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Clonal Evolution of TP53 c.375+1G>A Mutation in Pre- and Post- Neo-Adjuvant Chemotherapy (NACT) Tumor Samples in High-Grade Serous Ovarian Cancer (HGSOC).

ABSTRACT: Carboplatin/paclitaxel is the reference regimen in the treatment of advanced high-grade serous ovarian cancer (HGSOC) in neo-adjuvant chemotherapy (NACT) before interval debulking surgery (IDS). To identify new genetic markers of platinum-resistance, next-generation sequencing (NGS) analysis of 26 cancer-genes was performed on paired matched pre- and post-NACT tumor and blood samples in a patient with stage IV HGSOC treated with NACT-IDS, showing platinum-refractory/resistance and poor prognosis. Only the TP53 c.375+1G>A somatic mutation was identified in both tumor samples. This variant, associated with aberrant splicing, was in trans configuration with the 72Arg allele of the known germline polymorphism TP53 c.215C>G (p. Pro72Arg). In the post-NACT tumor sample we observed the complete expansion of the TP53 c.375+1G>A driver mutant clone with somatic loss of the treatment-sensitive 72Arg allele. NGS results were confirmed with Sanger method and immunostaining for p53, BRCA1, p16, WT1, and Ki-67 markers were evaluated. This study showed that (i) the splice mutation in TP53 was present as an early driver mutation at diagnosis; (ii) the mutational profile was shared in pre- and post-NACT tumor samples; (iii) the complete expansion of a single dominant mutant clone through loss of heterozygosity (LOH) had occurred, suggesting a possible mechanism of platinum-resistance in HGSOC under the pressure of NACT.

SUBMITTER: Garziera M

PROVIDER: S-EPMC6829309 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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Clonal Evolution of <i>TP53</i> c.375+1G>A Mutation in Pre- and Post- Neo-Adjuvant Chemotherapy (NACT) Tumor Samples in High-Grade Serous Ovarian Cancer (HGSOC).

Garziera Marica M Cecchin Erika E Giorda Giorgio G Sorio Roberto R Scalone Simona S De Mattia Elena E Roncato Rossana R Gagno Sara S Poletto Elena E Romanato Loredana L Ecca Fabrizio F Canzonieri Vincenzo V Toffoli Giuseppe G

Cells 20191001 10

Carboplatin/paclitaxel is the reference regimen in the treatment of advanced high-grade serous ovarian cancer (HGSOC) in neo-adjuvant chemotherapy (NACT) before interval debulking surgery (IDS). To identify new genetic markers of platinum-resistance, next-generation sequencing (NGS) analysis of 26 cancer-genes was performed on paired matched pre- and post-NACT tumor and blood samples in a patient with stage IV HGSOC treated with NACT-IDS, showing platinum-refractory/resistance and poor prognosis ...[more]

PMID: 31581548

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Project description:ImportanceThe low 5-year survival rate of women with high-grade serous epithelial ovarian cancer (HGS-EOC) is related to its late diagnosis; thus, improvement in diagnosis constitutes a crucial step to increase the curability of this disease.ObjectiveTo determine whether the presence of the clonal pathogenic TP53 variant detected in matched primary tumor biopsies can be identified in DNA purified from Papanicolaou test samples collected from women with HGS-EOC years before the diagnosis.Design, setting, and participantsThis cohort study was conducted among a single-center cohort of women with histologically confirmed diagnosis of HGS-EOC recruited at San Gerardo Hospital, Monza, Italy, from October 15, 2015, to January 4, 2019. Serial dilutions of DNA derived from tumor samples and DNA extracted from healthy women's Papanicolaou test samples were analyzed to define the sensitivity and specificity of droplet digital polymerase chain reaction assays designed to detect the TP53 variants identified in tumors. All available brush-based Papanicolaou test slides performed up to 6 years before diagnosis were investigated at the Mario Negri Institute, Milano, Italy. Data were analyzed from October 2018 to December 2019.Main outcomes and measuresThe presence of tumor pathogenic TP53 variants was assessed by the droplet digital polymerase chain reaction approach in DNA purified from Papanicolaou test samples obtained from the same patients before diagnosis during cervical cancer screenings.ResultsAmong 17 included patients (median [interquartile range] age at diagnosis, 60 [53-69] years), Papanicolaou tests withdrawn before diagnosis presented tumor-matched TP53 variants in 11 patients (64%). In 2 patients for whom longitudinal Papanicolaou tests were available, including 1 patient with Papanicolaou tests from 25 and 49 months before diagnosis and 1 patient with Papanicolaou tests from 27 and 68 months before diagnosis, the TP53 clonal variant was detected at all time points.Conclusions and relevanceThese findings suggest that noninvasive early molecular diagnosis of HGS-EOC is potentially achievable through detection of TP53 clonal variants in the DNA purified from Papanicolaou tests performed during cervical cancer screening.

Project description:BackgroundHigh grade serous ovarian cancer is characterised by high initial response to chemotherapy but poor outcome in the long term due to acquired resistance. One of the main genetic features of this disease is TP53 mutation. The majority of TP53 mutated tumors harbor missense mutations in this gene, correlated with p53 accumulation. TP53 null tumors constitute a specific subgroup characterised by nonsense, frameshift or splice-site mutations associated to complete absence of p53 expression. Different studies show that this kind of tumors may have a worse prognosis than other TP53 mutated HGSC.MethodsIn this study, we sought to characterise the intra-tumor heterogeneity of a TP53 null HGSC consisting of six primary tumor samples, two intra-pelvic and four extra-pelvic recurrences using exome sequencing and comparative genome hybridisation.ResultsSignificant heterogeneity was found among the different tumor samples, both at the mutational and copy number levels. Exome sequencing identified 102 variants, of which only 42 were common to all three samples; whereas 7 of the 18 copy number changes found by CGH analysis were presented in all samples. Sanger validation of 20 variants found by exome sequencing in additional regions of the primary tumor and the recurrence allowed us to establish a sequence of the tumor clonal evolution, identifying those populations that most likely gave rise to recurrences and genes potentially involved in this process, like GPNMB and TFDP1. Using functional annotation and network analysis, we identified those biological functions most significantly altered in this tumor. Remarkably, unexpected functions such as microtubule-based movement and lipid metabolism emerged as important for tumor development and progression, suggesting its potential interest as therapeutic targets.ConclusionsAltogether, our results shed light on the clonal evolution of the distinct tumor regions identifying the most aggressive subpopulations and at least some of the genes that may be implicated in its progression and recurrence, and highlights the importance of considering intra-tumor heterogeneity when carrying out genetic and genomic studies, especially when these are aimed to diagnostic procedures or to uncover possible therapeutic strategies.

Dataset Information

Clonal Evolution of TP53 c.375+1G>A Mutation in Pre- and Post- Neo-Adjuvant Chemotherapy (NACT) Tumor Samples in High-Grade Serous Ovarian Cancer (HGSOC).

Publications

Clonal Evolution of <i>TP53</i> c.375+1G>A Mutation in Pre- and Post- Neo-Adjuvant Chemotherapy (NACT) Tumor Samples in High-Grade Serous Ovarian Cancer (HGSOC).

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