Exome sequencing reveals a distinct somatic genomic landscape in breast cancer from women with germline PTEN variants.

Germline PTEN variants (PTEN hamartoma tumor syndrome [PHTS]) confer up to 85% lifetime risk of female breast cancer (BC). BCs arising in PHTS are clinically distinct from sporadic BCs, including younger age of onset, multifocality, and an increased risk of second primary BCs. Yet, there is no previous investigation into the underlying genomic landscape of this entity. We sought to address the hypothesis that BCs arising in PHTS have a distinct genomic landscape compared to sporadic counterparts. We performed and analyzed exome sequencing data from 44 women with germline PTEN variants who developed BCs. The control cohort comprised of 497 women with sporadic BCs from The Cancer Genome Atlas (TCGA) dataset. We demonstrate that PHTS-derived BCs have a distinct somatic mutational landscape compared to the sporadic counterparts, namely second somatic hits in PTEN, distinct mutational signatures, and increased genomic instability. The PHTS group had a significantly higher frequency of somatic PTEN variants compared to TCGA (22.7% versus 5.6%; odds ratio [OR] 4.93; 95% confidence interval [CI] 2.21 to 10.98; p < 0.001) and a lower mutational frequency in PIK3CA (22.7% versus 33.4%; OR 0.59; 95% CI 0.28 to 1.22; p = 0.15). Somatic variants in PTEN and PIK3CA were mutually exclusive in PHTS (p = 0.01) but not in TCGA. Our findings have important implications for the personalized management of PTEN-related BCs, especially in the context of more accessible genetic testing.

Sequential tumor molecular profiling identifies likely germline variants.

PURPOSE: To identify likely germline DNA variants from sequential tumor profiling data from hematopoietic malignancies (HMs). METHODS: The coefficient of variance was calculated from variant allele frequency of next-generation sequencing assays. Variants' likelihood of being germline was ranked on a 1 to 5 scale. Outcomes were examined in patients with such variants. RESULTS: In a pilot set of 33 genes, 89% of grade 1, 77% of grade 2, 62% of grade 3, 52% of grade 4, and 21% of grade 5 variants were confirmed to be germline. Among those, 22% were pathogenic or likely pathogenic in genes recognized as conferring hereditary HM risk, including BRCA1/2, CHEK2, CSF3R, and DDX41. To determine if this approach identified genes with known autosomal dominant inheritance, we analyzed sequential data from 1336 genes in 1135 HM patients. Among unique variants, 16% occurred in hereditary HM genes, and 15% were deleterious. Patients with grade 1/2 alleles had decreased survival 2 years after initial molecular testing (78% versus 88%, P = .0037) and increased all-cause mortality compared with those without (hazard ratio 2.02, 95% CI 1.18-3.46, P = .019). CONCLUSION: Variant germline status may be predicted using sequential tumor profiling and patients with likely germline variants experience inferior outcomes compared with those without.

Clinical and molecular features of pediatric cancer patients with Lynch syndrome.

BACKGROUND: The association of childhood cancer with Lynch syndrome is not established compared with the significant pediatric cancer risk in recessive constitutional mismatch repair deficiency syndrome (CMMRD). PROCEDURE: We describe the clinical features, germline analysis, and tumor genomic profiling of patients with Lynch syndrome among patients enrolled in pediatric cancer genomic studies. RESULTS: There were six of 773 (0.8%) pediatric patients with solid tumors identified with Lynch syndrome, defined as a germline heterozygous pathogenic variant in one of the mismatch repair (MMR) genes (three with MSH6, two with MLH1, and one with MSH2). Tumor analysis demonstrated evidence for somatic second hits and/or increased tumor mutation burden in three of four patients with available tumor with potential implications for therapy and identification of at-risk family members. Only one patient met current guidelines for pediatric cancer genetics evaluation at the time of tumor diagnosis. CONCLUSION: Approximately 1% of children with cancer have Lynch syndrome, which is missed with current referral guidelines, suggesting the importance of adding MMR genes to tumor and hereditary pediatric cancer panels. Tumor analysis may provide the first suggestion of an underlying cancer predisposition syndrome and is useful in distinguishing between Lynch syndrome and CMMRD.

ATM: Functions of ATM Kinase and Its Relevance to Hereditary Tumors.

Ataxia-telangiectasia mutated (ATM) functions as a key initiator and coordinator of DNA damage and cellular stress responses. ATM signaling pathways contain many downstream targets that regulate multiple important cellular processes, including DNA damage repair, apoptosis, cell cycle arrest, oxidative sensing, and proliferation. Over the past few decades, associations between germline ATM pathogenic variants and cancer risk have been reported, particularly for breast and pancreatic cancers. In addition, given that ATM plays a critical role in repairing double-strand breaks, inhibiting other DNA repair pathways could be a synthetic lethal approach. Based on this rationale, several DNA damage response inhibitors are currently being tested in ATM-deficient cancers. In this review, we discuss the current knowledge related to the structure of the ATM gene, function of ATM kinase, clinical significance of ATM germline pathogenic variants in patients with hereditary cancers, and ongoing efforts to target ATM for the benefit of cancer patients.

Acquired mutations and transcriptional remodeling in long-term estrogen-deprived locoregional breast cancer recurrences.

BACKGROUND: Endocrine therapy resistance is a hallmark of advanced estrogen receptor (ER)-positive breast cancer. In this study, we aimed to determine acquired genomic changes in endocrine-resistant disease. METHODS: We performed DNA/RNA hybrid-capture sequencing on 12 locoregional recurrences after long-term estrogen deprivation and identified acquired genomic changes versus each tumor's matched primary. RESULTS: Despite being up to 7 years removed from the primary lesion, most recurrences harbored similar intrinsic transcriptional and copy number profiles. Only two genes, AKAP9 and KMT2C, were found to have single nucleotide variant (SNV) enrichments in more than one recurrence. Enriched mutations in single cases included SNVs within transcriptional regulators such as ARID1A, TP53, FOXO1, BRD1, NCOA1, and NCOR2 with one local recurrence gaining three PIK3CA mutations. In contrast to DNA-level changes, we discovered recurrent outlier mRNA expression alterations were common-including outlier gains in TP63 (n = 5 cases [42%]), NTRK3 (n = 5 [42%]), NTRK2 (n = 4 [33%]), PAX3 (n = 4 [33%]), FGFR4 (n = 3 [25%]), and TERT (n = 3 [25%]). Recurrent losses involved ESR1 (n = 5 [42%]), RELN (n = 5 [42%]), SFRP4 (n = 4 [33%]), and FOSB (n = 4 [33%]). ESR1-depleted recurrences harbored shared transcriptional remodeling events including upregulation of PROM1 and other basal cancer markers. CONCLUSIONS: Taken together, this study defines acquired genomic changes in long-term, estrogen-deprived disease; highlights the importance of longitudinal RNA profiling; and identifies a common ESR1-depleted endocrine-resistant breast cancer subtype with basal-like transcriptional reprogramming.

Germline Whole-Gene Deletion of FH Diagnosed from Tumor Profiling.

Hereditary leiomyomatosis and renal cell carcinoma (HL (RCC)) entails cutaneous and uterine leiomyomatosis with aggressive type 2 papillary RCC-like histology. HLRCC is caused by pathogenic variants in the FH gene, which encodes fumarate hydratase (FH). Here, we describe an episode of young-onset RCC caused by a genomic FH deletion that was diagnosed via clinical sequencing. A 35-year-old woman was diagnosed with RCC and multiple metastases: histopathological analyses supported a diagnosis of FH-deficient RCC. Although the patient had neither skin tumors nor a family history of HLRCC, an aggressive clinical course at her age and pathological diagnosis of FH-deficient RCC suggested a germline FH variant. After counseling, the patient provided written informed consent for germline genetic testing. She was simultaneously subjected to paired tumor profiling tests targeting the exome to identify a therapeutic target. Although conventional germline sequencing did not detect FH variants, exome sequencing revealed a heterozygous germline FH deletion. As such, paired tumor profiling, not conventional sequencing, was required to identify this genetic deletion. RCC caused by a germline FH deletion has hitherto not been described in Japan, and the FH deletion detected in this patient was presumed to be of maternal European origin. Although the genotype-phenotype correlation in HLRCC-related tumors is unclear, the patient's family was advised to undergo genetic counseling to consider additional RCC screening.

Molecular Features and Clinical Management of Hereditary Gynecological Cancers.

Hereditary gynecological cancers are caused by several inherited genes. Tumors that arise in the female reproductive system, such as ovaries and the uterus, overlap with hereditary cancers. Several hereditary cancer-related genes are important because they might lead to therapeutic targets. Treatment of hereditary cancers should be updated in line with the advent of various new methods of evaluation. Next-generation sequencing has led to rapid, economical genetic analyses that have prompted a concomitant and significant paradigm shift with respect to hereditary cancers. Molecular tumor profiling is an epochal method for determining therapeutic targets. Clinical treatment strategies are now being designed based on biomarkers based on tumor profiling. Furthermore, the National Comprehensive Cancer Network (NCCN) guidelines significantly changed the genetic testing process in 2020 to initially consider multi-gene panel (MGP) evaluation. Here, we reviewed the molecular features and clinical management of hereditary gynecological malignancies, such as hereditary breast and ovarian cancer (HBOC), and Lynch, Li-Fraumeni, Cowden, and Peutz-Jeghers syndromes. We also reviewed cancer-susceptible genes revealed by MGP tests.

The Impact of Genetic Counseling Educational Tools on Patients' Knowledge of Molecular Testing Terminology.

Molecular testing is increasingly being integrated into cancer management. Despite rapid advancements, little work has been done to explore strategies for communicating with patients undergoing molecular tumor testing. This study evaluated the impact of genetic counseling educational tools on improving patients' understanding of key terms related to molecular testing. A genetic counseling intern designed a picture book to explain six words found in prior research to be difficult to understand (mutation, germline mutation, somatic mutation, biomarker, molecular testing, and targeted therapy). Participants who had previously discussed molecular testing with their oncologist were asked to define the terms. The same participants then received an explanation of each term either from the intern using the picture book in person or from a video presentation of the picture book. They were then asked to redefine each term afterward. The difference between the number of terms defined correctly pre- and post-intervention was compared between presentations. Sixty-three patients with melanoma, colon, lung, or breast cancer were recruited. After both interventions, correct understanding rates improved for all six terms, with significant improvement for germline mutation (p < 0.001), somatic mutation (p < 0.001), biomarker (p < 0.001), and molecular testing (p < 0.001). Understanding of targeted therapy improved significantly (p = 0.011) for the video presentation only. Mean change in knowledge scores did not differ between the two interventions (intern presentation 3.2 vs. video 2.9, p = 0.428). Our data suggest that genetic counseling educational tools can increase patient understanding of terms used to describe molecular testing.

Patient perspectives on molecular tumor profiling: "Why wouldn't you?"

AIM: This study explored the attitudes of patients with advanced cancer towards MTP and return of results, prior to undergoing genomic testing within a research program. METHODS: Participants were recruited as part of the longitudinal PiGeOn (Psychosocial Issues in Genomics in Oncology) study involving patients with advanced/metastatic solid cancer who had exhausted therapeutic options and who were offered MTP in order to identify cognate therapies. Twenty patients, selected by purposive sampling, were interviewed around the time they gave consent to MTP. Interviews were audio recorded, transcribed and analysed using thematic analysis. Themes identified in the transcripts were cross-validated via qualitative responses to the PiGeOn study survey (n = 569; 63%). RESULTS: All interviewed participants gave consent to MTP without reservation. Three themes were identified and further supported via the survey responses: (1) Obvious agreement to participate, primarily because of desire for new treatments and altruism. (2) The black box - while participant knowledge of genomics was generally poor, faith in their oncologists and the scientific process encouraged them to proceed with testing; and (3) Survival is the priority - receiving treatment to prolong life was the priority for all participants, and other issues such as identification of a germline variant were generally seen as ancillary. CONCLUSION: Having advanced cancer seemed to abrogate any potential concerns about MTP. Participants valued the research for varied reasons, but this was secondary to their priority to survive. While no negative attitudes toward MTP emerged, limitations in understanding of genomics were evident.

Inference of transcriptional regulation in cancers.

Despite the rapid accumulation of tumor-profiling data and transcription factor (TF) ChIP-seq profiles, efforts integrating TF binding with the tumor-profiling data to understand how TFs regulate tumor gene expression are still limited. To systematically search for cancer-associated TFs, we comprehensively integrated 686 ENCODE ChIP-seq profiles representing 150 TFs with 7484 TCGA tumor data in 18 cancer types. For efficient and accurate inference on gene regulatory rules across a large number and variety of datasets, we developed an algorithm, RABIT (regression analysis with background integration). In each tumor sample, RABIT tests whether the TF target genes from ChIP-seq show strong differential regulation after controlling for background effect from copy number alteration and DNA methylation. When multiple ChIP-seq profiles are available for a TF, RABIT prioritizes the most relevant ChIP-seq profile in each tumor. In each cancer type, RABIT further tests whether the TF expression and somatic mutation variations are correlated with differential expression patterns of its target genes across tumors. Our predicted TF impact on tumor gene expression is highly consistent with the knowledge from cancer-related gene databases and reveals many previously unidentified aspects of transcriptional regulation in tumor progression. We also applied RABIT on RNA-binding protein motifs and found that some alternative splicing factors could affect tumor-specific gene expression by binding to target gene 3'UTR regions. Thus, RABIT (rabit.dfci.harvard.edu) is a general platform for predicting the oncogenic role of gene expression regulators.

Molecular profiling of tumours for precision oncology - high hopes versus reality.

Treatment based on molecular profiling of tumor is advertised however there are very limited clinical data supporting this approach so far. Only one, relatively small, randomized clinical trial (SHIVA) have not met its primary endpoint - prolongation of PFS. Some other unpublished series were reported during ASCO 2017 and are discussed in this review. There are many issues to be resolved before the tumor profiling will enter the clinical practice with significant benefit for patients, eg. spatial and temporal heterogeneity of tumor cells in individual patient, wide access to targeted therapies, toxicity of combined targeted therapies.

Tumor profiling and the incidentalome: patient decisions and risks.

In recent years, the field of oncology has witnessed rapid advancements in genetic sequencing simultaneously with steeply declining costs of sequencing technology. As a result, genomics-driven cancer medicine and the use of tumor profiling are quickly becoming mainstays of cancer therapy. Oncology patients can benefit from tumor profiling by allowing the selection of targeted therapies tailored to their disease. However, it is increasingly recognized that the process of determining a tumor DNA sequence may lead to incidental discovery of underlying germline mutations which can impact other aspects of a patient's health, and that of their family. How to handle the 'incidentalome' has been the subject of recent public debate, yet patient education about the potential risks of tumor profiling remains sparse. Patient perspectives and clinical implications of the tumor incidentalome must be specifically addressed by the oncology community as tumor profiling expands to become a new standard of care.

Molecular profiling is not the future: it is now!

Bobby Reddy speaks to Gemma Westcott, Commissioning Editor: Dr Reddy graduated from the UCLA School of Medicine in 1996. Shortly after, he obtained an internship and did his residency in Internal Medicine at Harbor UCLA Medical Center. He then went on to do his fellowship in Hematology and Oncology at City of Hope. Since then, he has been working in private practice (full and part time) for the past 11 years and has had an academic appointment as teaching faculty at Harbor UCLA. Prior to his current role, Dr Reddy worked as a senior medical director as Caris Life Sciences.

Dynamic changes in tumor profiling reveal intra- and inter-tumoral heterogeneity focused on an uncharacterized HER2 mutation: a case report of a young breast cancer patient.

Despite multiple recent advances in systemic therapy for metastatic breast cancer, cases which display suboptimal response to guideline-driven treatment are frequently seen in the clinic. Effective options for such patients are limited, particularly in later line of therapy, and selection of optimal treatment options is essentially empirical and based largely on considerations of previous regimens received. Comprehensive cancer profiling includes detection of genetic alterations in tissue and circulating tumor DNA (ctDNA), immunohistochemistry (IHC) from re-biopsied metastatic disease, circulating tumor cells (CTCs), gene expression analysis and pharmacogenomics. The advent of this methodology and application to metastatic breast cancer, facilitates a more scientifically informed approach to identification of optimal systemic therapy approaches independent of the restrictions implied by clinical guidelines. Here we describe a case of metastatic breast cancer where consecutive comprehensive tumor profiling reveals ongoing tumor evolution, guiding the identification of novel effective therapeutic strategies.

Clinicogenomic characterization of inflammatory breast cancer.

Background: Inflammatory breast cancer (IBC) is a rare and poorly characterized type of breast cancer with an aggressive clinical presentation. The biological mechanisms driving the IBC phenotype are relatively undefined-partially due to a lack of comprehensive, large-scale genomic studies and limited clinical cohorts. Patients and Methods: A retrospective analysis of 2457 patients with metastatic breast cancer who underwent targeted tumor-only DNA-sequencing was performed at Dana-Farber Cancer Institute. Clinicopathologic, single nucleotide variant (SNV), copy number variant (CNV) and tumor mutational burden (TMB) comparisons were made between clinically confirmed IBC cases within a dedicated IBC center versus non-IBC cases. Results: Clinicopathologic differences between IBC and non-IBC cases were consistent with prior reports-including IBC being associated with younger age at diagnosis, higher grade, and enrichment with hormone receptor (HR)-negative and HER2-positive tumors. The most frequent somatic alterations in IBC involved TP53 (72%), ERBB2 (32%), PIK3CA (24%), CCND1 (12%), MYC (9%), FGFR1 (8%) and GATA3 (8%). A multivariate logistic regression analysis revealed a significant enrichment in TP53 SNVs in IBC; particularly in HER2-positive and HR-positive disease which was associated with worse outcomes. Tumor mutational burden (TMB) did not differ substantially between IBC and non-IBC cases and a pathway analysis revealed an enrichment in NOTCH pathway alterations in HER2-positive disease. Conclusion: Taken together, this study provides a comprehensive, clinically informed landscape of somatic alterations in a large cohort of patients with IBC. Our data support higher frequency of TP53 mutations and a potential enrichment in NOTCH pathway activation-but overall; a lack of major genomic differences. These results both reinforce the importance of TP53 alterations in IBC pathogenesis as well as their influence on clinical outcomes; but also suggest additional analyses beyond somatic DNA-level changes are warranted.

Prioritization of patients for germline testing based on tumor profiling of hematopoietic malignancies.

Germline predisposition to hematopoietic malignancies is more common than previously appreciated, with several clinical guidelines advocating for cancer risk testing in an expanding pool of patients. As molecular profiling of tumor cells becomes a standard practice for prognostication and defining options for targeted therapies, recognition that germline variants are present in all cells and can be identified by such testing becomes paramount. Although not to be substituted for proper germline cancer risk testing, tumor-based profiling can help prioritize DNA variants likely to be of germline origin, especially when they are present on sequential samples and persist into remission. Performing germline genetic testing as early during patient work-up as possible allows time to plan allogeneic stem cell transplantation using appropriate donors and optimize post-transplant prophylaxis. Health care providers need to be attentive to the differences between molecular profiling of tumor cells and germline genetic testing regarding ideal sample types, platform designs, capabilities, and limitations, to allow testing data to be interpreted as comprehensively as possible. The myriad of mutation types and growing number of genes involved in germline predisposition to hematopoietic malignancies makes reliance on detection of deleterious alleles using tumor-based testing alone very difficult and makes understanding how to ensure adequate testing of appropriate patients paramount.

Phenotypic deconvolution in heterogeneous cancer cell populations using drug-screening data.

Tumor heterogeneity is an important driver of treatment failure in cancer since therapies often select for drug-tolerant or drug-resistant cellular subpopulations that drive tumor growth and recurrence. Profiling the drug-response heterogeneity of tumor samples using traditional genomic deconvolution methods has yielded limited results, due in part to the imperfect mapping between genomic variation and functional characteristics. Here, we leverage mechanistic population modeling to develop a statistical framework for profiling phenotypic heterogeneity from standard drug-screen data on bulk tumor samples. This method, called PhenoPop, reliably identifies tumor subpopulations exhibiting differential drug responses and estimates their drug sensitivities and frequencies within the bulk population. We apply PhenoPop to synthetically generated cell populations, mixed cell-line experiments, and multiple myeloma patient samples and demonstrate how it can provide individualized predictions of tumor growth under candidate therapies. This methodology can also be applied to deconvolution problems in a variety of biological settings beyond cancer drug response.

Compliance with the Current NCCN Guidelines and Its Critical Role in Pancreatic Adenocarcinoma.

OBJECTIVES: Since 2019, the National Comprehensive Cancer Network (NCCN) has recommended genetic testing for patients diagnosed with pancreatic adenocarcinoma that includes universal germline testing and tumor gene profiling for metastatic, locally advanced, or recurrent disease. However, testing compliance with this guideline has not yet been published in the English literature. METHODS: A quality assurance/quality improvement retrospective review was done to identify patients diagnosed with pancreatic adenocarcinoma from January 2019 to February 2021 to include the patient's clinical status and genetic test results. RESULTS: There were 20 patient cases identified with pancreatic adenocarcinoma. A total of 11 cases had molecular tumor gene profiling and microsatellite instability/mismatch repair (MSI/MMR) testing performed and 1 case had only MSI/MMR testing by immunohistochemistry performed. Only 3 patients of the 20 in total received germline testing. CONCLUSION: There was a significant number of patients for whom tumor gene profiling or germline testing had never been attempted as per recommended NCCN guidelines.

Exploring the tumor micro-environment in primary and metastatic tumors of different ovarian cancer histotypes.

Ovarian cancer is a highly heterogeneous disease consisting of at least five different histological subtypes with varying clinical features, cells of origin, molecular composition, risk factors, and treatments. While most single-cell studies have focused on High grade serous ovarian cancer, a comprehensive landscape of the constituent cell types and their interactions within the tumor microenvironment are yet to be established in the different ovarian cancer histotypes. Further characterization of tumor progression, metastasis, and various histotypes are also needed to connect molecular signatures to pathological grading for personalized diagnosis and tailored treatment. In this study, we leveraged high-resolution single-cell RNA sequencing technology to elucidate the cellular compositions on 21 solid tumor samples collected from 12 patients with six ovarian cancer histotypes and both primary (ovaries) and metastatic (omentum, rectum) sites. The diverse collection allowed us to deconstruct the histotypes and tumor site-specific expression patterns of cells in the tumor, and identify key marker genes and ligand-receptor pairs that are active in the ovarian tumor microenvironment. Our findings can be used in improving precision disease stratification and optimizing treatment options.

Effectively communicating comprehensive tumor genomic profiling results: Mitigating uncertainty for advanced cancer patients.

OBJECTIVE: To understand advanced cancer patients' experience of uncertainty when receiving comprehensive tumor genomic profiling (CTGP) results, and their perceptions of how healthcare provider (HCP) communication impacts uncertainty. METHODS: Thirty-seven semi-structured interviews with advanced cancer patients were conducted within two weeks of patients receiving CTGP results. Transcripts were thematically analyzed, using an inductive approach. RESULTS: We identified three themes that illustrate patient experience of uncertainties when receiving CTGP results: 1. Type and degree of uncertainty fluctuates along with changing illness circumstances and the nature of the CTGP results; 2. HCPs' co-ordination of care and communication shapes uncertainty, with immediate, clearer and simpler information promoting certainty; and 3. Patients felt that communicating results to reduce relatives' uncertainty is important, with patients choosing the time and process for achieving this and desiring HCPs support. CONCLUSION: Oncology patients are confronted with an array of uncertainties. Clear, simple communication from HCPs about results and their implications, and support to manage uncertainty, will be of benefit. PRACTICE IMPLICATIONS: If CTGP is to become routine clinical practice, clear communication will be crucial in reducing uncertainty. Awareness of potential uncertainties experienced by patients when receiving results, will assist HCPs to address uncertainties, reduce uncertainty where possible, and offer targeted support to patients struggling with uncertainty.