Melanoma Antigen Research Articles

High-affinity T cell receptor ImmTAC® bispecific efficiently redirects T cells to kill tumor cells expressing the cancer testis antigen PRAME

Abstract PRAME (Preferentially expressed Antigen in Melanoma) is a cancer testis antigen expressed in several tumor indications, representing an attractive anti-cancer target. However, its intracellular location limits targeting by traditional methods. PRAME peptides are presented on the surface of tumor cells by human leukocyte antigen (HLA) molecules, indicating that a T cell receptor (TCR)-based strategy that redirects T cells to kill PRAME+ tumors could be a novel immunotherapeutic option. We confirm that PRAME protein is expressed in cutaneous melanoma, including rare subtypes with limited treatment options, as well as primary and metastatic lung, breast, endometrial and ovarian tumors. Furthermore, PRAME is expressed homogeneously across tumors with distinct oncogenic mutations, mutation burden, PD-L1 expression, immune infiltration and features of immune checkpoint resistance. Immunopeptidomic analysis of primary tumors detected HLA class I-restricted PRAME peptides. A TCR recognizing PRAME peptide SLLQHLIGL was engineered to high affinity and fused to a CD3 engaging domain to create a TCRxCD3 bispecific molecule (Immune mobilizing monoclonal TCR Against Cancer, ImmTAC®) with the ability to redirect polyclonal T cells to efficiently kill PRAME+ cells. The degree of T cell activation was positively correlated with peptide-HLA abundance, with as few as 10 epitopes per cell sufficient for target cell killing. Impaired ImmTAC®-redirected cytotoxicity of exhausted T cells was rescued using an anti-PD-1 antibody, supporting the use of a combination strategy to treat tumors with active PDL1-PD1 axes. Our data demonstrate selective and efficient T cell activation and killing by a PRAME-directed TCRxCD3 bispecific, supporting further investigation in multiple cancer indications.

The Utilization of PRAME in the Diagnosis, Prognosis, and Treatment of Melanoma.

Melanoma, a deadly form of skin cancer, has seen improved survival rates due to advances in diagnosis and treatment, yet the need for further improvement remains critical. Tumor-associated antigens, such as PRAME (Preferentially Expressed Antigen in Melanoma), offer promising avenues for enhanced diagnostic precision, prognostic assessment, and targeted immunotherapy. PRAME, a cancer testis antigen, is selectively expressed in various cancers, including melanoma, and plays a key role in promoting tumorigenesis through inhibition of retinoic acid signaling, epithelial-to-mesenchymal transition, and immune evasion. This review explores the diagnostic utility of PRAME in distinguishing melanoma from benign nevi, its prognostic value in aggressive melanoma subtypes, and its potential as a therapeutic target in cancer vaccines and adoptive T-cell therapies. While PRAME-targeted therapies face challenges such as tumor heterogeneity and immune suppression, ongoing research aims to overcome these barriers, offering hope for more effective melanoma treatments.

Utilizing PRAME Expression and a Meta-Analytic Framework for iSALT to Explore Atypical Late-Onset Nevi of the Elderly and Their Relationship With Lentiginous and Nested Nevoid Melanomas.

In contrast to early-onset dysplastic nevi, late-onset atypical nevi of the elderly are more often precursors to distinctive nevoid melanomas. PReferentially expressed Antigen in MElanoma (PRAME) immunohistochemistry was applied to delineate the nevoid aspect of late-onset oncogenic nevoid pathway. Inducible Skin-Associated Lymphoid Tissue, regulatory T-cell mesenchymal hubs, has emerged as a translational tool and was used to define nevoid oncogenesis within a dynamic meta-analytic pathway. PRAME immunohistochemistry was applied after designating a histopathologic diagnosis. Late-onset atypical nested lentiginous nevus, lentiginous nested melanoma, and hypercellular nested nevoid melanoma were the diagnostic categories. A positive PRAME for melanoma was set at 75% percentage labeling.A wide-ranging published evidence-based database was incorporated to develop a meta-analytic framework for oncogenic nevogenesis. This combined inducible Skin-Associated Lymphoid Tissue incorporating the pleiotropic functions of regulatory T cells regulating immunity and gene regulatory epigenetics as principal modulators. Concordant-negative PRAME expression was present in 64 of 81 (79%) atypical nested lentiginous nevi, concordant-positive PRAME expression occurred in 54 of 75 (72%) nevoid lentiginous and nested melanomas, and 18 of 23 (78%) nevoid hypercellular nested melanomas. PRAME expression confirmed the existence of a late-onset oncogenic nevoid pathway that can be defined by histopathology. Subsequent meta-analysis data linked to the meta-analytic framework revealed that PRAME is an epigenetic surrogate antigen expressed because of repression of retinoic acid receptor signaling, preventing ligand-induced retinoic acid cellular differentiation, growth arrest, and apoptosis, and promoting melanoma growth and survival for melanomas. PRAME is only a single antigen within a highly complex dynamic framework that governs nevoid oncogenesis. Significantly, the retinoic acid/retinoic acid receptor complex has been shown to modulate the immunosuppressive arm of regulatory T cells underpinning immune tolerance and is pertinent to the broad framework but is not linked to PRAME expression in this arm.

The Utility of PRAME and Ki-67 as Prognostic Markers for Cutaneous Melanoma.

Cutaneous melanoma can lead to metastasis, and it is associated with high mortality. Currently, there are no widely accepted immunohistochemistry markers for melanoma prognosis in routine staging. Preferentially expressed antigen in melanoma (PRAME) is a possible biomarker for prognosis in several noncutaneous neoplasms. Ki-67 is a cell proliferation marker correlated with poor outcomes in many cancers. This study assessed PRAME and Ki-67 as potential prognostic markers for sentinel lymph node outcomes and survival among melanoma patients. This is a retrospective study analyzing cutaneous melanoma cases from a Brazilian cancer center (2005-2021). All cases were tested using immunohistochemistry to evaluate PRAME expression and Ki-67 index. Descriptive analysis, Spearman correlations, means comparison, Kaplan-Meier analysis, χ2, and Cox models were performed. In univariate analysis of 123 cutaneous melanoma cases, high extent (P = 0.0267) and elevated intensity (P = 0.043) of PRAME were associated with decreased overall survival. The Ki-67 index was associated with overall survival (P = 0.05) and sentinel lymph node status (P = 0.0403), with a positive correlation between the markers (P = 0.0004) and between Ki-67 and Breslow thickness (P = 0.0001). However, in multivariate analysis, only Breslow thickness significantly influenced overall survival (P = 0.0003). Then, the present results can suggest that elevated PRAME and Ki-67 expression are associated with poor overall survival in cutaneous melanoma; however, in multivariate analysis, only the Breslow thickness had a significant influence. These findings highlight the potential of PRAME and Ki-67 as prognostic markers, opening frontiers that could improve strategies for treating cutaneous melanoma.

PRAME expression in fibrosarcomatous dermatofibrosarcoma protuberans

PRAME (PReferentially expressed Antigen in MElanoma) was first identified as a malignant melanoma-specific antigen. Recently, a few cases of fibrosarcomatous dermatofibrosarcoma protuberans (FS-DFSP) were shown to have positivity for PRAME, while conventional dermatofibrosarcoma protuberans (C-DFSP) was negative. Because PRAME may be of diagnostic utility in FS-DFSP and is raising expectations as a new immunotherapy target, we examined the positivity of PRAME in FS-DFSP. Twenty-one cases of FS-DFSP and age/sex/location-matched cases of C-DFSP as a control group were examined by immunohistochemistry for CD34 and PRAME. The results were then evaluated by H-score, which was objectively and semi-quantitatively calculated using the open-source bioimaging analysis software QuPath. The results revealed that the PRAME H-score in FS-DFSP was significantly higher than that in C-DFSP (p = 0.0137). As for CD34, the H-score in FS-DFSP was significantly lower than that in C-DFSP (p < 0.001). Using these two immunohistochemical analyses in combination, the sensitivity and specificity for the diagnosis of FS-DFSP were 86% and 90%, respectively. Double staining of CD34 and PRAME revealed that PRAME-positive and CD34-positive areas did not overlap. This is the largest study to examine PRAME expression in FS-DFSP, and it confirmed the usefulness of PRAME in diagnosing this condition.

DeepNeoAG: Neoantigen epitope prediction from melanoma antigens using a synergistic deep learning model combining protein language models and multi-window scanning convolutional neural networks

Neoantigens, derived from tumor-specific mutations, play a crucial role in eliciting anti-tumor immune responses and have emerged as promising targets for personalized cancer immunotherapy. Accurately identifying neoantigens from a vast pool of potential candidates is crucial for developing effective therapeutic strategies. This study presents a novel deep learning model that leverages the power of protein language models (PLMs) and multi-window scanning convolutional neural networks (CNNs) to predict neoantigens from normal tumor antigens with high accuracy. In this study, we present DeepNeoAG, a novel framework combines the global sequence-level information captured by a pre-trained PLM with the local sequence-based information features extracted by a multi-window scanning CNN, enabling a comprehensive representation of the protein's mutational landscape. We demonstrate the superior performance of DeepNeoAG compared to existing methods and highlight its potential to accelerate the development of personalized cancer immunotherapies.

A Narrative Review of the Evolution of Diagnostic Techniques and Treatment Strategies for Acral Lentiginous Melanoma.

Acral melanoma (AM) is a subtype of cutaneous melanoma located on the palms, soles, and nails. The pathogenesis of AM involves mechanical stimulation and characteristic tumor-promoting mutations, such as those in the KIT proto-oncogene. Dermoscopy is useful for diagnosing AM, which is characterized by parallel ridge patterns and irregular diffuse pigmentation. Although histopathological confirmation is the gold standard for diagnosing AM, lesions showing minimal histopathological changes should be considered early-stage AM if they clinically resemble it. Recently, immunohistochemical staining of preferentially expressed antigen in melanoma has been recognized as a useful method to distinguish benign from malignant melanocytic tumors. Research reveals that AM is associated with an immunosuppressive microenvironment characterized by increased numbers of M2 macrophages and regulatory T cells, alongside a decreased number of tumor-infiltrating lymphocytes. Mohs micrographic surgery or digit-sparing wide local excision has been explored to improve quality of life and replace wide local excision or proximal amputation. AM has a worse prognosis than other subtypes, even in the early stages, indicating its inherent aggressiveness.

BRCA1-associated-protein-1 inactivated melanocytic tumours: characterisation of the clinicopathological spectrum and immunohistochemical expression pattern of preferentially expressed antigen in melanoma.

BRCA1-associaed protein-1 (BAP1) inactivated tumours (BIMT) are rare melanocytic tumours that may be mistaken for Spitz tumours or melanoma. They occur sporadically or in association with the BAP1 tumour predisposition syndrome (BAP1-TPDS), which may be complicated by uveal or cutaneous melanoma, mesothelioma, basal cell carcinoma and renal cell carcinoma. The aim of this study was to characterise the clinicopathological features and the immunohistochemical expression pattern of preferentially expressed antigen in melanoma (PRAME) of BIMT in a large patient cohort. Ethical approval was obtained, haematoxylin and eosin-stained slides were reviewed, PRAME immunohistochemistry was performed and clinical follow-up was obtained from patient records. Sixty-five BIMT from 38 patients (F:M = 4.4:1) were identified. BIMT were typically located on the trunk and head and neck (median size = 0.5 cm). Seven patients with BAP1-TPDS (range = 16-66 years, median = 25) had multiple BIMT (median = 5), while sporadic BIMT were solitary (median patient age = 39 years). One of seven patients with BAP1-TPDS developed additional malignancies (mesothelioma and cutaneous spindle cell melanoma) and died of complications of mesothelioma. All other patients are alive without recurrence of BIMT (median follow-up = 42 months). BIMT presented as intradermal, nodular aggregates of epithelioid melanocytes with low mitotic activity and moderate to severe cytological atypia in 63% of cases. A background conventional naevus was present in 64%. PRAME immunohistochemistry showed negative or weakly patchy positive staining in all BIMT. BIMT are more common in a sporadic setting and behave indolently, despite worrying cytological atypia. PRAME immunohistochemistry is a reassuring tool in distinguishing BIMT from melanoma.

PRAME Immunohistochemistry in Thin Melanomas Compared to Melanocytic Nevi.

PRAME (PReferentially expressed Antigen in Melanoma) immunohistochemistry has proven helpful in distinguishing malignant from benign melanocytic tumors. We studied PRAME IHC expression in 46 thin melanomas and 39 melanocytic nevi, mostly dysplastic nevi. Twenty-six percent (26.09%) of the melanomas showed diffuse PRAME staining in over 76% of the tumor cells (4+), and 34.78% of the melanomas showed PRAME expression in over 51% of the tumor cells (3+ or 4+), while 8% were entirely negative for PRAME. No melanocytic nevi were PRAME 4+ or 3+. More than half of the nevi (64%) were entirely negative for PRAME staining, and 36% of the nevi showed staining expression in 1-25% (1+) or 26-50% of the cells (2+). No nevi were stained with a color intensity of 3, while 16.67% of the melanomas were stained with this color intensity. Most nevi (78.57%) were stained with an intensity of 1. With a lower positivity threshold, sensitivity increases with still reasonable specificity. The best accuracy was obtained for the 2+ positivity threshold. In conclusion, PRAME staining helps distinguish thin melanomas from dysplastic nevi. However, the threshold of positivity should be lowered in order not to miss thin melanomas.

Brief Communication on MAGE-A4 and Coexpression of Cancer Testis Antigens in Metastatic Synovial Sarcomas: Considerations for Development of Immunotherapeutics.

Therapeutic options for synovial sarcoma (SyS) have not evolved for several decades and the efficacy of second-line treatments is very limited. The expression of a large family of proteins known as cancer testis antigens (CTAs) in SyS has spurred the development of targeted T-cell therapies currently in clinical trials, such as those aimed at melanoma-associated antigen (MAGE)-A4 and New York esophageal squamous cell carcinoma 1 (NY-ESO-1), which have shown promising clinical efficacy. Extensive knowledge of the prevalence of expression and coexpression of CTAs is critical to design T-cell therapies with optimal coverage of the patient population. We analyzed the expression of CTAs of the MAGE-A family as well as NY-ESO-1 and preferentially expressed antigen in melanoma (PRAME) by RNA sequencing in a large cohort of 133 SyS samples from patients registered in the French sarcoma database (NETSARC+). Among MAGE-As, MAGE-A4 had the highest prevalence (65%), followed by MAGE-A10 (15%) and MAGE-A9 (13%). Almost all samples (92%) expressing any of the MAGE-As also expressed MAGE-A4. NY-ESO-1 was expressed in 65% of samples, with a large but incomplete overlap with MAGE-A4, whereas PRAME was present in 121 (91%) samples. Complementary immunohistochemical analyses were used to establish the positive correlation between RNA and protein expression for MAGE-A4 and NY-ESO-1. These data inform the strategy for optimal coverage of the SyS patient population with T-cell therapies, offering patients with SyS new options for single or combined second lines of treatment.

COMPREHENSIVE MOLECULAR PROFILING OF UVEAL MELANOMA EVALUATED WITH GENE EXPRESSION PROFILING, PREFERENTIALLY EXPRESSED ANTIGEN IN MELANOMA EXPRESSION, AND NEXT-GENERATION SEQUENCING.

To determine the association between gene-expression profiling (GEP), next-generation sequencing (NGS), preferentially expressed antigen in melanoma (PRAME) features, and metastatic risk in patients with uveal melanoma (UM). A retrospective analysis of patients with UM treated by brachytherapy or enucleation by a single ocular oncologist was conducted from November 2020 and July 2022. Clinicopathologic features, patient outcomes, GEP classification, NGS, and PRAME results were recorded. Comprehensive GEP, PRAME, and NGS testing was performed on 135 UMs. The presence of eukaryotic translation initiation factor 1A, X-chromosomal and splicing factor 3B subunit 1 mutations was significantly associated with GEP class 1A and GEP class 1B, respectively. The presence of BRCA- associated protein-1 mutation was significantly associated with GEP class 2. The average largest basal diameter for tumors with eukaryotic translation initiation factor 1A, X-chromosomal mutations was significantly smaller than those with splicing factor 3B subunit 1 mutations and BRCA1-associated protein-1 mutations. Class 2 tumors metastasized sooner than GEP class 1 tumors. Tumors with splicing factor 3B subunit 1 and/or BRCA1-associated protein-1 mutations metastasized sooner compared with tumors that had either no driver mutation or no mutations at all. Tumors with splicing factor 3B subunit 1 did not have a significantly different time to metastasis compared with tumors with BRCA1-associated protein-1 (P value = 0.97). Forty tumors (30%) were PRAME positive, and the remaining 95 tumors (70%) were PRAME negative. Tumors with PRAME-positive status did not have a significantly different time to metastasis compared with tumors without PRAME-positive status (P value = 0.11). GEP, NGS, and PRAME expression analysis help determine different levels of metastatic risk in UM. Although other prognostic tests exist, the following study reports on the use of NGS for metastatic prognostication in UM. However, limitations of NGS exist, especially with small lesions that are technically difficult to biopsy.

Beyond nest size: the clinicopathological spectrum of large nested melanocytic tumours and the value of comparative genomic hybridisation and messenger RNA expression analysis

Large nested melanomas (LNMs) are a rare subtype of naevoid melanoma consisting of large junctional melanocytic nests that are more common in older individuals and/or associated with sun damage. However, the presence of large melanocytic nests alone does not lead to a diagnosis of malignancy, ​as they can also be found in melanocytic naevi. LNMs are challenging because they lack most classic histological features of malignancy and require thorough clinicopathological evaluation. This ambiguity calls for a critical reassessment of the current diagnostic criteria for the subclassification of benign or malignant within the spectrum of large nested melanocytic tumours (LNMTs). Eighteen LNMTs and six special-site melanocytic naevi (SSMNs) ​were studied using different approaches: clinical features, dermoscopy, histopathology, immunohistochemistry, array comparative genomic hybridisation (aCGH) and messenger RNA (mRNA) sequencing analysis, with the aim of identifying novel and reproducible criteria for the recognition of LNMs.Careful clinicopathological evaluation of the 18 LNMTs led to the diagnosis of seven LNMs and 11 large nested melanocytic naevi (LNMNs). Lentiginous spread and nest bridging were significantly associated with LNMs after Holm–Bonferroni correction. Asymmetry, largest nest size, poor lateral demarcation, the number of colours and dermoscopic structures, and preferentially expressed antigen in melanoma (PRAME) immunostaining were more common in LNMs but did not reach statistical significance. Four of seven LNMs and nine of 11 LNMNs lacked the BRAF V600E mutation. Regarding aCGH, no LNMN or SSMN cases had ≥3 copy number variations (CNVs), in contrast to 50% of LNM cases. Importantly, LNM and LNMN could be distinguished by differential mRNA expression of nine genes. Our study demonstrates that there is a spectrum of LNMTs and that the clinicopathological diagnosis of LNM, for which we support the term ‘late-onset nested naevoid melanomas’, can be significantly strengthened by the presence of lentiginous pattern, nest bridging, gene CNV and differential mRNA expression.

Brief Communication: Treatment Outcomes for Advanced Melanoma of Unknown Primary Compared With Melanoma With Known Primary.

Most patients with advanced melanomas have a known primary site [melanoma of known primary (MKP)]. However, 2%-9% of patients are diagnosed with melanoma metastasis of unknown primary (MUP). As MUP and MKP have similar UV-induced mutations and molecular signatures, it is proposed that the primary tumor has regressed completely in patients with MUP. As regression of the primary tumor could be indicative of enhanced recognition of melanoma antigens, we hypothesize that patients with advanced MUP have a better outcome compared with MKP.Patients with advanced MUP from 10 German university hospitals were retrospectively analyzed and matched with MKP based on the type of systemic treatment (BRAF and MEK inhibitors, PD-1 inhibitor monotherapy, combined CTLA-4 and PD-1 inhibitor therapy) therapy line (first or second line) and AJCC stage (IIIC, IV M1a-M1d). Three hundred thirty-seven patients with MUP were identified, and 152 treatments with PD-1 and CTLA-4 inhibitors, 142 treatments with PD-1 inhibitors, and 101 treatments with BRAF and MEK inhibitors were evaluated. Median time to treatment failure was significantly prolonged in patients with MUP treated with PD-1 monotherapy (17mo, 95% CI: 9-25, P = 0.002) compared with MKP (5mo, 95% CI: 3.4-6.6), as well as in MUP treated with combined PD-1 and CTLA-4 therapy (11mo, 95% CI: 4.5-17.5, P < 0.0001) compared with MKP (4mo, 95% CI: 2.9-5.1) Occurrence of immune-related adverse events and time to treatment failure for patients with BRAF and MEK inhibitors was similar in MKP and MUP. In our multicentre collective, patients with MUP have better outcomes under immunotherapy compared with MKP.

Mutational signatures and their association with cancer survival and gene expression in multiple cancer types.

Different endogenous and exogenous mutational processes cause specific patterns of somatic mutations and mutational signatures. Although their biological research has been intensive, there are only rare studies assessing the possible prognostic role of mutational signatures. We used data from The Cancer Genome Atlas to study the associations between the activity of the mutational signatures and four survival endpoints in 18 types of malignancies. We further explored the prognostic differences according to, for example, the HPV status in head and neck squamous cell carcinomas and smoking status in lung cancers. The predictive power of the signatures over time was evaluated with a dynamic area under the curve model, and the links between mutational signature activities and differences in gene expression patterns were analyzed. In 12 of 18 studied cancer types, we identified at least one mutational signature whose activity predicted survival outcomes after adjusting for the established prognostic factors. For example, overall survival was associated with the activity of mutational signatures in nine cancer types and disease-specific survival in seven cancer types. The clock-like signatures SBS5 and SBS40 were most commonly associated with survival endpoints. The genes of the myosin binding protein and melanoma antigen families were among the most substantially dysregulated genes between the signatures of low and high activity. The differences in gene expression also revealed various enriched pathways. Based on these data, specific mutational signatures associate with the gene expression and have the potential to serve as strong prognostic factors in several cancer types.

Development of Ligands and Degraders Targeting MAGE-A3.

Type I melanoma antigen (MAGE) family members are detected in numerous tumor types, and expression is correlated with poor prognosis, high tumor grade, and increased metastasis. Type I MAGE proteins are typically restricted to reproductive tissues, but expression can recur during tumorigenesis. Several biochemical functions have been elucidated for them, and notably, MAGEs regulate proteostasis by serving as substrate recognition modules for E3 ligase complexes. The repertoire of E3 ligase complexes that can be hijacked for targeted protein degradation continues to expand, and MAGE-E3 complexes are an especially attractive platform given their cancer-selective expression. Additionally, type I MAGE-derived peptides are presented on cancer cell surfaces, so targeted MAGE degradation may increase antigen presentation and improve immunotherapy outcomes. Motivated by these applications, we developed novel, small-molecule ligands for MAGE-A3, a type I MAGE that is widely expressed in tumors and associates with TRIM28, a RING E3 ligase. Chemical matter was identified through DNA-encoded library (DEL) screening, and hit compounds were validated for in vitro binding to MAGE-A3. We obtained a cocrystal structure with a DEL analog and hypothesize that the small molecule binds at a dimer interface. We utilized this ligand to develop PROTAC molecules that induce MAGE-A3 degradation through VHL recruitment and inhibit the proliferation of MAGE-A3 positive cell lines. These ligands and degraders may serve as valuable probes for investigating MAGE-A3 biology and as foundations for the ongoing development of tumor-specific PROTACs.

Utility of PRAME Immunohistochemistry in the Detection of Subtle Melanoma Microsatellites.

Microsatellitosis is well established as a prognostic factor in malignant melanoma. Its identification leads to subsequent upstaging with implications for further management. We describe 6 cases in which immunohistochemical staining for PReferentially expressed Antigen in MElanoma facilitated detection of small foci of micrometastasis on scanning magnification, which may be potentially missed in routine sections.

Digital quantification of PRAME for distinguishing melanoma from nevi compared to manual assessment

AimsIn this proof-of-concept study, we propose a new method for automated digital quantification of PRAME (PReferentially expressed Antigen of MElanoma) as a diagnostic aid to distinguish between benign and malignant melanocytic lesions. The proposed method utilizes immunohistochemical virtual double nuclear staining for PRAME and SOX10 to precisely identify the melanocytic cells of interest, which is combined with digital image analyse to quantify a PRAME-index. MethodsOur study included 10 compound nevi, 3 halo nevi, and 10 melanomas. Tissue slides were stained with PRAME, scanned, the cover glass removed, stained with SOX10, scanned again, and finally analysed digitally. The digitally quantified PRAME-index was compared with a manual qualitative assessment by a dermatopathologist using the standard PRAME-scoring system. ResultsThe digitally quantified PRAME-index showed a sensitivity of 70 % and a specificity of 100 % for separating melanomas from benign lesions. The manual qualitative PRAME-score showed a sensitivity of 60 % and a specificity of 100 %. Comparing the two methods using ROC-analyses, our digital quantitative method (AUC: 0.931, 95 % CI: 0.834;1.00, SD: 0.050) remains on par with the manual qualitative method (AUC: 0.877, 95 % CI: 0.725;1.00, SD: 0.078). ConclusionWe found our novel digital quantitative method was at least as precise at classifying lesions as benign or malignant as the current manual qualitative assessment. Our method has the advantages of being operator-independent, objective, and replicable. Furthermore, our method can easily be implemented in an already digitalized pathology department. Given the small cohort size, more studies are to be done to validate our findings.

Reporting tumor genomic test results to SEER registries via linkages.

Precision medicine has become a mainstay of cancer care in recent years. The National Cancer Institute (NCI) Surveillance, Epidemiology, and End Results (SEER) Program has been an authoritative source of cancer statistics and data since 1973. However, tumor genomic information has not been adequately captured in the cancer surveillance data, which impedes population-based research on molecular subtypes. To address this, the SEER Program has developed and implemented a centralized process to link SEER registries' tumor cases with genomic test results that are provided by molecular laboratories to the registries. Data linkages were carried out following operating procedures for centralized linkages established by the SEER Program. The linkages used Match*Pro, a probabilistic linkage software, and were facilitated by the registries' trusted third party (an honest broker). The SEER registries provide to NCI limited datasets that undergo preliminary evaluation prior to their release to the research community. Recently conducted genomic linkages included OncotypeDX Breast Recurrence Score, OncotypeDX Breast Ductal Carcinoma in Situ, OncotypeDX Genomic Prostate Score, Decipher Prostate Genomic Classifier, DecisionDX Uveal Melanoma, DecisionDX Preferentially Expressed Antigen in Melanoma, DecisionDX Melanoma, and germline tests results in Georgia and California SEER registries. The linkages of cancer cases from SEER registries with genomic test results obtained from molecular laboratories offer an effective approach for data collection in cancer surveillance. By providing de-identified data to the research community, the NCI's SEER Program enables scientists to investigate numerous research inquiries.

Therapeutic Anti-Tumor Efficacy of DC-Based Vaccines Targeting TME-Associated Antigens Is Improved When Combined with a Chemokine-Modulating Regimen and/or Anti-PD-L1.

We previously reported that dendritic cell (DC)-based vaccines targeting antigens expressed by tumor-associated vascular endothelial cells (VECs) and pericytes effectively control tumor growth in translational mouse tumor models. In the current report, we examined whether the therapeutic benefits of such tumor blood vessel antigen (TBVA)-targeted vaccines could be improved by the cotargeting of tumor antigens in the s.c. B16 melanoma model. We also evaluated whether combination vaccines incorporating anti-PD-L1 checkpoint blockade and/or a chemokine-modulating (CKM; IFNα + TLR3-L [rintatolimod] + Celecoxib) regimen would improve T cell infiltration/functionality in tumors yielding enhanced treatment benefits. We report that DC-peptide or DC-tumor lysate vaccines coordinately targeting melanoma antigens and TBVAs were effective in slowing B16 growth in vivo and extending survival, with superior outcomes observed for DC-peptide-based vaccines. Peptide-based vaccines that selectively target either melanoma antigens or TBVAs elicited a CD8+ T cell repertoire recognizing both tumor cells and tumor-associated VECs and pericytes in vitro, consistent with a treatment-induced epitope spreading mechanism. Notably, combination vaccines including anti-PD-L1 + CKM yielded superior therapeutic effects on tumor growth and animal survival, in association with the potentiation of polyfunctional CD8+ T cell reactivity against both tumor cells and tumor-associated vascular cells and a pro-inflammatory TME.

PRAME Expression in Merkel Cell Carcinoma.

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine tumor of the skin. Risk factors include extensive sun damage, infection with Merkel cell polyomavirus, and an immunocompromised state. PRAME, also known as preferentially expressed antigen in melanoma, is a cancer-testis antigen recently found to be a useful diagnostic tool in the workup of melanocytic neoplasms. However, the expression pattern of PRAME in Merkel cell carcinoma is unknown. In this study, we examine PRAME expression in Merkel cell carcinoma and explore its prognostic implications. The institutional archives at the University of Virginia were used to search for tumors classified as Merkel cell carcinoma from 2004 to 2022. All potential cases were reviewed to confirm the diagnosis, and electronic medical records were searched for clinical and demographic data. Tumors were subsequently immunostained for PRAME and Merkel cell polyomavirus. Cox proportional hazards regression models were used to estimate relative (all-cause) survival of PRAME positivity and MCPyV positivity in our study as well as MCC-specific survival of PRAME positivity. Univariate and multivariable models were created for each outcome related to all-cause survival. A total of 39 cases were included in the study. Twenty-eight percent (11 cases) demonstrated strong PRAME expression, and 27% of cases were positive for Merkel cell polyomavirus. There was no statistically significant correlation between PRAME expression and virus positivity. With respect to PRAME, the adjusted all-cause mortality hazard ratio was 11.4 (95% CI: 1.8, 70.8). The unadjusted MCC-specific hazard ratio was 4.6 (95% CI: 0.8, 27.5). The adjusted hazard ratio pertaining to Merkel cell polyomavirus infection was 0.25 (95% CI: 0.02, 2.96). In this limited cohort, PRAME expression appears to correlate with worse outcomes in Merkel cell carcinoma.