiplex molecular assays (a solid tumor targeted next-generation sequencing [NGS]) assay and single nucleotide polymorphism [SNP] microarray) to selected tumors, exploring the current utility and limitations. Methods: We searched our database (2010-2020) for diagnostically challenging mesenchymal neoplasms. After histologic review of available slides, tissue blocks were selected for NGS, SNP microarray, or both. DNA and RNA were extracted using the AllPrep DNA/RNA FFPE Kit Protocol on the QIAcube instrument. The NGS platform used was the TruSight Tumor 170 (TST-170). For SNP array, copy number variant (CNV) analysis was performed using the OncoScanTM CNV Plus Assay. Results: DNA/RNA was successfully extracted from 50% of tumors (n = 10/20). Specimens not successfully extracted included 6 core biopsies, 3 incisional biopsies, and 1 resection; 4 were decalcified (3 hydrochloric acid, 1 ethylenediaminetetraacetic acid). Higher tumor proportion and number of tumor cells were parameters positively associated with sufficient DNA/RNA extraction whereas necrosis and decalcification were negatively associated with sufficient extraction. Molecular testing helped reach a definitive diagnosis in 50% of tumors (n = 5/10). Conclusions: Although the overall utility of this approach is limited, these molecular panels can be helpful in detecting a specific "driver" alteration.

A New Medium (HistoCold) for Surgical Specimens Preserving to Improve the Preanalytic Issues in Histopathological Samples Handling: Morphologic and Antigenic Analysis

Introduction: The onset of precision medicine has led to the integration of traditional morphologic tissues evaluation with biochemical and molecular data for a more appropriate pathological diagnosis. The preanalytic phase and, particularly, timing of cold ischemia are crucial to guarantee high-quality biorepositories of formalin-fixed paraffin-embedded (FFPE) tissues for patients' needs and scientific research. However, delayed fixation using the gold-standard and carcinogenic fixative neutral-buffered formalin (NBF) can be a significant limitation to diagnosis and biopathological characterization. HistoCold (patented; Bio-Optica Milano S.p.A., Milano, Italy) is a nontoxic, stable, and refrigerated preservative solution for tissue handling. This study examined HistoCold's potential role in improving the preanalytic phase of the pathological diagnostic process. Materials and Methods: Breast, lung, or colorectal cancers (20, 25, and 10 cases, respectively) that were to be surgically resected were recruited between 2019 and 2021. Once specimens were surgically removed, three residual samples for each patient were first promptly immersed into HistoCold for 24, 48, and 72 hours and then FFPE. These were compared with routine specimens regarding morphologic features (hematoxylin and eosin) and tissue antigenicity (immunohistochemical stains). Results: Good concordance regarding both the morphologic characteristics of the neoplasms and their proteins expression between the routine and HistoCold handled tissues were found. The tissue handling with the solution never affected the histopathological diagnosis. Conclusions: The use of HistoCold for samples transporting is easy, allows for improving the management of cold ischemia time, and monitoring the fixation times in NBF, resulting in good quality tissue blocks for biobanking. Moreover, it could be a candidate to eliminate formalin from operating theaters. HistoCold looks very promising for the preanalytic phase of human tissues handling in the era of precision medicine, to provide the best service to patients, and to scientific research.

Expansion of CD4+ cytotoxic T lymphocytes with specific gene expression patterns may contribute to suppression of tumor immunity in oral squamous cell carcinoma: single-cell analysis and in vitro experiments

Background

Cancer immunotherapy targeting CD8+ T cells has made remarkable progress, even for oral squamous cell carcinoma (OSCC), a heterogeneous epithelial tumor without a substantial increase in the overall survival rate over the past decade. However, the therapeutic effects remain limited due to therapy resistance. Thus, a more comprehensive understanding of the roles of CD4+ T cells and B cells is crucial for more robust development of cancer immunotherapy.

Methods

In this study, we examined immune responses and effector functions of CD4+ T cells, CD8+ T cells and B cells infiltrating in OSCC lesions using single-cell RNA sequencing analysis, T cell receptor (TCR) and B cell receptor (BCR) repertoire sequencing analysis, and multi-color immunofluorescence staining. Finally, two Kaplan-Meier curves and several Cox proportional hazards models were constructed for the survival analysis.

Results

We observed expansion of CD4+ cytotoxic T lymphocytes (CTLs) expressing granzymes, which are reported to induce cell apoptosis, with a unique gene expression patterns. CD4+ CTLs also expressed CXCL13, which is a B cell chemoattractant. Cell-cell communication analysis and multi-color immunofluorescence staining demonstrated potential interactions between CD4+ CTLs and B cells, particularly IgD- CD27- double negative (DN) B cells. Expansion of CD4+ CTLs, DN B cells, and their contacts has been reported in T and B cell-activated diseases, including IgG4-related disease and COVID-19. Notably, we observed upregulation of several inhibitory receptor genes including CTLA-4 in CD4+ CTLs, which possibly dampened T and B cell activity. We next demonstrated comprehensive delineation of the potential for CD8+ T cell differentiation towards dysfunctional states. Furthermore, prognostic analysis revealed unfavorable outcomes of patients with a high proportion of CD4+ CTLs in OSCC lesions.

Conclusion

Our study provides a dynamic landscape of lymphocytes and demonstrates a systemic investigation of CD4+ CTL effects infiltrating into OSCC lesions, which may share some pathogenesis reported in severe T and B cell-activated diseases such as autoimmune and infectious diseases.

Routine Workflow of Spatial Proteomics on Micro-formalin-Fixed Paraffin-Embedded Tissues

In the era of single-cell biology, spatial proteomics has emerged as an important frontier. However, it still faces several challenges in technology. Formalin-fixed paraffin-embedded (FFPE) tissues are an important material in spatial proteomics, in which fixed tissues are excised using laser capture microdissection (LCM), followed by protein identification with mass spectrometry. For a satisfied spatial proteomics upon FFPE tissues, the excision area is expected to be as small as possible, and the identified proteins are countered upon as much as possible. For a general laboratory for spatial proteomics, a routine workflow is required, not relying on any special device, and is easily operating. In view of these challenges in technology, we initiated a technology evaluation throughout the entire procedure of proteomic analysis with micro-FFPE tissues. In contrast to the protocols reported previously, several innovations in technology were proposed and conducted, such as removal of destaining, decross-linking with "hang-down", solution simplification for peptide generation and balancing to excision area, and capture rate of micro-FFPE tissues. After optimization of all the necessary steps, a routine workflow was established, in which the minimized area for protein identification was 0.002 mm2, while the excision area for a consistent proteomic analysis was 0.05 mm2. Using the developed workflow and collecting the micro-FFPE tissues continuously, for the first time, a spatial proteomic atlas of mouse brain was preliminarily constructed, which exhibited the typical characteristics of spatial-dependent protein abundance and functional enrichment.

Impact of formalin fixation on mismatch repair protein evaluation by immunohistochemistry

Mismatch repair/microsatellite instability (MMR/MSI) status in colorectal cancer (CRC) has become fundamental as a diagnostic, prognostic, and predictive factor. MMR immunohistochemistry (IHC) is considered a simple and reliable approach; however, its effectiveness depends on pre-analytic factors. Aim of this study was to investigate the impact of different fixation times/protocols on MMR protein IHC quality. Left over tissue from surgically resected CRC samples (cold ischemia time < 30 min) where fixed as follows: standard formalin fixation (24-48 h); hypo-fixation (<20 h); hyper-fixation (>90 h); cold (4°C) fixation (24-48 h); standard fixation for small sample size (0.5×0.5 cm). Samples for each group were collected from 30 resected CRC and the following parameters were evaluated on 600 immunohistochemical stains: intensity of expression; patchiness of staining; presence of central artefact. Forty-six immunoreactions were inadequate (score 0 intensity), the majority regarding MLH1 or PMS2 in the hypo-fixation group (47.8%), followed by the hyper-fixation group (28.1%); cold formalin fixation showed the least inadequate cases. Patchiness and central artefact were more frequent in hypo-fixation and standard fixation group compared to the others. MLH1 (closely followed by PMS2) performed worse with regard to immunostaining intensity (p=0.0002) in the standard and in the hypo-fixation group (p< 0.00001). Using a small sample size improved patchiness/central artefacts. This is the first study specifically created to evaluate the impact of fixation on MMR protein IHC, showing that both formalin hypo- and hyper-fixation can cause problems; 24-h formalin fixation as well as cold (4°C) formalin fixation are recommended for successful IHC MMR evaluation.

Improving the identification and diagnostic efficiency of Metagenomic Next-Generation Sequencing for mycobacterial granuloma on postoperative formalin-fixed paraffin-embedded specimens

OBJECTIVE

Metagenomic Next-Generation Sequencing (mNGS) has been validated to have an important role in the diagnosis of mycobacterium infection. The study aimed to further explore the mycobacteria identification ability of mNGS on formalin-fixed paraffin-embedded（FFPE）tissues from postoperative specimens.

METHODS

Patients who underwent surgical biopsy or resection for clarifying the diagnosis and whose initial postoperative pathology indicated granulomatous lesions were included. Fresh tissues were sent for mycobacterium culture and Xpert MTB/RIF (Xpert) to establish the diagnosis. FFPE specimens were sent for mNGS and molecular pathology，the diagnostic values were compared between the two methods.

RESULTS

A total of 65 cases with definite diagnoses were finally included in the study. 31 cases were confirmed as mycobacterium granuloma using the fresh specimen etiology as diagnostic criteria. The overall sensitivity and specificity of mNGS on FFPE specimens in the diagnosis of mycobacterium granuloma were 100% and 88.24%, respectively. In 19 cases diagnosed as tuberculous granulomas, the sensitivity (100% vs47.37%) and negative predictive value (NPV, 100%vs 82.14%) of mNGS were both significantly higher than that of molecular pathology on the FFPE section（both p 0.00）while the positive predictive value (PPV) and specificity were not significantly different. In 12 cases diagnosed as Non-tuberculous mycobacterium (NTM）granuloma, the sensitivity of mNGS was also significantly higher than that of molecular pathology on FFPE section (100% vs 66.67%, p 0.00) while the specificity, PPV and NPV were all not significantly different.

CONCLUSIONS

The mNGS could be used for one-time detection of pathogens on FFPE sections with high sensitivity. It could be recommended as a supplementary method for the identification of pathogenic bacteria in the diagnosis of postoperative granuloma lesions.

Low-melting point agarose as embedding medium for MALDI mass spectrometry imaging and laser-capture microdissection-based proteomics

The combination of MALDI mass spectrometry imaging, laser-capture microdissection, and quantitative proteomics allows the identification and characterization of molecularly distinct tissue compartments. Such workflows are typically performed using consecutive tissue sections, and so reliable sectioning and mounting of high-quality tissue sections is a prerequisite of such investigations. Embedding media facilitate the sectioning process but can introduce contaminants which may adversely affect either the mass spectrometry imaging or proteomics analyses. Seven low-temperature embedding media were tested in terms of embedding temperature and cutting performance. The two media that provided the best results (5% gelatin and 2% low-melting point agarose) were compared with non-embedded tissue by both MALDI mass spectrometry imaging of lipids and laser-capture microdissection followed by bottom-up proteomics. Two out of the seven tested media (5% gelatin and 2% low-melting point agarose) provided the best performances on terms of mechanical properties. These media allowed for low-temperature embedding and for the collection of high-quality consecutive sections. Comparisons with non-embedded tissues revealed that both embedding media had no discernable effect on proteomics analysis; 5% gelatin showed a light ion suppression effect in the MALDI mass spectrometry imaging experiments, 2% agarose performed similarly to the non-embedded tissue. 2% low-melting point agarose is proposed for tissue embedding in experiments involving MALDI mass spectrometry imaging of lipids and laser-capture microdissection, proteomics of consecutive tissue sections.

Quantitative analysis of lncRNA in formalin-fixed paraffin-embedded tissues of oral squamous cell carcinoma

The study evaluated expression profiles of few regulatory lncRNAs in oral squamous cell carcinoma and normal mucosa adjacent to oral cancer using paired fresh frozen and formalin-fixed paraffin-embedded (FFPE) tissues stored at a different duration of time (1-5 years) using real-time quantitative PCR. The quantity and quality of total RNA isolated from FFPE tissues was less compared with that of fresh frozen tissues, which resulted in a noncorrelation of quantification cycle values. Following normalization, the expression of lncRNAs in the paired tissues did not differ significantly. The differential expression of the lncRNAs in the study was consistent with The Cancer Genome Atlas head and neck squamous cell carcinoma database. The study findings demonstrate the possibility of performing accurate quantitative analysis of lncRNAs using short amplicons and standardized real-time quantitative PCR assays in oral squamous cell carcinoma FFPE samples.

Formalin Fixation, Delay to Fixation, and Time in Fixative Adversely Impact Copy Number Variation Analysis by aCGH

Although molecular profiling of DNA isolated from formalin-fixed, paraffin-embedded (FFPE) tumor specimens has become more common in recent years, it remains unclear how discrete FFPE processing variables may affect detection of copy number variation (CNV). To better understand such effects, array comparative genomic hybridization (aCGH) profiles of FFPE renal cell carcinoma specimens that experienced different delays to fixation (DTFs; 1, 2, 3, and 12 hours) and times in fixative (TIFs; 6, 12, 23, and 72 hours) were compared to snap-frozen tumor and blood specimens from the same patients. A greater number of regions containing CNVs relative to commercial reference DNA were detected in DNA from FFPE tumor specimens than snap-frozen tumor specimens even though they originated from the same tumor blocks. Extended DTF and TIF affected the number of DNA segments with a copy number status that differed between FFPE and frozen tumor specimens; a DTF ≥3 hours led to more segments, while a TIF of 72 hours led to fewer segments. Importantly, effects were not random as a higher guanine-cytosine (GC) content and/or a higher percentage of repeats were observed among stable regions. While limiting aCGH analysis to FFPE specimens with a DTF <3 hours and a TIF <72 hours may circumvent some effects, results from FFPE specimens should be validated against fresh or frozen specimens whenever possible.

The quality of DNA isolated from autopsy formalin-fixed and formalin-fixed paraffin-embedded tissues: study of 1662 samples

BACKGROUND

There are enormous formalin-fixed paraffin-embedded tissue archives and a constantly growing number of methods for molecular analyses but, the isolation of DNA from this tissue is still challenging due to the damaging effect of formalin on DNA. To determine the extent to which DNA purity, yield and integrity depend on the process of fixation in formalin, and to what extent on the process of tissue paraffin embedding, we compared the quality of DNA isolated from fixed tissues and DNA isolated from tissues embedded in paraffin blocks after fixation.

METHODS AND RESULTS

Heart, liver and brain tissues obtained from healthy people who suddenly died a violent death were fixed in 10% buffered formalin as well as in 4% unbuffered formalin for 6 h, 1-7 days (every 24 h), 10, 14, 28 days and 2 months. Additionally, the same tissues were fixed in 4% unbuffered formalin embedded in a paraffin block and stored from a few months to 30 years. The yield and purity of the DNA samples isolated from these tissues were measured using spectrophotometry. PCR amplification of the hTERT gene was performed to evaluate the degree of DNA fragmentation. Although the purity of the DNA isolated from almost all tissue samples was satisfactory, the DNA yields changed significantly. There was a decrease in successful PCR amplification of the hTERT gene in DNA samples isolated from tissue fixed in buffered and unbuffered formalin for up to 2 months from 100% to 8.3%. Archiving the tissue in paraffin blocks for up to 30 years also impacts the integrity of DNA, so there was a decrease in PCR amplification of the hTERT gene from 91% success to 3%.

CONCLUSION

The largest decrease in DNA yield was observed after tissue formalin fixation after 14 days of fixation in buffered and unbuffered formalin. DNA integrity depends on the time of tissue formalin fixation, especially after 6 days for tissue fixed in unbuffered formalin, while for tissue fixed in buffered formalin the time is prolonged up to 28 days. The age of paraffin blocks also impacted DNA integrity, after 1 year and 16 years of archiving the paraffin blocks of tissues, there was a decrease in the success of PCR amplification.

Segmentation of human functional tissue units in support of a Human Reference Atlas

The Human BioMolecular Atlas Program (HuBMAP) aims to compile a Human Reference Atlas (HRA) for the healthy adult body at the cellular level. Functional tissue units (FTUs), relevant for HRA construction, are of pathobiological significance. Manual segmentation of FTUs does not scale; highly accurate and performant, open-source machine-learning algorithms are needed. We designed and hosted a Kaggle competition that focused on development of such algorithms and 1200 teams from 60 countries participated. We present the competition outcomes and an expanded analysis of the winning algorithms on additional kidney and colon tissue data, and conduct a pilot study to understand spatial location and density of FTUs across the kidney. The top algorithm from the competition, Tom, outperforms other algorithms in the expanded study, while using fewer computational resources. Tom was added to the HuBMAP infrastructure to run kidney FTU segmentation at scale-showcasing the value of Kaggle competitions for advancing research.

ApoER2-Dab1 disruption as the origin of pTau-related neurodegeneration in sporadic Alzheimer's disease

BACKGROUND

Sporadic Alzheimer's disease (sAD) is not a global brain disease. Specific regions, layers and neurons degenerate early while others remain untouched even in advanced disease. The prevailing model used to explain this selective neurodegeneration-prion-like Tau spread-has key limitations and is not easily integrated with other defining sAD features. Instead, we propose that in humans Tau hyperphosphorylation occurs locally via disruption in ApoER2-Dab1 signaling and thus the presence of ApoER2 in neuronal membranes confers vulnerability to degeneration. Further, we propose that disruption of the Reelin/ApoE/ApoJ-ApoER2-Dab1-P85α-LIMK1-Tau-PSD95 (RAAAD-P-LTP) pathway induces deficits in memory and cognition by impeding neuronal lipoprotein internalization and destabilizing actin, microtubules, and synapses. This new model is based in part on our recent finding that ApoER2-Dab1 disruption is evident in entorhinal-hippocampal terminal zones in sAD. Here, we hypothesized that neurons that degenerate in the earliest stages of sAD (1) strongly express ApoER2 and (2) show evidence of ApoER2-Dab1 disruption through co-accumulation of multiple RAAAD-P-LTP components.

METHODS

We applied in situ hybridization and immunohistochemistry to characterize ApoER2 expression and accumulation of RAAAD-P-LTP components in five regions that are prone to early pTau pathology in 64 rapidly autopsied cases spanning the clinicopathological spectrum of sAD.

RESULTS

We found that: (1) selectively vulnerable neuron populations strongly express ApoER2; (2) numerous RAAAD-P-LTP pathway components accumulate in neuritic plaques and abnormal neurons; and (3) RAAAD-P-LTP components were higher in MCI and sAD cases and correlated with histological progression and cognitive deficits. Multiplex-IHC revealed that Dab1, pP85αTyr607, pLIMK1Thr508, pTau and pPSD95Thr19 accumulated together within dystrophic dendrites and soma of ApoER2-expressing neurons in the vicinity of ApoE/ApoJ-enriched extracellular plaques. These observations provide evidence for molecular derangements that can be traced back to ApoER2-Dab1 disruption, in each of the sampled regions, layers, and neuron populations that are prone to early pTau pathology.

CONCLUSION

Findings support the RAAAD-P-LTP hypothesis, a unifying model that implicates dendritic ApoER2-Dab1 disruption as the major driver of both pTau accumulation and neurodegeneration in sAD. This model provides a new conceptual framework to explain why specific neurons degenerate and identifies RAAAD-P-LTP pathway components as potential mechanism-based biomarkers and therapeutic targets for sAD.

ApoER2-Dab1 disruption as the origin of pTau-related neurodegeneration in sporadic Alzheimer's disease

BACKGROUND

Sporadic Alzheimer's disease (sAD) is not a global brain disease. Specific regions, layers and neurons degenerate early while others remain untouched even in advanced disease. The prevailing model used to explain this selective neurodegeneration-prion-like Tau spread-has key limitations and is not easily integrated with other defining sAD features. Instead, we propose that in humans Tau hyperphosphorylation occurs locally via disruption in ApoER2-Dab1 signaling and thus the presence of ApoER2 in neuronal membranes confers vulnerability to degeneration. Further, we propose that disruption of the Reelin/ApoE/ApoJ-ApoER2-Dab1-P85α-LIMK1-Tau-PSD95 (RAAAD-P-LTP) pathway induces deficits in memory and cognition by impeding neuronal lipoprotein internalization and destabilizing actin, microtubules, and synapses. This new model is based in part on our recent finding that ApoER2-Dab1 disruption is evident in entorhinal-hippocampal terminal zones in sAD. Here, we hypothesized that neurons that degenerate in the earliest stages of sAD (1) strongly express ApoER2 and (2) show evidence of ApoER2-Dab1 disruption through co-accumulation of multiple RAAAD-P-LTP components.

METHODS

We applied in situ hybridization and immunohistochemistry to characterize ApoER2 expression and accumulation of RAAAD-P-LTP components in five regions that are prone to early pTau pathology in 64 rapidly autopsied cases spanning the clinicopathological spectrum of sAD.

RESULTS

We found that: (1) selectively vulnerable neuron populations strongly express ApoER2; (2) numerous RAAAD-P-LTP pathway components accumulate in neuritic plaques and abnormal neurons; and (3) RAAAD-P-LTP components were higher in MCI and sAD cases and correlated with histological progression and cognitive deficits. Multiplex-IHC revealed that Dab1, pP85αTyr607, pLIMK1Thr508, pTau and pPSD95Thr19 accumulated together within dystrophic dendrites and soma of ApoER2-expressing neurons in the vicinity of ApoE/ApoJ-enriched extracellular plaques. These observations provide evidence for molecular derangements that can be traced back to ApoER2-Dab1 disruption, in each of the sampled regions, layers, and neuron populations that are prone to early pTau pathology.

CONCLUSION

Findings support the RAAAD-P-LTP hypothesis, a unifying model that implicates dendritic ApoER2-Dab1 disruption as the major driver of both pTau accumulation and neurodegeneration in sAD. This model provides a new conceptual framework to explain why specific neurons degenerate and identifies RAAAD-P-LTP pathway components as potential mechanism-based biomarkers and therapeutic targets for sAD.

Multi-Gene Next-Generation Sequencing Panel for Analysis of BRCA1/BRCA2 and Homologous Recombination Repair Genes Alterations Metastatic Castration-Resistant Prostate Cancer

Despite significant therapeutic advances, metastatic CRPC (mCRPC) remains a lethal disease. Mutations in homologous recombination repair (HRR) genes are frequent in mCRPC, and tumors harboring these mutations are known to be sensitive to PARP inhibitors. The aim of this study was to verify the technical effectiveness of this panel in the analysis of mCRPC, the frequency and type of mutations in the BRCA1/BRCA2 genes, as well as in the homologous recombination repair (HRR) genes. A total of 50 mCRPC cases were analyzed using a multi-gene next-generation sequencing panel evaluating a total of 1360 amplicons in 24 HRR genes. Of the 50 cases, 23 specimens (46.0%) had an mCRPC harboring a pathogenic variant or a variant of uncertain significance (VUS), whereas in 27 mCRPCs (54.0%), no mutations were detected (wild-type tumors). BRCA2 was the most commonly mutated gene (14.0% of samples), followed by ATM (12.0%), and BRCA1 (6.0%). In conclusion, we have set up an NGS multi-gene panel that is capable of analyzing BRCA1/BRCA2 and HRR alterations in mCRPC. Moreover, our clinical algorithm is currently being used in clinical practice for the management of patients with mCRPC.

Epitope Lability of Phosphorylated Biomarkers of the DNA Damage Response Pathway Results in Increased Vulnerability to Effects of Delayed or Incomplete Formalin Fixation

Phosphorylated biomarkers are crucial for our understanding of drug mechanism of action and dose selection during clinical trials, particularly for drugs that target protein kinases, such as DNA-damage-response (DDR) inhibitors. However, tissue fixation conditions needed to preserve DDR-specific phospho-biomarkers have not been previously investigated. Using xenograft tissues and tightly controlled formalin fixation conditions, we assessed how preanalytical factors affect phosphorylated DDR biomarkers pRAD50(Ser635), ɣH2AX(Ser139), pKAP1(Ser824), and non-phosphorylated biomarkers cMYC and ATM. Cold ischemia times ranged from 15 min to 6 hr, and the fixation duration ranged from 24 hr to 4 weeks. Epitopes pRAD50 and pKAP1 appeared the most labile assessed with staining loss after just 15 min of cold ischemia time, while ATM was more robust showing consistent expression up to 1 hr of cold ischemia. Notably, ɣH2AX expression was lost with formalin fixation over 48 hr. The use of core needle biopsies where possible and novel fixation methods such as the 2-step temperature-controlled formalin approach may improve phosphorylated biomarker preservation; however, practical challenges may affect wider clinical application. The most essential tissue-processing step when downstream analysis includes DDR phosphorylated biomarkers is immediate tissue submersion in formalin, without delay, upon excision from the patient, followed by room temperature fixation for 24 hr.

Lipocalin-2 Upregulation in Nasopharyngeal Carcinoma: A Novel Potential Diagnostic Biomarker

Background

Lipocalin-2 (LCN2) deregulation has been reported in several types of cancer and is implicated in the proliferation, migration, angiogenesis, and progression of tumors. However, its aberrant expression has been rarely studied in nasopharyngeal carcinoma (NPC). In the present study, we investigated the expression of LCN2 in NPC patients.

Methods

In this descriptive cross-sectional study, 29 NPC and 20 non-cancerous control paraffin pathology blocks were obtained from the seven-year (2011 to 2018) archive of Razi Laboratory in Rasht, Iran. LCN2 mRNA expression was evaluated through quantitative real-time PCR. In addition, immunohistochemistry was performed to evaluate LCN2 expression at the protein level. The fold change value and total immunostaining score (TIS) were applied for quantitative evaluation. The nonparametric Mann-Whitney U test and Fisher's exact test were used through GraphPad Prism 8.3.0 software. P<0.05 was considered statistically significant.

Results

Our results revealed that LCN2 mRNA and protein levels in NPC tissues were significantly higher than control tissues (P=0.028 and P=0.002, respectively). At the protein level, 65.51% (19/29) of NPC patients were categorized as having high LCN2 expression (TIS>3) and 34.47% (10/29) as low expression (TIS≤3). While in the control group, 25% (5/20) of subjects represented a high expression of LCN2 (TIS>3), and 75% (15/20) showed no or weak expression (TIS≤3). No significant correlation was found between the overexpression of LCN2 at the protein level and the demographic features of the patients.

Conclusion

Our findings suggest that LCN2 might be considered a potential new diagnostic marker for NPC. However, this warrants further studies.

Preanalytic and Analytic Quality System Considerations in Noncoding RNA Biomarker Development for Clinical Diagnostics

A frequent topic of biomedical research is the potential clinical use of non-coding (nc) RNAs as quantitative biomarkers for a broad spectrum of health and disease. However, ncRNA analyses have not been pressed into widespread diagnostic use. Strong preclinical evidence suggests obstacles in the translation and reproducibility of this type of biomarker which may result from preanalytical and analytical variation in the non-standardized processes used to collect, process, and store samples, as well as the substantive differences between small and long ncRNA. We performed a narrative review of selected literature, through the lens of key laboratory-developed test (LDT) regulations under the Clinical Laboratory Improvement Amendments (CLIA) in the United States, to study critical gaps in ncRNA validation studies. This review describes the leading candidate ncRNA subclasses, their biogenesis and cellular function, and identifies specific pre-analytical variables with disproportionate impact on testing performance. We summarize these findings with strategic recommendations to clinicians and biomedical scientists involved in the design, conduct, and translation of ncRNA biomarker development.

Residual Humidity in Paraffin-Embedded Tissue Reduces Nucleic Acid Stability

Molecular diagnostics in healthcare relies increasingly on genomic and transcriptomic methodologies and requires appropriate tissue specimens from which nucleic acids (NA) of sufficiently high quality can be obtained. Besides the duration of ischemia and fixation type, NA quality depends on a variety of other pre-analytical parameters, such as storage conditions and duration. It has been discussed that the improper dehydration of tissue during processing influences the quality of NAs and the shelf life of fixed tissue. Here, we report on establishing a method for determining the amount of residual water in fixed, paraffin-embedded tissue (fixed by neutral buffered formalin or a non-crosslinking fixative) and its correlation to the performance of NAs in quantitative real-time polymerase chain reaction (qRT-PCR) analyses. The amount of residual water depended primarily on the fixative type and the dehydration protocol and, to a lesser extent, on storage conditions and time. Moreover, we found that these parameters were associated with the qRT-PCR performance of extracted NAs. Besides the cross-linking of NAs and the modification of nucleobases by formalin, the hydrolysis of NAs by residual water was found to contribute to reduced qRT-PCR performance. The negative effects of residual water on NA stability are not only important for the design and interpretation of research but must also be taken into account in clinical diagnostics where the reanalysis of archived tissue from a primary tumor may be required (e.g., after disease recurrence). We conclude that improving the shelf life of fixed tissue requires meticulous dehydration and dry storage to minimize the degradative influence of residual water on NAs.

European Society of Toxicologic Pathology (Pathology 2.0 Molecular Pathology Special Interest Group): Review of In Situ Hybridization Techniques for Drug Research and Development

In situ hybridization (ISH) is used for the localization of specific nucleic acid sequences in cells or tissues by complementary binding of a nucleotide probe to a specific target nucleic acid sequence. In the last years, the specificity and sensitivity of ISH assays were improved by innovative techniques like synthetic nucleic acids and tandem oligonucleotide probes combined with signal amplification methods like branched DNA, hybridization chain reaction and tyramide signal amplification. These improvements increased the application spectrum for ISH on formalin-fixed paraffin-embedded tissues. ISH is a powerful tool to investigate DNA, mRNA transcripts, regulatory noncoding RNA, and therapeutic oligonucleotides. ISH can be used to obtain spatial information of a cell type, subcellular localization, or expression levels of targets. Since immunohistochemistry and ISH share similar workflows, their combination can address simultaneous transcriptomics and proteomics questions. The goal of this review paper is to revisit the current state of the scientific approaches in ISH and its application in drug research and development.

An approach to genetic testing in patients with metastatic castration-resistant prostate cancer in Singapore

Introduction

There has been a rapid evolution in the treatment strategies for metastatic castration-resistant prostate cancer (mCRPC) following the identification of targetable mutations, making genetic testing essential for patient selection. Although several international guidelines recommend genetic testing for patients with mCRPC, there is a lack of locally endorsed clinical practice guidelines in Singapore.

Method

A multidisciplinary specialist panel with representation from medical and radiation oncology, urology, pathology, interventional radiology, and medical genetics discussed the challenges associated with patient selection, genetic counselling and sample processing in mCRPC.

Results

A clinical model for incorporating genetic testing into routine clinical practice in Singapore was formulated. Tumour testing with an assay that is able to detect both somatic and germline mutations should be utilised. The panel also recommended the "mainstreaming" approach for genetic counselling in which pre-test counselling is conducted by the managing clinician and post-test discussion with a genetic counsellor, to alleviate the bottlenecks at genetic counselling stage in Singapore. The need for training of clinicians to provide pre-test genetic counselling and educating the laboratory personnel for appropriate sample processing that facilitates downstream genetic testing was recognised. Molecular tumour boards and multidisciplinary discussions are recommended to guide therapeutic decisions in mCRPC. The panel also highlighted the issue of reimbursement for genetic testing to reduce patient-borne costs and increase the reach of genetic testing among this patient population.

Conclusion

This article aims to provide strategic and implementable recommendations to overcome the challenges in genetic testing for patients with mCRPC in Singapore.

Improving sarcoma classification by using RNA hybridisation capture sequencing in sarcomas of uncertain histogenesis of young individuals

Our aim was to utilise a 241-gene RNA hybridisation capture sequencing (CaptureSeq) gene panel to identify unexpected fusions in undifferentiated, unclassified or partly classified sarcomas of young individuals (<40 years). The purpose was to determine the utility and yield of a large, targeted fusion panel as a tool for classifying tumours that do not fit typical diagnostic entities at the time of the original diagnosis. RNA hybridisation capture sequencing was performed on 21 archival resection specimens. Successful sequencing was obtained in 12 of 21 samples (57%), two of which (16.6%) harboured translocations. A novel NEAT1::GLI1 fusion, not previously reported in the literature, presented in a young patient with a tumour in the retroperitoneum, which displayed low grade epithelioid cells. The second case, a localised lung metastasis in a young male, demonstrated a EWSR1::NFATC2 translocation. No targeted fusions were identified in the remaining 83.4% (n=10) of cases. Forty-three per cent of the samples failed sequencing as a result of RNA degradation. RNA-based sequencing is an important tool, which helps to redefine the classification of unclassified or partly classified sarcomas of young adults by identifying pathogenic gene fusions in up to 16.6% of the cases. Unfortunately, 43% of the samples underwent significant RNA degradation, falling below the sequencing threshold. As CaptureSeq is not yet available in routine pathology practice, increasing awareness of the yield, failure rate and possible aetiological factors for RNA degradation is fundamental to maximise laboratory procedures to improve RNA integrity, allowing the potential identification of significant gene alterations in solid tumours.

The impact of impaired tissue fixation in resected non-small-cell lung cancer on protein deterioration and DNA degradation

OBJECTIVES

The objective is to assess the impact of the quality of tissue fixation in surgical pathology on immunohistochemical (IHC) staining and DNA degradation.

MATERIALS AND METHODS

Twenty-five non-small cell lung cancer (NSCLC) resection specimens were analyzed. After resection, all tumors were processed according to the protocols in our center. In haematoxylin and eosin (H&E) stained tissue slides, adequately- and inadequately fixed tumor areas were microscopically demarcated, based on basement membrane detachment. In 10 IHC stains ALK (clone 5A4), PD-L (clone 22C3), CAM5.2, CK7, c-Met, KER-MNF116, NapsinA, p40, ROS1, TTF1) the immunoreactivity in H-scores was determined in adequately- and inadequately fixed, and necrotic tumor areas. From the same areas DNA was isolated, and DNA fragmentation in base pairs (bp) was measured.

RESULTS

H-scores were significantly higher in H&E adequately fixed tumor areas in IHC stains KER-MNF116 (H-score 256 vs 15, p=0.001) and p40 (H-score 293 vs 248, p=0.028). All other stains showed a trend towards higher immunoreactivity in H&E adequately fixed areas. Independent of H&E adequatelty- or inadequately fixed areas, all IHC stains showed significant different IHC staining intensity within tumors, suggesting heterogeneous immunoreactivity (H-scores: PD-L1 123 vs 6, p = 0.001; CAM5.2 242 vs 101, p=<0.001; CK7 242 vs 128, p=<0.001; c-MET 99 vs 20, p=<0.001; KER-MNF116 281 vs 120, p=<0.001; Napsin A 268 vs 130, p = 0.005; p40 292 vs 166, p = 0.008; TTF1 199 vs 63, p=<0.001). DNA fragments rarely exceeded a length of 300 bp, independent of adequate fixation. However, DNA fragments of 300 and 400 bp had higher concentrations in tumors with short fixation delay (<6 h vs >16 h) and short fixation time (<24 h vs >24 h).

CONCLUSIONS

Impaired tissue fixation of resected lung tumors results in decreased IHC staining intensity in some parts of the tumor. This may impact the reliability of IHC analysis.

Selection and Evaluation of mRNA and miRNA Reference Genes for Expression Studies (qPCR) in Archived Formalin-Fixed and Paraffin-Embedded (FFPE) Colon Samples of DSS-Induced Colitis Mouse Model

The choice of appropriate reference genes is essential for correctly interpreting qPCR data and results. However, the majority of animal studies use a single reference gene without any prior evaluation. Therefore, many qPCR results from rodent studies can be misleading, affecting not only reproducibility but also translatability. In this study, the expression stability of reference genes for mRNA and miRNA in archived FFPE samples of 117 C57BL/6JOlaHsd mice (males and females) from 9 colitis experiments (dextran sulfate sodium; DSS) were evaluated and their expression analysis was performed. In addition, we investigated whether normalization reduced/neutralized the influence of inter/intra-experimental factors which we systematically included in the study. Two statistical algorithms (NormFinder and Bestkeeper) were used to determine the stability of reference genes. Multivariate analysis was made to evaluate the influence of normalization with different reference genes on target gene expression in regard to inter/intra-experimental factors. Results show that archived FFPE samples are a reliable source of RNA and imply that the FFPE procedure does not change the ranking of stability of reference genes obtained in fresh tissues. Multivariate analysis showed that the histological picture is an important factor affecting the expression levels of target genes.

Highly Accurate and Robust Absolute Quantification of Target Proteins in Formalin-Fixed Paraffin-Embedded (FFPE) Tissues by LC-MS

Accurate, absolute liquid chromatography-mass spectrometry (LC-MS)-based quantification of target proteins in formalin-fixed paraffin-embedded (FFPE) tissues would greatly expand sample availability for pharmaceutical/clinical investigations but remains challenging owing to the following issues: (i) efficient/quantitative recovery of target signature peptides from FFPE tissues is essential but an optimal procedure for targeted, absolute quantification is lacking; (ii) most FFPE samples are long-term-stored; severe immunohistochemistry (IHC) signal losses of target proteins during storage were widely reported, while the effect of storage on LC-MS-based methods was unknown; and (iii) the proper strategy to prepare calibration/quality-control samples to ensure accurate targeted protein analysis in FFPE tissues remained elusive. Using targeted quantification of monoclonal antibody (mAb), antigen, and 40 tissue markers in FFPE tissues as a model system, we extensively investigate those issues and develope an LC-MS-based strategy enabling accurate and precise targeted protein quantification in FFPE samples. First, we demonstrated a surfactant cocktail-based procedure (f-SEPOD), providing high/reproducible recovery of target signature peptides from FFPE tissues. Second, a heat-accelerated degradation study within a roughly estimated 5 year storage period recapitulated the loss of protein IHC signals while LC-MS signals of all targets remained constant. This indicates that the storage of FFPE tissues mainly causes decreased immunoreactivity but unlikely chemical degradation of proteins, which strongly suggests that the storage of FFPE tissues does not cause significant quantitative bias for LC-MS-based methods. Third, while a conventional spike-and-extract approach for calibration caused substantial negative biases, a novel approach, using FFPE-treated calibration standards, enabled accurate and precise quantification. With the pipeline, we conducted the first-ever pharmacokinetics measurement of mAb and its target in FFPE tissues, where time courses by FFPE vs fresh tissues showed excellent correlation.