Identification of a rare MET variant in three siblings with extramammary Paget disease.

Extramammary Paget disease (EMPD) is an intraepithelial adenocarcinoma that primarily affects the genital and axillary areas in older individuals. A limited number of paired patients with familial EMPD (i.e. parent-offspring, siblings) have been reported but the genetics have not yet been adequately studied. We report, to the best of our knowledge, the first familial cases of patients with EMPD involving three affected siblings. The tumour-only multigene panel testing using surgical specimens revealed a heterozygous c.2997A>C (p.Glu999Asp) nonsynonymous variant in the proto-oncogene MET (NM_000245.4) in the three affected siblings. The germline multigene panel testing using peripheral blood lymphocytes revealed the same missense MET variant in all five family members who were tested, including two asymptomatic offspring (51 and 37 years of age). The MET variant we identified could be involved in EMPD carcinogenesis. Further genomic analyses of patients with familial EMPD are warranted to validate the pathogenic relevance of MET variants in EMPD development.

Loss of p16 Immunoexpression and Deletions of CDKN2A in the Progression of Extramammary Paget Disease: An Immunohistochemical and Genetic Study of 24 Invasive/Metastatic Cases.

ABSTRACT: Information regarding the genetic alterations in extramammary Paget disease (EMPD) is scarce. This study investigated the significance of CDKN2A and MTAP alterations in EMPD progression using immunohistochemistry and panel DNA sequencing. In total, 24 invasive/metastatic EMPD cases were included in this study. The immunoexpression of p16 and MTAP in the primary in situ, primary invasive, and metastatic tumor components was evaluated. Panel DNA sequencing was performed for metastatic tumor components in 5 of the 24 cases. Immunoexpression of p16 in the in situ tumor component was at least partially preserved in all 19 tested cases (100%). By contrast, the invasive tumor component was diffusely or partially lost in 18 (81.8%) of 22 tested cases. Regarding the foci of lymph node metastasis, 13 (81.2%) of the 16 patients showed a significant loss of p16 expression. Loss of MTAP immunoexpression was observed less frequently compared with the loss of p16 expression. CDKN2A homozygous deletions were confirmed in all 5 tested cases by sequencing, whereas MTAP deletions were detected in only 2 cases. In conclusion, p16 expression loss and CDKN2A deletions can be frequently seen in invasive/metastatic cases of EMPD.

Whole genome methylation sequencing reveals epigenetic landscape and abnormal expression of FABP5 in extramammary Paget's disease.

BACKGROUND: Extramammary Paget's disease (EMPD) is a rare cutaneous malignant tumor with a high recurrence rate after surgery. However, the genetic and epigenetic alterations underlying its pathogenesis remain unknown. DNA methylation is an important epigenetic modification involved in many biological processes. METHODS: In this study, enzymatic methyl-sequencing (EM-seq) technique was used to investigate the landscape of genome-wide DNA methylation from three pairs of tumor tissues and adjacent tissues of patients with EMPD. Additionally, we conducted histopathological examinations to assess the expression of fatty acid-binding protein 5 (FABP5) in another three paired samples from EMPD patients. RESULTS: The cluster analysis showed the good quality of the samples. A differential methylation region (DMR) heat map was used to quantitatively characterize genome-wide methylation differences between tumors and controls. Global DNA methylation level is lower in EMPD tissue compared to matched controls, indicating that DNA methylation discriminates between tumor and normal skin. And the top hypomethylation gene on the promoter region in tumor tissues was FABP5 on chromosome 8 with 38.44% decreased median methylation. We next identified the expression of FABP5 in paired tumors and adjacent tissues in three additional patients with EMPD. Immunofluorescence results showed FABP5 highly expressed in tumor tissues and co-located with CK7, CK20 and EMA. GO and KEGG enrichment analysis showed DMR genes on promoter are mainly enriched in the calcium ion transport, GTPase mediated signal transduction, Rap1 signaling pathway and GnRH signaling pathway. CONCLUSION: Taken together, our findings provide the first description of the whole genome methylation map of EMPD and identify FABP5 as a pathogenic target of EMPD.

Genomic landscape of circulating tumour DNA in metastatic extramammary Paget's disease.

Although cancer personalized profiling by deep sequencing (CAPP-Seq) of cell-free DNA (cfDNA) has gained attention, the clinical utility of circulating tumour DNA (ctDNA) in extramammary Paget's disease (EMPD) has not been investigated. In this study, genomic alterations in the cfDNA and tumour tissue DNA were investigated in seven patients with metastatic EMPD. CAPP-Seq revealed mutations in 18 genes, 11 of which have not yet been reported in EMPD. The variant allele frequency of some of the mutated genes reflected the disease course in patients with EMPD. In one patient, the mutation was detected even though imaging findings revealed no metastasis. In another patient with triple EMPD (genital area and both axilla), cfDNA sequencing detected the mutation in a rib metastatic lesion, which was also detected in both axilla lesions but not the genital region. Investigations of the ctDNA may be useful towards the elucidation of clonal evolution in EMPD.

Trop2 Expression in Extramammary Paget's Disease and Normal Skin.

Extramammary Paget's disease (EMPD) is a rare skin cancer arising in the apocrine gland-rich areas. Most EMPD tumors are dormant, but metastatic lesions are associated with poor outcomes owing to the lack of effective systemic therapies. Trophoblast cell surface antigen 2 (Trop2), a surface glycoprotein, has drawn attention as a potential therapeutic target for solid tumors. Sacituzumab govitecan, an antibody-drug conjugate of Trop2, has recently entered clinical use for the treatment of various solid cancers. However, little is known about the role of Trop2 in EMPD. In this study, we immunohistochemically examined Trop2 expression in 116 EMPD tissue samples and 10 normal skin tissues. In normal skin, Trop2 was expressed in the epidermal keratinocytes, inner root sheaths, and infundibulum/isthmus epithelium of hair follicles, eccrine/apocrine glands, and sebaceous glands. Most EMPD tissues exhibited homogeneous and strong Trop2 expression, and high Trop2 expression was significantly associated with worse disease-free survival (p = 0.0343). These results suggest the potential use of Trop2-targeted therapy for EMPD and improve our understanding of the skin-related adverse effects of current Trop2-targeted therapies such as sacituzumab govitecan.

The Warburg effect and tumour immune microenvironment in extramammary Paget's disease: overexpression of lactate dehydrogenase A correlates with immune resistance.

BACKGROUND: Extramammary Paget's disease (EMPD) is a rare malignant skin cancer. One of the hallmarks of cancers, including EMPD, is an enhancement of aerobic glycolysis, which is also known as the Warburg effect. In the last step of glycolysis, the enzyme lactate dehydrogenase A (LDHA) catalyzes the conversion of pyruvate to lactic acid, the accumulation of which contributes to the creation of an acidic tumour microenvironment. This in turn results in immunosuppression in various types of cancers. However, the contribution of these pathways has not been well-studied in EMPD. OBJECTIVE: To investigate the significance of the Warburg effect and its contribution to the tumour immune microenvironment in EMPD. METHODS: The mRNA expression levels of molecules involved in glycolysis and immune-related cytokines were examined by ddPCR. The number of immune cells was assessed by immunohistochemistry (IHC). RESULTS: The levels of two glycolytic enzymes, HK2 and LDHA, in tumour tissues were significantly increased compared to those in paired-normal tissues. IHC analyses revealed increased numbers of PD-L1+ , PD-1+ , CD163+ M2 macrophages, Iba1+ macrophages and Foxp3+ Tregs that were associated with high LDHA levels in EMPD. ddPCR demonstrated that multiple cytokines including IL-4, IL-6, IL-10, TGF-ß and CCL-2 were upregulated and associated with high LDHA levels in EMPD. Statistical analyses showed that IL-6 mRNA expression correlated with the number of CD163+ , Iba-1+ and Foxp3+ cells. CONCLUSION: The Warburg effect contributes to immunomodulation in the tumour microenvironment and further elucidation may lead to better understanding of the pathogenesis of EMPD.

Serum cell-free DNA levels are a useful marker for extramammary Paget disease.

BACKGROUND: Although carcinoembryonic antigen (CEA) and cytokeratin 19 fragment (CYFRA) are useful markers for extramammary Paget disease (EMPD), serum CEA and CYFRA levels are not elevated in most patients with EMPD without metastasis. Cell-free (cf)DNA has attracted attention as an indicator of clinical conditions in several cancers. OBJECTIVES: To identify further useful biomarkers for the detection of EMPD, including early lesions, and to study the clinical implications of cfDNA in EMPD. METHODS: cfDNA were isolated from serum of patients with EMPD with and without metastasis, and from healthy volunteers. Serum extracts were amplified using polymerase chain reaction. RESULTS: Serum cfDNA levels were significantly elevated in patients with EMPD with or without metastasis compared with those in healthy controls. Serum cfDNA was a better diagnostic marker for the presence of EMPD than serum CYFRA. Moreover, the postoperative serum cfDNA levels were significantly lower than those from the preoperative samples, and the change in serum cfDNA levels reflected the clinical courses of patients with EMPD treated with chemotherapy. CONCLUSIONS: Taking the evidence together, serum cfDNA levels may be a useful marker for diagnosis and disease progression in EMPD. What's already known about this topic? Serum levels of carcinoembryonic antigen (CEA) and cytokeratin 19 fragment (CYFRA) are not elevated in most patients with extramammary Paget disease (EMPD) without metastasis. Cell-free (cf)DNA has attracted attention as an indicator of clinical conditions in several cancers. There are few reports of the clinical implications of cfDNA in dermatology. What does this study add? Serum cfDNA levels were significantly elevated in patients with EMPD with or without metastasis compared with those in healthy controls. Postoperative serum cfDNA levels were significantly lower than those from the preoperative samples. Changes in serum cfDNA levels reflected the clinical courses of patients with EMPD treated with chemotherapy. What is the translational message? Serum cfDNA levels in patients with EMPD are a useful marker for the detection of EMPD, including localized EMPD. Changes in serum cfDNA levels in an individual patient may reflect the clinical course of EMPD.

Methylation and expression analysis of mismatch repair genes in extramammary Paget's disease.

BACKGROUND: Extramammary Paget's disease (EMPD) is a rare skin cancer with relative high frequencies of germline and somatic mismatch repair (MMR) genes mutations. However, the methylation and expression of these genes have not been validated in EMPD. OBJECTIVE: This study aims to confirm the methylation and expression of MMR genes in EMPD. METHODS: Immunohistochemical (IHC) staining detection and Methylation-specific PCR (MSP) were used to analyse MLH1, MSH2, MSH6 and PMS2 proteins' expression and promoters' methylation in 57 EMMD samples, and pyro-sequence was used to find highly methylated CpG sites in MSH2 promoter. RESULTS: Immunohistochemical detection displayed reduced expression of MSH2 in 38.6% EMPD cases but normal expression of MLH1, MSH6 and PMS2 in all tumour tissues. Hypermethylation also was found in the promoter of MSH2 but not in other MMR genes. Pyrosequencing of MSH2 promoter showed CpG6 (-87) and CpG3 (-98) were the most common two methylated CpG dinucleotides. There is a significant correlation between reduced MSH2 expression and MSH2 methylation. CONCLUSION: Reduced MSH2 expression and hypermethylation in this gene promoter were common genetic changes in EMPD, which expands our understanding of the role of MMR function in this skin cancer.

MiR-155, a potential serum marker of extramammary Paget's disease.

BACKGROUND: Extramammary Paget's disease (EMPD), a rare skin malignancy with non-specific manifestations, is often misdiagnosed as eczema of scrotum or tinea cruris. Although the diagnosis of EMPD could be confirmed by biopsy, it can be delayed as patients are reluctant to receive invasive operations. Herein, we investigated the serum miRNA expressions of EMPD patients and compared to that of the eczema of scrotum or tinea cruris patients as well as health volunteers for potential diagnostic markers for EMPD. METHODS: Altogether 45 subjects including 16 patients diagnosed with EMPD, 12 patients diagnosed with eczema of scrotum or tinea cruris and 17 healthy volunteers were enrolled in this study. Serum from all of subjects were collected to identify miRNAs (by miRNA array global normalization, RT-PCR validation, and receiver operating characteristic curve analysis) that could be potential diagnostic markers for EMPD. RESULTS: The miRNA array analyses revealed that the expressions of 37 miRNAs from the EMPD patients were different (change ≥4-fold) from health volunteers. Among these miRNAs, the expression of miR-155 was significantly increased (p < 0.01) in the EMPD patients as compared with that of the health volunteers and the eczema of scrotum or the tinea cruris patients (no difference between these two control groups). In addition, receiver operating characteristic (ROC) curve analysis showed that diagnostic capacities (defined as the area under curve of ROC) of miR-155 are 0.85 (as compared with health volunteers group) and 0.81 (as compared with the eczema of scrotum or the tinea cruris patients group), respectively. CONCLUSION: The serum miRNA expression of gene miR-155 in the EMPD patients was differentiated from that of other subjects warranting further validation of miR-155 as a diagnostic marker of EMPD.

Study of Selected BRCA1, BRCA2, and PIK3CA Mutations in Benign and Malignant Lesions of Anogenital Mammary-Like Glands.

Anogenital mammary-like glands (AGMLGs) are nowadays considered a normal component of the anogenital area. Lesions involving AGMLGs are histopathologically very similar to their mammary counterparts, but the information on molecular biological mechanisms in these vulvar/perianal tumors is scarce. Mutations in the PI3K-AKT cascade have been found in hidradenoma papilliferum. The authors studied selected BRCA1, BRCA2, and PIK3CA mutations in series of benign and malignant neoplasms thought to be associated with AGMLGs, including 9 cases of primary extramammary Paget disease, 3 different cases of mammary-type carcinoma (adenoid cystic like, tubulolobular, and invasive ductal like), and 5 cases of hidradenoma papilliferum. No BRCA mutation was detected, whereas 3 neoplasms yielded PIK3CA mutation, including extramammary Paget disease, mammary-type invasive ductal carcinoma, and tubulolobular carcinoma. Our study expands the spectrum of lesions of AGMLGs harboring mutations in genes encoding the PI3K-AKT cascade. Further studies of the whole BRCA1 and BRCA2 genes using a larger cohort are needed to clarify their role in the pathogenesis of AGMLG lesions.

Successful human epidermal growth receptor 2-targeted therapy beyond disease progression for extramammary Paget's disease.

Extramammary Paget's disease is a malignant intraepithelial carcinoma, which constitutes less than 1 % of all vulvar malignancies. Surgical resection is the first treatment of choice and standard chemotherapy has not been established for advanced or recurrent disease. Experimental and clinical studies have identified human epidermal growth receptor 2 as a potential therapeutic target. A 63-year-old male was referred for recurrent extramammary Paget's disease after surgery. Human epidermal growth receptor 2 was shown to be overexpressed and amplified by immunohistochemical analysis and fluorescence in situ hybridization analysis, respectively. After two cycles of trastuzumab monotherapy, all lymph node metastases decreased in size. However, he experienced recurrence in the lymph nodes during the seven courses of trastuzumab. As a subsequent treatment, trastuzumab was administered in combination with docetaxel and pertuzumab; clinical response was sustained for 12 months without significant adverse events.

MUC5AC expression correlates with invasiveness and progression of extramammary Paget's disease.

BACKGROUND: Patients with in situ extramammary Paget's disease (EMPD) tend to have a good prognosis, although dermal invasion and metastasis are associated with significantly increased morbidity and mortality. Previous studies have addressed mechanisms underlying the EMPD pathogenesis; however, no molecular markers that reflect invasiveness or progression have been established. OBJECTIVE: This study aims to identify a reliable marker for predicting the risk of invasion and metastasis in EMPD. METHODS: We performed an initial microarray screening for in situ, invasive or metastatic lymph node lesions of EMPD. We analysed 44 specimens from 38 primary EMPD cases by immunohistochemical staining. RESULTS: We found that expressions of MUC5AC directly correlate with invasion and prognosis. Labelling rates of tumour cells were scored by staining intensity on a four-tiered scale (- to 3+) to investigate the correlation between the expression score of these molecular markers and the type of EMPD lesion. All the specimens scored positive (3+) for MUC1 and negative (-) for MUC6. MUC5AC expression was detected in 19 of 44 (43.2%) specimens. Invasive lesions and metastatic lymph nodes tended to express MUC5AC significantly higher than in situ lesions (P < 0.01). MUC2 was positive in 10 specimens (22.7%). There was no significant difference between the degree of MUC2 expression and invasiveness. CONCLUSION: The degree of MUC5AC expression may correlate with the invasiveness and progression of EMPD, and may be a useful marker for identifying high-risk EMPD cases.

FOXM1: a new therapeutic target of extramammary Paget disease.

Extramammary Paget disease (EMPD) is a rare skin cancer that primarily affects older individuals predominantly in areas with apocrine sweat glands. Although most early EMPD lesions are indolent, patients with metastatic EMPD have a poor prognosis due to the lack of effective systemic treatment. In this study, we investigated the role of forkhead box M1 (FOXM1), a potent transcription factor, in EMPD and assessed the potential of FOXM1 as a therapeutic target. Immunohistochemistry of 112 primary and 17 metastatic EMPD samples revealed that FOXM1 expression increased with tumor progression. Patients in whom FOXM1 was expressed in more than 10% of tumor cells had significantly shorter disease-specific survival than the other patients (p = 0.0397). In in vitro studies using our newly established EMPD cell line, KS-EMPD-1, we found high expression of FOXM1. Knockdown of FOXM1 impaired tumor cell viability, migration, and invasion. Inhibition of FOXM1 using thiostrepton also reduced tumor cell viability in a dose-dependent manner. These findings suggest that FOXM1 is a promising therapeutic target for patients with EMPD.

Genetic intratumour heterogeneity and clonal evolution in extramammary Paget's disease.

All tumour cells in a patient have shared and non-shared genetic alterations, and the diversity of mutations is described as intratumoural heterogeneity (ITH). Multiregion sequencing is a genome sequencing analytical technique used for multiple, spatially-separated biopsy tissues that may further our understanding of ITH and tumour evolution. Although genetic mutations in extramammary Paget's disease (EMPD) have recently been detected by next-generation sequencing analysis, there have been no reports of ITH based on multiregion sequencing in EMPD. Thus, we clarified the landscape of ITH and tumour evolution in EMPD. We performed whole-exome sequencing on 35 tissues (30 tumour tissues and five normal skin samples as a paired control), collected from five patients with EMPD. The rate of private mutations was significantly higher than that of ubiquitous and shared mutations. Ubiquitous mutations were not present in driver genes, and most driver genes exhibited private and shared mutations. The most frequent base substitution was C>T in almost all lesions, and most mutational signatures corresponded to signature 1, 2, 3, and 8. The types of proposed aetiology in most lesions were based on age and AID/APOBEC family and BRCA1/BRCA2 mutations. Evolutionary trees were characterized by short trunks and long branches due to the extremely high ratio of private mutations. In contrast, pathogenic factors, such as base substitutions, mutational signatures, and proposed aetiology, were shared. Tumour evolution in EMPD appears to be characterized by a high level of genetic ITH with shared background factors.

Whole genome sequencing of HER2-positive metastatic extramammary Paget's disease: a case report.

BACKGROUND: Extramammary Paget's disease (EMPD) is a rare cancer that occurs within the epithelium of the skin, arising predominantly in areas with high apocrine gland concentration such as the vulva, scrotum, penis and perianal regions. Here, we aim to integrate clinicopathological data with genomic analysis of aggressive, rapidly-progressing de novo metastatic EMPD responding to HER2-directed treatment in combination with other agents, to attain a more comprehensive understanding of the disease landscape. METHODS: Immunohistochemical staining on the scrotal wall tumor and bone marrow metastasis demonstrated HER2 overexpression. Whole genome sequencing of the tumor and matched blood was performed. RESULTS: Notable copy number gains (log2FC > 0.9) on chromosomes 7 and 8 were detected (n = 81), with 92.6% of these unique genes specifically located on chromosome 8. Prominent cancer-associated genes include ZNF703, HOOK3, DDHD2, LSM1, NSD3, ADAM9, BRF2, KAT6A and FGFR1. Interestingly, ERBB2 gene did not exhibit high copy number gain (log2FC = 0.4) although 90% of tumor cells stained HER2-positive. Enrichment in pathways associated with transforming growth factor-beta (TGFß) (FDR = 0.0376, Enrichment Ratio = 8.12) and fibroblast growth factor receptor (FGFR1) signaling (FDR = 0.0082, Enrichment Ratio = 2.3) was detected. Amplicon structure analysis revealed that this was a simple-linear amplification event. CONCLUSION: Whole genome sequencing revealed the underlying copy number variation landscape in HER2-positive metastatic EMPD. The presence of alternative signalling pathways and genetic variants suggests potential interactions with HER2 signalling, which possibly contributed to the HER2 overexpression and observed response to HER2-directed therapy combined with other agents in a comprehensive treatment regimen.

Oncogenic mutations in extramammary Paget's disease and their clinical relevance.

Extramammary Paget's disease (EMPD) is a rare cutaneous malignant neoplasm. The genetic alterations underlying its pathogenesis have less been described. Therefore, we analyzed the possible mutations in the KRAS, HRAS, NRAS, BRAF, ARAF, RAF1, PIK3CA, AKT1, CTNNB1 and APC genes as well as methylation and expression of CDH1 in 144 EMPD cases and 42 matched normal skin tissues. A distinct mutation profile was identified in EMPDs with 27 (19%) cases mutant for RAS and RAF genes and 50 (35%) cases harboring oncogenic mutations in PIK3CA and AKT1. Moreover, a mutually exclusive pattern was observed in the genetic variants in these two signaling pathways. No mutation was detected in CTNNB1 and APC genes. High prevalence of low expression and hypermethylation of CDH1 gene was detected in 33 and 48% of the EMPD cases, respectively. Furthermore, PIK3CA and AKT1 mutations were significantly correlated with CDH1 hypermethylation which could explain why the majority of EMPD cases with mutant PIK3CA and AKT1 were invasive. Our study demonstrates that genetic variants associated with constitutive activation of RAS/RAF and PI3K/AKT pathways are involved in the pathogenesis of EMPD. This may represent novel therapeutic targets for this skin cancer.

Human epidermal growth factor receptor 2 protein overexpression and gene amplification in extramammary Paget disease.

BACKGROUND: Several recent studies have reported on the overexpression of human epidermal growth factor receptor (HER)2 in extramammary Paget disease (EMPD). However, there are only a few cases in which both overexpression and gene amplification of HER2 have been examined. OBJECTIVES: To evaluate the overexpression and gene amplification of HER2 using a standardized method with a large number of cases of EMPD. METHODS: Immunohistochemically, the overexpression of the HER2 protein was examined in 104 cases of EMPD, including 31 intraepithelial cases and 73 invasive cases (35 superficially invasive and 38 deeply invasive). When the HER2 protein was overexpressed or potentially overexpressed, further analysis of amplification of the gene encoding HER2, ERBB2, was undertaken using fluorescence in situ hybridization. RESULTS: The HER2 protein was overexpressed in 16 cases (15%) in total, and in 13 of 73 cases (18%) of invasive EMPD. The ERBB2 gene was amplified in all cases with a HER2 score of 3+. A HER2 score of 3+ or 2+, and ERBB2 amplification were significantly more frequent in the cases of deeply invasive EMPD than in intraepithelial/superficially invasive EMPD (24% vs. 6%/3%, P=0·012) and were correlated with a larger number of lymph-node metastases (P=0·047). Log-rank tests for survival curves showed that lymph-node metastasis and ERBB2 amplification were significant prognostic factors (P=0·0001 and P=0·043, respectively). However, by a multivariate analysis, only lymph-node status was a significant indicator of Paget-disease-specific survival (P=0·0001). CONCLUSIONS: A subset of EMPD, both intraepithelial and invasive, showed HER2 overexpression and gene amplification. These HER2 alterations were correlated with biologically aggressive EMPDs, i.e. those with deep invasion and lymph-node metastasis. Clinical trials of HER2-targeted therapy are awaited for improvement of the prognosis of patients with aggressive EMPD.