Developing an enhanced 7-color multiplex IHC protocol to dissect immune infiltration in human cancers

Cutaneous melanoma

Cutaneous melanoma is a common cancer in Australia and New Zealand, Europe, and North America, and its incidence is still increasing in many regions. Ultraviolet (UV) radiation exposure (for example, through excessive sunlight exposure) remains the primary risk factor for melanoma; however, public awareness campaigns have led to a marked reduction in mortality. In addition to genetic damage from UV radiation, specific genetic alterations have been linked to melanoma. The stage of the tumour at the time of diagnosis is of greater importance for melanoma prognosis than in almost any other cancer. Context-dependent genetic mutations that attenuate tumour-suppressive mechanisms or activate growth-promoting signalling pathways are crucial factors in the development of cutaneous melanoma. In addition to external factors such as UV radiation, the tumour microenvironment can contribute to melanoma progression, invasion and metastasis. Cutaneous melanoma treatment has improved considerably over the past decade with the discovery and development of immune checkpoint inhibitors and therapy targeting BRAF and MEK. Over the next decade, several priorities are likely to influence melanoma research and management, including the continued advance of precision medicine methods to identify the most suitable patients for the most effective treatment, with the aim of improving clinical outcomes.

Expression of T cell-related proteins in breast ductal carcinoma in situ

This study aims to explore the expression of T cell subtype markers within the immune cells constituting the tumor microenvironment of ductal carcinoma in situ (DCIS) and to assess its implications. A tissue microarray comprising 191 cases of breast DCIS was created, and immunohistochemistry staining for T cell subtype markers (STAT3, STAT4, STAT-6, and FOXP3) was conducted. The DCIS cases were categorized into luminal, HER-2, and TNBC (Triple-negative breast cancer) types based on ER, PR, HER-2, and Ki-67 results. Additionally, they were classified as low-TIL (tumor-infiltrating lymphocytes) (<10%) or high-TIL (≥10%) types according to stromal TIL. Results revealed that 54.6% were luminal, 39.5% HER-2, and 5.9% TNBC. STAT3 exhibited a high positivity rate in luminal-type tumor cells, while STAT3, STAT4, STAT6, and FOXP3 showed elevated positivity rates in TNBC immune cells (p<0.05). Furthermore, a higher positivity rate was observed in high-TIL immune cells compared with low-TIL (p<0.001). The strongest agreement between T cell subtype markers in immune cells was found between STAT3 and STAT4 (OA=83.7%, κ=0.658), whereas the lowest was between STAT4 and FOXP3 (OA=71.7%, κ=0.370). In immune cells, STAT3 and STAT4 positivity correlated with necrosis (p<0.001), and the absence of positivity in all immune cell-related proteins in DCIS with necrosis was associated with poor prognosis (p=0.013). In conclusion, the immune cells in DCIS exhibit positivity for diverse T cell subtype markers, with TNBC and high-TIL DCIS displaying heightened positivity.

Major Human Leukocyte Antigen Expression in Respiratory Papillomatosis Clinical Specimens

OBJECTIVES

Prior studies have reported low or absent major HLA class I expression on respiratory papilloma cells, conflicting with the recent clinical success of immunotherapy designed to activate HPV-specific T cells in patients with recurrent respiratory papillomatosis (RRP). We aimed to determine major human leukocyte antigen (HLA) class I expression on respiratory papilloma cells in untreated RRP clinical specimens using contemporary techniques.

METHODS

Formalin-fixed, paraffin-embedded RRP sections were subjected to signal-amplified multispectral immunofluorescence using the OPAL system to determine major and minor HLA class I expression, and digitally scanned slides were analyzed using digital pathology software. Positive and negative controls were used to optimize primary antibody conditions.

RESULTS

All samples harbored major HLA class I expression on varying proportions of papilloma cells. Considering all samples, major HLA class I expression was observed on the majority (74%) of papilloma cells. Nearly all (98%) papilloma infiltrating immune cells were positive for major HLA class I expression, serving as an internal control for each stained sample. Major HLA class I negative papilloma cells were enriched in the apical, suprabasal layers compared to the basal layers of the papillomatous epithelium, suggesting an association with the epithelial cell differentiation state. Fewer papilloma cells inconsistently expressed the minor HLA class I HLA-E across the basal and suprabasal epithelial layers.

CONCLUSION

Papilloma cells express major HLA class I molecules. Using contemporary immunofluorescent techniques with signal amplification that likely provide improved sensitivity, these results clarify the major HLA class I expression status on papilloma cells in clinical specimens.

LEVEL OF EVIDENCE

N/A.

Exploring the characteristics of immortalized human ovarian surface epithelial cell lines

The origins of epithelial ovarian cancer (EOC) have long been debated, with proposed sources including ovarian surface epithelial (OSE) cells, secondary Müllerian tract structures, or fallopian tube epithelium. Despite being the second most common gynecological cancer and a leading cause of death in the United States, in vitro cell models mimicking normal ovarian epithelial cells and their malignant counterparts are lacking. To address this gap, we established immortalized human OSE (IHOSE) cell lines that demonstrate stable in vitro growth without malignant properties. IHOSE cell lines were unique cell lines by analyzing short tandem repeat (STR) profiling. In addition, the epithelial characteristics were confirmed by cytokeratin 7 and cytokeratin 18 marker expression. IHOSE cell lines were subjected to Opal multiplex immunohistochemistry (IHC) analysis, which established four distinct subtypes based on marker dominance. These studies offer the most basic but essential cellular characterization information for IHOSE cell lines, providing critical data that can guide the selection of cells when inducing normal controls or disease models.

Research progress and perspectives on the application of tyramide signal amplification-based multiplex immunohistochemistry/immunofluorescence: a bibliometrics analysis

Background and aims

Multiplex immunohistochemistry/immunofluorescence (mIHC/IF), which uses the tyramide signal amplification (TSA) technique, enables sequential staining of multiple targets in formalin-fixed paraffin-embedded (FFPE) samples without worrying about cross-reactivity. This approach has received considerable attention from researchers over the past decades. This article aims to provide a bibliometric analysis of the research progress and perspectives on the application of TSA-based mIHC/IF.

Methods

We collected all the TSA-based mIHC/IF documents published between 2007 and 2023 from the Web of Science Core Collection (WoSCC) database. CiteSpace, VOSviewer and Bibliometrix R Package were used to perform the bibliometrics analysis, including details about annual publications, countries, institutions, authors, journals, and research topics and hotspots.

Results

A total of 873 relevant publications (811 articles and 62 reviews) with a time span of 17 years (2007-2023) were obtained. The number of annual publications started to increase rapidly since 2016. The United States (307, 35.17%) and the People's Republic of China (297, 34.02%) are the top two listed countries for both the number of articles produced and the citations. The University of Texas System (53, 6.07%) was the most productive institution. Integrating these results of hotspot and frontier analysis, TSA-based mIHC/IF provides significant benefits, particularly in neurology, cancer and immunology.

Conclusion

This study conducted a comprehensive bibliometric analysis for the use of TSA-based mIHC/IF. As TSA-based mIHC/IF and its associated imaging systems and analytic software progress, it will become the most promising tool for describing the variety of the whole tissue for a better understanding of pathological or physiological behavior.

Ovarian tumor cells gain competitive advantage by actively reducing the cellular fitness of microenvironment cells

Cell competition and fitness comparison between cancer and tumor microenvironment (TME) cells determine oncogenic fate. Our previous study established a role for human Flower isoforms as fitness fingerprints, where the expression of Flower Win isoforms in tumor cells leads to growth advantage over TME cells expressing Lose isoforms. Here we demonstrate that the expression of Flower Lose and reduced microenvironment fitness is not a pre-existing condition but, rather, a cancer-induced phenomenon. Cancer cells actively reduce TME fitness by the exosome-mediated release of a cancer-specific long non-coding RNA, Tu-Stroma, which controls the splicing of the Flower gene in the TME cells and expression of Flower Lose isoform, which leads to reduced fitness status. This mechanism controls cancer growth, metastasis and host survival in ovarian cancer. Targeting Flower protein with humanized monoclonal antibody (mAb) in mice significantly reduces cancer growth and metastasis and improves survival. Pre-treatment with Flower mAb protects intraperitoneal organs from developing lesions despite the presence of aggressive tumor cells.

Increased Multiplexity in Optical Tissue Clearing-Based Three-Dimensional Immunofluorescence Microscopy of the Tumor Microenvironment by Light-Emitting Diode Photobleaching

Optical tissue clearing and three-dimensional (3D) immunofluorescence (IF) microscopy is transforming imaging of the complex tumor microenvironment (TME). However, current 3D IF microscopy has restricted multiplexity; only 3 or 4 cellular and noncellular TME components can be localized in cleared tumor tissue. Here we report a light-emitting diode (LED) photobleaching method and its application for 3D multiplexed optical mapping of the TME. We built a high-power LED light irradiation device and temperature-controlled chamber for completely bleaching fluorescent signals throughout optically cleared tumor tissues without compromise of tissue and protein antigen integrity. With newly developed tissue mounting and selected region-tracking methods, we established a cyclic workflow involving IF staining, tissue clearing, 3D confocal microscopy, and LED photobleaching. By registering microscope channel images generated through 3 work cycles, we produced 8-plex image data from individual 400 μm-thick tumor macrosections that visualize various vascular, immune, and cancer cells in the same TME at tissue-wide and cellular levels in 3D. Our method was also validated for quantitative 3D spatial analysis of cellular remodeling in the TME after immunotherapy. These results demonstrate that our LED photobleaching system and its workflow offer a novel approach to increase the multiplexing power of 3D IF microscopy for studying tumor heterogeneity and response to therapy.

Roles of tissue-resident immune cells in immunotherapy of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the most common and lethal type of lung cancer, with limited treatment options and poor prognosis. Immunotherapy offers hope for improving the survival and quality of life of NSCLC patients, but its efficacy depends on the tumor immune microenvironment (TME). Tissue-resident immune cells are a subset of immune cells that reside in various tissues and organs, and play an important role in fighting tumors. In NSCLC, tissue-resident immune cells are heterogeneous in their distribution, phenotype, and function, and can either promote or inhibit tumor progression and response to immunotherapy. In this review, we summarize the current understanding on the characteristics, interactions, and roles of tissue-resident immune cells in NSCLC. We also discuss the potential applications of tissue-resident immune cells in NSCLC immunotherapy, including immune checkpoint inhibitors (ICIs), other immunomodulatory agents, and personalized cell-based therapies. We highlight the challenges and opportunities for developing targeted therapies for tissue-resident immune cells and optimizing existing immunotherapeutic approaches for NSCLC patients. We propose that tissue-resident immune cells are a key determinant of NSCLC outcome and immunotherapy response, and warrant further investigation in future research.

Increased multiplexity in optical tissue clearing-based 3D immunofluorescence microscopy of the tumor microenvironment by LED photobleaching

Optical tissue clearing and three-dimensional (3D) immunofluorescence (IF) microscopy have been transforming imaging of the complex tumor microenvironment (TME). However, current 3D IF microscopy has restricted multiplexity; only three or four cellular and non-cellular TME components can be localized in a cleared tumor tissue. Here we report a LED photobleaching method and its application for 3D multiplexed optical mapping of the TME. We built a high-power LED light irradiation device and temperature-controlled chamber for completely bleaching fluorescent signals throughout optically cleared tumor tissues without compromise of tissue and protein antigen integrity. With newly developed tissue mounting and selected region-tracking methods, we established a cyclic workflow involving IF staining, tissue clearing, 3D confocal microscopy, and LED photobleaching. By registering microscope channel images generated through three work cycles, we produced 8-plex image data from individual 400 μm-thick tumor macrosections that visualize various vascular, immune, and cancer cells in the same TME at tissue-wide and cellular levels in 3D. Our method was also validated for quantitative 3D spatial analysis of cellular remodeling in the TME after immunotherapy. These results demonstrate that our LED photobleaching system and its workflow offer a novel approach to increase the multiplexing power of 3D IF microscopy for studying tumor heterogeneity and response to therapy.

Optimising multiplex immunofluorescence staining for characterising the tumour immune micro-environment

Exploring the tumour microenvironment provides insight into the unique interaction between the host and tumour. Ultimately, its study improves understanding of how an individual mounts and achieves an anti-tumour immune response. In the context of colorectal cancer, immune biomarkers within the tumour microenvironment outperform traditional histopathological staging in predicting disease recurrence. Multiplex immunofluorescence enables simultaneous assessment of multiple markers to provide a highly accurate classification of immune cells and their spatial characterisation relative to tumour tissue. Further, automated slide staining provides staining consistency and reduces labour costs. Image acquisition using a non-spectral scanner allows more researchers to utilise multiplexed immunofluorescence for translational research. Herein we describe the optimisation process of conducting automated staining using a five-colour, tyramide signal amplification-based multiplex immunofluorescence panel. Using antibodies against CD3, CD8, CD103 and cytokeratin, the panel characterises T cell populations within human colorectal adenocarcinoma tissue. We provide an overview of primary antibody titration and the development of tyramide signal amplification immunofluorescence monoplex assays. We detail the processes of antibody stripping and the role of exogenous horseradish peroxidase inhibition to facilitate multiplexing. An account of determining the staining sequence and fluorophore assignment is provided. We describe image acquisition using a standard fluorescence microscope slide scanner and the management of spectral crosstalk using this system. Finally, we briefly document the digital image analysis required to characterise cells and determine their spatial distribution within the colorectal tumour microenvironment.

Exploring the Complex and Multifaceted Interplay between Melanoma Cells and the Tumor Microenvironment

Malignant melanoma is a very aggressive skin cancer, characterized by a heterogeneous nature and high metastatic potential. The incidence of melanoma is continuously increasing worldwide, and it is one of the most common cancers in young adults. In the past twenty years, our understanding of melanoma biology has increased profoundly, and disease management for patients with disseminated disease has improved due to the emergence of immunotherapy and targeted therapy. However, a significant fraction of patients relapse or do not respond adequately to treatment. This can partly be explained by the complex signaling between the tumor and its microenvironment, giving rise to melanoma phenotypes with different patterns of disease progression. This review focuses on the key aspects and complex relationship between pathogenesis, genetic abnormalities, tumor microenvironment, cellular plasticity, and metabolic reprogramming in melanoma. By acquiring a deeper understanding of the multifaceted features of melanomagenesis, we can reach a point of more individualized and patient-centered disease management and reduced costs of ineffective treatments.

Abnormal generation of IL-17A represses tumor infiltration of stem-like exhausted CD8+ T cells to demote the antitumor immunity

BACKGROUND

Variated anti-cancer therapies are combined with immune checkpoint blockades (ICBs) for improving ICB therapeutic efficacy. Occurrence of tissue damage is common that triggers multiple inflammatory cytokine generation. Gastrointestinal organs are the commonly affected. We investigated the impact of acute colitis on tumor infiltration of antigen-specific CD8+ cytotoxic T lymphocytes (CTLs) for controlling tumor growth and responding to antibody against PD-1 (anti-PD-1).

METHODS

Several tumor cell lines were inoculated into syngeneic mice subcutaneously or intra-hepatically. When tumor mass formed, activated CTLs were intravenously transferred into the tumor-bearing mice, that were given the drinking water containing 2% dextran sulfate sodium (DSS) for acute colitis induction. Tumor growth, infiltration of two exhausted CTL subsets, and the CTL interaction with tumor vascular endothelium were examined.

RESULTS

Acute colitis dampened CTL-mediated antitumor effects, correlating with IL-17A elevation in the inflamed intestine. In the tumor bed, stem-like exhausted CTLs, which were defined as PD-1+Slamf6+Tim3-, expressed higher IL-17A receptor heterodimers and lower leukocyte function-associated antigen-1 (LFA-1) than terminally exhausted CTLs did, that were defined as PD-1+Slamf6-Tim3+. IL-17A stimulation reduced LFA-1 surface expression on stem-like exhausted CTLs and the counterpart ICAM-1 (intracellular adhesion molecule-1) on tumor vascular endothelium. IL-17A stimulation suppressed the extravasation across tumor vascular endothelium and self-renewal of stem-like, not the terminally exhausted CTLs. Administration of anti-IL-17A neutralizing antibody to the colitis mice restored the CTL tumor infiltration and enhanced anti-PD-1 treatment efficacy against tumors. In 33 hepatocellular carcinoma patients being treated with anti-PD-1 plus antibody against vascular endothelial growth factor, disease progression of 15 patients, that exhibited serum IL-17A increase 24 h post-therapy as compared to pre-therapy level, was poorer than that of 18 patients that exhibited serum IL-17A no-increase.

CONCLUSIONS

Abnormal generation of IL-17A mainly repressed tumor infiltration of stem-like exhausted CTLs. ICB-based immunotherapeutic efficacy could be upgraded with administration of anti-IL-17A, when treatment-related IL-17A elevation occurred due to tissue damage, such as acute colitis.

Spatial Profile of Tumor Microenvironment in PD-L1-Negative and PD-L1-Positive Triple-Negative Breast Cancer

The problem of finding more precise stratification criteria for identifying the cohort of patients who would obtain the maximum benefit from immunotherapy is acute in modern times. In our study were enrolled 18 triple-negative breast cancer patients. The Ventana SP142 test was used for PD-L1 detection. Spatial transcriptomic analysis by 10x Genomics was used to compare PD-L1-positive and PD-L1-negative tumors. The seven-color multiplex immunofluorescence (by Akoya) was used for the detection of the type of cells that carried the PD1 receptor and the PD-L1 ligand. Using pathway analysis, we showed that PD-L1-positive tumors demonstrate signatures of a cell response to cytokines, among others, and PD-L1-negative tumors demonstrate signatures of antigen presentation. PD-L1-positive and PD-L1-negative tumors have different tumor microenvironment (TME) compositions according to CIBERSORT analysis. Multiplex immunohistochemistry (IHC) confirmed the prevalence of PD1-negative M2 macrophages and PD1-negative T lymphocytes in PD-L1-positive tumors. PD-L1-positive tumors are not characterized by direct contact between cells carrying the PD1 receptor and the PD-L1 ligand. So, the absence of specific immune reactions against the tumor, predominance of pro-tumor microenvironment, and rare contact between PDL1 and PD1-positive cells may be the potential reasons for the lack of an immune checkpoint inhibitor (ICI) effect in triple-negative breast cancer patients.

Bright-Field Multiplex Immunohistochemistry Assay for Tumor Microenvironment Evaluation in Melanoma Tissues

Simple Summary

Bright-field (BF) immunohistochemistry (IHC) remains the gold standard for histopathological evaluations. The development of new BF multiplex IHC could be very useful for the study and characterization of the tumor microenvironment (TME) in melanoma samples. We herein compared different BF IHC multiplex protocols for the study of TME in primary cutaneous melanoma tissues and offered the best optimized protocol for visualization and evaluation. These methodologies are studied to maximize the quality of staining considering the tissue characteristics under examination, maintaining a high level of standardization and reproducibility.

Abstract

The tumor microenvironment (TME) plays a crucial role in melanoma development, progression and response to treatment. As many of the most relevant TME cell phenotypes are defined by the simultaneous detection of more than two markers, the bright-field (BF) multiplex immunohistochemistry (IHC) technique has been introduced for the quantitative assessment and evaluation of the relative spatial distances between immune cells and melanoma cells. In the current study, we aimed to validate BF multiplex IHC techniques in the Ventana Discovery Ultra Immunostainer to be applied to the evaluation of the TME in variably pigmented melanoma tissues. The BF multiplex IHC staining was performed using different combinations of six immune-cell markers—CD3, CD4, CD8, CD20, CD68 and CD163—and the melanoma cell marker SOX10. Our results show that the BF double IHC Yellow/Purple protocol guarantees the maximum contrast in all the cell populations tested and the combination SOX10 (Green), CD8 (Yellow) and CD163 (Purple) of the BF triple IHC protocol ensures the best contrast and discrimination between the three stained cell populations. Furthermore, the labeled cells were clearly distinct and easily identifiable using the image analysis software. Our standardized BF IHC multiplex protocols can be used to better assess the immune contexts of melanoma patients with potential applications to drive therapeutic decisions within clinical trials.

B Lymphocytes Are a Predictive Marker of Eribulin Response and Overall Survival in Locally Advanced or Metastatic Breast Cancer: A Multicenter, Two-Cohort, Non-Randomized, Open-Label, Retrospective Study

Triple-negative breast cancer has no specific treatment and unfavorable prognosis. Eribulin is one of the drugs widely used in this cohort of patients. In addition to its antimitotic effect, eribulin has an immunomodulant effect on the tumor microenvironment. In this study, we discover immunological markers, such as tumor-infiltrating lymphocytes, CD8+, CD4+, FoxP3+, CD20+ lymphocytes, and their PD1 positivity or negativity, with the ability to predict benefits from eribulin within locally advanced or metastatic triple-negative breast cancer. The primary objective was to explore the association of composition of immune cells in the microenvironment with response to eribulin. The key secondary objective was overall survival. Seven-color multiplex immunofluorescence was used to phenotype lymphocytes in the primary tumor. It has been shown that the PD1-negative-to-PD1-positive B cells ratio in primary tumors more than 3 is an independent predictor of the short-term effectiveness of eribulin [OR (95%CI) 14.09 (1.29-153.35), p=0.0029] and worse overall survival [HR (95%CI) 11.25 (1.37-70.25), p=0.0009] in patients with locally advanced or metastatic triple-negative breast cancer.

SPCS: a spatial and pattern combined smoothing method for spatial transcriptomic expression

High-dimensional, localized ribonucleic acid (RNA) sequencing is now possible owing to recent developments in spatial transcriptomics (ST). ST is based on highly multiplexed sequence analysis and uses barcodes to match the sequenced reads to their respective tissue locations. ST expression data suffer from high noise and dropout events; however, smoothing techniques have the promise to improve the data interpretability prior to performing downstream analyses. Single-cell RNA sequencing (scRNA-seq) data similarly suffer from these limitations, and smoothing methods developed for scRNA-seq can only utilize associations in transcriptome space (also known as one-factor smoothing methods). Since they do not account for spatial relationships, these one-factor smoothing methods cannot take full advantage of ST data. In this study, we present a novel two-factor smoothing technique, spatial and pattern combined smoothing (SPCS), that employs the k-nearest neighbor (kNN) technique to utilize information from transcriptome and spatial relationships. By performing SPCS on multiple ST slides from pancreatic ductal adenocarcinoma (PDAC), dorsolateral prefrontal cortex (DLPFC) and simulated high-grade serous ovarian cancer (HGSOC) datasets, smoothed ST slides have better separability, partition accuracy and biological interpretability than the ones smoothed by preexisting one-factor methods. Source code of SPCS is provided in Github (https://github.com/Usos/SPCS).

Profiling Tumor Immune Microenvironment of Non-Small Cell Lung Cancer Using Multiplex Immunofluorescence

This study attempted to profile the tumor immune microenvironment (TIME) of non-small cell lung cancer (NSCLC) by multiplex immunofluorescence of 681 NSCLC cases. The number, density, and proportion of 26 types of immune cells in tumor nest and tumor stroma were evaluated, revealing some close interactions particularly between intrastromal neutrophils and intratumoral regulatory T cells (Treg) (r² = 0.439, P < 0.001), intrastromal CD4+CD38+ T cells and CD20-positive B cells (r² = 0.539, P < 0.001), and intratumoral CD8-positive T cells and M2 macrophages expressing PD-L1 (r² = 0.339, P < 0.001). Three immune subtypes correlated with distinct immune characteristics were identified using the unsupervised consensus clustering approach. The immune-activated subtype had the longest disease-free survival (DFS) and demonstrated the highest infiltration of CD4-positive T cells, CD8-positive T cells, and CD20-positive B cells. The immune-defected subtype was rich in cancer stem cells and macrophages, and these patients had the worst prognosis. The immune-exempted subtype had the highest levels of neutrophils and Tregs. Intratumoral CD68-positive macrophages, M1 macrophages, and intrastromal CD4+ cells, CD4+FOXP3- cells, CD8+ cells, and PD-L1+ cells were further found to be the most robust prognostic biomarkers for DFS, which were used to construct and validate the immune-related risk score for risk stratification (high vs. median vs. low) and the prediction of 5-year DFS rates (23.2% vs. 37.9% vs. 43.1%, P < 0.001). In conclusion, the intricate and intrinsic structure of TIME in NSCLC was demonstrated, showing potency in subtyping and prognostication.

BDNF expression in GISTs predicts poor prognosis when associated with PD-L1 positive tumor-infiltrating lymphocytes

Substantial evidence indicates that brain-derived neurotrophic factor (BDNF) plays an important role in tumorigenesis, in addition to its primary role in neuronal activity. Gastrointestinal stromal tumors (GISTs), which are the most common mesenchymal neoplasms of the gastrointestinal tract, contain multiple types of tumor-infiltrating lymphocytes (TILs) that express relevant immune checkpoint proteins. However, no data have been reported on the role of BDNF in GISTs. This study aimed to investigate the expression pattern and prognostic value of BDNF in GIST patients with different degrees of risk, as well as the relationship between BDNF expression and immune checkpoints. Immunohistochemistry (IHC) demonstrated that higher BDNF expression was more likely to be present in high-risk patients and suggested a poor prognosis. A similar phenomenon was demonstrated in plasma. Even more interesting was that a positive correlation was present between BDNF and PD-L1⁺ expression on TILs. Moreover, high BDNF expression levels in combination with a high PD-L1⁺ TIL count predict extremely poor survival. The combination of BDNF expression and TIL PD-L1⁺ expression as a single biomarker was a powerful significant independent predictor of prognosis. Taken together, BDNF expression may serve as a significant prognostic factor, as the combination of BDNF expression and the PD-L1⁺ TIL subset led to superior prediction of GIST prognosis. Furthermore, our research coupled a neurotrophin with immunity, which provides novel evidence of neural and immune regulation in a clinical study of GIST.

Spatial Profiles of Intratumoral PD-1+ Helper T Cells Predict Prognosis in Head and Neck Squamous Cell Carcinoma

Background

Functional interactions between immune cells and neoplastic cells in the tumor immune microenvironment have been actively pursued for both biomarker discovery for patient stratification, as well as therapeutic anti-cancer targets to improve clinical outcomes. Although accumulating evidence indicates that intratumoral infiltration of immune cells has prognostic significance, limited information is available on the spatial infiltration patterns of immune cells within intratumoral regions. This study aimed to understand the intratumoral heterogeneity and spatial distribution of immune cell infiltrates associated with cell phenotypes and prognosis in head and neck squamous cell carcinoma (HNSCC).

Methods

A total of 88 specimens of oropharyngeal squamous cell carcinoma, categorized into discovery (n = 38) and validation cohorts (n = 51), were analyzed for immune contexture by multiplexed immunohistochemistry (IHC) and image cytometry-based quantification. Tissue segmentation was performed according to a mathematical morphological approach using neoplastic cell IHC images to dissect intratumoral regions into tumor cell nests versus intratumoral stroma.

Results

Tissue segmentation revealed heterogeneity in intratumoral T cells, varying from tumor cell nest-polarized to intratumoral stroma-polarized distributions. Leukocyte composition analysis revealed higher ratios of TH1/TH2 in tumor cell nests with higher percentages of helper T cells, B cells, and CD66b+ granulocytes within intratumoral stroma. A discovery and validation approach revealed a high density of programmed death receptor-1 (PD-1)+ helper T cells in tumor cell nests as a negative prognostic factor for short overall survival. CD163+ tumor-associated macrophages (TAM) provided the strongest correlation with PD-1+ helper T cells, and cases with a high density of PD-1+ helper T cells and CD163+ TAM had a significantly shorter overall survival than other cases.

Conclusion

This study reveals the significance of analyzing intratumoral cell nests and reports that an immune microenvironment with a high density of PD-1+ helper T cells in tumoral cell nests is a poor prognostic factor for HNSCC.

Development of a Multiplex Immunohistochemistry Workflow to Investigate the Immune Microenvironment in Mouse Models of Inflammatory Bowel Disease and Colon Cancer

Multiplex immunohistochemistry (mIHC) enables simultaneous staining of multiple immune markers on a single tissue section. Mounting studies have demonstrated the versatility of mIHC in evaluating immune infiltrates in different diseases and the tumour microenvironment (TME). However, the majority of published studies are limited to the analysis of human patient samples. Performing mIHC on formalin-fixed paraffin-embedded (FFPE) mouse tissues, particularly with sensitive antigens, remain challenging. The aim of our study was to develop a robust and reproducible protocol to uncover the immune landscape in mouse FFPE tissues. Effective antibody stripping while maintaining sensitivity to antigens and tissue adhesion to the glass slide is critical in developing an mIHC panel to allow successive rounds of staining. Thus, we identified a highly efficient stripping method that preserves signal intensity and antigenicity to allow multiple rounds of staining. We subsequently optimised an mIHC workflow with antibodies specific against CD4, CD8α, FOXP3 and B220 to identify distinct T and B cell populations on mouse FFPE tissues. Lastly, the application of this mIHC panel was validated in a mouse model of inflammatory bowel cancer, two allograft mouse models of spontaneous colon adenocarcinoma and a sporadic mouse model of colon cancer. Together, these demonstrate the utility of the aforementioned protocol in establishing the quantity and spatial localisation of immune cells in different pathological tissues.

Next-Generation Digital Histopathology of the Tumor Microenvironment

Progress in cancer research is substantially dependent on innovative technologies that permit a concerted analysis of the tumor microenvironment and the cellular phenotypes resulting from somatic mutations and post-translational modifications. In view of a large number of genes, multiplied by differential splicing as well as post-translational protein modifications, the ability to identify and quantify the actual phenotypes of individual cell populations in situ, i.e., in their tissue environment, has become a prerequisite for understanding tumorigenesis and cancer progression. The need for quantitative analyses has led to a renaissance of optical instruments and imaging techniques. With the emergence of precision medicine, automated analysis of a constantly increasing number of cellular markers and their measurement in spatial context have become increasingly necessary to understand the molecular mechanisms that lead to different pathways of disease progression in individual patients. In this review, we summarize the joint effort that academia and industry have undertaken to establish methods and protocols for molecular profiling and immunophenotyping of cancer tissues for next-generation digital histopathology-which is characterized by the use of whole-slide imaging (brightfield, widefield fluorescence, confocal, multispectral, and/or multiplexing technologies) combined with state-of-the-art image cytometry and advanced methods for machine and deep learning.