Genes

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Absence of microsatellite instability in extramammary Paget's disease

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Absence of microsatellite instability in extramammary Paget's disease

Deficiency of DNA mismatch repair (MMR) induces micro-satellite instability (MSI). Pembrolizumab, an antibody targeting PD‐1 (an immune checkpoint inhibitor), is more effective against MMR‐deficient tumours than against MMR‐proficient tumours. The status of MMR is a useful biomarker for predicting the effectiveness of pembrolizumab administration. Although the status of MMR has attracted attention in skin tumours, there are few reports on MSI in extramammary Paget's disease (EMPD). MSI testing showed the occurrence rates of MSI‐high (more than two markers are unstable), MSI‐low (one marker is unstable) and MSS (all markers are stable) tumour tissues were 0% (0/101), 1.0% (1/101) and 99.0% (100/101), respectively. The status of MMR may not be useful for the potential therapeutic application of pembrolizumab.

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Comparison of the biomarkers for targeted therapies in primary extra‐mammary and mammary Paget's disease

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Comparison of the biomarkers for targeted therapies in primary extra‐mammary and mammary Paget's disease

Primary Extra‐mammary Paget's disease (EMPD) is a very rare cutaneous adenocarcinoma affecting anogenital or axillary regions. It is characterized by a prolonged course with recurrences and eventually distant metastatic spread for which no specific therapy is known.

Eighteen EMPD (13 vulvar and five scrotal) and ten mammary Paget's disease (MPD) cases were comprehensively profiled for gene mutations, fusions and copy number alterations, and for therapy‐relevant protein biomarkers).

Mutations in TP53 and PIK3CA were the most frequent in both cohorts: 7/15 and 5/15 in EMPD; 1/6 and 4/7 in MPD HER2 gene amplification was detected in 4/18 EMPD (3 vulvar and 1 scrotal case) in contrast to MPD where it was detected in the majority (7/8) of cases. TOP2A gene amplification was seen in 2/12 EMPD and 1/6 MPD, respectively. Similarly, no difference in estrogen receptor expression was seen between the EMPD (4/15) and MPD (3/10). Androgen receptor was also expressed in the majority of both cohorts (12/16 EMPD) and (7/8 MPD).Here ARv7 splice variant was detected in 1/7 EMPD and 1/4 MPD cases, respectively. PD‐L1 expression on immune cells was exclusively observed in three vulvar EMPD. In contrast to MPD, six EMPDs harbored a “high” tumor mutation burden (≥10 mutations/Mb). All tested cases from both cohorts were MSI stable.

Extramammary Paget disease shows differential expression of B7 family members B7-H3, B7-H4, PD-L1, PD-L2 and cancer/ testis antigens NY-ESO-1 and MAGE-A

Extramammary Paget disease shows differential expression of B7 family members B7-H3, B7-H4, PD-L1, PD-L2 and cancer/ testis antigens NY-ESO-1 and MAGE-A

Extramammary Paget disease (EMPD) is a rare cutaneous adenocarcinoma of the anogenital region most commonly treated with surgical excision. Surgical margin clearance is often problematic and recurrence rates remain high indicating the need for additional therapeutic options. Topical immunomodulators have been used with reported success suggesting EMPD may respond to other immunotherapies. This study investigates EMPD protein expression of targetable B7 family members and cancer/testis antigens (CTAs) B7-H3, B7-H4, PD-L1, PD-L2, MAGE-A, and NY-ESO-1 and components of antigen presenting machinery B2M and MHC-I.

Identification of genetic alterations in extramammary Paget disease using whole exome analysis

Identification of genetic alterations in extramammary Paget disease using whole exome analysis

Exome analysis revealed recurrent somatic mutations in several genes, including TP53, PIK3CA, and ERBB2. We identified additional candidate exons by searching the COSMIC database for exons that are frequently mutated in other adenocarcinomas. We obtained 19 exons in 12 genes as candidate exons, and performed target amplicon sequencing in samples obtained from EMPD patients. New somatic mutations in the TP53 gene were identified in six EMPD patients. Single nucleotide polymorphism analysis revealed multiple chromosomal alterations in three EMPD specimens, and two specimens exhibited amplification of chromosome 12p13 and losses of 3p21–24, 7q22 and 13q12–21.

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

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

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.

This study aims to confirm the methylation and expression of MMR genes in EMPD.

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