Estimating CDKN2A mutation carrier probability among global familial melanoma cases using GenoMELPREDICT.

BACKGROUND: Although rare in the general population, highly penetrant germline mutations in CDKN2A are responsible for 5%-40% of melanoma cases reported in melanoma-prone families. We sought to determine whether MELPREDICT was generalizable to a global series of families with melanoma and whether performance improvements can be achieved. METHODS: In total, 2116 familial melanoma cases were ascertained by the international GenoMEL Consortium. We recapitulated the MELPREDICT model within our data (GenoMELPREDICT) to assess performance improvements by adding phenotypic risk factors and history of pancreatic cancer. We report areas under the curve (AUC) with 95% confidence intervals (CIs) along with net reclassification indices (NRIs) as performance metrics. RESULTS: MELPREDICT performed well (AUC 0.752, 95% CI 0.730-0.775), and GenoMELPREDICT performance was similar (AUC 0.748, 95% CI 0.726-0.771). Adding a reported history of pancreatic cancer yielded discriminatory improvement (P < .0001) in GenoMELPREDICT (AUC 0.772, 95% CI 0.750-0.793, NRI 0.40). Including phenotypic risk factors did not improve performance. CONCLUSION: The MELPREDICT model functioned well in a global data set of familial melanoma cases. Adding pancreatic cancer history improved model prediction. GenoMELPREDICT is a simple tool for predicting CDKN2A mutational status among melanoma patients from melanoma-prone families and can aid in directing these patients to receive genetic testing or cancer risk counseling.

Pembrolizumab for Unresectable or Metastatic Melanoma in Patients Older than 85 Years of Age.

BACKGROUND: Programmed cell death protein-1 (PD-1) inhibitors (pembrolizumab and nivolumab) have been approved for the treatment of advanced melanoma. Over the past decades, patients older than 85 years represent an expanding group of patients in developed countries. In France, 25% of melanomas are diagnosed in patients older than 75 years. OBJECTIVE: To perform a monocentric retrospective study of patients older than 85 years and treated with pembrolizu-mab for unresectable or metastatic melanoma in order to evaluate tolerance and potential benefits of this immunotherapy. METHODS: Medical records of patients treated with the PD-1 inhibitor pembrolizumab between January 2015 and January 2018 were reviewed. RESULTS: Nine patients (6 women and 3 men) older than 85 years were included in the study. The mean age was 89.6 (85-97) years at inclusion. All patients were PS 0 or 1. The mean number of infusions was 4 (1-12). However, most patients were not able to tolerate the 4-infusion schedule. One patient refused the second infusion for personal reasons. Seven patients had grade 3 or 4 treatment-related adverse events. CONCLUSION: These results indicate that pembrolizumab treatment in patients older than 85 years may induce responses but is associated with a high risk of toxicity and impaired autonomy.

Germline CDKN2A/P16INK4A mutations contribute to genetic determinism of sarcoma.

BACKGROUND: Sarcomas are rare mesenchymal malignancies whose pathogenesis is poorly understood; both environmental and genetic risk factors could contribute to their aetiology. METHODS AND RESULTS: We performed whole-exome sequencing (WES) in a familial aggregation of three individuals affected with soft-tissue sarcoma (STS) without TP53 mutation (Li-Fraumeni-like, LFL) and found a shared pathogenic mutation in CDKN2A tumour suppressor gene. We searched for individuals with sarcoma among 474 melanoma-prone families with a CDKN2A-/+ genotype and for CDKN2A mutations in 190 TP53-negative LFL families where the index case was a sarcoma. Including the initial family, eight independent sarcoma cases carried a germline mutation in the CDKN2A/p16INK4A gene. In five out of seven formalin-fixed paraffin-embedded sarcomas, heterozygosity was lost at germline CDKN2A mutations sites demonstrating complete loss of function. As sarcomas are rare in CDKN2A/p16INK4A carriers, we searched in constitutional WES of nine carriers for potential modifying rare variants and identified three in platelet-derived growth factor receptor (PDGFRA) gene. Molecular modelling showed that two never-described variants could impact the PDGFRA extracellular domain structure. CONCLUSION: Germline mutations in CDKN2A/P16INK4A, a gene known to predispose to hereditary melanoma, pancreatic cancer and tobacco-related cancers, account also for a subset of hereditary sarcoma. In addition, we identified PDGFRA as a candidate modifier gene.

Clinical parameters associated with anti-programmed death-1 (PD-1) inhibitors-induced tumor response in melanoma patients.

Background The identification of the melanoma patients sensitive to anti-PD-1 inhibitors, nivolumab or pembrolizumab, is a major therapeutic challenge and an urgent need. We hypothesized that the natural history of the disease might partly reflect the immune state of the patients. Methods We analyzed our cohort of melanoma patients treated with anti-PD-1 from August 2014 to January 2016 in our institution. Objective response was defined as a complete or partial response according to v1.1 RECIST criteria. Results Among 63 metastatic melanoma patients, the overall response rate was 43%. Median time from diagnosis to anti-PD-1 initiation was longer among responders than non-responders (64 months vs. 35 months, p = 0.02). The response rate was 10% in patients starting anti-PD-1 within 1 year, 35% after 1 to 5 years and 63% after 5 years. Performance status (PS) 0 was also associated with enhanced tumor response: 70% of responders were PS 0 vs. 36% of non-responders (p = 0.04). PS 0, normal LDH levels and wild-type BRAF status were significant predictors of progression free survival. Conclusion A long time lapse from diagnosis to anti-PD-1 initiation and PS 0 are associated with higher sensitivity to anti-PD-1 in melanoma patients. These two clinical features might reflect a potentially intact immune system of the host.

Sarcopenic overweight is associated with early acute limiting toxicity of anti-PD1 checkpoint inhibitors in melanoma patients.

Little is known on factors predicting toxicity of anti-PD1 checkpoint inhibitors. Sarcopenic obesity is associated with increased acute toxicity of cytotoxic agents and targeted therapies. We explored whether body composition also influenced the occurrence of early acute limiting toxicity (ALT) of anti-PD1 in melanoma patients. This is a monocentric, retrospective study analyzing toxicity outcome in consecutive melanoma patients treated with nivolumab or pembrolizumab. Various parameters linked to the patient or the disease status have been analysed. Body mass index (BMI; kg/m2) and muscle mass using CT were measured prior to treatment initiation. Chi-squared test and Mann-Whitney's tests were used for the comparison of categorical and continuous variables respectively. Among 68 melanoma patients treated with anti-PD1 (47 pembrolizumab, 21 nivolumab), 38 (56%) patients had a BMI ≥ 25 kg/m2 and 11 (16%) a BMI ≥ 30, while 13 (19%) had both sarcopenia and a BMI ≥ 25 kg/m2. For the 11 (16%) patients who experienced early ALT, the mean BMI was higher (27.9 versus 24.7 kg/m2; p = 0.04). Among the 32 female patients, sarcopenic overweight patients had a 6.5-fold increased risk of ALT (50 versus 7.7%; p = 0.01). Sarcopenic overweight is associated with more early ALT of anti-PD1 in melanoma patients.

A comprehensive genome-wide analysis of melanoma Breslow thickness identifies interaction between CDC42 and SCIN genetic variants.

Breslow thickness (BT) is a major prognostic factor of cutaneous melanoma (CM), the most fatal skin cancer. The genetic component of BT has only been explored by candidate gene studies with inconsistent results. Our objective was to uncover the genetic factors underlying BT using an hypothesis-free genome-wide approach. Our analysis strategy integrated a genome-wide association study (GWAS) of single nucleotide polymorphisms (SNPs) for BT followed by pathway analysis of GWAS outcomes using the gene-set enrichment analysis (GSEA) method and epistasis analysis within BT-associated pathways. This strategy was applied to two large CM datasets with Hapmap3-imputed SNP data: the French MELARISK study for discovery (966 cases) and the MD Anderson Cancer Center study (1,546 cases) for replication. While no marginal effect of individual SNPs was revealed through GWAS, three pathways, defined by gene ontology (GO) categories were significantly enriched in genes associated with BT (false discovery rate ≤5% in both studies): hormone activity, cytokine activity and myeloid cell differentiation. Epistasis analysis, within each significant GO, identified a statistically significant interaction between CDC42 and SCIN SNPs (pmeta-int =2.2 × 10(-6) , which met the overall multiple-testing corrected threshold of 2.5 × 10(-6) ). These two SNPs (and proxies) are strongly associated with CDC42 and SCIN gene expression levels and map to regulatory elements in skin cells. This interaction has important biological relevance since CDC42 and SCIN proteins have opposite effects in actin cytoskeleton organization and dynamics, a key mechanism underlying melanoma cell migration and invasion.

Germline BAP1 mutations predispose to renal cell carcinomas.

The genetic cause of some familial nonsyndromic renal cell carcinomas (RCC) defined by at least two affected first-degree relatives is unknown. By combining whole-exome sequencing and tumor profiling in a family prone to cases of RCC, we identified a germline BAP1 mutation c.277A>G (p.Thr93Ala) as the probable genetic basis of RCC predisposition. This mutation segregated with all four RCC-affected relatives. Furthermore, BAP1 was found to be inactivated in RCC-affected individuals from this family. No BAP1 mutations were identified in 32 familial cases presenting with only RCC. We then screened for germline BAP1 deleterious mutations in familial aggregations of cancers within the spectrum of the recently described BAP1-associated tumor predisposition syndrome, including uveal melanoma, malignant pleural mesothelioma, and cutaneous melanoma. Among the 11 families that included individuals identified as carrying germline deleterious BAP1 mutations, 6 families presented with 9 RCC-affected individuals, demonstrating a significantly increased risk for RCC. This strongly argues that RCC belongs to the BAP1 syndrome and that BAP1 is a RCC-predisposition gene.

Vulvar hidradenoma papilliferum (HP) is located on the sites of mammary-like anogenital glands (MLAGs): Analysis of the photographs of 52 tumors.

BACKGROUND: Hidradenoma papilliferum (HP) is a benign tumor that primarily affects the anogenital area of adult women. Previously considered apocrine tumors, anogenital HP tumors are now interpreted as adenomas of mammary-like anogenital glands based on their histologic features. OBJECTIVE: This clinical study was undertaken to determine whether vulvar HP is located on mammary-like anogenital gland sites and to describe its morphologic features. METHODS: The clinical photographs of 52 histologically confirmed vulvar HP provided by 7 vulva specialists were analyzed. RESULTS: In all, 90.4% of the HP were located on the interlabial sulcus, adjacent zone, or the perineum. These tumors were polymorphous in terms of number (1 or multiple), size (<1-4.5 cm), color (pink, red, blue), surface (ulcerated or not), and architecture (unilobular or multilobular). LIMITATIONS: Eight histologic reports could not be reviewed by the authors but the contributors confirmed that the photographs sent were only those of histologically confirmed HPs. CONCLUSIONS: Vulvar HP is mainly located on mammary-like anogenital gland sites, thereby providing further evidence to their histogenesis. Although a nonulcerated or ulcerated tumor of the interlabial sulcus should evoke a HP diagnosis, the latter must be confirmed histologically.

Complete Penetrance and Absence of Intrafamilial Variability in a Large Family with Hereditary Leiomyomatosis and Renal Cell Carcinoma.

BACKGROUND: Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is an autosomal dominant familial disorder due to FH mutation. Despite a considerable increase in information about the genetic background, inter- and intrafamilial phenotypic variability/penetrance are not well documented. OBJECTIVE: To describe a large French HLRCC family and provide new data on penetrance and intrafamilial variability. MATERIALS AND METHODS: The whole family was contacted for clinical examination, skin biopsy, uterine and kidney imagery and molecular analysis. RESULTS: The family included 22 members in 3 generations. The second generation consisted of 13 members who were older than the expected age of onset of disease manifestations. Of the 12 available members of this second generation, 6 (1 man and 5 women, aged 44-57 years) had a novel FH mutation. All had the same mild phenotype with cutaneous asymptomatic leiomyomas, uterine fibroids (if women) and no kidney tumor. The other 6 members not bearing the familial mutation had normal clinical and radiological findings. In this second generation, the penetrance was therefore complete, and there was no intrafamilial variability in the clinical expression of the mutation. CONCLUSION: This study provides additional data on genotype/phenotype correlation, intrafamilial variability and penetrance that should help to improve prognosis and genetic counseling.

Inflammatory monocytes are potent antitumor effectors controlled by regulatory CD4+ T cells.

The present study evaluates the impact of immune cell populations on metastatic development in a model of spontaneous melanoma [mice expressing the human RET oncogene under the control of the metallothionein promoter (MT/ret mice)]. In this model, cancer cells disseminate early but remain dormant for several weeks. Then, MT/ret mice develop cutaneous metastases and, finally, distant metastases. A total of 35% of MT/ret mice develop a vitiligo, a skin depigmentation attributable to the lysis of normal melanocytes, associated with a delay in tumor progression. Here, we find that regulatory CD4(+) T cells accumulate in the skin, the spleen, and tumor-draining lymph nodes of MT/ret mice not developing vitiligo. Regulatory T-cell depletion and IL-10 neutralization led to increased occurrence of vitiligo that correlated with a decreased incidence of melanoma metastases. In contrast, inflammatory monocytes/dendritic cells accumulate in the skin of MT/ret mice with active vitiligo. Moreover, they inhibit tumor cell proliferation in vitro through a reactive oxygen species-dependent mechanism, and both their depletion and reactive oxygen species neutralization in vivo increased tumor cell dissemination. Altogether, our data suggest that regulatory CD4(+) T cells favor tumor progression, in part, by inhibiting recruitment and/or differentiation of inflammatory monocytes in the skin.

Integrated pathway and epistasis analysis reveals interactive effect of genetic variants at TERF1 and AFAP1L2 loci on melanoma risk.

Genome-wide association studies (GWASs) have characterized 13 loci associated with melanoma, which only account for a small part of melanoma risk. To identify new genes with too small an effect to be detected individually but which collectively influence melanoma risk and/or show interactive effects, we used a two-step analysis strategy including pathway analysis of genome-wide SNP data, in a first step, and epistasis analysis within significant pathways, in a second step. Pathway analysis, using the gene-set enrichment analysis (GSEA) approach and the gene ontology (GO) database, was applied to the outcomes of MELARISK (3,976 subjects) and MDACC (2,827 subjects) GWASs. Cross-gene SNP-SNP interaction analysis within melanoma-associated GOs was performed using the INTERSNP software. Five GO categories were significantly enriched in genes associated with melanoma (false discovery rate ≤ 5% in both studies): response to light stimulus, regulation of mitotic cell cycle, induction of programmed cell death, cytokine activity and oxidative phosphorylation. Epistasis analysis, within each of the five significant GOs, showed significant evidence for interaction for one SNP pair at TERF1 and AFAP1L2 loci (pmeta-int = 2.0 × 10(-7) , which met both the pathway and overall multiple-testing corrected thresholds that are equal to 9.8 × 10(-7) and 2.0 × 10(-7) , respectively) and suggestive evidence for another pair involving correlated SNPs at the same loci (pmeta-int = 3.6 × 10(-6) ). This interaction has important biological relevance given the key role of TERF1 in telomere biology and the reported physical interaction between TERF1 and AFAP1L2 proteins. This finding brings a novel piece of evidence for the emerging role of telomere dysfunction into melanoma development.

Fine mapping of genetic susceptibility loci for melanoma reveals a mixture of single variant and multiple variant regions.

At least 17 genomic regions are established as harboring melanoma susceptibility variants, in most instances with genome-wide levels of significance and replication in independent samples. Based on genome-wide single nucleotide polymorphism (SNP) data augmented by imputation to the 1,000 Genomes reference panel, we have fine mapped these regions in over 5,000 individuals with melanoma (mainly from the GenoMEL consortium) and over 7,000 ethnically matched controls. A penalized regression approach was used to discover those SNP markers that most parsimoniously explain the observed association in each genomic region. For the majority of the regions, the signal is best explained by a single SNP, which sometimes, as in the tyrosinase region, is a known functional variant. However in five regions the explanation is more complex. At the CDKN2A locus, for example, there is strong evidence that not only multiple SNPs but also multiple genes are involved. Our results illustrate the variability in the biology underlying genome-wide susceptibility loci and make steps toward accounting for some of the "missing heritability."

Sarcoidosis in Patients Treated with Vemurafenib for Metastatic Melanoma: A Paradoxical Autoimmune Activation.

BACKGROUND: Vemurafenib, a BRAF inhibitor, is a first-line treatment for inoperable melanoma. Sarcoidosis has never been reported in patients on vemurafenib. OBJECTIVES: We describe 5 cases of sarcoidosis in patients treated with vemurafenib. METHODS: Seventy patients receiving vemurafenib for a BRAF-mutated inoperable stage III or IV melanoma were treated in our centre. RESULTS: Five patients (7.1%) developed sarcoidosis or a sarcoid-like reaction on vemurafenib; 4 patients had cutaneous signs and 3 had extracutaneous disorders (bilateral hilar lymph nodes, uveitis). Histological analysis of skin lesions revealed epithelioid granulomas without necrosis, consistent with sarcoidosis. Angiotensin-converting enzyme levels were high in 2 patients. Cutaneous and ophthalmological lesions rapidly disappeared on topical corticosteroid treatment without the cessation of vemurafenib treatment. Complete remission of melanoma was observed in 3 patients and partial remission was observed in another. CONCLUSION: BRAF inhibitors probably have immune system-enhancing effects and should therefore be recognized as potential inducers of sarcoidosis.

Malignant Melanoma Arising in Patients with a Large Congenital Melanocytic Naevus: Retrospective Study of 10 Cases with Cytogenetic Analysis.

Large congenital melanocytic naevi (LCMN) represent the main risk factor for development of melanoma in childhood. This retrospective study of 10 cases of melanoma in patients with LCMN used fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH) (6 cases) to elucidate the clinical, histological, and cytogenetic characteristics of this rare disorder. Six melanomas were found within the LCMN, the others in lymph nodes, subcutis and brain. The LCMN was located on the trunk in 8 cases, with satellite naevi in 6 cases. Two distinct groups emerged: 5 melanomas that developed before the age of 10 years and the other after 20 years. The mortality rate was 60% and clearly correlated with clinical stage at diagnosis. Histological diagnosis was difficult in only 2 patients in whom neither immunohistochemistry nor FISH were helpful. Otherwise, CGH showed a high number of chromosomal aberrations leading to a formal diagnosis.

Melanoma prone families with CDK4 germline mutation: phenotypic profile and associations with MC1R variants.

BACKGROUND: CDKN2A and CDK4 are high risk susceptibility genes for cutaneous malignant melanoma. Melanoma families with CDKN2A germline mutations have been extensively characterised, whereas CDK4 families are rare and lack a systematic investigation of their phenotype. METHODS: All known families with CDK4 germline mutations (n=17) were recruited for the study by contacting the authors of published papers or by requests via the Melanoma Genetics Consortium (GenoMEL). Phenotypic data related to primary melanoma and pigmentation characteristics were collected. The CDK4 exon 2 and the complete coding region of the MC1R gene were sequenced. RESULTS: Eleven families carried the CDK4 R24H mutation whereas six families had the R24C mutation. The total number of subjects with verified melanoma was 103, with a median age at first melanoma diagnosis of 39 years. Forty-three (41.7%) subjects had developed multiple primary melanomas (MPM). A CDK4 mutation was found in 89 (including 62 melanoma cases) of 209 tested subjects. CDK4 positive family members (both melanoma cases and unaffected subjects) were more likely to have clinically atypical nevi than CDK4 negative family members (p<0.001). MPM subjects had a higher frequency of MC1R red hair colour variants compared with subjects with one tumour (p=0.010). CONCLUSION: Our study shows that families with CDK4 germline mutations cannot be distinguished phenotypically from CDKN2A melanoma families, which are characterised by early onset of disease, increased occurrence of clinically atypical nevi, and development of MPM. In a clinical setting, the CDK4 gene should therefore always be examined when a melanoma family tests negative for CDKN2A mutation.

[Screening for melanoma, an advanced practice nurse consultation]. / Dépistage du mélanome, pratique collaborative d'une infirmière experte.

In the dermatology consultation, at Cochin hospital, Paris, a nurse cooperates with a dermatologist in order to insure the clinical follow-up for high-risk melanoma patients. To adopt this innovative public health approach, the nurse has received theoretical, clinical and educational knowledge.

Subacute cutaneous lupus erythematosus induced and exacerbated by proton pump inhibitors.

BACKGROUND: Subacute cutaneous lupus erythematosus (SCLE) can be induced by numerous drugs. We report 3 cases of SCLE induced by proton pump inhibitors (PPIs). OBJECTIVE: To highlight a rare cutaneous side effect induced by a frequently prescribed drug such as a PPI. CASE REPORTS: Case 1 was a 30-year-old man who developed multiple annular plaques over the trunk and lower limbs 1 month after the initiation of pantoprazole. Antinuclear antibodies (ANA) were positive with anti-Ro/SSA and anti-La/SSB antibodies, and histology confirmed the diagnosis. Clinical improvement was achieved 8 weeks after the discontinuation of pantoprazole and the introduction of a treatment combining topical steroids and hydroxychloroquine. Lesions relapsed when pantoprazole was accidentally rechallenged. The second case was a 31-year-old woman, 28 weeks pregnant, who presented erythematous annular plaques over the trunk 7 weeks after starting esomeprazole. ANA and anti-Ro/SSA antibodies were positive, and the histology was compatible with SCLE. Fetal ultrasound was normal. She was treated with topical and oral steroids and hydroxychloroquine. Clinical improvement was achieved 4 weeks after the discontinuation of esomeprazole. The third case was a 57-year-old woman with systemic erythematosus lupus presenting annular and psoriasiform lesions on the trunk for 15 months. She was treated successively with hydroxychloroquine, azathioprine, mycophenolate mofetil and methotrexate with prednisone. A review of her drug history revealed the introduction of omeprazole a few weeks before the first appearance of skin lesions and omeprazole was contraindicated. CONCLUSION: SCLE should systematically be suspected in case of eruption after the introduction of PPI. The risk of fetal cardiac complications is important in pregnant women.

Preclinical corrective gene transfer in xeroderma pigmentosum human skin stem cells.

Xeroderma pigmentosum (XP) is a devastating disease associated with dramatic skin cancer proneness. XP cells are deficient in nucleotide excision repair (NER) of bulky DNA adducts including ultraviolet (UV)-induced mutagenic lesions. Approaches of corrective gene transfer in NER-deficient keratinocyte stem cells hold great hope for the long-term treatment of XP patients. To face this challenge, we developed a retrovirus-based strategy to safely transduce the wild-type XPC gene into clonogenic human primary XP-C keratinocytes. De novo expression of XPC was maintained in both mass population and derived independent candidate stem cells (holoclones) after more than 130 population doublings (PD) in culture upon serial propagation (>10(40) cells). Analyses of retrovirus integration sequences in isolated keratinocyte stem cells suggested the absence of adverse effects such as oncogenic activation or clonal expansion. Furthermore, corrected XP-C keratinocytes exhibited full NER capacity as well as normal features of epidermal differentiation in both organotypic skin cultures and in a preclinical murine model of human skin regeneration in vivo. The achievement of a long-term genetic correction of XP-C epidermal stem cells constitutes the first preclinical model of ex vivo gene therapy for XP-C patients.

Genetic correction of stem cells in the treatment of inherited diseases and focus on xeroderma pigmentosum.

Somatic stem cells ensure tissue renewal along life and healing of injuries. Their safe isolation, genetic manipulation ex vivo and reinfusion in patients suffering from life threatening immune deficiencies (for example, severe combined immunodeficiency (SCID)) have demonstrated the efficacy of ex vivo gene therapy. Similarly, adult epidermal stem cells have the capacity to renew epidermis, the fully differentiated, protective envelope of our body. Stable skin replacement of severely burned patients have proven life saving. Xeroderma pigmentosum (XP) is a devastating disease due to severe defects in the repair of mutagenic DNA lesions introduced upon exposure to solar radiations. Most patients die from the consequences of budding hundreds of skin cancers in the absence of photoprotection. We have developed a safe procedure of genetic correction of epidermal stem cells isolated from XP patients. Preclinical and safety assessments indicate successful correction of XP epidermal stem cells in the long term and their capacity to regenerate a normal skin with full capacities of DNA repair.

Distinct merkel cell polyomavirus molecular features in tumour and non tumour specimens from patients with merkel cell carcinoma.

Merkel Cell Polyomavirus (MCPyV) is associated with Merkel Cell carcinoma (MCC), a rare, aggressive skin cancer with neuroendocrine features. The causal role of MCPyV is highly suggested by monoclonal integration of its genome and expression of the viral large T (LT) antigen in MCC cells. We investigated and characterized MCPyV molecular features in MCC, respiratory, urine and blood samples from 33 patients by quantitative PCR, sequencing and detection of integrated viral DNA. We examined associations between either MCPyV viral load in primary MCC or MCPyV DNAemia and survival. Results were interpreted with respect to the viral molecular signature in each compartment. Patients with MCC containing more than 1 viral genome copy per cell had a longer period in complete remission than patients with less than 1 copy per cell (34 vs 10 months, P = 0.037). Peripheral blood mononuclear cells (PBMC) contained MCPyV more frequently in patients sampled with disease than in patients in complete remission (60% vs 11%, P = 0.00083). Moreover, the detection of MCPyV in at least one PBMC sample during follow-up was associated with a shorter overall survival (P = 0.003). Sequencing of viral DNA from MCC and non MCC samples characterized common single nucleotide polymorphisms defining 8 patient specific strains. However, specific molecular signatures truncating MCPyV LT were observed in 8/12 MCC cases but not in respiratory and urinary samples from 15 patients. New integration sites were identified in 4 MCC cases. Finally, mutated-integrated forms of MCPyV were detected in PBMC of two patients with disseminated MCC disease, indicating circulation of metastatic cells. We conclude that MCPyV molecular features in primary MCC tumour and PBMC may help to predict the course of the disease.