Establishing the origin of metastatic deposits in the setting of multiple primary malignancies: the role of massively parallel sequencing

BRCA1 and BRCA2 carriers with breast, ovarian and prostate cancer demonstrate a different pattern of metastatic disease compared with non-carriers: results from a rapid autopsy programme

AIM

To catalogue and compare the pattern of metastatic disease in germline BRCA1/2 pathogenic mutation carriers and non-carriers with breast, ovarian and prostate cancer from a rapid autopsy programme.

METHODS AND RESULTS

The number of metastases in the major body systems and the proportion of participants with metastases were documented in 50 participants (19 germline mutation carriers). Analysis was conducted on the participants' pattern of disease for the different cancers and mutation subgroups. The four commonly affected organ systems were the digestive (liver only) (82%), respiratory (76%), gastrointestinal (65%) and reticuloendothelial (42%). There were significant differences in the pattern of metastatic breast cancer in BRCA1/2 germline carriers compared with non-carriers. Breast cancer carriers had significantly fewer organ systems involved (median n = 3, range = 1-3) compared with non-carriers (median n = 9, range = 1-7) (P = 0.03). BRCA1/2 carriers with ovarian carcinomas had significantly more organ systems with metastatic carcinoma (median n = 10, range = 3-8) than non-carriers (median n = 5, range = 3-5) (P < 0.001). There were no significant differences in the number of involved systems in BRCA2 carriers compared with non-carriers with prostate cancer (P = 1.0). There was an absence of locoregional disease (6.5%) compared with distant disease (93.5%) among the three cancer subtypes (P < 0.001). The majority of metastatic deposits (97%) collected during the autopsy were identified by recent diagnostic imaging.

CONCLUSION

Even though a major limitation of this study is that our numbers are small, especially in the breast cancer carrier group, the metastatic patterns of breast and ovarian cancers may be impacted by BRCA1/2 carrier status, suggesting that tumours derived from patients with these mutations use different mechanisms of dissemination. The findings may focus clinical diagnostic imaging for monitoring metastases where whole-body imaging resources are scant.

4-1BB co-stimulation further enhances anti-PD-1-mediated reinvigoration of exhausted CD39+ CD8 T cells from primary and metastatic sites of epithelial ovarian cancers

BACKGROUND

Responses to immunotherapy vary between different cancer types and sites. Here, we aimed to investigate features of exhaustion and activation in tumor-infiltrating CD8 T cells at both the primary and metastatic sites in epithelial ovarian cancer.

METHODS

Tumor tissues and peripheral blood were obtained from 65 patients with ovarian cancer. From these samples, we isolated tumor-infiltrating lymphocytes (TILs) and peripheral blood mononuclear cells. These cells were used for immunophenotype using multicolor flow cytometry, gene expression profile using RNA sequencing and ex vivo functional restoration assays.

RESULTS

We found that CD39+ CD8 TILs were enriched with tumor-specific CD8 TILs, and that the activation status of these cells was determined by the differential programmed cell death protein 1 (PD-1) expression level. CD39+ CD8 TILs with high PD-1 expression (PD-1high) exhibited features of highly tumor-reactive and terminally exhausted phenotypes. Notably, PD-1high CD39+ CD8 TILs showed similar characteristics in terms of T-cell exhaustion and activation between the primary and metastatic sites. Among co-stimulatory receptors, 4-1BB was exclusively overexpressed in CD39+ CD8 TILs, especially on PD-1high cells, and 4-1BB-expressing cells displayed immunophenotypes indicating higher degrees of T-cell activation and proliferation, and less exhaustion, compared with cells not expressing 4-1BB. Importantly, 4-1BB agonistic antibodies further enhanced the anti-PD-1-mediated reinvigoration of exhausted CD8 TILs from both primary and metastatic sites.

CONCLUSION

Severely exhausted PD-1high CD39+ CD8 TILs displayed a distinctly heterogeneous exhaustion and activation status determined by differential 4-1BB expression levels, providing rationale and evidence for immunotherapies targeting co-stimulatory receptor 4-1BB in ovarian cancers.

Establishment of Peritoneal and Hepatic Metastasis Mouse Xenograft Models Using Gastric Cancer Cell Lines

BACKGROUND/AIM

Establishment of mouse xenograft models is necessary for oncological research and depends on the characteristics of the cell lines and the immune system of the host. In this study, we describe the development of mouse xenograft models using human gastric cancer (GC) cell lines.

MATERIALS AND METHODS

MKN1 stably-expressing luciferase (MKN1-Luc), N87, KATO III, MKN45 stably-expressing luciferase (MKN45-Luc), NUGC4, and OCUM-1 human GC cell lines were injected intraperitoneally into mice to establish peritoneal metastasis models. MKN45-Luc were injected into subcutaneously implanted spleen, and MKN1-Luc and MKN45-Luc were injected directly into the portal veins of mice for the establishment of hepatic metastasis models.

RESULTS

Peritoneal metastasis was formed after implantation of MKN1-Luc, N87, KATO III, MKN45-Luc, and NUGC4 in nude mice, but not formed in OCUM-1 even in NOD/SCID mice. After intrasplenic injection of MKN45-Luc, we found no hepatic metastasis formation. We identified hepatic metastasis formation after direct injection of MKN45-Luc and MKN1-Luc into the portal veins of NOD/SCID mice.

CONCLUSION

Peritoneal and hepatic metastasis mouse xenograft models were successfully established using several human GC cell lines.

Detection of EGFR gene mutation status from pleural effusions and other body fluid specimens in patients with lung adenocarcinoma

Background

Epidermal growth factor receptor (EGFR) gene mutation status is essential to the optimal management of lung adenocarcinoma. Liquid biopsy has advantages such as noninvasiveness, speediness, and convenience. This study aimed to detect EGFR gene mutations using next‐generation sequencing (NGS) from different types of body fluids from patients with lung adenocarcinoma.

Methods

This was a prospective study of 20 patients with lung adenocarcinoma recruited between January 2017 and December 2018 at the Beijing Hospital. All patients had adenocarcinoma with confirmed sensitizing EGFR mutations. Body fluid specimens included pleural effusion, ascites, pericardial effusion, and cerebrospinal fluid. NGS was conducted to test for nine lung cancer‐related gene in body fluid supernatant free DNA, sedimentary tumor cells, and plasma free DNA.

Results

The EGFR gene mutation abundance of body fluid supernatant free DNA was higher than that of body fluid sedimentary tumor cells and plasma free DNA specimens (100% vs. 90% vs. 80%, respectively, all P < 0.05). The results of EGFR mutation from the body fluid supernatants were consistent with the results from the tissue biopsy.

Conclusions

This study showed that compared with body fluid sediment tumor cells and plasma free DNA samples, body fluid supernatant free DNA has a higher detection rate and sensitivity of tumor‐specific mutations. Free DNA obtained from body fluid supernatants could be used as high‐quality specimens for gene mutation detection in patients with lung cancer. This could be applied in treatment decisions and patient management.

Peritoneal Metastases from Breast Cancer: A Scoping Review

Breast cancer is the leading cause of cancer deaths amongst American women aged 20 to 59. While the incidence of breast cancer has been increasing, its mortality rates have significantly declined from 1989 to 2016. As a result, the number of survivors considerably increased. This impacts the detection and management of recurrences. Peritoneal metastases from breast cancer is a rare and challenging clinical presentation. There is a lack of knowledge syntheses and specific recommendations for the management of breast cancer peritoneal metastases. This review aims to determine the pattern of spread, prognosis, diagnosis, and role of surgery in this subset of patients.

Relevant studies were searched in PubMed and Web of Science between April and June 2019. Included studies were written in English and reported data on breast cancer peritoneal or gastrointestinal metastases. Articles published before 1990, case reports, editorials, and articles with no full text available were excluded. Data abstraction was performed for citation information, population, sample, methods, relevant results, mentioned limitations, and study design.

The search identified 505 unique reports. A total of 21 articles were included in the synthesis. Sixteen articles were observational studies, four were experimental, and one article was a proof-of-concept study. Amongst all observational studies, the diagnostic methods and criteria for breast cancer carcinomatosis were particularly heterogeneous, including ascites cytology, biopsy, surgical exploration, and various computed tomography (CT) findings. The majority of pathology and imaging reports demonstrated that breast cancer peritoneal metastases are mainly associated with invasive lobular carcinoma (ILC) and the following intrinsic subtypes: HER2-enriched, luminal B and basal-like. Experimental studies demonstrated that peritoneal metastases can be studied using breast cancer xenograft models. Somatic loss of both p53 and E-cadherin was associated with ILC peritoneal spread. Studies on prognosis and treatment highlighted that peritoneal metastases were associated with a poorer prognosis than other metastatic sites. In terms of surgical management, there is a paucity of data on the outcomes of hyperthermic intraperitoneal chemotherapy (HIPEC) in these patients. However, included studies suggested a role for cytoreductive surgery in selected patients when there is no residual disease after the procedure.

This review summarizes data on the development, diagnosis, prognosis, and treatment of breast cancer peritoneal and gastrointestinal metastases. Patients’ survival is significantly reduced in comparison with other distant metastatic sites. A deeper understanding of the invasion mechanisms and the role of surgery will be important.

Cell-Free DNA in the Liquid Biopsy Context: Role and Differences Between ctDNA and CTC Marker in Cancer Management

Liquid biopsy is a new diagnostic concept to investigate the molecular features of solid tumors by blood, saliva, urine, and any other body fluids which show a source of potential biomarkers. In cancer patients, it is a simple and less invasive mean, representing a sustainable alternative to interrogate all tumor cells longitudinally, quantifying and characterizing the biological materials (DNAs, RNAs, proteins) which originate from cancer tissues. Circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) analysis from a simple blood draw received enormous attention for the related clinical research results. A rich scientific literature demonstrates that liquid biopsy is a valid instrument to assess the tumor biomarkers in real time and profile the cancer genotype in diagnostic and prognostic field, as well to quantify minimal residual disease, during patient follow-up. This could be a breakthrough for a companion diagnostic and personalized medicine. Liquid biopsy needs further implementation in the methodological aspects as well as cost-based assessment. The number of new molecular diagnostic assays increases day by day, but the standards for their adoption and clinical validation are still to be achieved.

Molecular Insights into the Classification of Luminal Breast Cancers: The Genomic Heterogeneity of Progesterone-Negative Tumors

Estrogen receptor (ER)-positive progesterone receptor (PR)-negative breast cancers are infrequent but clinically challenging. Despite the volume of genomic data available on these tumors, their biology remains poorly understood. Here, we aimed to identify clinically relevant subclasses of ER+/PR- breast cancers based on their mutational landscape. The Cancer Genomics Data Server was interrogated for mutational and clinical data of all ER+ breast cancers with information on PR status from The Cancer Genome Atlas (TCGA), Memorial Sloan Kettering (MSK), and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) projects. Clustering analysis was performed using gplots, ggplot2, and ComplexHeatmap packages. Comparisons between groups were performed using the Student's t-test and the test of Equal or Given Proportions. Survival curves were built according to the Kaplan⁻Meier method; differences in survival were assessed with the log-rank test. A total of 3570 ER+ breast cancers (PR- n = 959, 27%; PR+ n = 2611, 73%) were analyzed. Mutations in well-known cancer genes such as TP53, GATA3, CDH1, HER2, CDH1, and BRAF were private to or enriched for in PR- tumors. Mutual exclusivity analysis revealed the presence of four molecular clusters with significantly different prognosis on the basis of PIK3CA and TP53 status. ER+/PR- breast cancers are genetically heterogeneous and encompass a variety of distinct entities in terms of prognostic and predictive information.

Circulating cell-free DNA for non-invasive cancer management

Cell-free DNA (cfDNA) was first identified in human plasma in 1948 and is thought to be released from cells throughout the body into the circulatory system. In cancer, a portion of the cfDNA originates from tumour cells, referred to as circulating-tumour DNA (ctDNA), and can contain mutations corresponding to the patient's tumour, for instance specific TP53 alleles. Profiling of cfDNA has recently become an area of increasing clinical relevance in oncology, in particular due to advances in the sensitivity of molecular biology techniques and development of next generation sequencing technologies, as this allows tumour mutations to be identified and tracked non-invasively. This has opened up new possibilities for monitoring tumour evolution and acquisition of resistance, as well as for guiding treatment decisions when tumour biopsy tissue is insufficient or unavailable. In this review, we will discuss the biology of cell-free nucleic acids, methods of analysis, and the potential clinical uses of these techniques, as well as the on-going clinical development of ctDNA assays.

TERT Promoter Mutation Detection in Cell-Free Tumor-Derived DNA in Patients with IDH Wild-Type Glioblastomas: A Pilot Prospective Study

Purpose: We conducted a pilot study to assess the feasibility and the potential implications of detecting TERT promoter (TERTp)-mutant cell-free tumor-derived DNA (tDNA) in the cerebrospinal fluid (CSF) and plasma of glioblastoma patients.Experimental Design: Matched CSF and plasma samples were collected in 60 patients with glial tumors. The CSF collection was obtained during surgery, before any surgical manipulation of the tumor. The extracted tDNA and corresponding tumor DNA samples were analyzed for TERTp and isocitrate dehydrogenase (IDH) hotspot mutations. In addition, the variant allele frequency (VAF) of TERTp mutation in the CSF-tDNA was correlated with tumor features and patients' outcome.Results: Thirty-eight patients had TERTp-mutant/IDH wild-type glioblastomas. The matched TERTp mutation in the CSF-tDNA was successfully detected with 100% specificity (95% CI, 87.6-100%) and 92.1% sensitivity (95% CI, 78.6-98.3%) (n = 35/38). In contrast, the sensitivity in the plasma-tDNA was far lower [n = 3/38, 7.9% (95% CI, 1.6-21.4%)]. We concordantly observed a longer overall survival of patients with low VAF in the CSF-tDNA when compared with patients with high VAF, irrespective of using the lower quartile VAF [11.45%; 14.0 mo. (95% confidence interval, CI, 10.3-17.6) vs. 8.6 mo. (95% CI, 4.1-13.2), P = 0.035], the lower third VAF [13%; 15.4 mo. (95% CI, 11.6-19.2) vs. 8.3 mo. (95% CI, 2.3-14.4), P = 0.008], or the median VAF [20.3%; 14.0 mo. (95% CI, 9.2-18.7) vs. 8.6 mo. (95% CI, 7.5-9.8), P = 0.062] to dichotomize the patients.Conclusions: This pilot study highlights the value of CSF-tDNA for an accurate and reliable detection of TERTp mutations. Furthermore, our findings suggest that high TERTp mutation VAF levels in the CSF-tDNA may represent a suitable predictor of poor survival in glioblastoma patients. Further studies are needed to complement the findings of our exploratory analysis. Clin Cancer Res; 24(21); 5282-91. ©2018 AACR.

Emerging evidence of the molecular landscape specific for hematogenous metastasis from gastric cancer

Gastric cancer (GC) is one of the most frequently diagnosed cancers in the world. Most GC patients are diagnosed when the cancer is in an advanced stage, and consequently, some develop metastatic lesions that generally cause cancer-related death. Metastasis establishment is affected by various conditions, such as tumor location, hemodynamics and organotropism. While digestive cancers may share a primary site, certain cases develop hematogenous metastasis with the absence of peritoneal metastasis, and vice versa. Numerous studies have revealed the clinicopathological risk factors for hematogenous metastasis from GC, such as vascular invasion, advanced age, differentiation, Borrmann type 1 or 2 and expansive growth. Recently, molecular mechanisms that contribute to metastatic site determination have been elucidated by advanced molecular biological techniques. Investigating the molecules that specifically participate in metastasis establishment in distinct secondary organs will lead to the development of novel biomarkers for patient stratification according to their metastatic risk and strategies for preventing and treating distinct metastases. We reviewed articles related to the molecular landscape of hematogenous metastasis from GC.

Inferring parsimonious migration histories for metastatic cancers

Metastasis is the migration of cancerous cells from a primary tumor to other anatomical sites. Although metastasis was long thought to result from monoclonal seeding, or single cellular migrations, recent phylogenetic analyses of metastatic cancers have reported complex patterns of cellular migrations between sites, including polyclonal migrations and reseeding. However, accurate determination of migration patterns from somatic mutation data is complicated by intratumor heterogeneity and discordance between clonal lineage and cellular migration. We introduce MACHINA, a multi-objective optimization algorithm that jointly infers clonal lineages and parsimonious migration histories of metastatic cancers from DNA sequencing data. MACHINA analysis of data from multiple cancers shows that migration patterns are often not uniquely determined from sequencing data alone and that complicated migration patterns among primary tumors and metastases may be less prevalent than previously reported. MACHINA's rigorous analysis of migration histories will aid in studies of the drivers of metastasis.

Identifying the clonal origin of synchronous multifocal tumors in the hepatobiliary and pancreatic system using multi-omic platforms

Synchronous multifocal tumors often pose a diagnostic challenge for oncologists. The purpose of this study was to determine the clonal origin and metastatic relationship of synchronous multifocal tumors in the hepatobiliary and pancreatic system using multi-omic platforms. DNA samples were extracted from three masses harvested from a 50-year-old Han Chinese male patient who suffered from synchronous multifocal tumors in the pancreatic tail, upper biliary duct, and omentum at the time of diagnosis. The clonal origin of these samples was tested using two platforms: next-generation sequencing (NGS) of 390 key genes harboring cancer-relevant actionable mutations and whole-genome copy number variation (CNV) chip analysis. The NGS approach revealed high mutational concordance, and the gene CNV profiles were similar between lesions. Whole-genome CNVs for the three samples were further investigated using an Affymetrix chip. Using matched CNV chip data from The Cancer Genome Atlas (TCGA), we developed a computational model that generated tissue-specific CNV signatures for hepatocellular carcinoma, pancreatic carcinoma, and cholangiocarcinoma to accurately identify the origin of the tumor samples. After adding the patient's CNV chip data to the model, all three samples were clustered into the pancreatic cancer branch. Both our NGS and CNV chip analyses suggested that clinically diagnosed synchronous pancreatic cancer and cholangiocarcinoma originated from the same cell population in the pancreas in our patient. This study highlights the use of genomic tools to infer the origin of synchronous multifocal tumors, which could help to improve the accuracy of cancer diagnosis.

Contralateral breast cancers: Independent cancers or metastases?

A cancer in the contralateral breast in a woman with a previous or synchronous breast cancer is typically considered to be an independent primary tumor. Emerging evidence suggests that in a small subset of these cases the second tumor represents a metastasis. We sought to investigate the issue using massively parallel sequencing targeting 254 genes recurrently mutated in breast cancer. We examined the tumor archives at Memorial Sloan Kettering Cancer Center for the period 1995-2006 to identify cases of contralateral breast cancer where surgery for both tumors was performed at the Center. We report results from 49 patients successfully analyzed by a targeted massively parallel sequencing assay. Somatic mutations and copy number alterations were defined by state-of-the-art algorithms. Clonal relatedness was evaluated by statistical tests specifically designed for this purpose. We found evidence that the tumors in contralateral breasts were clonally related in three cases (6%) on the basis of matching mutations at codons where somatic mutations are rare. Clinical data and the presence of similar patterns of gene copy number alterations were consistent with metastasis for all three cases. In three additional cases, there was a solitary matching mutation at a common PIK3CA locus. The results suggest that a subset of contralateral breast cancers represent metastases rather than independent primary tumors. Massively parallel sequencing analysis can provide important evidence to clarify the diagnosis. However, given the inter-tumor mutational heterogeneity in breast cancer, sufficiently large gene panels need to be employed to define clonality convincingly in all cases.

Metastatic pathway-specific transcriptome analysis identifies MFSD4 as a putative tumor suppressor and biomarker for hepatic metastasis in patients with gastric cancer

Gastric cancer (GC) with hepatic metastasis remains a fatal disease. Global expression profiling was conducted using tissues from patients who had GC with synchronous hepatic metastasis, and major facilitator superfamily domain containing 4 (MFSD4) was identified as a candidate biomarker for hepatic metastasis in GC. Functional and expression analyses of this molecule in GC cell lines and clinical samples were conducted. We analyzed MFSD4 expression, DNA methylation, and copy number. RNA interference experiments evaluated the effects of MFSD4 expression on cell phenotype and apoptosis. We analyzed tissues of 200 patients with GC to assess the diagnostic performance of MFSD4 levels for predicting hepatic recurrence, metastasis, or both. Differential expression of MFSD4 mRNA by GC cell lines correlated positively with the levels of NUDT13 and OCLN mRNAs and inversely with those of BMP2. Hypermethylation of the MFSD4 promoter was detected in cells with lower levels of MFSD4 mRNA. Inhibition of MFSD4 expression significantly increased the invasiveness and motility of GC cells but did not influence cell proliferation or apoptosis. MFSD4 mRNA levels in primary GC tissues were reduced in patients with concomitant hepatic metastasis or recurrence compared with those without. Low levels of MFSD4 mRNA in primary GC tissues were an independent risk factor of hepatic recurrence and metastasis. MFSD4 expression in gastric tissues may represent a useful biomarker for identification of patients at high risk for hepatic recurrence, metastasis, or both.

A naive Bayes algorithm for tissue origin diagnosis (TOD-Bayes) of synchronous multifocal tumors in the hepatobiliary and pancreatic system

Synchronous multifocal tumors are common in the hepatobiliary and pancreatic system but because of similarities in their histological features, oncologists have difficulty in identifying their precise tissue clonal origin through routine histopathological methods. To address this problem and assist in more precise diagnosis, we developed a computational approach for tissue origin diagnosis based on naive Bayes algorithm (TOD-Bayes) using ubiquitous RNA-Seq data. Massive tissue-specific RNA-Seq data sets were first obtained from The Cancer Genome Atlas (TCGA) and ∼1,000 feature genes were used to train and validate the TOD-Bayes algorithm. The accuracy of the model was >95% based on tenfold cross validation by the data from TCGA. A total of 18 clinical cancer samples (including six negative controls) with definitive tissue origin were subsequently used for external validation and 17 of the 18 samples were classified correctly in our study (94.4%). Furthermore, we included as cases studies seven tumor samples, taken from two individuals who suffered from synchronous multifocal tumors across tissues, where the efforts to make a definitive primary cancer diagnosis by traditional diagnostic methods had failed. Using our TOD-Bayes analysis, the two clinical test cases were successfully diagnosed as pancreatic cancer (PC) and cholangiocarcinoma (CC), respectively, in agreement with their clinical outcomes. Based on our findings, we believe that the TOD-Bayes algorithm is a powerful novel methodology to accurately identify the tissue origin of synchronous multifocal tumors of unknown primary cancers using RNA-Seq data and an important step toward more precision-based medicine in cancer diagnosis and treatment.

Heterogeneous Tumor-Immune Microenvironments among Differentially Growing Metastases in an Ovarian Cancer Patient

We present an exceptional case of a patient with high-grade serous ovarian cancer, treated with multiple chemotherapy regimens, who exhibited regression of some metastatic lesions with concomitant progression of other lesions during a treatment-free period. Using immunogenomic approaches, we found that progressing metastases were characterized by immune cell exclusion, whereas regressing and stable metastases were infiltrated by CD8+ and CD4+ T cells and exhibited oligoclonal expansion of specific T cell subsets. We also detected CD8+ T cell reactivity against predicted neoepitopes after isolation of cells from a blood sample taken almost 3 years after the tumors were resected. These findings suggest that multiple distinct tumor immune microenvironments co-exist within a single individual and may explain in part the heterogeneous fates of metastatic lesions often observed in the clinic post-therapy. VIDEO ABSTRACT.

Liquid biopsies come of age: towards implementation of circulating tumour DNA

Improvements in genomic and molecular methods are expanding the range of potential applications for circulating tumour DNA (ctDNA), both in a research setting and as a 'liquid biopsy' for cancer management. Proof-of-principle studies have demonstrated the translational potential of ctDNA for prognostication, molecular profiling and monitoring. The field is now in an exciting transitional period in which ctDNA analysis is beginning to be applied clinically, although there is still much to learn about the biology of cell-free DNA. This is an opportune time to appraise potential approaches to ctDNA analysis, and to consider their applications in personalized oncology and in cancer research.

GPR155 Serves as a Predictive Biomarker for Hematogenous Metastasis in Patients with Gastric Cancer

The prognosis of patients with gastric cancer (GC) with hematogenous metastasis is dismal. Identification of biomarkers specific for hematogenous metastasis is required to develop personalized treatments that improve patients' outcomes. Global expression profiling of GC tissues with synchronous hepatic metastasis without metastasis to the peritoneal cavity or distant lymph nodes was conducted using next-generation sequencing and identified the G protein-coupled receptor 155 (GPR155) as a candidate biomarker. GPR155 transcription was suppressed in GC cell lines compared with a nontumorigenic cell line. DNA methylation of the GPR155 promoter region was not detected, albeit 20% of GC cell lines harbored copy number loss at GPR155 locus. The expression levels of GPR155 mRNA correlated inversely with those of TWIST1 and WNT5B. Inhibition of GPR155 expression increased the levels of p-ERK1/2 and p-STAT1, significantly increased cell proliferation, and increased the invasiveness of a GC cell lines. GPR155 mRNA levels in GC clinical samples correlated with hematogenous metastasis and recurrence. Multivariate analysis revealed that reduced expression of GPR155 mRNA was an independent predictive marker of hematogenous metastasis. GPR155 may represent a biomarker for diagnosing and predicting hematogenous metastasis of GC.

Molecular determination of the clonal relationships between multiple tumors in BRCA1/2-associated breast and/or ovarian cancer patients is clinically relevant

Female BRCA1/2 mutation carriers affected with breast and/or ovarian cancer may develop new tumor deposits over time. It is of utmost importance to know the clonal relationships between multiple tumor localizations, enabling differentiation between multiple primaries or metastatic disease with consequences for therapy and prognosis. We evaluated the value of targeted next generation sequencing in the diagnostic workup of BRCA1/2 mutation carriers with ≥2 tumor localizations and uncertain tumor origins. Forty-two female BRCA1/2 mutation carriers with ≥2 tumor localizations were selected. Patients with inconclusive tumor origin after histopathological revision were 'cases'; patients with certain tumor origin of ≥3 tumors served as 'controls'. Tumors of cases and controls were analyzed by targeted next generation sequencing using a panel including CDKN2A, PTEN and TP53, hotspot mutation sites for 27 different genes and 143 single nucleotide polymorphisms for detection of loss of heterozygosity. Based on prevalence of identical or different mutations and/or loss of heterozygosity patterns, tumors were classified as 'multiple primaries' or 'one entity'. Conventional histopathology yielded a conclusive result in 38/42 (90%) of patients. Four cases and 10 controls were analyzed by next generation sequencing. In 44 tumor samples, 48 mutations were found; 39 (81%) concerned TP53 mutations. In all 4 cases, the intra-patient clonal relationships between the tumor localizations could be unequivocally identified by molecular analysis. In all controls, molecular outcomes matched the conventional histopathological results. In most BRCA1/2 mutation carriers with multiple tumors routine pathology work-up is sufficient to determine tumor origins and relatedness. In case of inconclusive conventional pathology results, molecular analyses using next generation sequencing can reliably determine clonal relationships between tumors, enabling optimal treatment of individual patients.

Next-Generation Sequencing and Applications to the Diagnosis and Treatment of Lung Cancer

Cancer is a genetic disease characterized by uncontrolled growth of abnormal cells. Over time, somatic mutations accumulate in the cells of an individual due to replication errors, chromosome segregation errors, or DNA damage. When not caught by traditional mechanisms, these somatic mutations can lead to cellular proliferation, the hallmark of cancer. Lung cancer is the leading cause of cancer-related mortality in the United States, accounting for approximately 160,000 deaths annually. Five year survival rates for lung cancer remain low (<50 %) for all stages, with even worse prognosis (<15 %) in late stage cases. Technological advances, including advances in next-generation sequencing (NGS), offer the vision of personalized medicine or precision oncology, wherein an individual's treatment can be based on his or her individual molecular profile, rather than on historical population-based medicine. Towards this end, NGS has already been used to identify new biomarker candidates for the early diagnosis of lung cancer and is increasingly used to guide personalized treatment decisions. In this review we will provide a high-level overview of NGS technology and summarize its application to the diagnosis and treatment of lung cancer. We will also describe how NGS can drive advances that bring us closer to precision oncology and discuss some of the technical challenges that will need to be overcome in order to realize this ultimate goal.

Rediscovering Secondary Tumors of the Prostate in the Molecular Era

Metastatic involvement of the prostate from noncontiguous solid tumors is a rare event occurring by means of vascular dissemination. The reported cases of biopsy and surgical samples with metastatic involvement have increased; however, a comprehensive understanding of secondary tumors of the prostate is currently missing. Metastases to the prostate carry a dismal prognosis and may pose serious diagnostic challenges to both clinicians and pathologists, with crucial therapeutic implications. Secondary tumors of the prostate spread more frequently from the digestive tract, the lung, and the kidney. The integration of clinicoradiologic data with appropriate pathologic and immunohistochemical analyses is essential for the identification and the characterization of secondary tumors of the prostate, whereas molecular analyses could provide additional and complementary information, enabling precise diagnosis and appropriate clinical management. Patients with solitary metastases could benefit from prostatic resection and adjuvant therapy, whereas in cases of disseminated diseases, symptom control may be obtained with palliative procedures. The purpose of this review was to assess the current state of knowledge of secondary tumors involving the prostate gland and to discuss short-term future perspectives, while providing a practical approach to these uncommon conditions for pathologists and oncologists.

Mutational Profiling Can Establish Clonal or Independent Origin in Synchronous Bilateral Breast and Other Tumors

Background

Synchronous tumors can be independent primary tumors or a primary-metastatic (clonal) pair, which may have clinical implications. Mutational profiling of tumor DNA is increasingly common in the clinic. We investigated whether mutational profiling can distinguish independent from clonal tumors in breast and other cancers, using a carefully defined test based on the Clonal Likelihood Score (CLS = 100 x # shared high confidence (HC) mutations/ # total HC mutations).

Methods

Statistical properties of a formal test using the CLS were investigated. A high CLS is evidence in favor of clonality; the test is implemented as a one-sided binomial test of proportions. Test parameters were empirically determined using 16,422 independent breast tumor pairs and 15 primary-metastatic tumor pairs from 10 cancer types using The Cancer Genome Atlas.

Results

We validated performance of the test with its established parameters, using five published data sets comprising 15,758 known independent tumor pairs (maximum CLS = 4.1%, minimum p-value = 0.48) and 283 known tumor clonal pairs (minimum CLS 13%, maximum p-value <0.01), across renal cell, testicular, and colorectal cancer. The CLS test correctly classified all validation samples but one, which it appears may have been incorrectly classified in the published data. As proof-of-concept we then applied the CLS test to two new cases of invasive synchronous bilateral breast cancer at our institution, each with one hormone receptor positive (ER+/PR+/HER2-) lobular and one triple negative ductal carcinoma. High confidence mutations were identified by exome sequencing and results were validated using deep targeted sequencing. The first tumor pair had CLS of 81% (p-value < 10–15), supporting clonality. In the second pair, no common mutations of 184 variants were validated (p-value >0.99), supporting independence. A plausible molecular mechanism for the shift from hormone receptor positive to triple negative was identified in the clonal pair.

Conclusion

We have developed the statistical properties of a carefully defined Clonal Likelihood Score test from mutational profiling of tumor DNA. Under identified conditions, the test appears to reliably distinguish between synchronous tumors of clonal and of independent origin in several cancer types. This approach may have scientific and clinical utility.

USING SOMATIC MUTATION DATA TO TEST TUMORS FOR CLONAL RELATEDNESS

A major challenge for cancer pathologists is to determine whether a new tumor in a patient with cancer is a metastasis or an independent occurrence of the disease. In recent years numerous studies have evaluated pairs of tumor specimens to examine the similarity of the somatic characteristics of the tumors and to test for clonal relatedness. As the landscape of mutation testing has evolved a number of statistical methods for determining clonality have developed, notably for comparing losses of heterozygosity at candidate markers, and for comparing copy number profiles. Increasingly tumors are being evaluated for point mutations in panels of candidate genes using gene sequencing technologies. Comparison of the mutational profiles of pairs of tumors presents unusual methodological challenges: mutations at some loci are much more common than others; knowledge of the marginal mutation probabilities is scanty for most loci at which mutations might occur; the sample space of potential mutational profiles is vast. In this article we examine this problem and propose a test for clonal relatedness of a pair of tumors from a single patient. Using simulations, its properties are shown to be promising. The method is illustrated using several examples from the literature.

Mutation tracking in circulating tumor DNA predicts relapse in early breast cancer

The identification of early-stage breast cancer patients at high risk of relapse would allow tailoring of adjuvant therapy approaches. We assessed whether analysis of circulating tumor DNA (ctDNA) in plasma can be used to monitor for minimal residual disease (MRD) in breast cancer. In a prospective cohort of 55 early breast cancer patients receiving neoadjuvant chemotherapy, detection of ctDNA in plasma after completion of apparently curative treatment-either at a single postsurgical time point or with serial follow-up plasma samples-predicted metastatic relapse with high accuracy [hazard ratio, 25.1 (confidence interval, 4.08 to 130.5; log-rank P < 0.0001) or 12.0 (confidence interval, 3.36 to 43.07; log-rank P < 0.0001), respectively]. Mutation tracking in serial samples increased sensitivity for the prediction of relapse, with a median lead time of 7.9 months over clinical relapse. We further demonstrated that targeted capture sequencing analysis of ctDNA could define the genetic events of MRD, and that MRD sequencing predicted the genetic events of the subsequent metastatic relapse more accurately than sequencing of the primary cancer. Mutation tracking can therefore identify early breast cancer patients at high risk of relapse. Subsequent adjuvant therapeutic interventions could be tailored to the genetic events present in the MRD, a therapeutic approach that could in part combat the challenge posed by intratumor genetic heterogeneity.

The repertoire of somatic genetic alterations of acinic cell carcinomas of the breast: an exploratory, hypothesis-generating study

Acinic cell carcinoma (ACC) of the breast is a rare form of triple-negative (that is, oestrogen receptor-negative, progesterone receptor-negative, HER2-negative) salivary gland-type tumour displaying serous acinar differentiation. Despite its triple-negative phenotype, breast ACCs are reported to have an indolent clinical behaviour. Here, we sought to define whether ACCs have a mutational repertoire distinct from that of other triple-negative breast cancers (TNBCs). DNA was extracted from microdissected formalin-fixed, paraffin-embedded sections of tumour and normal tissue from two pure and six mixed breast ACCs. Each tumour component of the mixed cases was microdissected separately. Tumour and normal samples were subjected to targeted capture massively parallel sequencing targeting all exons of 254 genes, including genes most frequently mutated in breast cancer and related to DNA repair. Selected somatic mutations were validated by targeted amplicon resequencing and Sanger sequencing. Akin to other forms of TNBC, the most frequently mutated gene found in breast ACCs was TP53 (one pure and six mixed cases). Additional somatic mutations affecting breast cancer-related genes found in ACCs included PIK3CA, MTOR, CTNNB1, BRCA1, ERBB4, ERBB3, INPP4B, and FGFR2. Copy number alteration analysis revealed complex patterns of gains and losses similar to those of common forms of TNBCs. Of the mixed cases analysed, identical somatic mutations were found in the acinic and the high-grade non-acinic components in two out of four cases analysed, providing evidence of their clonal relatedness. In conclusion, breast ACCs display the hallmark somatic genetic alterations found in high-grade forms of TNBC, including complex patterns of gene copy number alterations and recurrent TP53 mutations. Furthermore, we provide circumstantial genetic evidence to suggest that ACCs may constitute the substrate for the development of more aggressive forms of triple-negative disease.

Inferring mutational timing and reconstructing tumour evolutionary histories

Cancer evolution can be considered within a Darwinian framework. Both micro and macro-evolutionary theories can be applied to understand tumour progression and treatment failure. Owing to cancers' complexity and heterogeneity the rules of tumour evolution, such as the role of selection, remain incompletely understood. The timing of mutational events during tumour evolution presents diagnostic, prognostic and therapeutic opportunities. Here we review the current sampling and computational approaches for inferring mutational timing and the evidence from next generation sequencing-informed data on mutational timing across all tumour types. We discuss how this knowledge can be used to illuminate the genes and pathways that drive cancer initiation and relapse; and to support drug development and clinical trial design.

Capturing intra-tumor genetic heterogeneity by de novo mutation profiling of circulating cell-free tumor DNA: a proof-of-principle

BACKGROUND

Plasma-derived cell-free tumor DNA (ctDNA) constitutes a potential surrogate for tumor DNA obtained from tissue biopsies. We posit that massively parallel sequencing (MPS) analysis of ctDNA may help define the repertoire of mutations in breast cancer and monitor tumor somatic alterations during the course of targeted therapy.

PATIENT AND METHODS

A 66-year-old patient presented with synchronous estrogen receptor-positive/HER2-negative, highly proliferative, grade 2, mixed invasive ductal-lobular carcinoma with bone and liver metastases at diagnosis. DNA extracted from archival tumor material, plasma and peripheral blood leukocytes was subjected to targeted MPS using a platform comprising 300 cancer genes known to harbor actionable mutations. Multiple plasma samples were collected during the fourth line of treatment with an AKT inhibitor.

RESULTS

Average read depths of 287x were obtained from the archival primary tumor, 139x from the liver metastasis and between 200x and 900x from ctDNA samples. Sixteen somatic non-synonymous mutations were detected in the liver metastasis, of which 9 (CDKN2A, AKT1, TP53, JAK3, TSC1, NF1, CDH1, MML3 and CTNNB1) were also detected in >5% of the alleles found in the primary tumor sample. Not all mutations identified in the metastasis were reliably identified in the primary tumor (e.g. FLT4). Analysis of ctDNA, nevertheless, captured all mutations present in the primary tumor and/or liver metastasis. In the longitudinal monitoring of the patient, the mutant allele fractions identified in ctDNA samples varied over time and mirrored the pharmacodynamic response to the targeted therapy as assessed by positron emission tomography-computed tomography.

CONCLUSIONS

This proof-of-principle study is one of the first to demonstrate that high-depth targeted MPS of plasma-derived ctDNA constitutes a potential tool for de novo mutation identification and monitoring of somatic genetic alterations during the course of targeted therapy, and may be employed to overcome the challenges posed by intra-tumor genetic heterogeneity.

REGISTERED CLINICAL TRIAL

www.clinicaltrials.gov, NCT01090960.

The challenge of intratumour heterogeneity in precision medicine

Cells within tumours have diverse genomes and epigenomes and interact differentially with their surrounding microenvironment generating intratumour heterogeneity, which has critical implications for treating cancer patients. Understanding the cellular and microenvironment composition and characteristics in individual tumours is critical to stratify the patient population that is likely to benefit from specific treatment regimens. Here, we will review the current understanding of intratumour heterogeneity at the genomic, epigenomic and microenvironmental levels. We will also discuss the clinical implications and the challenges posed by intratumour heterogeneity and evaluate noninvasive methods such as circulating biomarkers to characterize the cellular diversity of tumours. Comprehensive assessment of the molecular features of patients based on tumour specimen characterization (including intratumour spatial and temporal variations), ancillary noninvasive methods (such as circulating biomarkers and molecular imaging approaches) and the correct design of clinical trials are required to guide administration of targeted therapy and to control therapeutic resistance. Finding the means to accurately determine and effectively control tumour heterogeneity and translate these achievements into patient benefit are major goals in modern oncology.

Desmoplastic melanoma with sarcomatoid dedifferentiation

Desmoplastic melanoma (DM) is a variant of melanoma, which typically affects chronically sun-damaged skin of elderly patients. Pure DM displays a low density of fusiform melanocytes in a collagen-rich matrix. In mixed DM, tumor cell density is higher, and parts of the tumor lack abundant stromal fibrosis. Both pure and mixed DMs usually express S100 protein homogenously. We report herein an unusual biphenotypic tumor characterized by the association of a pure DM with an undifferentiated solid spindle cell nodule. It occurred on the scalp of a 66-year-old man. A biopsy of the undifferentiated spindle cell nodule was initially interpreted at a commercial laboratory as atypical fibroxanthoma. The pure DM was seen only in the excisional specimen. All cells of the pure DM stained for S100 protein and SOX10. The adjacent solid sarcomatoid spindle cell nodule lacked expression of S100 protein, SOX10, as well as melan-A, gp100, and microphthalmia-associated transcription factor in >95% of its tumor cells. Although focal expression of melanocyte differentiation antigens in the solid tumor component made us favor a combined DM with sarcomatoid dedifferentiation, we also considered the possibility of a collision scenario, that is, a pleomorphic dermal sarcoma incidentally colliding with a DM. To further assess a possible relationship of the sarcomatoid nodule with the DM, we performed next-generation sequencing analysis on each component separately. The analysis revealed shared chromosomal copy number changes and a high number of common mutations, thereby supporting the concept of a DM with a dedifferentiated sarcomatoid component. An interesting finding is the presence of mutations of the neurofibromin 1 (NF1) gene in both tumor components.

Characterization of the genomic features and expressed fusion genes in micropapillary carcinomas of the breast

Micropapillary carcinoma (MPC) is a rare histological special type of breast cancer, characterized by an aggressive clinical behaviour and a pattern of copy number aberrations (CNAs) distinct from that of grade- and oestrogen receptor (ER)-matched invasive carcinomas of no special type (IC-NSTs). The aims of this study were to determine whether MPCs are underpinned by a recurrent fusion gene(s) or mutations in 273 genes recurrently mutated in breast cancer. Sixteen MPCs were subjected to microarray-based comparative genomic hybridization (aCGH) analysis and Sequenom OncoCarta mutation analysis. Eight and five MPCs were subjected to targeted capture and RNA sequencing, respectively. aCGH analysis confirmed our previous observations about the repertoire of CNAs of MPCs. Sequencing analysis revealed a spectrum of mutations similar to those of luminal B IC-NSTs, and recurrent mutations affecting mitogen-activated protein kinase family genes and NBPF10. RNA-sequencing analysis identified 17 high-confidence fusion genes, eight of which were validated and two of which were in-frame. No recurrent fusions were identified in an independent series of MPCs and IC-NSTs. Forced expression of in-frame fusion genes (SLC2A1-FAF1 and BCAS4-AURKA) resulted in increased viability of breast cancer cells. In addition, genomic disruption of CDK12 caused by out-of-frame rearrangements was found in one MPC and in 13% of HER2-positive breast cancers, identified through a re-analysis of publicly available massively parallel sequencing data. In vitro analyses revealed that CDK12 gene disruption results in sensitivity to PARP inhibition, and forced expression of wild-type CDK12 in a CDK12-null cell line model resulted in relative resistance to PARP inhibition. Our findings demonstrate that MPCs are neither defined by highly recurrent mutations in the 273 genes tested, nor underpinned by a recurrent fusion gene. Although seemingly private genetic events, some of the fusion transcripts found in MPCs may play a role in maintenance of a malignant phenotype and potentially offer therapeutic opportunities.

Establishing the origin of metastatic deposits in the setting of multiple primary malignancies: the role of massively parallel sequencing

In this proof-of-principle study, we sought to define whether targeted capture massively parallel sequencing can be employed to determine the origin of metastatic deposits in cases of synchronous primary malignancies and metastases in distinct anatomical sites. DNA samples extracted from synchronous tumor masses in the breast, adnexal, and pelvic-peritoneal regions from a 62-year-old BRCA1 germline mutation carrier were subjected to targeted massively parallel sequencing using a platform comprising 300 cancer genes known to harbor actionable mutations. In addition to BRCA1 germline mutations, all lesions harbored somatic loss of the BRCA1 wild-type allele and TP53 somatic mutations. The primary breast cancer displayed a TP53 frameshift (p.Q317fs) mutation, whereas and the adnexal lesion harbored a TP53 nonsense (p.R213*) mutation, consistent with a diagnosis of two independent primary tumors (i.e. breast and ovarian cancer). The adnexal tumor and all pelvic-peritoneal implants harbored identical TP53 (p.R213*) and NCOA2 (p.G952R) somatic mutations. Evidence of genetic heterogeneity within and between lesions was observed, both in terms of somatic mutations and copy number aberrations. The repertoires of somatic genetic aberrations found in the breast, ovarian, and pelvic-peritoneal lesions provided direct evidence in support of the distinct origin of the breast and ovarian cancers, and established that the pelvic-peritoneal implants were clonally related to the ovarian lesion. These observations were consistent with those obtained with immunohistochemical analyses employing markers to differentiate between carcinomas of the breast and ovary, including WT1 and PAX8. Our results on this case of a patient with BRCA1-mutant breast and ovarian cancer demonstrate that massively parallel sequencing may constitute a useful tool to define the relationship, clonality and intra-tumor genetic heterogeneity between primary tumor masses and their metastatic deposits in patients with multiple primary malignancies and synchronous metastases.