Patterns of BAP1 protein expression provide insights into prognostic significance and the biology of uveal melanoma

Heterogeneity and molecular landscape of melanoma: implications for targeted therapy

Uveal cancer (UM) offers a complex molecular landscape characterized by substantial heterogeneity, both on the genetic and epigenetic levels. This heterogeneity plays a critical position in shaping the behavior and response to therapy for this uncommon ocular malignancy. Targeted treatments with gene-specific therapeutic molecules may prove useful in overcoming radiation resistance, however, the diverse molecular makeups of UM call for a patient-specific approach in therapy procedures. We need to understand the intricate molecular landscape of UM to develop targeted treatments customized to each patient's specific genetic mutations. One of the promising approaches is using liquid biopsies, such as circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA), for detecting and monitoring the disease at the early stages. These non-invasive methods can help us identify the most effective treatment strategies for each patient. Single-cellular is a brand-new analysis platform that gives treasured insights into diagnosis, prognosis, and remedy. The incorporation of this data with known clinical and genomics information will give a better understanding of the complicated molecular mechanisms that UM diseases exploit. In this review, we focused on the heterogeneity and molecular panorama of UM, and to achieve this goal, the authors conducted an exhaustive literature evaluation spanning 1998 to 2023, using keywords like "uveal melanoma, "heterogeneity". "Targeted therapies"," "CTCs," and "single-cellular analysis".

Pleural mesothelioma (PMe): The evolving molecular knowledge of a rare and aggressive cancer

Mesothelioma is a type of late-onset cancer that develops in cells covering the outer surface of organs. Although it can affect the peritoneum, heart, or testicles, it mainly targets the lining of the lungs, making pleural mesothelioma (PMe) the most common and widely studied mesothelioma type. PMe is caused by exposure to fibres of asbestos, which when inhaled leads to inflammation and scarring of the pleura. Despite the ban on asbestos by most Western countries, the incidence of PMe is on the rise, also facilitated by a lack of specific symptomatology and diagnostic methods. Therapeutic options are also limited to mainly palliative care, making this disease untreatable. Here we present an overview of biological aspects underlying PMe by listing genetic and molecular mechanisms behind its onset, aggressive nature, and fast-paced progression. To this end, we report on the role of deubiquitinase BRCA1-associated protein-1 (BAP1), a tumour suppressor gene with a widely acknowledged role in the corrupted signalling and metabolism of PMe. This review aims to enhance our understanding of this devastating malignancy and propel efforts for its investigation.

Prognostic Value of BAP1 Protein Expression in Uveal Melanoma

The prognostic value of the traditional pathologic parameters that form part of the American Joint Committee on Cancer staging system and genetic classifications using monosomy chromosome 3 and structural alterations in chromosome 8 are well established and are part of the diagnostic workup of uveal melanoma (UM). However, it has not been fully clarified whether nuclear protein expression of the tumor suppressor gene BAP1 (nBAP1) by immunohistochemistry alone is as powerful a predictor of overall survival (OS) and/or disease-specific survival (DSS) as chromosome analysis. The protein expression of nBAP1 was evaluated in a retrospective cohort study of 308 consecutive patients treated by primary enucleation between January 1974 and December 2022. We correlated clinical, pathologic, and cytogenetic characteristics to identify the best prognostic indicators for OS and DSS. Loss of nBAP1 was detected in 144/308 (47%) of patients. Loss of nBAP1 expression was significantly associated with poor survival. In patients with disomy chromosome 3, nBAP1 negative is significantly associated with poorer OS but not DSS. We observed that older age (>63 years), presence of metastasis, and nBAP1 negative remained independent prognostic factors in multivariate analysis. nBAP1 protein expression proved to be a more reliable prognostic indicator for OS than the American Joint Committee on Cancer staging, M3 status, or The Cancer Genome Atlas classification in this cohort. This study provides support for accurate prognostication of UM patients in routine histology laboratories by immunohistochemistry for nBAP1 alone.

Cross talk between tumor stemness and microenvironment for prognosis and immunotherapy of uveal melanoma

PURPOSE

Tumor stem cells have emerged as a crucial focus of investigation and a therapeutic target in the context of cancer metastasis and drug resistance. They represent a promising novel approach to address the treatment of uveal melanoma (UVM).

METHODS

According to the one-class logistic regression (OCLR) approach, we first estimated two stemness indices (mDNAsi and mRNAsi) in a cohort of UVM (n = 80). The prognostic value of stemness indices among four subtypes of UVM (subtype A-D) was investigated. Moreover, univariate Cox regression and Lasso-penalized algorithms were conducted to identify a stemness-associated signature and verify in several independent cohorts. Besides, UVM patients classified into subgroups based on the stemness-associated signature. The differences in clinical outcomes, tumor microenvironment, and probability of immunotherapeutic response were investigated further.

RESULTS

We observed that mDNAsi was significantly linked with overall survival (OS) time of UVM, but no association was discovered between mRNAsi and OS. Stratification analysis indicated that the prognostic value of mDNAsi was only limited in subtype D of UVM. Besides, we established and verified a prognostic stemness-associated gene signature which can classify UVM patients into subgroups with distinct clinical outcomes, tumor mutation, immune microenvironment, and molecular pathways. The high risk of UVM is more sensitive to immunotherapy. Finally, a well-performed nomogram was constructed to predict the mortality of UVM patients.

CONCLUSIONS

This study offers a comprehensive examination of UVM stemness characteristics. We discovered mDNAsi-associated signatures improved the prediction capacity of individualized UVM prognosis and indicated prospective targets for stemness-regulated immunotherapy. Analysis of the interaction between stemness and tumor microenvironment may shed light on combinational treatment that targets both stem cell and the tumor microenvironment.

BAP1 mutations inhibit the NF-κB signaling pathway to induce an immunosuppressive microenvironment in uveal melanoma

BACKGROUND

Tumor immune microenvironment regulates the growth and metastasis of uveal melanoma (UM). This study aims to reveal the possible molecular mechanism of BRCA1-associated protein 1 (BAP1) mutations in affecting the tumor immune microenvironment in UM through mediating the nuclear factor-κB (NF-κB) signaling pathway.

METHODS

TCGA and cBioPortal databases jointly analyzed the genes with high mutation frequency in UM samples. Following survival analysis of UM patients, UM samples with BAP1 mutations were subjected to immune cell infiltration analysis. The signaling pathways associated with the mutated genes were screened by GSEA. Subsequently, the differential BAP1 expression was analyzed in the selected UM cell lines with wild type (WT) or mutant type (MUT) BAP1.

RESULTS

Bioinformatics analysis identified 12 genes mutated in the UM samples, while only BAP1 mutations were related to the prognosis of UM patients. UM patients with BAP1 mutations had higher immune cell infiltration. BAP1 mutations inhibited the NF-κB signaling pathway, suppressing the cytokine secretion and antigen presentation by macrophages. Rescue experiments confirmed that overexpressed NF-κB could reverse the effect of BAP1 mutations on the immunosuppressive microenvironment, thus suppressing the malignant phenotypes of UM cells.

CONCLUSION

BAP1 mutations may inhibit the NF-κB signaling pathway, repressing the cytokine secretion and antigen presentation by macrophages, which induces the immunosuppressive microenvironment, enhances the malignant phenotypes of UM cells and ultimately promotes the growth and metastasis of UM.

Deep learning classification of uveal melanoma based on histopathological images and identification of a novel indicator for prognosis of patients

BACKGROUND

Deep learning has been extensively used in digital histopathology. The purpose of this study was to test deep learning (DL) algorithms for predicting the vital status of whole-slide image (WSI) of uveal melanoma (UM).

METHODS

We developed a deep learning model (Google-net) to predict the vital status of UM patients from histopathological images in TCGA-UVM cohort and validated it in an internal cohort. The histopathological DL features extracted from the model and then were applied to classify UM patients into two subtypes. The differences between two subtypes in clinical outcomes, tumor mutation, and microenvironment, and probability of drug therapeutic response were investigated further.

RESULTS

We observed that the developed DL model can achieve a high accuracy of >  = 90% for patches and WSIs prediction. Using 14 histopathological DL features, we successfully classified UM patients into Cluster1 and Cluster2 subtypes. Compared to Cluster2, patients in the Cluster1 subtype have a poor survival outcome, increased expression levels of immune-checkpoint genes, higher immune-infiltration of CD8 + T cell and CD4 + T cells, and more sensitivity to anti-PD-1 therapy. Besides, we established and verified prognostic histopathological DL-signature and gene-signature which outperformed the traditional clinical features. Finally, a well-performed nomogram combining the DL-signature and gene-signature was constructed to predict the mortality of UM patients.

CONCLUSIONS

Our findings suggest that DL model can accurately predict vital status in UM patents just using histopathological images. We found out two subgroups based on histopathological DL features, which may in favor of immunotherapy and chemotherapy. Finally, a well-performing nomogram that combines DL-signature and gene-signature was constructed to give a more straightforward and reliable prognosis for UM patients in treatment and management.

Digital morphometry and cluster analysis identifies four types of melanocyte during uveal melanoma progression

BACKGROUND

Several types of benign and malignant uveal melanocytes have been described based on their histological appearance. However, their characteristics have not been quantified, and their distribution during progression from normal choroidal melanocytes to primary tumors and metastases has not been reported.

METHODS

A total of 1,245,411 digitally scanned melanocytes from normal choroid, choroidal nevi, primary uveal melanomas, and liver metastases were entered into two-step cluster analyses to delineate cell types based on measured morphometric characteristics and expression of protein markers.

RESULTS

Here we show that a combination of the area and circularity of cell nuclei, and BAP-1 expression in nuclei and cytoplasms yields the highest silhouette of cohesion and separation. Normal choroidal melanocytes and three types of uveal melanoma cells are outlined: Epithelioid (large, rounded nuclei; BAP-1 low; IGF-1R, IDO, and TIGIT high), spindle A (small, elongated nuclei; BAP-1 high; IGF-1R low; IDO, and TIGIT intermediate), and spindle B (large, elongated nuclei; BAP-1, IGF-1R, IDO, and TIGIT low). In normal choroidal tissue and nevi, only normal melanocytes and spindle A cells are represented. Epithelioid and spindle B cells are overrepresented in the base and apex, and spindle A cells in the center of primary tumors. Liver metastases contain no normal melanocytes or spindle A cells.

CONCLUSIONS

Four basic cell types can be outlined in uveal melanoma progression: normal, spindle A and B, and epithelioid. Differential expression of tumor suppressors, growth factors, and immune checkpoints could contribute to their relative over- and underrepresentation in benign, primary tumor, and metastatic samples.

Advances in the clinical management of uveal melanoma

Melanomas arising in the uveal tract of the eye are a rare form of the disease with a biology and clinical phenotype distinct from their more common cutaneous counterparts. Treatment of primary uveal melanoma with radiotherapy, enucleation or other modalities achieves local control in more than 90% of patients, although 40% or more ultimately develop distant metastases, most commonly in the liver. Until January 2022, no systemic therapy had received regulatory approval for patients with metastatic uveal melanoma, and these patients have historically had a dismal prognosis owing to the limited efficacy of the available treatments. A series of seminal studies over the past two decades have identified highly prevalent early, tumour-initiating oncogenic genomic aberrations, later recurring prognostic alterations and immunological features that characterize uveal melanoma. These advances have driven the development of a number of novel emerging treatments, including tebentafusp, the first systemic therapy to achieve regulatory approval for this disease. In this Review, our multidisciplinary and international group of authors summarize the biology of uveal melanoma, management of primary disease and surveillance strategies to detect recurrent disease, and then focus on the current standard and emerging regional and systemic treatment approaches for metastatic uveal melanoma.

Correlation between BAP1 Localization, Driver Mutations, and Patient Survival in Uveal Melanoma

Uveal melanoma (UM) is an uncommon but highly aggressive ocular malignancy. Poor overall survival is associated with deleterious BAP1 alterations, which frequently occur with monosomy 3 (LOH3) and a characteristic gene expression profile. Tumor DNA from a cohort of 100 UM patients from Moorfields Biobank (UK) that had undergone enucleation were sequenced for known UM driver genes (BAP1, SF3B1, EIF1AX, GNAQ, and GNA11). Immunohistochemical staining of BAP1 and interphase FISH for chromosomes 3 and 8 was performed, and cellular localization of BAP1 was correlated with BAP1 mutations. Wildtype (WT) BAP1 staining was characterized by nBAP1 expression with <10% cytoplasmic BAP1 (cBAP1). Tumors exhibited heterogeneity with respect to BAP1 staining with different percentages of nBAP1 loss: ≥25% loss of nuclear BAP1 (nBAP1) was superior to chr8q and LOH3 as a prognostic indicator. Of the successfully sequenced UMs, 38% harbored oncogenic mutations in GNA11 and 48% harbored mutations in GNAQ at residues 209 or 183. Of the secondary drivers, 39% of mutations were in BAP1, 11% were in EIF1AX, and 20% were in the SF3B1 R625 hotspot. Most tumors with SF3B1 or EIF1AX mutations retained nuclear BAP1 (nBAP1). The majority of tumor samples with likely pathogenic BAP1 mutations, regardless of mutation class, displayed ≥25% loss of nBAP1. This included all tumors with truncating mutations and 80% of tumors with missense mutations. In addition, 60% of tumors with truncating mutations and 82% of tumors with missense mutations expressed >10% cBAP1.

Aggressive uveal melanoma displays a high degree of centrosome amplification, opening the door to therapeutic intervention

Uveal melanoma (UM) is the most common intraocular cancer in adults. Whilst treatment of primary UM (PUM) is often successful, around 50% of patients develop metastatic disease with poor outcomes, linked to chromosome 3 loss (monosomy 3, M3). Advances in understanding UM cell biology may indicate new therapeutic options. We report that UM exhibits centrosome abnormalities, which in other cancers are associated with increased invasiveness and worse prognosis, but also represent a potential Achilles' heel for cancer-specific therapeutics. Analysis of 75 PUM patient samples revealed both higher centrosome numbers and an increase in centrosomes with enlarged pericentriolar matrix (PCM) compared to surrounding normal tissue, both indicative of centrosome amplification. The PCM phenotype was significantly associated with M3 (t-test, p < 0.01). Centrosomes naturally enlarge as cells approach mitosis; however, whilst UM with higher mitotic scores had enlarged PCM regardless of genetic status, the PCM phenotype remained significantly associated with M3 in UM with low mitotic scores (ANOVA, p = 0.021) suggesting that this is independent of proliferation. Phenotypic analysis of patient-derived cultures and established UM lines revealed comparable levels of centrosome amplification in PUM cells to archetypal triple-negative breast cancer cell lines, whilst metastatic UM (MUM) cell lines had even higher levels. Importantly, many UM cells also exhibit centrosome clustering, a common strategy employed by other cancer cells with centrosome amplification to survive cell division. As UM samples with M3 display centrosome abnormalities indicative of amplification, this phenotype may contribute to the development of MUM, suggesting that centrosome de-clustering drugs may provide a novel therapeutic approach.

Tumor suppressor BAP1 nuclear import is governed by transportin-1

Subcellular localization of the deubiquitinating enzyme BAP1 is deterministic for its tumor suppressor activity. While the monoubiquitination of BAP1 by an atypical E2/E3-conjugated enzyme UBE2O and BAP1 auto-deubiquitination are known to regulate its nuclear localization, the molecular mechanism by which BAP1 is imported into the nucleus has remained elusive. Here, we demonstrated that transportin-1 (TNPO1, also known as Karyopherin β2 or Kapβ2) targets an atypical C-terminal proline-tyrosine nuclear localization signal (PY-NLS) motif of BAP1 and serves as the primary nuclear transporter of BAP1 to achieve its nuclear import. TNPO1 binding dissociates dimeric BAP1 and sequesters the monoubiquitination sites flanking the PY-NLS of BAP1 to counteract the function of UBE2O that retains BAP1 in the cytosol. Our findings shed light on how TNPO1 regulates the nuclear import, self-association, and monoubiquitination of BAP1 pertinent to oncogenesis.

A Novel Four Genes of Prognostic Signature for Uveal Melanoma

Autophagy and immunity play critical roles in various cancers, but the prognostic impact of autophagy and immunity for uveal melanoma (UM) remains lacking. Therefore, the RNA sequencing of data in the TCGA-UVM dataset was downloaded from UCSC Xena database. The prognostic autophagy- and immunity-related genes (AIRGs) were selected via univariate Cox regression. Next, we applied LASSO method to construct four genes of signature in the TCGA-UVM and verified in another two GEO datasets (GSE84976 and GSE22138). This signature intimately associated with overall survival (OS) time and metastasis-free survival (MFS) time of UM, which could be considered as a prognostic indicator. Besides, by applying risk assessment, the patients of UM can be divided into two subgroups (high/low risk) with different survival time, distinct clinical outcomes, and immune microenvironments. Gene set enrichment analysis (GSEA) manifested that cancer hallmark epithelial-mesenchymal transition and KRAS pathways were positively activated in the high-risk group. Moreover, the high-risk group could be more sensitive to chemotherapies than the low-risk group. Thus, our finding suggested that the four genes of signature closely linked with UM risk and survival can afford more accurate survival prediction and potential therapeutic targets for clinical application.

Landscape of Infiltrated Immune Cell Characterization in Uveal Melanoma to Improve Immune Checkpoint Blockade Therapy

Background

Numerous studies indicated that tumor-infiltrated immune cells (TIC) in the microenvironment are substantially linked to immunotherapy response and cancer prognosis. However, systematic studies of infiltrated immune cell characterization in uveal melanoma (UM) for prognosis and immune checkpoint blockade therapy are lacking.

Methods

UM datasets were extracted from open access resources (TCGA and GEO databases). The tumor-infiltrated immune cells in the microenvironment were decoded by using the CIBERSORT algorithm, which was further applied to classify UM patients into subgroups using an unsupervised clustering method. The Boruta algorithm and principal component analysis were used to calculate the TIC scores for UM patients. Kaplan–Meier curves were plotted to prove the prognostic value of TIC scores. Besides, the correlations of the TIC score with clinical features, mutated characteristics, and the immune therapeutic response were subsequently investigated.

Results

As a result, we defined three subtypes among 171 UM patients according to the TIC profiles and then calculated the TIC score to characterize the immune patterns for all patients. We discovered that high-TIC score patients with low BAP1 and high EIF1AX mutations have a better prognosis than low-TIC score patients. Activation of immune inflammatory response and increase in immune checkpoint-related genes in high-TIC score patients may account for good prognosis and immunotherapy response. Three melanoma cohorts received immunotherapy, proving that high-TIC score patients have substantial clinical and immune therapeutic improvements. Besides, several potential therapeutic agents were identified in the low-TIC score group.

Conclusion

Our study afforded a comprehensive view of infiltrated immune cell characterization to elucidate different immune patterns of UM. We also established a robust TIC-score signature, which may work as a prognostic biomarker and immune therapeutic predictor.

Vascular Lakes in Uveal Melanoma and Their Association With Outcome

Purpose

Prognostic predictors in uveal melanoma (UM) consist of clinical, histomorphologic, and genetic features. Vascular lakes (VLs) are immature blood vessels within UM with unknown significance for metastatic risk.

Methods

A clinically well-phenotyped cohort of 136 hematoxylin and eosin–stained slides of UM enucleation specimens were retrospectively analyzed on scanned whole-slide images. These were annotated for VL in QuPath, assessing VL number and area. Using SPSS (V27.0), the Mann–Whitney U test and Cox regression were applied to evaluate whether there was any correlation between VL number and area within the tumor (VL-TA) compared with other prognostic parameters and patient survival times.

Results

UMs with monosomy 3 (M3) have significant differences in their VL numbers (P = 0.008) and VL-TA ratios (P = 0.002) compared with disomy 3-UM. Nuclear BAP1-negative (nBAP1^–) UMs have significant differences in their VL-TA ratio (P = 0.002) compared to nBAP1⁺ UMs. Survival times of patients with UM with epithelioid-celled tumors varied depending on their VL-TA ratio (P = 0.057). Similarly, in M3-UM, significant differences in survival (P = 0.009) were seen in patients, depending on VL number. Finally, patients with UM with shorter overall survival showed significant differences in their tumor VL-TA ratios (P = 0.043) and the number of VLs present (P = 0.002) than patients with UM who had longer survival.

Conclusions

Our pilot data suggest that VL-TA is an additional poor prognostic parameter in UM.

Translational Relevance

Digital analysis of UM can be easily performed to assess various prognostic parameters. Our pilot study demonstrates that UM-VL could be combined with other parameters to determine metastatic risk of patients with UM.

DNA damage repair-related gene signature predicts prognosis and indicates immune cell infiltration landscape in skin cutaneous melanoma

BACKGROUND

DNA damage repair plays an important role in the onset and progression of cancers and its resistance to treatment therapy. This study aims to assess the prognostic potential of DNA damage repair markers in skin cutaneous melanoma (SKCM).

METHOD

In this study, we have analyzed the gene expression profiles being downloaded from TCGA, GTEx, and GEO databases. We sequentially used univariate and LASSO Cox regression analyses to screen DNA repair genes associated with prognosis. Then, we have conducted a multivariate regression analysis to construct the prognostic profile of DNA repair-related genes (DRRGs). The risk coefficient is used to calculate the risk scores and divide the patients into two cohorts. Additionally, we validated our prognosis model on an external cohort as well as evaluated the link between immune response and the DRRGs prognostic profiles. The risk signature is compared to immune cell infiltration, chemotherapy, and immune checkpoint inhibitors (ICIs) treatment.

RESULTS

An analysis using LASSO-Cox stepwise regression established a prognostic signature consisting of twelve DRRGs with strong predictive ability. Disease-specific survival (DSS) is found to be lower among high-risk patients group as compared to low-risk patients. The signature may be employed as an independent prognostic predictor after controlling for clinicopathological factors, as demonstrated by validation on one external GSE65904 cohort. A strong correlation is also found between the risk score and the immune microenvironment, along with the infiltrating immune cells, and ICIs key molecules. The gene enrichment analysis results indicate a wide range of biological activities and pathways to be exhibited by high-risk groups. Furthermore, Cisplatin exhibited a considerable response sensitivity in low-risk groups as opposed to the high-risk incidents, while docetaxel exhibited a considerable response sensitivity in high-risk groups.

CONCLUSIONS

Our findings provide a thorough investigation of DRRGs to develop an DSS-related prognostic indicator which may be useful in forecasting SKCM progression and enabling more enhanced clinical benefits from immunotherapy.

Prognostic Biomarkers in Uveal Melanoma: The Status Quo, Recent Advances and Future Directions

Simple Summary

Although rare, uveal melanoma (UM) is the most common cancer that develops inside adult eyes. The prognosis is poor, since 50% of patients will develop lethal metastases in the first decade, especially to the liver. Once metastases are detected, life expectancy is limited, given that the available treatments are mostly unsuccessful. Thus, there is a need to find methods that can accurately predict UM prognosis and also effective therapeutic strategies to treat this cancer. In this manuscript, we initially compile the current knowledge on epidemiological, clinical, pathological and molecular features of UM. Then, we cover the most relevant prognostic factors currently used for the evaluation and follow-up of UM patients. Afterwards, we highlight emerging molecular markers in UM published over the last three years. Finally, we discuss the problems preventing meaningful advances in the treatment and prognostication of UM patients, as well as forecast new roadblocks and paths of UM-related research.

Abstract

Uveal melanoma (UM) is the most common malignant intraocular tumour in the adult population. It is a rare cancer with an incidence of nearly five cases per million inhabitants per year, which develops from the uncontrolled proliferation of melanocytes in the choroid (≈90%), ciliary body (≈6%) or iris (≈4%). Patients initially present either with symptoms like blurred vision or photopsia, or without symptoms, with the tumour being detected in routine eye exams. Over the course of the disease, metastases, which are initially dormant, develop in nearly 50% of patients, preferentially in the liver. Despite decades of intensive research, the only approach proven to mildly control disease spread are early treatments directed to ablate liver metastases, such as surgical excision or chemoembolization. However, most patients have a limited life expectancy once metastases are detected, since there are limited therapeutic approaches for the metastatic disease, including immunotherapy, which unlike in cutaneous melanoma, has been mostly ineffective for UM patients. Therefore, in order to offer the best care possible to these patients, there is an urgent need to find robust models that can accurately predict the prognosis of UM, as well as therapeutic strategies that effectively block and/or limit the spread of the metastatic disease. Here, we initially summarized the current knowledge about UM by compiling the most relevant epidemiological, clinical, pathological and molecular data. Then, we revisited the most important prognostic factors currently used for the evaluation and follow-up of primary UM cases. Afterwards, we addressed emerging prognostic biomarkers in UM, by comprehensively reviewing gene signatures, immunohistochemistry-based markers and proteomic markers resulting from research studies conducted over the past three years. Finally, we discussed the current hurdles in the field and anticipated the future challenges and novel avenues of research in UM.

Prognostic Factor Utility of BAP1 Immunohistochemistry in Uveal Melanoma: A Single Center Study in Spain

Simple Summary

As uveal melanoma metastasis rates are still very high, the mechanisms by which it spreads need to be evaluated. Our research sought to determine which pathological and clinical features were correlated with the prognosis of uveal melanoma in a Spanish community. BAP1 (BRCA1-Associated Protein 1) gene mutation is one of the strongest predictors for metastasis in uveal melanoma. The BAP1 protein has a tumor suppressor function and the presence of the BAP1 protein can be shown using immunohistochemical staining. Our study showed that nuclear BAP1 immunostaining had a significant correlation with survival rate in our sample, and patients with a lack of nuclear BAP1 immunostaining should be considered high-risk and receive a close follow-up. This stain can be used as routine technique in the pathological examination of uveal melanoma.

Abstract

Even today, the mortality rate for uveal melanoma (UM) remains very high. In our research, we sought to determine which pathological and clinical features were correlated with the prognosis of UM. BAP1 (BRCA1-Associated Protein 1) gene mutation has been analyzed as one of the strongest predictors for metastasis in UM. The BAP1 gene codifies the BAP1 protein which has a tumor suppressor function. The presence of this protein can be determined by BAP1 immunohistochemical staining. Eighty-four uveal melanoma patients and forty enucleated eyeballs were examined. Metastasis was present in 24 patients. Nuclear BAP1 staining was low in 23 patients. The presence of a higher large basal diameter tumor (p < 0.001), tumor infiltrating lymphocytes (p = 0.020), and a lack of nuclear BAP1 immunostaining (p = 0.001) ocurred significantly more often in the metastatic group. Metastasis-free survival was lower in patients with low nuclear BAP1 staining (p = 0.003). In conclusion, to the best of our knowledge, this is the first time that BAP1 staining has been studied in uveal melanoma in a Spanish community. We believe that this technique should become routine in the pathological examination of uveal melanoma in order to allow adequate classification of patients and to establish an individual follow-up plan.

Diagnostic Utility of BAP1, EZH2 and Survivin in Differentiating Pleural Epithelioid Mesothelioma and Reactive Mesothelial Hyperplasia: Immunohistochemical Study

Background: Epithelioid mesothelioma (EM) is the commonest subtype of malignant pleural mesothelioma. Its histopathological discrimination from reactive mesothelial hyperplasia (RMH) could be challenging. Thus, an immunohistochemical panel is mandatory for better discrimination. BAP1 is a newly identified diagnostic marker whose loss is specific to malignant mesothelioma. EZH2 overexpression is reported in different cancers, but its relation to BAP1 in malignant mesothelioma has not been fully understood. Survivin expression is said to be significantly higher in EM than in non-neoplastic pleural tissue, but its diagnostic utility as an immunohistochemical marker has not been thoroughly investigated in this field. To the best of our knowledge, no previous studies have been conducted to assess the diagnostic accuracy of the combined use of these three nuclear markers (BAP1, EZH2 and Survivin) in discriminating pleural EM from RMH. Methods: This retrospective study includes two groups: 81 cases of pleural EM and 67 cases of RMH, retrieved from the archives of Pathology Department of Ain Shams University Hospitals and Ain-Shams University Specialized Hospital during the period from January 2016 to December 2019. An immunohistochemical study was performed using BAP1, EZH2 and Survivin antibodies. Results: There were highly statistically significant relations between study groups as regards the studied markers (p = 0.001 for each). The specificity was 100% for all combinations of immunohistochemical markers. Sensitivity of any combination of the immunohistochemical markers used in this study was found to be higher than the sensitivity of any of these markers used individually. The combination of all three markers showed the highest diagnostic accuracy (95.9%) and the highest sensitivity (92.6%). However, the combination of Survivin and EZH2 yielded the same diagnostic accuracy and sensitivity. Conclusion: Adding EZH2, Survivin and BAP1 to the diagnostic IHC panel for differentiating pleural EM and RMH could enhance diagnostic sensitivity. Moreover, Survivin is a potentially promising marker in this context, especially when combined with EZH2.

Cost-utility analysis of a decade of liver screening for metastases using the Liverpool Uveal Melanoma Prognosticator Online (LUMPO)

This paper outlines a method for cost-utility analysis of liver screening for metastases in patients with posterior uveal melanoma (UM). A semiparametric model of the cumulative incidence of onset of liver metastases was fitted to a retrospective data set of 615 subjects with clinical follow-up with respect to liver surveillance imaging and outcome. The model was internally validated via bootstrap resampling in terms of its discrimination and calibration performance. Receiver operating characteristics (ROC) were derived at different time points. The discrimination performances are consistent across time. The area under the ROC curve at 5 years post treatment was 0.85 [95% CI: 0.81-0.88]. A goodness-of-fit test gives χ²(10)=5.3,p=0.9 demonstrating no evidence against the null hypothesis of zero difference between observed and expected onset of metastatic events. Results showed that at 80% sensitivity, 87% of UM patients will avoid unnecessary radiological scans. This provides potential cost savings of between £46,000 and £97,000 per year to the National Health Service assuming 600 new cases per year.

Roles and mechanisms of BAP1 deubiquitinase in tumor suppression

The BAP1 gene has emerged as a major tumor suppressor mutated with various frequencies in numerous human malignancies, including uveal melanoma, malignant pleural mesothelioma, clear cell renal cell carcinoma, intrahepatic cholangiocarcinoma, hepatocellular carcinoma, and thymic epithelial tumors. BAP1 mutations are also observed at low frequency in other malignancies including breast, colorectal, pancreatic, and bladder cancers. BAP1 germline mutations are associated with high incidence of mesothelioma, uveal melanoma, and other cancers, defining the "BAP1 cancer syndrome." Interestingly, germline BAP1 mutations constitute an important paradigm for gene-environment interactions, as loss of BAP1 predisposes to carcinogen-induced tumorigenesis. Inactivating mutations of BAP1 are also identified in sporadic cancers, denoting the importance of this gene for normal tissue homeostasis and tumor suppression, although some oncogenic properties have also been attributed to BAP1. BAP1 belongs to the deubiquitinase superfamily of enzymes, which are responsible for the maturation and turnover of ubiquitin as well as the reversal of substrate ubiquitination, thus regulating ubiquitin signaling. BAP1 is predominantly nuclear and interacts with several chromatin-associated factors, assembling multi-protein complexes with mutually exclusive partners. BAP1 exerts its function through highly regulated deubiquitination of its substrates. As such, BAP1 orchestrates chromatin-associated processes including gene expression, DNA replication, and DNA repair. BAP1 also exerts cytoplasmic functions, notably in regulating Ca²⁺ signaling at the endoplasmic reticulum. This DUB is also subjected to multiple post-translational modifications, notably phosphorylation and ubiquitination, indicating that several signaling pathways tightly regulate its function. Recent progress indicated that BAP1 plays essential roles in multiple cellular processes including cell proliferation and differentiation, cell metabolism, as well as cell survival and death. In this review, we summarize the biological and molecular functions of BAP1 and explain how the inactivation of this DUB might cause human cancers. We also highlight some of the unresolved questions and suggest potential new directions.

Applying Single-Cell Technology in Uveal Melanomas: Current Trends and Perspectives for Improving Uveal Melanoma Metastasis Surveillance and Tumor Profiling

Uveal melanoma (UM) is the most common primary adult intraocular malignancy. This rare but devastating cancer causes vision loss and confers a poor survival rate due to distant metastases. Identifying clinical and molecular features that portend a metastatic risk is an important part of UM workup and prognostication. Current UM prognostication tools are based on determining the tumor size, gene expression profile, and chromosomal rearrangements. Although we can predict the risk of metastasis fairly accurately, we cannot obtain preclinical evidence of metastasis or identify biomarkers that might form the basis of targeted therapy. These gaps in UM research might be addressed by single-cell research. Indeed, single-cell technologies are being increasingly used to identify circulating tumor cells and profile transcriptomic signatures in single, drug-resistant tumor cells. Such advances have led to the identification of suitable biomarkers for targeted treatment. Here, we review the approaches used in cutaneous melanomas and other cancers to isolate single cells and profile them at the transcriptomic and/or genomic level. We discuss how these approaches might enhance our current approach to UM management and review the emerging data from single-cell analyses in UM.

A Comprehensive Prognostic and Immunological Analysis of a Six-Gene Signature Associated With Glycolysis and Immune Response in Uveal Melanoma

Uveal melanoma (UM) is a subtype of melanoma with poor prognosis. This study aimed to construct a new prognostic gene signature that can be used for survival prediction and risk stratification of UM patients. In this work, transcriptome data from the Molecular Signatures Database were used to identify the cancer hallmarks most relevant to the prognosis of UM patients. Weighted gene co-expression network, univariate least absolute contraction and selection operator (LASSO), and multivariate Cox regression analyses were used to construct the prognostic gene characteristics. Kaplan-Meier and receiver operating characteristic (ROC) curves were used to evaluate the survival predictive ability of the gene signature. The results showed that glycolysis and immune response were the main risk factors for overall survival (OS) in UM patients. Using univariate Cox regression analysis, 238 candidates related to the prognosis of UM patients were identified (p < 0.05). Using LASSO and multivariate Cox regression analyses, a six-gene signature including ARPC1B, BTBD6, GUSB, KRTCAP2, RHBDD3, and SLC39A4 was constructed. Kaplan-Meier analysis of the UM cohort in the training set showed that patients with higher risk scores had worse OS (HR = 2.61, p < 0.001). The time-dependent ROC (t-ROC) curve showed that the risk score had good predictive efficiency for UM patients in the training set (AUC > 0.9). Besides, t-ROC analysis showed that the predictive ability of risk scores was significantly higher than that of other clinicopathological characteristics. Univariate and multivariate Cox regression analyses showed that risk score was an independent risk factor for OS in UM patients. The prognostic value of risk scores was further verified in two external UM cohorts (GSE22138 and GSE84976). Two-factor survival analysis showed that UM patients with high hypoxia or immune response scores and high risk scores had the worst prognosis. Moreover, a nomogram based on the six-gene signature was established for clinical practice. In addition, risk scores were related to the immune infiltration profiles. Taken together, this study identified a new prognostic six-gene signature related to glycolysis and immune response. This six-gene signature can not only be used for survival prediction and risk stratification but also may be a potential therapeutic target for UM patients.

Transcriptome Profiling Reveals New Insights into the Immune Microenvironment and Upregulation of Novel Biomarkers in Metastatic Uveal Melanoma

Simple Summary

Uveal melanoma (UM) is a rare aggressive eye cancer. Although treatment of the eye tumour is successful, about 50% of UM patients develop a relapse of their cancer in the liver. At present, such advanced disease is not curable. A better understanding of the metastatic UM (mUM) in the liver is essential to improve patient survival. This study examines both the response of immune cells within the liver to the UM secondaries (metastases), as well as the expression of various proteins by the UM cells. Our study demonstrates that there is a limited immune response to the mUM, but reveals that a certain type of reactive immune cell: a protumourigenic subset of macrophage is dominant within the mUM. Our research also reveals novel proteins within the mUM, which are specific to these cells and therefore may be targetable in future therapies.

Abstract

Metastatic uveal melanoma (mUM) to the liver is incurable. Transcriptome profiling of 40 formalin-fixed paraffin-embedded mUM liver resections and 6 control liver specimens was undertaken. mUMs were assessed for morphology, nuclear BAP1 (nBAP1) expression, and their tumour microenvironments (TME) using an “immunoscore” (absent/altered/high) for tumour-infiltrating lymphocytes (TILs) and macrophages (TAMs). Transcriptomes were compared between mUM and control liver; intersegmental and intratumoural analyses were also undertaken. Most mUM were epithelioid cell-type (75%), amelanotic (55%), and nBAP1-ve (70%). They had intermediate (68%) or absent (15%) immunoscores for TILs and intermediate (53%) or high (45%) immunoscores for TAMs. M2-TAMs were dominant in the mUM-TME, with upregulated expression of ANXA1, CD74, CXCR4, MIF, STAT3, PLA2G6, and TGFB1. Compared to control liver, mUM showed significant (p < 0.01) upregulation of 10 genes: DUSP4, PRAME, CD44, IRF4/MUM1, BCL2, CD146/MCAM/MUC18, IGF1R, PNMA1, MFGE8/lactadherin, and LGALS3/Galectin-3. Protein expression of DUSP4, CD44, IRF4, BCL-2, CD146, and IGF1R was validated in all mUMs, whereas protein expression of PRAME was validated in 10% cases; LGALS3 stained TAMs, and MFGEF8 highlighted bile ducts only. Intersegmental mUMs show differing transcriptomes, whereas those within a single mUM were similar. Our results show that M2-TAMs dominate mUM-TME with upregulation of genes contributing to immunosuppression. mUM significantly overexpress genes with targetable signalling pathways, and yet these may differ between intersegmental lesions.

Piloting a Deep Learning Model for Predicting Nuclear BAP1 Immunohistochemical Expression of Uveal Melanoma from Hematoxylin-and-Eosin Sections

Background

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. Monosomy 3 and BAP1 mutation are strong prognostic factors predicting metastatic risk in UM. Nuclear BAP1 (nBAP1) expression is a close immunohistochemical surrogate for both genetic alterations. Not all laboratories perform routine BAP1 immunohistochemistry or genetic testing, and rely mainly on clinical information and anatomic/morphologic analyses for UM prognostication. The purpose of our study was to pilot deep learning (DL) techniques to predict nBAP1 expression on whole slide images (WSIs) of hematoxylin and eosin (H&E) stained UM sections.

Methods

One hundred forty H&E-stained UMs were scanned at 40 × magnification, using commercially available WSI image scanners. The training cohort comprised 66 BAP1⁺ and 74 BAP1⁻ UM, with known chromosome 3 status and clinical outcomes. Nonoverlapping areas of three different dimensions (512 × 512, 1024 × 1024, and 2048 × 2048 pixels) for comparison were extracted from tumor regions in each WSI, and were resized to 256 × 256 pixels. Deep convolutional neural networks (Resnet18 pre-trained on Imagenet) and auto-encoder-decoders (U-Net) were trained to predict nBAP1 expression of these patches. Trained models were tested on the patches cropped from a test cohort of WSIs of 16 BAP1⁺ and 28 BAP1⁻ UM cases.

Results

The trained model with best performance achieved area under the curve values of 0.90 for patches and 0.93 for slides on the test set.

Conclusions

Our results show the effectiveness of DL for predicting nBAP1 expression in UM on the basis of H&E sections only.

Translational Relevance

Our pilot demonstrates a high capacity of artificial intelligence-related techniques for automated prediction on the basis of histomorphology, and may be translatable into routine histology laboratories.

MicroRNAs and Uveal Melanoma: Understanding the Diverse Role of These Small Molecular Regulators

Uveal melanoma (UM) is a rare tumour of the eye, characterised by a high propensity to metastasise in half of all patients, most frequently to the liver. Although there are effective treatment options for the primary tumour, once metastasis has occurred prognosis is poor, with overall survival limited to months. Currently, there are no effective treatments for metastatic UM, despite the tumour having a well-defined signalling pathway to which many therapies have been directed. In an effort to develop novel treatment approaches, understanding the role of other signalling molecules, such as microRNAs, is fundamental. MicroRNAs (miRNAs) are small non-coding RNA molecules involved in posttranscriptional gene regulation, resulting in reduced target gene expression and subsequent protein translation. In UM, several dysregulated miRNAs have been proposed to play a functional role in disease progression, whereas others have been put forward as clinical biomarkers of high-risk disease following isolation from blood, plasma and exosomes. Most recently, analyses of large datasets have identified promising prognostic miRNA signatures and panels. This review navigates the plethora of aberrant miRNAs disclosed so far in UM, and maps these to signalling pathways, which could be targeted in future therapies for the disseminated disease.

Biological Mechanisms and Clinical Significance of BAP1 Mutations in Human Cancer

Among more than 200 BAP1-mutant families affected by the "BAP1 cancer syndrome," nearly all individuals inheriting a BAP1 mutant allele developed one or more malignancies during their lifetime, mostly uveal and cutaneous melanoma, mesothelioma, and clear-cell renal cell carcinoma. These cancer types are also those that, when they occur sporadically, are more likely to carry somatic biallelic BAP1 mutations. Mechanistic studies revealed that the tumor suppressor function of BAP1 is linked to its dual activity in the nucleus, where it is implicated in a variety of processes including DNA repair and transcription, and in the cytoplasm, where it regulates cell death and mitochondrial metabolism. BAP1 activity in tumor suppression is cell type- and context-dependent. BAP1 has emerged as a critical tumor suppressor across multiple cancer types, predisposing to tumor development when mutated in the germline as well as somatically. Moreover, BAP1 has emerged as a key regulator of gene-environment interaction.This article is highlighted in the In This Issue feature, p. 1079.

Loss of BAP1 expression is associated with an immunosuppressive microenvironment in uveal melanoma, with implications for immunotherapy development

Immunotherapy using immune checkpoint inhibitors (ICIs) induces durable responses in many metastatic cancers. Metastatic uveal melanoma (mUM), typically occurring in the liver, is one of the most refractory tumours to ICIs and has dismal outcomes. Monosomy 3 (M3), polysomy 8q, and BAP1 loss in primary uveal melanoma (pUM) are associated with poor prognoses. The presence of tumour‐infiltrating lymphocytes (TILs) within pUM and surrounding mUM – and some evidence of clinical responses to adoptive TIL transfer – strongly suggests that UMs are indeed immunogenic despite their low mutational burden. The mechanisms that suppress TILs in pUM and mUM are unknown. We show that BAP1 loss is correlated with upregulation of several genes associated with suppressive immune responses, some of which build an immune suppressive axis, including HLA‐DR, CD38, and CD74. Further, single‐cell analysis of pUM by mass cytometry confirmed the expression of these and other markers revealing important functions of infiltrating immune cells in UM, most being regulatory CD8⁺ T lymphocytes and tumour‐associated macrophages (TAMs). Transcriptomic analysis of hepatic mUM revealed similar immune profiles to pUM with BAP1 loss, including the expression of IDO1. At the protein level, we observed TAMs and TILs entrapped within peritumoural fibrotic areas surrounding mUM, with increased expression of IDO1, PD‐L1, and β‐catenin (CTNNB1), suggesting tumour‐driven immune exclusion and hence the immunotherapy resistance. These findings aid the understanding of how the immune response is organised in BAP1⁻ mUM, which will further enable functional validation of detected biomarkers and the development of focused immunotherapeutic approaches. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

The diagnostic utility of next-generation sequencing on FNA biopsies of melanocytic uveal lesions

BACKGROUND

Uveal melanoma is highly aggressive, and overall prognosis depends on mutation status. Fine-needle aspiration biopsies (FNABs) play an important role in obtaining fresh tissue for cytologic diagnosis and molecular studies. It has been suggested that, although FNAB usually provides high diagnostic accuracy, there may be limited cellularity, which may compromise diagnostic potential for molecular studies. FNABs of uveal melanocytic lesions were evaluated to assess sample adequacy for both cytologic evaluation and next-generation sequencing (NGS).

METHODS

The authors retrospectively evaluated 36 cases of melanocytic uveal lesions from 2015 to 2018. Samples were obtained by ophthalmologist-performed FNAB and aliquoted for cytology and NGS. Various combinations of direct smears, liquid-based cytology slides, cell blocks, and immunohistochemical stains for melanocytic markers were performed. All samples were tested for molecular alterations using hybrid-capture-based NGS.

RESULTS

There was sufficient material for cytologic diagnosis in 33 of 36 cases (92%), for NGS testing in 30 of 36 cases (83%), and for both cytologic diagnosis and NGS testing in 28 of 36 cases (78%). Of 7 cases that were cytologically categorized as indeterminate or diagnosed as "atypical" or "nondiagnostic," NGS testing was sufficient and diagnostic for melanoma in 5 cases. Of the cases diagnosed as melanoma on pathology, 20 cases (87%) had concordant NGS testing results, 2 lacked molecular alterations, and 1 was insufficient for testing.

CONCLUSIONS

FNA sampling of melanocytic uveal lesions is adequate for both cytologic diagnosis and NGS testing. In a subset of cases in which pathologic findings were indeterminate, NGS testing results were clarifying for diagnosis. In addition, specific molecular alterations identified can aid in evaluating prognosis and guide further management.

Nuclear expression of BAP-1 in transvitreal incisional biopsies and subsequent enucleation of eyes with posterior choroidal melanoma

BACKGROUND

As a majority of patients with choroidal melanoma do not undergo enucleation, tumour tissue for prognostic testing has to be obtained with alternate methods. Transvitreal incisional biopsies enable histological examination as well as immunohistochemical staining of BRCA1-associated protein-1 (BAP-1).

METHODS

Fifty-nine patients diagnosed with choroidal melanoma in transvitreal biopsies between years 2003 and 2019 were included. Twenty-one of these patients subsequently underwent enucleation. The level of nuclear expression of BAP-1 in transvitreal biopsies and enucleations was evaluated and the concordance calculated. Metastasis-free survival and HR for metastasis were analysed.

RESULTS

The mean tumour thickness and diameter at biopsy was 3.8 mm (SD 2.1) and 9.3 mm (SD 4.8), respectively. For biopsies, 37 of 59 tumours (63%) were classified as having high nuclear BAP-1 expression, and 22 (37%) as low. For enucleations, 13 of 21 tumours (62%) were classified as having high nuclear BAP-1 expression, and 8 (38%) as low. Eighty-six per cent of biopsies had an identical BAP-1 classification as the subsequent enucleation, yielding a Cohen's kappa coefficient of 0.70. Patients with low nuclear BAP-1 expression in transvitreal biopsies had a significantly shorter metastasis-free survival (p=0.001), with a size-adjusted Cox regression HR for metastasis of 13.0 (95% CI 3.1 to 54.4, p=0.0004).

CONCLUSION

Loss of nuclear BAP-1 expression occurred in a large proportion of the small tumours included in this study. BAP-1 immunoreactivity in transvitreal incisional biopsies of choroidal melanoma is substantially concordant with immunoreactivity in enucleated specimens and identifies patients with poor metastasis-free survival.

Uveal melanoma pathobiology: Metastasis to the liver

Uveal melanoma (UM) is a type of intraocular tumor with a propensity to disseminate to the liver. Despite the identification of the early driver mutations during the development of the pathology, the process of UM metastasis is still not fully comprehended. A better understanding of the genetic, molecular, and environmental factors participating to its spread and metastatic outgrowth could provide additional approaches for UM treatment. In this review, we will discuss the advances made towards the understanding of the pathogenesis of metastatic UM, summarize the current and prospective treatments, and introduce some of the ongoing research in this field.

The prognostic landscape of adaptive immune resistance signatures and infiltrating immune cells in the tumor microenvironment of uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults and has a high mortality rate. Tumor microenvironment (TME) is crucial in controlling and influencing the behavior of malignant tumors. Thus, illustrating the prognostic values of adaptive immune resistance signatures and infiltrating immune cells in the TME of UM may provide scientific rationales for immunotherapy. In this study, the gene expression data of 80 primary UM and 103 primary skin cutaneous melanoma (SKCM) samples with relevant clinical information were obtained from The Cancer Genome Atlas (TCGA) database. The TME was analyzed by the xCell, EPIC, ESTIMATE and TIMER algorithms. The relationships and prognostic values of immune infiltrates and mutated genes were further investigated. We found that primary UM and primary SKCM exhibited distinct TMEs. Higher levels of infiltrating stromal and immune cells in UM were related to more aggressive biology and poor prognosis. Increased CD8⁺ T cell level, as well as several adaptive immune resistance markers, was a predictive factor of poor prognosis in UM. Furthermore, some common mutations of UM were associated with its TME. This study analyzed the immune landscape of adaptive immune resistance signatures and infiltrating immune cells in the TME of UM. Identification of these immune-related biomarkers may thus enable the prediction of prognosis and the selection of optimal immunotherapy strategies in UM.

Targeted Next-Generation Sequencing of 117 Routine Clinical Samples Provides Further Insights into the Molecular Landscape of Uveal Melanoma

Uveal melanoma (UM) has well-characterised somatic copy number alterations (SCNA) in chromosomes 1, 3, 6 and 8, in addition to mutations in GNAQ, GNA11, CYSLTR2, PLCB4, BAP1, SF3B1 and EIF1AX, most being linked to metastatic-risk. To gain further insight into the molecular landscape of UM, we designed a targeted next-generation sequencing (NGS) panel to detect SCNA and mutations in routine clinical UM samples. We compared hybrid-capture and amplicon-based target enrichment methods and tested a larger cohort of primary UM samples on the best performing panel. UM clinical samples processed either as fresh-frozen, formalin-fixed paraffin embedded (FFPE), small intraocular biopsies or following irradiation were successfully profiled using NGS, with hybrid capture outperforming the PCR-based enrichment methodology. We identified monosomy 3 (M3)-UM that were wild-type for BAP1 but harbored SF3B1 mutations, novel frameshift deletions in SF3B1 and EIF1AX, as well as a PLCB4 mutation outside of the hotspot on exon 20 coinciding with a GNAQ mutation in some UM. We observed samples that harboured mutations in both BAP1 and SF3B1, and SF3B1 and EIF1AX, respectively. Novel mutations were also identified in TTC28, KTN1, CSMD1 and TP53BP1. NGS can simultaneously assess SCNA and mutation data in UM, in a reliable and reproducible way, irrespective of sample type or previous processing. BAP1 and SF3B1 mutations, in addition to 8q copy number, are of added importance when determining UM patient outcome.

Spontaneous Necrosis of a Large Choroidal Melanoma: Unusual Presentation in a 49-Year-Old Male

Purpose

To demonstrate a case of massive vitreous haemorrhage obscuring the underlying diagnosis of a large mixed-cell choroidal melanoma which had undergone spontaneous necrosis.

Case Report

A 49-year-old man in good general health suddenly lost vision in his right eye due to an extensive vitreous haemorrhage 1 day after a workout at the gym. He reported good vision prior to that without any symptoms of flashes, floaters, or shadows. He was referred to the vitreoretinal department of a tertiary eye hospital, where he presented with a drop in vision to light perception only in the right phakic eye. Pars plana vitrectomy was performed in the right eye, which revealed intraoperatively massive retinal ischemia and choroidal haemorrhage, but no obvious tumour mass that could have been biopsied. The vitrectomy cassette specimen was sent for histopathology, where "ghost-like" melanoma cells were identified. The eye was subsequently enucleated, revealing an extensively necrotic and haemorrhagic choroidal melanoma of mixed cell type with only small viable tumour foci at the base and almost complete lysis of the detached retina.

Conclusion

Some uveal melanomas (UMs) undergo spontaneous necrosis due to rapid growth, with the centre of the tumour outstripping its established blood supply in the "watershed area" of the eye, and becoming hypoxic with associated necrosis of intraocular structures. Such UMs are often associated with haemorrhage and/or inflammation and usually cause significant destruction of ocular tissues, resulting in enucleation as the only treatment option.

Loss of BAP1 in Pheochromocytomas and Paragangliomas Seems Unrelated to Genetic Mutations

Breast cancer-associated protein 1 (BAP1) gene is a broad-spectrum tumor suppressor. Indeed, its loss of expression, due to biallelic inactivating mutations or deletions, has been described in several types of tumors including melanoma, malignant mesothelioma, renal cell carcinoma, and others. There are so far only two reports of BAP1-mutated paraganglioma, suggesting the possible involvement of this gene in paraganglioma (PGL) and pheochromocytoma (PCC) pathogenesis. We assessed BAP1 expression by immunohistochemistry (IHC) in a cohort of 56 PCC/PGL patients (and corresponding metastases, when available). Confirmatory Sanger sequencing (exons 1-17) of BAP1 has been performed in those samples which resulted negative by IHC. BAP1 nuclear expression was lost in 2/22 (9.1%) PGLs and in 12/34 (35.3%) PCCs, five of which harboring a germline mutation predisposing the development of such tumors (MENIN, MAX, SDHB, SDHD, and RET gene). Confirmatory Sanger sequencing revealed the wild-type BAP1 status of all the analyzed samples. No heterogeneity between primary and metastatic tissue was observed. This study documents that the loss of BAP1 nuclear expression is quite a frequent finding in PCC/PGL, suggesting a possible role of BAP1 in the pathogenesis of these tumors. Gene mutations do not seem to be involved in this loss of expression, at least in most cases. Other genetic and epigenetic mechanisms need to be further investigated.

Mutational Landscape of the BAP1 Locus Reveals an Intrinsic Control to Regulate the miRNA Network and the Binding of Protein Complexes in Uveal Melanoma

The BAP1 (BRCA1-associated protein 1) gene is associated with a variety of human cancers. With its gene product being a nuclear ubiquitin carboxy-terminal hydrolase with deubiquitinase activity, BAP1 acts as a tumor suppressor gene with potential pleiotropic effects in multiple tumor types. Herein, we focused specifically on uveal melanoma (UM) in which BAP1 mutations are associated with a metastasizing phenotype and decreased survival rates. We identified the ubiquitin carboxyl hydrolase (UCH) domain as a major hotspot region for the pathogenic mutations with a high evolutionary action (EA) score. This also includes the mutations at conserved catalytic sites and the ones overlapping with the phosphorylation residues. Computational protein interaction studies revealed that distant BAP1-associated protein complexes (FOXK2, ASXL1, BARD1, BRCA1) could be directly impacted by this mutation paradigm. We also described the conformational transition related to BAP1-BRCA-BARD1 complex, which may pose critical implications for mutations, especially at the docking interfaces of these three proteins. The mutations affect - independent of being somatic or germline - the binding affinity of miRNAs embedded within the BAP1 locus, thereby altering the unique regulatory network. Apart from UM, BAP1 gene expression and survival associations were found to be predictive for the prognosis in several (n = 29) other cancer types. Herein, we suggest that although BAP1 is conceptually a driver gene in UM, it might contribute through its interaction partners and its regulatory miRNA network to various aspects of cancer. Taken together, these findings will pave the way to evaluate BAP1 in a variety of other human cancers with a shared mutational spectrum.

Prediction of BAP1 Expression in Uveal Melanoma Using Densely-Connected Deep Classification Networks

Uveal melanoma is the most common primary intraocular malignancy in adults, with nearly half of all patients eventually developing metastases, which are invariably fatal. Manual assessment of the level of expression of the tumor suppressor BRCA1-associated protein 1 (BAP1) in tumor cell nuclei can identify patients with a high risk of developing metastases, but may suffer from poor reproducibility. In this study, we verified whether artificial intelligence could predict manual assessments of BAP1 expression in 47 enucleated eyes with uveal melanoma, collected from one European and one American referral center. Digitally scanned pathology slides were divided into 8176 patches, each with a size of 256 × 256 pixels. These were in turn divided into a training cohort of 6800 patches and a validation cohort of 1376 patches. A densely-connected classification network based on deep learning was then applied to each patch. This achieved a sensitivity of 97.1%, a specificity of 98.1%, an overall diagnostic accuracy of 97.1%, and an F1-score of 97.8% for the prediction of BAP1 expression in individual high resolution patches, and slightly less with lower resolution. The area under the receiver operating characteristic (ROC) curves of the deep learning model achieved an average of 0.99. On a full tumor level, our network classified all 47 tumors identically with an ophthalmic pathologist. We conclude that this deep learning model provides an accurate and reproducible method for the prediction of BAP1 expression in uveal melanoma.

Uveal melanoma: Towards a molecular understanding

Uveal melanoma is an aggressive malignancy that originates from melanocytes in the eye. Even if the primary tumor has been successfully treated with radiation or surgery, up to half of all UM patients will eventually develop metastatic disease. Despite the common origin from neural crest-derived cells, uveal and cutaneous melanoma have few overlapping genetic signatures and uveal melanoma has been shown to have a lower mutational burden. As a consequence, many therapies that have proven effective in cutaneous melanoma -such as immunotherapy- have little or no success in uveal melanoma. Several independent studies have recently identified the underlying genetic aberrancies in uveal melanoma, which allow improved tumor classification and prognostication of metastatic disease. In most cases, activating mutations in the Gα11/Q pathway drive uveal melanoma oncogenesis, whereas mutations in the BAP1, SF3B1 or EIF1AX genes predict progression towards metastasis. Intriguingly, the composition of chromosomal anomalies of chromosome 3, 6 and 8, shown to correlate with an adverse outcome, are distinctive in the BAP1^mut, SF3B1^mut and EIF1AX^mut uveal melanoma subtypes. Expression profiling and epigenetic studies underline this subdivision in high-, intermediate-, or low-metastatic risk subgroups and suggest a different approach in the future towards prevention and/or treatment based on the specific mutation present in the tumor of the patients. In this review we discuss the current knowledge of the underlying genetic events that lead to uveal melanoma, their implication for the disease course and prognosis, as well as the therapeutic possibilities that arise from targeting these different aberrant pathways.

The Autocrine FGF/FGFR System in both Skin and Uveal Melanoma: FGF Trapping as a Possible Therapeutic Approach

Fibroblast growth factors (FGFs) play non-redundant autocrine/paracrine functions in various human cancers. The Cancer Genome Atlas (TCGA) data mining indicates that high levels of FGF and/or FGF receptor (FGFR) expression are associated with reduced overall survival, chromosome 3 monosomy and BAP1 mutation in human uveal melanoma (UM), pointing to the FGF/FGFR system as a target for UM treatment. Here, we investigated the impact of different FGF trapping approaches on the tumorigenic and liver metastatic activity of liver metastasis-derived murine melanoma B16-LS9 cells that, similar to human UM, are characterized by a distinctive hepatic tropism. In vitro and in vivo experiments demonstrated that the overexpression of the natural FGF trap inhibitor long-pentraxin 3 (PTX3) inhibits the oncogenic activity of B16-LS9 cells. In addition, B16-LS9 cells showed a reduced tumor growth and liver metastatic activity when grafted in PTX3-overexpressing transgenic mice. The efficacy of the FGF trapping approach was confirmed by the capacity of the PTX3-derived pan-FGF trap small molecule NSC12 to inhibit B16-LS9 cell growth in vitro, in a zebrafish embryo orthotopic tumor model and in an experimental model of liver metastasis. Possible translational implications for these observations were provided by the capacity of NSC12 to inhibit FGF signaling and cell proliferation in human UM Mel285, Mel270, 92.1, and OMM2.3 cells. In addition, NSC12 caused caspase-3 activation and PARP cleavage followed by apoptotic cell death as well as β-catenin degradation and inhibition of UM cell migration. Together, our findings indicate that FGF trapping may represent a novel therapeutic strategy in UM.

Aberrant MicroRNA Expression and Its Implications for Uveal Melanoma Metastasis

Uveal melanoma (UM) is the most frequently found primary intra-ocular tumor in adults. It is a highly aggressive cancer that causes metastasis-related mortality in up to half of the patients. Many independent studies have reported somatic genetic changes associated with high metastatic risk, such as monosomy of chromosome 3 and mutations in BAP1. Still, the mechanisms that drive metastatic spread are largely unknown. This study aimed to elucidate the potential role of microRNAs in the metastasis of UM. Using a next-generation sequencing approach in 26 UM samples we identified thirteen differentially expressed microRNAs between high-risk UM and low/intermediate-risk UM, including the known oncomirs microRNA-17-5p, microRNA-21-5p, and miR-151a-3p. Integration of the differentially expressed microRNAs with expression data of predicted target genes revealed 106 genes likely to be affected by aberrant microRNA expression. These genes were involved in pathways such as cell cycle regulation, EGF signaling and EIF2 signaling. Our findings demonstrate that aberrant microRNA expression in UM may affect the expression of genes in a variety of cancer-related pathways. This implies that some microRNAs can be responsible for UM metastasis and are promising potential targets for future treatment.

PARP Inhibition Increases the Response to Chemotherapy in Uveal Melanoma

Uveal melanoma (UM) remains without effective therapy at the metastatic stage, which is associated with BAP-1 (BRCA1 associated protein) mutations. However, no data on DNA repair capacities in UM are available. Here, we use UM patient-derived xenografts (PDXs) to study the therapeutic activity of the PARP inhibitor olaparib, alone or in combination. First, we show that the expression and the activity of PARP proteins is similar between the PDXs and the corresponding patient’s tumors. In vivo experiments in the PDX models showed that olaparib was not efficient alone, but significantly increased the efficacy of dacarbazine. Finally, using reverse phase protein arrays and immunohistochemistry, we identified proteins involved in DNA repair and apoptosis as potential biomarkers predicting response to the combination of olaparib and dacarbazine. We also observed a high increase of phosphorylated YAP and TAZ proteins after dacarbazine + olaparib treatment. Our results suggest that PARP inhibition in combination with the alkylating agent dacarbazine could be of clinical interest for UM treatment. We also observe an interesting effect of dacarbazine on the Hippo pathway, confirming the importance of this pathway in UM.

Detection of mutations in SF3B1, EIF1AX and GNAQ in primary orbital melanoma by candidate gene analysis

Background

Ocular melanoma is a rare but often deadly malignancy that arises in the uvea (commonest primary site), conjunctiva or the orbit. Primary orbital melanoma (POM) is exceedingly rare, with approximately 60 cases reported to date. Despite recent advances in our understanding of the genetics of primary uveal and conjunctival melanomas, this information is lacking for POM.

Methods

DNA was extracted from 12 POM tissues, with matched germline DNA (where available). MLPA was conducted to detect chromosomal alterations and Sanger sequencing used to identify point mutations in candidate melanoma driver genes (BRAF, NRAS, KRAS, GNA11, GNAQ), and other genes implicated in melanoma prognosis (EIF1AX, SF3B1). Immunohistochemistry was performed to analyse BAP1 nuclear expression.

Results

MLPA detected copy number alterations in chromosomes 1p, 3, 6 and 8. Sequencing of melanoma driver genes revealed GNAQ (p.Q209L) mutations in two samples; although it is possible that these samples represent extraocular spread of an occult uveal melanoma. A recurrent mutation in SF3B1 (p.R625H) was observed in indolent, but not aggressive, tumours; a mutation in EIF1AX (p.N4S) was detected in one patient with non-aggressive disease.

Conclusions

EIF1AX and SF3B1 mutations appear have a role in determining the clinical course of POM and detection of these changes could have clinical significance. Further in depth analysis of this rare group using differing ‘omic technologies will provide novel insights into tumour pathogenesis.

Comprehensive Study of the Clinical Phenotype of Germline BAP1 Variant-Carrying Families Worldwide

Background

The BRCA1-associated protein-1 (BAP1) tumor predisposition syndrome (BAP1-TPDS) is a hereditary tumor syndrome caused by germline pathogenic variants in BAP1 encoding a tumor suppressor associated with uveal melanoma, mesothelioma, cutaneous melanoma, renal cell carcinoma, and cutaneous BAP1-inactivated melanocytic tumors. However, the full spectrum of tumors associated with the syndrome is yet to be determined. Improved understanding of the BAP1-TPDS is crucial for appropriate clinical management of BAP1 germline variant carriers and their families, including genetic counseling and surveillance for new tumors.

Methods

We collated germline variant status, tumor diagnoses, and information on BAP1 immunohistochemistry or loss of somatic heterozygosity on 106 published and 75 unpublished BAP1 germline variant-positive families worldwide to better characterize the genotypes and phenotypes associated with the BAP1-TPDS. Tumor spectrum and ages of onset were compared between missense and null variants. All statistical tests were two-sided.

Results

The 181 families carried 140 unique BAP1 germline variants. The collated data confirmed the core tumor spectrum associated with the BAP1-TPDS and showed that some families carrying missense variants can exhibit this phenotype. A variety of noncore BAP1-TPDS -associated tumors were found in families of variant carriers. Median ages of onset of core tumor types were lower in null than missense variant carriers for all tumors combined (P < .001), mesothelioma (P < .001), cutaneous melanoma (P < .001), and nonmelanoma skin cancer (P < .001).

Conclusions

This analysis substantially increases the number of pathogenic BAP1 germline variants and refines the phenotype. It highlights the need for a curated registry of germline variant carriers for proper assessment of the clinical phenotype of the BAP1-TPDS and pathogenicity of new variants, thus guiding management of patients and informing areas requiring further research.

Replacement and desmoplastic histopathological growth patterns: A pilot study of prediction of outcome in patients with uveal melanoma liver metastases

Up to 50% of uveal melanomas (UM) metastasise to the liver within 10 years of diagnosis, and these almost always prove rapidly fatal. As histopathological growth patterns (HGPs) of liver metastases of the replacement and desmoplastic type, particularly from colon and breast carcinoma, may import valuable biological and prognostic information, we have studied HGP in a series of 41 UM liver metastases originating from 41 patients from the period 2006–2017. Twenty patients underwent enucleation while 21 had radiation therapy. Analysis of UM by array comparative genomic hybridisation revealed: 25 (64%) patients with high risk (monosomy3/8q gain); 13 (33%) intermediate risk (M3/8normal or disomy3/8q gain); and 1 low risk (disomy3/8normal). The principal HGP was replacement in 30 (73%) cases and desmoplastic in 11 (27%) cases. Cases with replacement demonstrated striking vascular co‐option/angiotropism. With the development of liver metastasis, only the replacement pattern, largest primary tumour diameter, and R2 (incomplete resection) status predicted diminished overall survival (OS; p < 0.041, p < 0.017, p < 0.047, respectively). On multivariate analysis, only HGP (hazard ratio; HR = 6.51, p = 0.008) and resection status remained significant. The genomic high‐risk variable had no prognostic value at this stage of liver metastasis. Chi‐square test showed no association of HGP with monosomy 3 or 8q gain. Eighteen of 41 (44%) patients are alive with disease and 23 (56%) patients died with follow‐up ranging from 12 to 318 months (mean: 70 months, median: 47 months). In conclusion, we report for the first time the frequency of the replacement and desmoplastic HGPs in liver UM metastases resected from living patients, and their potential important prognostic value for UM patients, as in other solid cancers. These results may potentially be utilised to develop radiological correlates and therapeutic targets for following and treating patients with UM metastases.

Altered Nuclear Expression of the Deubiquitylase BAP1 Cannot be Used as a Prognostic Marker for Canine Melanoma

BRCA1-associated protein-1 (BAP1) is a nuclear localized deubiquitylating enzyme that belongs to the ubiquitin c-terminal hydrolase subfamily. The encoded protein is highly homologous between man and dogs, suggesting a functional significance preserved by evolution. BAP1 has multiple properties, including tumour suppressor activity. Loss of BAP1 function is implicated in the oncogenesis of several types of cancers including uveal, mucosal and some cutaneous melanomas in humans, as well as in mesothelioma. In this study we investigate the significance of BAP1 in canine melanoma. Nuclear BAP1 protein was detected in five canine oral melanoma cell lines using an antibody commonly used for analysis of human tissues. BAP1 loss of function mutations often lead to loss of nuclear BAP1 (nBAP1) expression in humans; this is associated with a poorer prognosis in uveal and mucosal melanoma. Therefore, as a prelude to a study evaluating the prognostic significance of nBAP1 expression in dogs, immunohistochemistry (IHC) was used to assess cases of canine melanoma for nBAP1 expression. In 89 cases where tumour cells were identified by melan-A labelling, 100% of tumour cells were positive for nBAP1 expression, including eight uveal tract and 29 oral mucosal melanomas. This finding indicates that BAP1 IHC cannot be used as a prognostic marker in canine uveal and mucosal melanoma. Moreover, this observation suggests that either BAP1 has a different functional significance in canine melanoma or that loss of BAP1 function is achieved by a different route. This is a novel finding that warrants further investigation to determine the comparative biological relevance.