Intratumoral Genetic Heterogeneity Research Articles

Germline and somatic DNA damage repair gene mutations potentially predict the efficacy of relevant treatment in Chinese patients with pancreatic ductal adenocarcinoma.

e16732 Background: PDAC is a fatal disease with molecular heterogeneity, inducing differences in biological behaviour and therapeutic strategy. We conducted a study to reveal the mutation landscape of Chinese PDAC patients, and investigate the predictive role of germline and somatic DNA damage repair (DDR) status in precise treatment. Methods: 195 PDAC patients were enrolled from multiple medical centers of China between Jan 2016 to Nov 2019. Baseline clinical or genetic characteristics, and survival status were collected. NGS were performed on paraffin-embedded resected tissues or peripheral blood using a panel of 417 genes, including 50 DDR-related genes. Survival analysis was conducted using Kaplan-Meier, and Cox proportional hazard regression model. Results: The main driver genes were KRAS, TP53, CDKN2A, and SMAD4. Patients with KRAS mutation showed worse OS than those without (p = 0.048). DDR deficiency were identified in 15.38% of overall patients, mainly occurred in BRCA2 (4.62%), ATM (4.10%), RAD50 (1.54%) and MLH1 genes (1.03%). No significant improvement of OS existed between patients with or without DDR mutations (p = 0.88). Treatment with olaparib (adjusted HR, 0.2550; P = 0.0720) or platinum-based chemotherapy (adjusted HR, 0.1308; P = 0.0185) respectively decreased hazard of death in patients with DDR mutation. Besides BRCA gene, ATM mutant patients treated with olaparib harbored prolonged median OS than those without olaparib treatment (22.25 vs 15.2 month). Despite a little higher PD-L1 expression rate were seen in DDR mutant patients (29.17% vs 20.51%), no statistical correlation between tumor mutation burden level and DDR mutation was identified. And in patients treated with PD-1 blockade, 2 patients of DDR wild-type group both had SD, whereas of the remaining 5 patients with DDR deficiency, 1 was evaluated as PR, 3 as SD, and 1 as PD (ORR, 0 wt vs 20% mut). Conclusions: In this multi-center retrospective study, we deciphered the intra-tumoral genetic heterogeneity in Chinese PDAC population, which differs from western patients cohort to some extent. We found the potential role of germline and somatic DDR mutation status in predicting the response to olaparib and platinum-based chemotherapy, especially with BRCA or ATM mutation. However, DDR alteration was limited in prediction of hypermutational status and sensitivity to PD-1 blockade. Our study may provide a valuable evidence for clinical application of DDR mutation as a potential biomarker for precise treatment.

Genetic and epigenetic intratumor heterogeneity impacts prognosis of lung adenocarcinoma

Intratumor heterogeneity (ITH) of genomic alterations may impact prognosis of lung adenocarcinoma (LUAD). Here, we investigate ITH of somatic copy number alterations (SCNAs), DNA methylation, and point mutations in lung cancer driver genes in 292 tumor samples from 84 patients with LUAD. LUAD samples show substantial SCNA and methylation ITH, and clonal architecture analyses present congruent evolutionary trajectories for SCNAs and DNA methylation aberrations. Methylation ITH mapping to gene promoter areas or tumor suppressor genes is low. Moreover, ITH composed of genetic and epigenetic mechanisms altering the same cancer driver genes is shown in several tumors. To quantify ITH for valid statistical association analyses, we develope an average pairwise ITH index (APITH), which does not depend on the number of samples per tumor. Both APITH indexes for SCNAs and methylation aberrations show significant associations with poor prognosis. This study further establishes the important clinical implications of genetic and epigenetic ITH in LUAD.

Novel insights into breast cancer copy number genetic heterogeneity revealed by single-cell genome sequencing.

Copy number alterations (CNAs) play an important role in molding the genomes of breast cancers and have been shown to be clinically useful for prognostic and therapeutic purposes. However, our knowledge of intra-tumoral genetic heterogeneity of this important class of somatic alterations is limited. Here, using single-cell sequencing, we comprehensively map out the facets of copy number alteration heterogeneity in a cohort of breast cancer tumors. Ou/var/www/html/elife/12-05-2020/backup/r analyses reveal: genetic heterogeneity of non-tumor cells (i.e. stroma) within the tumor mass; the extent to which copy number heterogeneity impacts breast cancer genomes and the importance of both the genomic location and dosage of sub-clonal events; the pervasive nature of genetic heterogeneity of chromosomal amplifications; and the association of copy number heterogeneity with clinical and biological parameters such as polyploidy and estrogen receptor negative status. Our data highlight the power of single-cell genomics in dissecting, in its many forms, intra-tumoral genetic heterogeneity of CNAs, the magnitude with which CNA heterogeneity affects the genomes of breast cancers, and the potential importance of CNA heterogeneity in phenomena such as therapeutic resistance and disease relapse.

MP18-14 CHARACTERISING DNA METHYLATION PATTERNS IN TISSUE AND CIRCULATING TUMOUR DNA TO ENABLE DIFFERENTIATION OF SMALL RENAL MASSES

You have accessJournal of UrologyKidney Cancer: Basic Research & Pathophysiology II (MP18)1 Apr 2020MP18-14 CHARACTERISING DNA METHYLATION PATTERNS IN TISSUE AND CIRCULATING TUMOUR DNA TO ENABLE DIFFERENTIATION OF SMALL RENAL MASSES Sabrina Rossi*, Sara Pita, Anne Babbage, Gahee Park, Radoslaw Lach, Christopher Smith, Kevin Brennan, Tom Mitchell, Anne Warren, Olivier Gevaert, Charlie Massie, Grant Stewart, and DIAMOND Biobank Study Group Sabrina Rossi*Sabrina Rossi* More articles by this author , Sara PitaSara Pita More articles by this author , Anne BabbageAnne Babbage More articles by this author , Gahee ParkGahee Park More articles by this author , Radoslaw LachRadoslaw Lach More articles by this author , Christopher SmithChristopher Smith More articles by this author , Kevin BrennanKevin Brennan More articles by this author , Tom MitchellTom Mitchell More articles by this author , Anne WarrenAnne Warren More articles by this author , Olivier GevaertOlivier Gevaert More articles by this author , Charlie MassieCharlie Massie More articles by this author , Grant StewartGrant Stewart More articles by this author , and DIAMOND Biobank Study GroupDIAMOND Biobank Study Group More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000843.014AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Small renal masses (SRM) represent a diagnostic challenge. Indeed, ∼20% of SRM removed at surgery are found to be benign post-operatively. Renal biopsy may be non-diagnostic due to small tumour size, challenging anatomy or tumour heterogeneity. Circulating tumour DNA (ctDNA) analysis of DNA methylation in plasma or urine may overcome sampling bias associated with genetic intratumoral heterogeneity and offer a non-invasive method to derive a diagnosis. To test whether epigenetic markers differentiate pathological subtypes of renal masses we aim to (a) analyse multi-region samples from patients with renal tumours to map the landscape of DNA methylation heterogeneity and (b) evaluate methylation markers in triplicates of tissue, plasma and urine. METHODS: We recruited a cohort of patients across the RCC disease spectrum, from small renal masses to metastatic disease, including different pathological subtypes. Ethical approval was obtained (DIAMOND biobank; REC ID 03/018). Multi-region kidney tumour samples were collected from the nephrectomy specimen, including adjacent normal tissue, as well as urine and plasma samples from the same patients. Methylation analysis was performed in tissue using the Illumina EPIC Methyl Capture library preparation kit, with post capture bisulfite conversion. RESULTS: Tumour and normal samples were collected from 75 individuals with clear cell (N=35), chromophobe (N=10), papillary (N=20) RCC and oncocytoma (N=10). Additionally, we sequenced 142 multi-region samples from a subset of 26 patients and performed epigenetic phylogenetic analyses. We identified sets of differentially methylated cytosines at base-pair resolution in tumour tissue that (a) classify pathological subtypes of RCC and oncocytomas and (b) represent early ‘stem’ markers for ctDNA analysis. We present a summary of epigenetic clonal evolution and identify markers for high-sensitivity targeted analysis of DNA methylation in liquid samples. CONCLUSIONS: We evaluate DNA methylation in a large cohort of patients with pathological subtypes of renal tumours. This may represent a promising target for non-invasive liquid biopsy to differentiate benign from malignant small renal masses. Source of Funding: SHR is funded by a Cancer Research UK PhD Fellowship. © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e240-e241 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Sabrina Rossi* More articles by this author Sara Pita More articles by this author Anne Babbage More articles by this author Gahee Park More articles by this author Radoslaw Lach More articles by this author Christopher Smith More articles by this author Kevin Brennan More articles by this author Tom Mitchell More articles by this author Anne Warren More articles by this author Olivier Gevaert More articles by this author Charlie Massie More articles by this author Grant Stewart More articles by this author DIAMOND Biobank Study Group More articles by this author Expand All Advertisement PDF downloadLoading ...

Intratumoral heterogeneity and genetic characteristics of prostate cancer.

Prostate cancer is a heterogeneous disease and optimum gene targeting treatment is often impermissible. We aim to determine the intratumoral genomic heterogeneity of prostate cancer and explore candidate genes for targeted therapy. Exome sequencing was performed on 37 samples from 16 patients with prostate cancer. Somatic variant analysis, copy number variant (CNV) analysis, clonal evolution analysis and variant spectrum analysis were used to study the intratumoral genomic heterogeneity and genetic characteristics of metastatic prostate cancer. Our study confirmed the high intratumoral genetic heterogeneity of prostate cancer in many aspects, including number of shared variants, tumor mutation burden (TMB), variant genes, CNV burden, weighted genome instability index (wGII), CNV profiles, clonal evolutionary process, variant spectrum and mutational signatures. Moreover, we identified several common genetic characteristics of prostate cancer. Alterations of DNA damage repair genes, RTK/RAS pathway associated gene RASGRF1 and autophagy gene EPG5 may be involved in tumorigenesis in prostate cancer. CNV burden and DNA damage repair (DDR) genes may be associated with metastasis of prostate cancer.

A Combination of Three Biomarkers for HNSCC Prognostication Following Chemoradiotherapy

Accurate therapeutic prognostication continues to elude the head and neck oncologist, hindering de-intensification efforts and maximizing adjuvant therapy related toxicity. We examined three biomarkers: mutant allele tumor heterogeneity (MATH, a quantitative measure of intra-tumor genetic heterogeneity), and HPV and Estrogen Receptor alpha (ER-alpha) status in patients from the Cancer Genome Atlas (TCGA) treated with chemoradiotherapy (CRT). We hypothesized that this combination of biomarkers would prognosticate treatment outcome better than HPV status alone, allowing improved identification of patients at low and high risk of treatment failure.

Genomic profiling of primary and recurrent adult granulosa cell tumors of the ovary.

Adult-type granulosa cell tumor (aGCT) is a rare malignant ovarian sex cord-stromal tumor, harboring recurrent FOXL2 c.C402G/p.C134W hotspot mutations in 97% of cases. These tumors are considered to have a favorable prognosis, however aGCTs have a tendency for local spread and late recurrences, which are associated with poor survival rates. We sought to determine the genetic alterations associated with aGCT disease progression. We subjected primary non-recurrent aGCTs (n=7), primary aGCTs that subsequently recurred (n=9) and their matched recurrences (n=9), and aGCT recurrences without matched primary tumors (n=10) to targeted massively parallel sequencing of ≥410 cancer-related genes. In addition, 3 primary non-recurrent aGCTs and 9 aGCT recurrences were subjected to FOXL2 and TERT promoter Sanger sequencing analysis. All aGCTs harbored the FOXL2 C134W hotspot mutation. TERT promoter mutations were found to be significantly more frequent in recurrent (18/28, 64%) than primary aGCTs (5/19, 26%, p=0.017). In addition, mutations affecting TP53, MED12 and TET2 were restricted to aGCT recurrences. Pathway annotation of altered genes demonstrated that aGCT recurrences displayed an enrichment for genetic alterations affecting cell cycle pathway-related genes. Analysis of paired primary and recurrent aGCTs revealed that TERT promoter mutations were either present in both primary tumors and matched recurrences or were restricted to the recurrence and absent in the respective primary aGCT. Clonal composition analysis of these paired samples further revealed that aGCTs display intra-tumor genetic heterogeneity and harbor multiple clones at diagnosis and relapse. We observed that in a subset of cases, recurrences acquired additional genetic alterations not present in primary aGCTs, including TERT, MED12 and TP53 mutations and CDKN2A/B homozygous deletions. Albeit harboring relatively simple genomes, our data provide evidence to suggest that aGCTs are genetically heterogeneous tumors and that TERT promoter mutations and/or genetic alterations affecting other cell cycle-related genes may be associated with disease progression and recurrences.

Biomarkers for Early Cancer Diagnosis: Prospects for Success through the Lens of Tumor Genetics.

Thousands of candidate cancer biomarkers have been proposed, but so far, few are used in cancer screening. Failure to implement these biomarkers is attributed to technical and design flaws in the discovery and validation phases, but a major obstacle stems from cancer biology itself. Oncogenomics has revealed broad genetic heterogeneity among tumors of the same histology and same tissue (or organ) from different patients, while tumors of different tissue origins also share common genetic mutations. Moreover, there is wide intratumor genetic heterogeneity among cells within any single neoplasm. These findings seriously limit the prospects of finding a single biomarker with high specificity for early cancer detection. Current research focuses on developing biomarker panels, with data assessment by machine-learning algorithms. Whether such approaches will overcome the inherent limitations posed by tumor biology and lead to tests with true clinical value remains to be seen.

Intratumor heterogeneity could inform the use and type of postoperative adjuvant therapy in patients with head and neck squamous cell carcinoma.

After surgery for head and neck squamous cell carcinoma (HNSCC), decisions regarding adjuvant radiotherapy (RT) or chemoradiotherapy (CRT) are based on staging and the presence of high-risk pathology. Because higher mutant allele tumor heterogeneity (MATH; a measure of intratumor genetic heterogeneity) is associated with shorter overall survival (OS) in patients with HNSCC, the authors sought to determine whether MATH analysis might further inform these decisions. Adjuvant therapy-associated relationships between MATH and OS were analyzed for 389 patients with HNSCC who were treated surgically. Data were obtained from The Cancer Genome Atlas and analyzed with Cox proportional hazards multiple regression accounting for 7 other patient characteristics. The relationship between MATH and OS differed with adjuvant therapy in a way that could inform therapy decisions. Adjuvant RT alone was found to provide substantial benefit for patients having high-MATH tumors (RT vs no adjuvant therapy: hazard ratio, 0.29 [95% CI, 0.17-0.51]) but no benefit for those having low-MATH tumors. In contrast, adjuvant CRT provided no benefit beyond that of adjuvant RT for patients with high-MATH tumors but substantially improved OS among patients with low-MATH tumors (CRT vs no adjuvant therapy: hazard ratio, 0.34 [95% CI, 0.15-0.78]). The results of the current analysis suggested that patients with HNSCC with high-MATH tumors who underwent surgical treatment could benefit from adjuvant RT, even when current clinical guidelines indicate otherwise. The addition of adjuvant chemotherapy for patients with high-MATH tumors would not be indicated. Adding chemotherapy might be necessary to radiosensitize low-MATH tumors to adjuvant RT. This potential predictive role of tumor MATH analysis should be evaluated in prospective clinical trials.

Intratumoral Genetic Heterogeneity in Papillary Thyroid Cancer: Occurrence and Clinical Significance.

Intratumoral heterogeneity (ITH) refers to a subclonal genetic diversity observed within a tumor. ITH is the consequence of genetic instability and accumulation of genetic alterations, two mechanisms involved in the progression from an early tumor stage to a more aggressive cancer. While this process is widely accepted, the ITH of early stage papillary thyroid carcinoma (PTC) is debated. By different genetic analysis, several authors reported the frequent occurrence of PTCs composed of both tumor cells with and without RET/PTC or BRAFV600E genetic alterations. While these data, and the report of discrepancies in the genetic pattern between metastases and the primary tumor, demonstrate the existence of ITH in PTC, its extension and biological significance is debated. The ITH takes on a great significance when involves oncogenes, such as RET rearrangements and BRAFV600E as it calls into question their role of driver genes. ITH is also predicted to play a major clinical role as it could have a significant impact on prognosis and on the response to targeted therapy. In this review, we analyzed several data indicating that ITH is not a marginal event, occurring in PTC at any step of development, and suggesting the existence of unknown genetic or epigenetic alterations that still need to be identified.

Genetic heterogeneity and clonal evolution during metastasis in breast cancer patient-derived tumor xenograft models

Genetic heterogeneity within a tumor arises by clonal evolution, and patients with highly heterogeneous tumors are more likely to be resistant to therapy and have reduced survival. Clonal evolution also occurs when a subset of cells leave the primary tumor to form metastases, which leads to reduced genetic heterogeneity at the metastatic site. Although this process has been observed in human cancer, experimental models which recapitulate this process are lacking. Patient-derived tumor xenografts (PDX) have been shown to recapitulate the patient’s original tumor’s intra-tumor genetic heterogeneity, as well as its genomics and response to treatment, but whether they can be used to model clonal evolution in the metastatic process is currently unknown. Here, we address this question by following genetic changes in two breast cancer PDX models during metastasis. First, we discovered that mouse stroma can be a confounding factor in assessing intra-tumor heterogeneity by whole exome sequencing, thus we developed a new bioinformatic approach to correct for this. Finally, in a spontaneous, but not experimental (tail-vein) metastasis model we observed a loss of heterogeneity in PDX metastases compared to their orthotopic “primary” tumors, confirming that PDX models can faithfully mimic the clonal evolution process undergone in human patients during metastatic spreading.

Identification of functionally distinct and interacting cancer cell subpopulations from glioblastoma with intratumoral genetic heterogeneity.

BackgroundGlioblastomas display a high level of intratumoral heterogeneity with regard to both genetic and histological features. Within single tumors, subclones have been shown to communicate with each other to affect overall tumor growth. The aim of this study was to broaden the understanding of interclonal communication in glioblastoma.MethodsWe have used the U-343 model, consisting of U-343 MG, U-343 MGa, U-343 MGa 31L, and U-343 MGa Cl2:6, a set of distinct glioblastoma cell lines that have been derived from the same tumor. We characterized these with regard to temozolomide sensitivity, protein secretome, gene expression, DNA copy number, and cancer cell phenotypic traits. Furthermore, we performed coculture and conditioned media-based experiments to model cell-to-cell signaling in a setting of intratumoral heterogeneity.ResultsTemozolomide treatment of a coculture composed of all 4 U-343 cell lines presents a tumor relapse model where the least sensitive population, U-343 MGa 31L, outlives the others. Interestingly, the U-343 cell lines were shown to have distinct gene expression signatures and phenotypes although they were derived from a single tumor. The DNA copy number analysis revealed both common and unique alterations, indicating the evolutionary relationship between the cells. Moreover, these cells were found to communicate and affect each other’s proliferation, both via contact-dependent and -independent interactions, where NOTCH1, TGFBI, and ADAMTS1 signaling effects were involved, respectively.ConclusionsThese results provide insight into how complex the signaling events may prove to be in a setting of intratumoral heterogeneity in glioblastoma and provide a map for future studies.

Breast HER2 Intratumoral Heterogeneity as a Biomarker for Improving HER2-Targeted Therapy.

Development of HER2-targeted therapy drugs, particularly trastuzumab, demonstrated significant improvement of clinical outcomes among HER2 positive breast cancer patients during the last two decades. The exact biological mechanism of HER2 gene amplification occurrence remains unsolved. HER2 gene amplification and/or HER2 protein overexpression are the primary predictors for selecting invasive breast cancer patients as candidates for anti-HER2 agent-based chemotherapy protocol. However, HER2-targeted therapy is not completely successful: as it is well-documented, only one half of HER2 positive breast cancer patients achieve a pathological complete response after such a precision therapy. In the past, various HER2 drug resistance mechanisms were proposed for explaining incomplete the efficacy with anti-HER2 drugs. Recent studies suggested that HER2 intratumoral heterogeneity (ITH) determined by a concomitant HER2 gene and protein analyses are a significant primary resistance mechanism to HER2-targeted therapy. Recent discovery of undocumented "nonclassic" HER2-positive tumor cells with the amplified HER2 gene but no HER2 protein overexpression redefined HER2 ITH. The HER2 ITH consists of two groups of tumor heterogeneity subtypes: (1) genetic ITH (a mixture of HER2 negative tumor cells and classic HER2 positive tumor cells) and (2) nongenetic ITH (a mixture of classic HER2 positive tumor cells and nonclassic HER2 positive tumor cells). The mechanism underlining these nonclassic HER2 positive tumor cells with the amplified HER2 gene, but no HER2 protein overexpression, is unknown. Investigation of impaired HER2 and/or protein translation in these tumor cells could lead to a further improvement of cancer therapy by identifying new therapeutic targets for patients with HER2 ITH.

Intratumoral molecular genetic heterogeneity of glioblastomas

Intratumoral molecular genetic heterogeneity is not a less significant challenge in modern oncology than the intertumoral. The presence of cell populations within the same tumor, differing in their molecular properties, translated into phenotypic features of the cells, is one of the reasons for the inefficiency of many developments in the field of tumor therapy and the basis for the progression of malignant neoplasms. The issue under consideration is very relevant for glioblastoma (GBM) – being one of the deadliest human tumors; it practically does not lend itself to even promising experimental treatment methods. Therefore, this paper reviews intratumoral heterogeneity. The review in this aspect examines new experimental data, including those obtained using single-cell technologies, in particular, the key cell populations that make up the pool of tumor cells in glioblastoma, and their molecular metamodules, the presumptive role of some cell populations and their subpopulations in providing tumor malignancy properties. A promising groundwork for fundamentally new approaches to creating personalized diagnostic and therapeutic methods is indicated. Keywords: glioblastoma, intratumoral heterogeneity, glioblastoma genetics, single-cell sequencing

Intratumor heterogeneity reflects clinical disease course.

Intratumoral genetic heterogeneity of driver somatic mutations is present in a variety of tumor types, yet the extent of heterogeneity is variable. We propose that this variation is a reflection of the inherent biology of a given tumor type, representing the pace of metastatic dissemination and hence clinical disease course.

Genetic alterations in colorectal cancer: implications for the prognosis and treatment of the disease.

In recent years, important advances have been achieved in the understanding of the genetic abnormalities present in colorectal tumors and their association with their ontogeny and progression. Accordingly, while the presence of mutations in the APC and/or KRAS genes is associated with neoplastic transformation, mutations in SMAD and DCC, different chromosomal abnormalities located at 7, 17p and 18q, and complex karyotypes are frequently linked with tumor progression. From a clinical point of view, the presence of microsatellite instability (MSI) is associated with lower relapse rates and a greater overall survival, as well as resistance to adjuvant treatment with fluoropyrimidines, whereas mutations in the BRAF gene have been associated with early relapse. At the molecular level, studies of intratumoral genetic heterogeneity associated with the metastatic process of colorectal cancer (CRC) have focused on analyzing mutations in the genes involved in the treatment of the disease. In fact, different mutational profiles have been observed among primary tumors, lymph node metastases and liver metastases in the same patient. In this sense, the genetic heterogeneity of CRC at the intratumor level may explain the high relapse rates reported and the refractory nature of tumors treated with monoclonal antibodies.

Is high-risk cutaneous squamous cell carcinoma of the head and neck a suitable candidate for current targeted therapies?

ObjectiveCutaneous squamous cell carcinoma (cSCC) is the second most common malignancy, most frequently affecting the head and neck. Treatment often requires surgery and can have significant functional morbidity. Research into...

Genomic landscapes by multiregion sequencing combined with circulation tumor DNA detection contribute to molecular diagnosis in glioblastomas.

Glioblastoma is a highly aggressive brain malignancy with a poor prognosis. Its high intratumor heterogeneity contributes to therapeutic resistance, tumor progression and recurrence. We sequenced 31 loci in 11 patients with glioblastoma (including one patient with samples available from the primary and recurrent tumors) to determine the genetic basis and intratumor heterogeneity of glioblastoma. By analyzing the somatic mutations, known driver genes were identified, including EGFR, PTEN and TP53, and the MUC16 gene exhibited the highest mutation rate in the samples examined. Through an evolutionary analysis of the sequencing results, the EGFR p.L861Q mutation was determined to play a role in the progression from the primary tumor to a relapsing tumor in one patient. We analyzed 1403 genes in blood-derived ctDNA that were previously revealed to play a role in tumorigenesis and the progression of cancer. Somatic mutations identified through ctDNA sequencing that match the results of multipoint exon sequencing in tumor tissues were detected, such as EGFR p.L861Q. These findings provide new insights into the intratumor heterogeneity and evolution of glioblastoma. In addition, ctDNA detection in blood samples represents a convenient method to dynamically identify the genetic changes and new therapeutic targets during the treatment of glioblastoma.

Intra- and Inter-Tumor BRAF Heterogeneity in Acral Melanoma: An Immunohistochemical Analysis.

The current development of BRAF inhibitors has revolutionized the treatment of unresectable melanoma. As the potential heterogeneity of BRAF mutations in melanoma has been reported, accurate detection of BRAF mutations are important. However, the genetic heterogeneity of acral melanoma—a distinct type of melanoma with a unique genetic background—has not fully been investigated. We conducted a retrospective review of our acral melanoma patients. Of the 196 patients with acral melanoma, we retrieved 31 pairs of primary and matched metastatic melanomas. We immunostained the 31 pairs with VE1, a BRAFV600E-mutation-specific monoclonal antibody. Immunohistochemistry with VE1 showed a high degree of sensitivity and specificity for detecting BRAFV600E mutations compared with the real-time polymerase chain reaction method. A total of nine primary (29.0%) and eight metastatic (25.8%) acral melanomas were positive for VE1. In three patients (9.7%), we observed a discordance of VE1 staining between the primary and metastatic lesions. Of note, VE1 immunohistochemical staining revealed a remarkable degree of intra-tumor genetic heterogeneity in acral melanoma. Our study reveals that VE1 immunostaining is a useful ancillary method for detecting BRAFV600E mutations in acral melanoma and allows for a clear visualization of intra- and inter-tumor BRAF heterogeneity.

Intra-tumor genetic heterogeneity in Wilms tumor samples.

Childhood renal tumors account for ~7% of all childhood cancers, and most cases are embryonic Wilms' tumors (WT). Children with WT are usually treated by either COG or SIOP. The later treats the children using preoperative chemotherapy, but both have around 90% of overall survival in five years. WT is a genetically heterogeneous group with a low prevalence of known somatic alterations. Only around 30% of the cases present mutation in known genes, and there is a relatively high degree of intra-tumor genetic heterogeneity (ITGH). Besides potentially having an impact on the clinical outcome of patients, ITGH may interfere with the search for molecular markers that are prospectively being tested by COG and SIOP. In this review, we present the proposal of the current UMBRELLA SIOP Study 2017/Brazilian Renal Tumor Group that requires the multi-sampling collection of each tumor to better evaluate possible molecular markers, as well as to understand WT biology.