The Rapp–Hodgkin syndrome results from mutations of the TP63 gene

International audienceThe Rapp-Hodgkin syndrome (RHS, MIM 129400) corresponds to a rare form of anhydrotic ectodermal dysplasia, which shares some features with the ectrodactyly, ectodermal dysplasia and cleft lip/palate syndrome (EEC, MIM 604292) resulting from TP63 mutations. We report here, in two unrelated patients with RHS, the identification of two distinct TP63 mutations, corresponding to a novel frameshift mutation (1709DelA, exon 14) located downstream the sterile alpha motif (SAM) domain and to a missense mutation (R279H, exon 7) within the DNA binding domain. Functional analysis of the R279H mutation, which had previously been reported in several EEC families, shows that this mutation disrupted the dominant negative activity of the DeltaNp63alpha and gamma isoforms on the transcriptional activity of TP53. This report shows, on a molecular basis, that RHS is also an EEC-like syndrome resulting from mutations of the TP63 gene, and highlights the wide phenotypic spectrum associated to TP63 mutations

Intérêt clinique de la détection des mutations circulantes d’ ESR1 chez les patientes traitées pour un cancer du sein métastatique exprimant les récepteurs hormonaux

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Direct circulating tumor DNA detection from unpurified plasma using a digital PCR platform

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Comparison of the quantification of KRAS mutations by digital PCR and E-ice-COLD-PCR in circulating-cell-free DNA from metastatic colorectal cancer patients

International audienceCirculating cell-free DNA (ccfDNA) bears great promise as biomarker for personalized medicine, but ccfDNA ispresent only at low levels in the plasma or serum of cancer patients. E-ice-COLD-PCR is a recently developed enrichmentmethod to detect and identify mutations present at low-abundance in clinical samples. However, recentstudies have shown the importance to accurately quantify low-abundance mutations as clinicallyimportant decisions will depend on certainmutation thresholds. The possibility for an enrichmentmethod to accuratelyquantify the mutation levels remains a point of concern and might limit its clinical applicability.In the present study, we compared the quantification of KRAS mutations in ccfDNA from metastatic colorectalcancer patients by E-ice-COLD-PCR with two digital PCR approaches. For the quantification of mutations by Eice-COLD-PCR, cell lines with known mutations diluted into WT genomic DNA were used for calibration. E-ice-COLD-PCR and the two digital PCR approaches showed the same range of the mutation level and were concordantfor mutation levels below the clinical relevant threshold.E-ice-COLD-PCR can accurately detect and quantify low-abundantmutations in ccfDNA and has a shorter time toresults making it compatible with the requirements of analyses in a clinical setting without the loss of quantitativeaccuracy

Circulating ESR1 mutations at the end of aromatase inhibitor adjuvant treatment and after relapse in breast cancer patients

Abstract Background Detection of circulating ESR1 mutations is associated with acquired resistance to aromatase inhibitor (AI) in metastatic breast cancer. Until now, the presence of circulating ESR1 mutations at the end of adjuvant treatment by AI in early breast cancer had never been clearly established. In this context, the aim of the present study was to evaluate the circulating ESR1 mutation frequency at the end of adjuvant treatment and after relapse. Methods This monocentric retrospective study was based on available stored plasmas and included all early breast cancer patients who completed at least 2 years of AI adjuvant treatment and experienced a documented relapse after the end of their treatment. Circulating ESR1 mutations (D538G, Y537S/N/C) were assessed by droplet digital PCR in plasma samples taken at the end of adjuvant treatment, at time of relapse and at time of progression under first line metastatic treatment. Results A total of 42 patients were included, with a median adjuvant AI exposure of 60 months (range 41–85). No circulating ESR1 mutation was detectable at the end of AI adjuvant therapy. At first relapse, 5.3% of the patients (2/38) had a detectable circulating ESR1 mutation. At time of progression on first-line metastatic treatment, 33% of the patients (7/21) under AI had a detectable circulating ESR1 mutation compared to none of the patients under chemotherapy (0/10). The two patients with a detectable ESR1 mutation at relapse were treated by AI and had an increase of their variant allele fraction at time of progression on first-line metastatic treatment. Conclusions Circulating ESR1 mutation detection at the end of AI-based adjuvant treatment is not clinically useful. Circulating ESR1 mutation could be assessed as soon as first relapse to guide interventional studies

Heparinase enables reliable quantification of circulating tumor DNA from heparinized plasma samples by droplet digital PCR

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Real-time molecular optical micro-imaging of EGFR mutations using a fluorescent erlotinib based tracer

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Prognostic value of circulating short-length DNA fragments in unresected glioblastoma patients

Background: Liquid biopsy application is still challenging in glioblastoma patients and the usefulness of short-length DNA (slDNA) fragments is not established. The aim was to investigate slDNA concentration as a prognostic marker in unresected glioblastoma patients. Methods: Patients with unresected glioblastoma and treated by radiochemotherapy (RT/TMZ) were included. Plasmas were prospectively collected at three times: before (pre-) RT, after (post-) RT and at the time of progression. Primary objective was to investigate the impact on survival of slDNA concentration [slDNA] variation during RT/TMZ. Secondary objectives were to explore the association between tumor volume, corticosteroid exposition and [slDNA]; and the impact of slDNA detection at pre-RT on survival. Results: Thirty-six patients were analyzed: 11 patients (30.6 %) experienced [slDNA] decrease during RT/TMZ, 22 patients (61.1 %) experienced increase and 3 patients (8.3 %) had stability. Decrease of [slDNA] during RT/TMZ was associated with better outcome compared to increase or stability: median OS, since end of RT, of 13.2 months [11.4 - NA] vs 10.1 months [7.8 - 12.6] and 6.8 months [4.5 - NA], p = 0.015, respectively. slDNA detection at pre-RT time was associated with improved OS: 11.7 months in the slDNA(+) group versus 8.8 months in the slDNA(-) group, p = 0.004. [slDNA] was not associated with corticosteroids exposition or tumor volume. No influence on survival was observed for both whole cfDNA concentration or slDNA peak size. Conclusion: [slDNA] decrease during radiochemotherapy phase is a favorable prognostic marker on OS for unresected glioblastoma patients. Larger and independent cohorts are now required. Trial registration: ClinicalTrial, NCT02617745. Registered 1 December 2015, https://clinicaltrials.gov/ct2/show/NCT02617745?term=glioplak&draw=2&rank=

Clinical value of chip-based digital-PCR platform for the detection of circulating DNA in metastatic colorectal cancer

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Genetic variations of the A13/A14 repeat located within the EGFR 3[prime] untranslated region have no oncogenic effect in patients with colorectal cancer.

International audienceBACKGROUND: The EGFR 3[prime] untranslated region (UTR) harbors a polyadenine repeat which is polymorphic (A13/A14) and undergoes somatic deletions in microsatellite instability (MSI) colorectal cancer (CRC). These mutations could be oncogenic in colorectal tissue since they were shown to result into increased EGFR mRNA stability in CRC cell lines. METHODS: First, we determined in a case control study including 429 CRC patients corresponding to different groups selected or not on age of tumor onset and/or familial history and/or MSI, whether or not, the germline EGFR A13/A14 polymorphism constitutes a genetic risk factor for CRC; second, we investigated the frequency of somatic mutations of this repeat in 179 CRC and their impact on EGFR expression. RESULTS: No statistically significant difference in allelic frequencies of the EGFR polyA repeat polymorphism was observed between CRC patients and controls. Somatic mutations affecting the EGFR 3[prime]UTR polyA tract were detected in 47/80 (58.8%) MSI CRC versus 0/99 microsatellite stable (MSS) tumors. Comparative analysis in 21 CRC samples of EGFR expression, between tumor and non malignant tissues, using two independent methods showed that somatic mutations of the EGFR polyA repeat did not result into an EGFR mRNA increase. CONCLUSION: Germline and somatic genetic variations occurring within the EGFR 3[prime]UTR polyA tract have no impact on CRC genetic risk and EGFR expression, respectively. Genotyping of the EGFR polyA tract has no clinical utility to identify patients with a high risk for CRC or patients who could benefit from anti-EGFR antibodies