Discovery Of Gene Fusions Research Articles

Case report: High grade serous fallopian tube carcinoma with rare NRG1 gene fusion presenting as widespread peritoneal carcinomatosis

The discovery of gene fusions involving Neuregulin-1 (NRG1) within solid tumors has important therapeutic implications, as they are being actively explored as targets for emerging ERBB/ERBB2/ERBB3-directed anti-cancer agents. NRG1 fusions are very uncommon across all tumor types and are infrequently documented in the medical literature. We report a female patient presenting with widespread peritoneal carcinomatosis diagnosed as high grade serous fallopian tube carcinoma, which harbored a previously undescribed MYH10::NRG1 fusion. Moreover, we queried the whole transcriptome sequencing results of neoplasms analyzed by a commercial laboratory (Caris Life Sciences) to determine the overall incidence of NRG1 fusions in carcinomas of the ovary, fallopian tube, and peritoneum (0.18%). Twenty-five additional tumors were found to demonstrate NRG1 fusions, including 20 new genes partners that had not been previously identified in gynecologic carcinomas. Overall, NRG1 fusion events are rare in ovarian, fallopian tube, and primary peritoneal carcinomas, but they may carry diagnostic significance in the context of borderline/low grade serous tumors, which demonstrated exclusively CLU::NRG1 fusions, and could have important predictive implications for response to ERBB/ERBB2/ERBB3-directed therapies.

Clinically aggressive follicular cell-derived thyroid carcinoma: A comprehensive series with histomolecular characterization and discovery of novel gene fusions

Thyroid cancer rates are increasing, mostly with a good prognosis and less than 2 % of cases are more aggressive. Recent efforts focus on understanding molecular events predicting tumor aggressiveness and treatment targets in advanced thyroid cancer. This study concerned 57 patients with aggressive metastatic, and/or radioiodine-refractory thyroid carcinomas, excluding anaplastic cases. Molecular profiling, including next-generation sequencing and RNA sequencing, was conducted to dissect the complex molecular landscape of these aggressive tumors. Histopathological analysis indicated that papillary carcinomas and high-grade thyroid carcinomas were predominant. The molecular analysis revealed a spectrum of mutations, with prevalent occurrences of BRAF V600E, TERT promoter, and RAS mutations. RNA sequencing identified ten gene fusions, such as NTRK and RET fusions. Three novel fusions were discovered: UGGT1::TERT, BTBD9::TERT, and TG::IGF1R, potentially driving aggressive behavior. UGGT1::TERT was linked to radioiodine-refractory tall cell PTC, BTBD9::TERT to high-grade follicular PTC, and TG::IGF1R to oncocytic carcinoma. These findings underscore the importance of TERT alterations in aggressive phenotypes and offer insights into molecular mechanisms guiding targeted therapies. Further research is necessary to confirm their significance as diagnostic and prognostic markers in thyroid cancer.

Mechanistic Insights and Molecular Diagnostics of TMPRSS2-ERG: Overview of the Journey from Regulation of Signaling Landscape in Fusion Positive Prostate Cancer to Appraisal as a Diagnostic Marker.

Chromosomal rearrangements and recurrent gene fusions were previously presumed to be the primary oncogenic mechanisms of hematological malignancies. However, the discovery of gene fusions in different cancers has opened new horizons to comprehensively investigate how cell type-specific fusion oncoproteins modulate signaling cascades. Prostate cancer (PCa) is a multifaceted and therapeutically challenging disease, and functional genomics have helped us develop a better understanding of the mechanisms underlying prostate carcinogenesis, castration-resistant PCa, and metastasis. Keeping in mind the fact that gene fusions have also been discovered in PCa, there has been rapid expansion in the field of molecular oncology and researchers are uncovering new facets regarding the mechanistic regulation of signaling pathways by fusion oncoproteins.

Abstract 315: Cost-effective, comprehensive detection of gene fusions from DNA and RNA using the UG100 sequencer

Abstract Background: Gene fusions, resulting from chromosomal rearrangements, play a critical role in the oncogenesis of various cancers, often acting as diagnostic markers and therapeutic targets. Their detection is important for understanding tumor biology and guiding personalized treatment strategies. With the evolution of economical sequencing technologies, hypothesis-free gene fusion detection in cancer genomics is becoming more accessible. This study demonstrates the use of the cost-effective Ultima Genomics UG100 platform for a comprehensive analysis of gene fusions, uniquely integrating Whole Genome Sequencing (WGS) and Whole Transcriptome Sequencing (WTS). This integration capitalizes on the strengths of both methods: WGS, which enables a broad analysis of structural variations including extragenic events, and WTS for more functional characterization of expressed gene fusions and abnormal isoforms, offering a synergistic approach that enhances the detection and characterization of genomic rearrangements. Methods: Five cancer cell lines (K562, THP-1, NCI-H660, Kasumi-1, MV4-11) with 29 previously detected gene fusions were sequenced, using both WTS and WGS, in addition to a standard fusion reference sample (Seraseq Fusion RNA Mix, with 16 RNA fusions). The libraries were sequenced on a UG100 sequencer using single ended reads of length ~250bp and analyzed with publicly available software: STAR-Fusion, combined with FusionInspector were used to detect RNA fusions; Manta and GridSS were used to detect DNA structural variations, including translocations. Results: 93% of the documented fusion events were detected in DNA and in RNA, in addition to the 16 evaluated just in RNA (100% detected). Sequence data from both WTS and WGS on the UG100 platform successfully identified a spectrum of gene fusions in both DNA and RNA, thereby confirming the platform's detection capabilities in both types of assays. The structural variation events detected in the WGS were comprised mainly of translocations, but also deletions and duplications. Conclusions: The Ultima Genomics UG100 sequencer has proven to be a cost-effective and efficient tool for the genome-wide discovery and validation of gene fusions, which can be impactful in clinical oncology settings. This study underscores the potential of using an integrated WTS and WGS approach on a single platform to advance our understanding of the genomic complexity of cancer, paving the way for more effective diagnostic and therapeutic strategies. Citation Format: Gila Lithwick-Yanai, Sarah Pollock, Danit Lebanony, Keren Ben Simhon, Sima Benjamin, David Bogumil, Nika Iremadze, Matt Sexton, Peleg Winer, Maya Levy, Shlomit Gilad, Josh Haimes, Giulia Corbet, Jennifer Pavlica, Doron Lipson. Cost-effective, comprehensive detection of gene fusions from DNA and RNA using the UG100 sequencer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 315.

Novel gene fusion discovery in Spitz tumours and its relevance in diagnostics.

In addition to morphologic analysis, molecular diagnostic work up of Spitz tumours is often of great value for their accurate diagnosis/classification. Nowadays, next-generation sequencing (NGS) is the predominant screening method in molecular diagnostics. Up to 80% of these melanocytic neoplasms comprise gene fusions as genetic anomalies for which the driver codes for a protein harbouring a kinase domain. However, because of the variety of fusion partners the use of PCR-based targeted enrichment NGS methods is not recommended. We describe a series of four Spitz tumour samples in which distinct gene fusions were detected by hybridisation-based capture NGS (TPM3::ALK, LIMA1::ROS1, LRRFIP2::ROS1 and MYO5A::RET). Two of these fusions are not previously described. All 4 fusions were confirmed by reverse transcription-PCR. These findings demonstrate the need for molecular analysis that can detect unknown fusions in Spitz neoplasms for optimal diagnosis.

Systematic discovery of gene fusions in pediatric cancer by integrating RNA-seq and WGS

BackgroundGene fusions are important cancer drivers in pediatric cancer and their accurate detection is essential for diagnosis and treatment. Clinical decision-making requires high confidence and precision of detection. Recent developments show RNA sequencing (RNA-seq) is promising for genome-wide detection of fusion products but hindered by many false positives that require extensive manual curation and impede discovery of pathogenic fusions.MethodsWe developed Fusion-sq to overcome existing disadvantages of detecting gene fusions. Fusion-sq integrates and “fuses” evidence from RNA-seq and whole genome sequencing (WGS) using intron–exon gene structure to identify tumor-specific protein coding gene fusions. Fusion-sq was then applied to the data generated from a pediatric pan-cancer cohort of 128 patients by WGS and RNA sequencing.ResultsIn a pediatric pan-cancer cohort of 128 patients, we identified 155 high confidence tumor-specific gene fusions and their underlying structural variants (SVs). This includes all clinically relevant fusions known to be present in this cohort (30 patients). Fusion-sq distinguishes healthy-occurring from tumor-specific fusions and resolves fusions in amplified regions and copy number unstable genomes. A high gene fusion burden is associated with copy number instability. We identified 27 potentially pathogenic fusions involving oncogenes or tumor-suppressor genes characterized by underlying SVs, in some cases leading to expression changes indicative of activating or disruptive effects.ConclusionsOur results indicate how clinically relevant and potentially pathogenic gene fusions can be identified and their functional effects investigated by combining WGS and RNA-seq. Integrating RNA fusion predictions with underlying SVs advances fusion detection beyond extensive manual filtering. Taken together, we developed a method for identifying candidate gene fusions that is suitable for precision oncology applications. Our method provides multi-omics evidence for assessing the pathogenicity of tumor-specific gene fusions for future clinical decision making.

Discovery of gene fusions in driver-negative NCI-MATCH screening samples.

3112 Background: NCI-MATCH aimed to determine the treatment efficacy of identifying actionable genetic alterations, irrespective of cancer histology, and to tailor treatment to the putative molecular drivers of tumors. Leveraging next-generation sequencing (NGS) and ThermoFisher’s Oncomine assay, this phase II trial genotyped 5,540 patient samples during active screening. Reviewing the genotyping statistics, we noted that NCI-MATCH identified fusions in 164 tumors, only 2.96%. This result is substantially lower than expected, given that clinical assays used at MGH’s and Yale’s diagnostic laboratories identified fusions in 8.5% of the 7,500 sequenced cases, 2.5% of which were novel. Notably, the Oncomine assay, based on multiplexed PCR, is unable to detect driver fusion events when either of the gene partners are unknown, or a novel breakpoint is involved. Cross-referencing identified fusions from MGH’s cohort with Oncomine’s primers, 5-30% of these fusions were potentially missed, suggesting that we could detect up to 30% more fusions than originally identified. Developed at MGH’s Molecular Diagnostics Laboratory, Anchored Multiplex PCR (AMP) interrogates 138 known fusion partners, enabling unbiased fusion detection when only one partner is known. With a high likelihood of identifying novel fusion drivers using AMP technology, we sequenced 663 cases that had no identified mutations of interest (MOI) from the NCI-MATCH cohort. Methods: A total of 200ng of RNA per sample was shipped from ECOG-ACRIN’s repository at MD Anderson Cancer Center to MGH (n = 319) and Yale (n = 349). Samples were processed with ArcherDX’s FusionPlex Pan Solid Tumor v2 kit and sequenced on the NextSeq500 with 150 base pair (bp) Paired-End (PE) kits. Data analysis was completed with ArcherDX’s analytics platform in conjunction with custom Python and R code. Reported fusions were manually verified on a case-by-case basis. All statistical tests were conducted in R. Results: Of the cases sequenced, most (663/693, 95.7%) were successfully processed with AMP. We identified 142 cases with at least one gene fusion out of 663 MOI-Negative cases (21%; 95% CI [18%, 25%]), with 90 as unique fusions, significantly more than the 8.5% observed at MGH (P < .001). Of the 142 fusion-positive cases, 36 have potentially actionable driver events, 27 contain novel fusions not previously described, and in 63 cases no drugs are available to target either component of the fusion. Additionally, we identified fusions in (12/34, 35%) Cholangiocarcinoma and (38/101, 37.6%) Sarcoma cases, 9 and 3 of which were potentially actionable respectively. Conclusions: As hypothesized, we identified fusions that the NCI-MATCH screening had missed, detailing sequencing technology improvement that could be broadly applicable to many clinical laboratories sequencing tumors. Clinical trial information: NCT02465060 .

Diagnosis of Fusion-Associated Sarcomas by Exon Expression Imbalance and Gene Expression

Sarcomas are a diverse group of tumors, with >70 subtypes in the current World Health Organization classification, each with distinct biological behavior requiring specific clinical management. A significant portion of sarcomas are molecularly defined by expression of a driver fusion gene; identification of such fusions is the basis of molecular diagnostics in sarcomas, which is of increasing complexity due to the ongoing discovery of new gene fusions. Recently, a multiplex NanoString platform-based assay was developed and clinically implemented, with fusion junction-spanning probes that detect the majority of sarcoma fusion types, with high sensitivity and specificity, and with lower cost and shorter turnaround time than those of targeted next-generation sequencing-based alternatives. Despite the effectiveness of this assay, there are several entities for which fusion-junction probes are not suitable due to multiple possible gene partners or excessive variability at the exon junctions. Here, the development and evaluation of a companion assay are described that uses NanoString-based gene expression analysis to detect aberrant 3'/5' exon expression imbalance and/or total gene overexpression as a surrogate marker for fusion gene rearrangement. This assay evaluates exon imbalance in 23 genes involved in over 25 mesenchymal tumor types and five genes specific to sarcomas with CIC rearrangements. Based on evaluation of 115 retrospectively and 91 prospectively collected cases, an assay sensitivity of 92.8% and specificity of 93.5% are demonstrated.

Unraveling Gene Fusions with Optical Genome Mapping in Hematological Malignancies: The Unexplored Terrain

Introduction: The cytogenetic analysis currently relies on a combination of traditional techniques, which are low resolution (karyotyping), targeted and require prior knowledge (Fluorescence in-situ hybridization, FISH), or cannot detect balanced SVs and orientation of duplicated segments of the genome (chromosomal microarrays). As a result, additional clinically relevant information remains intractable with this current standard-of-care (SOC) technique. Importantly, hematologic neoplasms frequently harbor acquired balanced translocations, but the discovery of new gene fusions has not been possible due to the lack of gene-level resolution with karyotyping, and analysis of only recurrent gene fusion with FISH panels. Therefore, this study aimed to assess the burden of translocation and gene fusions in hematological malignancies, which could potentially serve as therapeutic targets, and prognostic markers. Methods: This retrospective study included 59 unique and well-characterized samples that were received in our clinical laboratory for cytogenetic analysis with karyotyping and/or FISH testing. These 59 hematological neoplasms included adult acute myeloid leukemia (AML) (n=18), chronic lymphocytic leukemia (CLL) (n=15), myelodysplastic syndromes (MDS) (n=12), plasma cell myeloma (PCM) (n=6), lymphoma (n=3), myeloproliferative disorders/myeloproliferative neoplasms (MPD/MPN) (n=3), and chronic myeloid leukemia (CML) (n=2). Results: Of the 45 cases classified as simple, 38 cases had both karyotyping and FISH results. Of these 38 simple cases (<4 aberrations), seven were found to have ≥4 aberrations with OGM, while 5 out of 7 cases that had only FISH testing showed ≥4 aberrations with OGM. OGM identified several additional SVs, including 69 translocations and 38 potential gene fusions. In the 14 complex cases, OGM identified several additional SVs, including eight chromoanagenesis events (4 cases), 148 translocations, and 68 potential gene fusions Conclusion: OGM demonstrated its unique ability to detect balanced and unbalanced events in one assay. OGM detected 217 additional translocations and 106 novel putative gene fusions in this study and showed that these tumors harbor a significant translocation/gene-fusion burden. The use of OGM might lead to novel therapeutic targets and better patient management as it delineates the complexity of the genome with high resolution intractable with standard-of-care methods. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Fusion genes as diagnostic and predictive biomarkers for tumor

Structural variants, including chromosomal rearrangements and translocations, may result in the formation of fusion genes. Glioma is the most frequent brain tumor among adults. Due to complex tumor classifications, characterization of recurrence, inadequate sample size and controversial mechanisms of tumor malignancy, clinical strategies have not been developed for almost 30 years. Fusion gene is one of the strong driver events in glioma tumorigenesis and has provided fundamental insights into the disease mechanisms. This review elucidates the literature on the discovery of fusion genes, the development of detection techniques, and their clinical implementations. In conclusion, fusion genes are important diagnostic and predictive biomarkers for brain tumors.

Genion, an accurate tool to detect gene fusion from long transcriptomics reads

BackgroundThe advent of next-generation sequencing technologies empowered a wide variety of transcriptomics studies. A widely studied topic is gene fusion which is observed in many cancer types and suspected of having oncogenic properties. Gene fusions are the result of structural genomic events that bring two genes closely located and result in a fused transcript. This is different from fusion transcripts created during or after the transcription process. These chimeric transcripts are also known as read-through and trans-splicing transcripts. Gene fusion discovery with short reads is a well-studied problem, and many methods have been developed. But the sensitivity of these methods is limited by the technology, especially the short read length. Advances in long-read sequencing technologies allow the generation of long transcriptomics reads at a low cost. Transcriptomic long-read sequencing presents unique opportunities to overcome the shortcomings of short-read technologies for gene fusion detection while introducing new challenges.ResultsWe present Genion, a sensitive and fast gene fusion detection method that can also detect read-through events. We compare Genion against a recently introduced long-read gene fusion discovery method, LongGF, both on simulated and real datasets. On simulated data, Genion accurately identifies the gene fusions and its clustering accuracy for detecting fusion reads is better than LongGF. Furthermore, our results on the breast cancer cell line MCF-7 show that Genion correctly identifies all the experimentally validated gene fusions.ConclusionsGenion is an accurate gene fusion caller. Genion is implemented in C++ and is available at https://github.com/vpc-ccg/genion.

Fusion-positive non-small cell lung carcinoma: Biological principles, clinical practice, and diagnostic implications.

Based on superior efficacy and tolerability, targeted therapy is currently preferred over chemotherapy and/or immunotherapy for actionable gene fusions that occur in late-stage non-small cell lung carcinoma (NSCLC). Consequently, current clinical practice guidelines mandate testing for ALK, ROS1, NTRK, and RET gene fusions in all patients with newly diagnosed advanced non-squamous NSCLC (NS-NSCLC). Gene fusions can be detected using different approaches, but today RNA next-generation sequencing (NGS) or combined DNA/RNA NGS is the method of choice. The discovery of other gene fusions (involving, eg, NRG1, NUT, FGFR1, FGFR2, MET, BRAF, EGFR, SMARC fusions) and their partners has increased progressively in recent years, leading to the development of new and promising therapies and mandating the development and implementation of comprehensive detection methods. The purpose of this review is to focus on recent data concerning the main gene fusions identified in NSCLC, followed by the discussion of major challenges in this domain.

Gene fusions in glioblastoma: Results of Gliocat project.

2042 Background: Malignant gliomas are heterogeneous diseases in genetic basis. The development of sequencing techniques, such as RNA-Sequencing, has identified many gene rearrangements encoding novel oncogenic fusions. Gene fusion discovery can potentially lead to the development of novel treatments, however studies of gene fusions in glioma remain limited. Methods: The GLIOCAT project studied 139 patient samples of newly diagnosed glioblastoma who had received the standard first-line treatment from 2004 to 2015, to identify gene fusion events from glioblastoma transcriptome data (RNA-Seq). The molecular subtype could be studied in 124 cases. RNA-Seq reads were mapped against the reference human genome with STAR-fusion version 0.7.0, specifically, with FusionInspector validate ( http://star-fusion.github.io ). Two other platforms, FusionHub ( https://fusionhub.persistent.co.in ) and Oncofuse ( www.unav.es/genetica/oncofuse.html ), were applied to eliminate false positives or previously described in healthy tissue and to predict of the oncogenic potential each fusion. Results: A total of61 patients showed 103 different fusions, a median of two fusions by sample. The majority of gene fusions were intrachromosomal and most frequently implied chromosome was 12 followed by 7. In addition, fusions were more common in patients with MGMT promoter methylation, TCGA classical subtype and 18 IGS subtype. There were no differences in age, sex, type of surgery or long survivors ( &gt; 30 months). Ten fusions were already described in cancer, including three in gliomas (FRS2-KIF5A, EGFR-SEPT14 and FGFR3-TACC3). From the detected fusions, 22 of them included an oncogene or protooncogene. Conclusions: In our study, we report the landscape of gene fusions from a large data set of glioblastomas analyzed by RNA-seq. The majority of the fusions were private fusions. A minority of these recur in a low frequency but as many as a quarter of them included an oncogene or protooncogene. RNA-seq of GBM patient samples it is an important tool for the identification of patient-specific fusions that could drive personalized therapy. Furtherless, we will plan to validate this gene fusions.

Plasma cell myeloma: role of histopathology, immunophenotyping, and genetic testing.

Myeloma is a malignant neoplasm of plasma cells with complex pathogenesis. Diagnosis and risk stratification require the integration of histology, radiology, serology, and genetic data. Bone marrow biopsies are essential for myeloma diagnosis by providing material for histologic and cytologic assessment as well as immunophenotypic and genetic studies. Flow cytometry and genetic studies are, in particular, becoming increasingly important for diagnosis, risk stratification, and assessment of treatment response. Myeloma has traditionally been characterized by recurrent cytogenetic abnormalities that can be divided into two subtypes: hyperdiploid, characterized by trisomies, and non-hyperdiploid, characterized by translocations involving chromosome 14. These abnormalities are thought to be primary events, initiating a premalignant state, which progresses to myeloma through the acquisition of secondary mutations. The emergence of next-generation sequencing has led to the discovery of numerous mutations and gene fusions that comprise the heterogenous genomic landscape of myeloma. As the underlying pathogenesis of myeloma continues to be delineated, possible therapeutic targets have also emerged. Herein, we describe the importance of histology, immunophenotype, and mutational analysis in the assessment of myeloma.

Neurofibrosarcoma Revisited: An Institutional Case Series of Uterine Sarcomas Harboring Kinase-related Fusions With Report of a Novel FGFR1-TACC1 Fusion.

Uterine sarcomas with variable CD34 and S100 expression represent an emerging class of tumor in the female genital tract which commonly presents in the endocervix of premenopausal women. Initial molecular characterization identified NTRK1 and NTRK3 gene fusions as oncogenic drivers in these tumors; however, the repertoire of genetic alterations is likely more diverse given the recent discovery of PDGFB and RET gene fusions in similarly described tumors. Importantly, these fusion events lead to the aberrant activation of kinases that are potentially therapeutically targetable; therefore, recognizing this class of tumor becomes critical for initiating the molecular testing required for an accurate diagnosis and identification of clinically actionable fusions. Here, we report our institutional experience with 12 cases of uterine spindle cell sarcomas harboring kinase-related fusions. Patients ranged from 21 to 80 years old (median, 38 y) and presented either asymptomatically or with pelvic pain and/or uterine bleeding. Eleven (92%; 11/12) tumors were localized to the cervix and 1 (8%; 1/12) tumor was localized in the anterior fundus of the uterine corpus. Tumors ranged in size from 1.5 to 15.0 cm (median, 6.0 cm) and were histologically characterized by a moderately cellular, infiltrative proliferation of spindle cells with features of benign gland entrapment, stromal collagen deposition, perivascular hyalinization, occasionally myxoid stroma, a lymphocytic infiltrate, occasional nuclear pseudoinclusions, and a pseudophyllodes architecture. RNA-sequencing identified NTRK1 (8/12), NTRK3 (1/12), and PDGFB (2/12) gene fusions, which have been previously implicated in this tumor class, as well as a novel FGFR1-TACC1 (1/12) fusion. All tumors in this cohort showed coexpression of CD34 and S100 by immunohistochemistry except for those tumors with PDGFB fusions which showed solely CD34 expression. Of the 10 surgically resected tumors with follow-up, outcomes best correlated with the stage of disease. One of 4 patients with stage IA tumors (1/4) had recurrences, half of the stage IB (2/4) tumors had recurrences and all of the stage IIB tumors (2/2) had recurrences and died of disease. Future studies are still required to better understand the spectrum of genetic alterations as well as evaluate the efficacy of targeted kinase inhibitors in this class of tumor.

Comprehensive analysis of ALK, ROS1 and RET rearrangements in locally advanced rectal cancer

Gene rearrangements, such as anaplastic lymphoma kinase (ALK), c-ros oncogene 1 receptor tyrosine kinase (ROS1), rearranged during transfection (RET) and neurotrophic receptor tyrosine kinase 1 (NTRK1), identified in cancer have been indicated to be robust therapeutic targets in lung carcinomas. However, a few studies have focussed on locally advanced rectal cancer (LARC). The discovery of novel gene fusions is also valuable for LARC research. We used mass spectrometry-based assays and RNA sequencing to detect both known ALK, ROS1, RET and NTRK1 rearrangements and novel gene fusions in LARC patients. FusionMap was also used to find gene fusions. None of the ALK, ROS1, RET or NTRK1 gene fusions were detected by mass spectrometry-based assays or RNA sequencing. Three fusion candidates, integrin subunit beta 7 (ITGB7)-ROS1, lamin A/C (LMNA)-NTRK1 and Golgi-associated PDZ and coiled-coil motif containing (GOPC)-keratin 8 (KRT8), showed relatively high junction-spanning reads by the FusionMap algorithm, but did not pass validation. These results suggest that no ALK, ROS1 or RET rearrangements were found in LARC.

Epithelioid hemangioma of bone harboring FOS and FOSB gene rearrangements: A clinicopathologic and molecular study.

The diagnosis of epithelioid hemangioma (EH) remains challenging due to its rarity, worrisome histologic features, and locally aggressive clinical and radiographic presentation. Especially in the bone, EH can be misdiagnosed as a malignant vascular neoplasm due its lytic, often destructive or multifocal growth, as well as atypical morphology. The discovery of recurrent FOS and FOSB gene fusions in the pathogenesis of most EH has strengthened its stand-alone classification, distinct from other malignant epithelioid vascular lesions, such as epithelioid hemangioendothelioma or angiosarcoma. In this study we investigate a group of molecularly confirmed skeletal EH by the presence of FOS or FOSB gene rearrangements to better define its clinical and pathologic characteristics within a homogenous molecular subset. The cohort included 38 patients (25 males, 13 females), with a mean age at diagnosis of 38 years (range, 4-75). Regional, multifocal presentation was noted in 10 cases. Only six cases were correctly recognized as EH by the referring institutions, while most were misdiagnosed as other vascular tumors. Of the 17 patients with follow-up data available, five patients (29%) developed local recurrence after marginal en bloc excision (n = 3) or curettage (n = 2). Local recurrence-free survival rates were 84% at 3 years and 38% at 5 years. No metastasis or disease-related death was identified. Imaging studies exhibited no specific features, showing cortical bone destruction and soft-tissue extension in 14 (38%) cases. FOS gene rearrangements were detected in 28 (74%) of cases, while FOSB rearrangements in 10 (26%) cases. Our results highlight the significant challenges encountered in establishing a correct diagnosis exclusive of the molecular testing, mainly due to its overlap to other malignant epithelioid vascular tumors. Skeletal EH emerges as a genetically defined locally aggressive vascular neoplasm, with a high rate of local recurrence, but lacking the propensity for distant spread.

FGFR Fusions in Cancer: From Diagnostic Approaches to Therapeutic Intervention.

Fibroblast growth factor receptors (FGFRs) are tyrosine kinase receptors involved in many biological processes. Deregulated FGFR signaling plays an important role in tumor development and progression in different cancer types. FGFR genomic alterations, including FGFR gene fusions that originate by chromosomal rearrangements, represent a promising therapeutic target. Next-generation-sequencing (NGS) approaches have significantly improved the discovery of FGFR gene fusions and their detection in clinical samples. A variety of FGFR inhibitors have been developed, and several studies are trying to evaluate the efficacy of these agents in molecularly selected patients carrying FGFR genomic alterations. In this review, we describe the most frequent FGFR aberrations in human cancer. We also discuss the different approaches employed for the detection of FGFR fusions and the potential role of these genomic alterations as prognostic/predictive biomarkers.

Gene Fusions in Ocular Adnexal Tumors

To highlight the increasing importance of gene fusions in the diagnosis, prognosis, and therapy of ocular adnexal tumors. Perspective. A focused review of gene fusions, their pathogenic mechanism, and gene fusion detection methods in lacrimal gland and primary orbital and ocular adnexal soft tissue tumors; reappraisal of diagnostic, prognostic, and therapeutic approach to ocular adnexal tumors in light of emerging molecular genetic data. The widespread implementation of fluorescence insitu hybridization and next-generation sequencing methods in pathology practice has led to identification of recurrent gene rearrangements and fusions in a variety of tumors. As a result, molecular genetic methods have become the gold standard for diagnosis of tumors with overlapping histology and immunophenotype, such as small round blue cell tumors. Identification of canonic gene fusions has led to development of sensitive and specific immunohistochemical markers, such as STAT6 in solitary fibrous tumor. In addition to diagnostic accuracy, gene fusions have prognostic implications, such as unfavorable prognosis of PAX3-FOXO1 fusion in alveolar rhabdomyosarcoma. Finally, recognition of gene fusions as a driving mechanism in neoplasia has led to development of U.S. Food and Drug Administration-approved targeted therapies, such as TRK inhibitors for NTRK fusion-positive cancers. The discovery of recurrent gene fusions in various tumors, including those involving ocular adnexa, has led to a deeper insight into the molecular mechanisms of these neoplasms, revolutionizing our approach to their diagnosis, prognostication, and therapy.

Abstract B13: Leveraging cloud-based computational resources for gene fusion discovery with potential clinical implications for pediatric solid tumor patients

Abstract Introduction: Gene fusions are important oncogenic drivers with significant clinical impact in some cancer types. This is particularly true in pediatric cancers that often have low mutational burden and lack other diagnostic markers and therapeutic targets. Many gene fusions are rare or private to the individual patient and can be difficult to detect with methods optimized for common fusions. Unbiased sequencing methods and expansive computational resources are needed for expanding our ability to characterize fusions. Building a comprehensive catalog of oncogenic gene fusions will improve our understanding of their diversity and fully harness their potential for clinical impact. Methods: Patients are eligible for the GAIN/iCat2 study if they have been diagnosed with high-risk or recurrent/refractory extracranial solid tumor at age 30 or less and have a sample available for sequencing. Enrolled patients with an unclear diagnosis after standard clinical testing are nominated for transcriptome sequencing by the study investigators. We developed a computational pipeline in Google Cloud for gene fusion discovery utilizing paired end Illumina RNA-Seq data, multiple fusion callers, and a custom algorithm for integrative data analysis. The multicaller fusion detection approach enables us to address the high false-positive rate typical for gene fusion calling in transcriptomic data while improving the sensitivity to detect the more challenging fusions. After filtering, the fusions are annotated using the databases of known fusions and cancer genes. The predicted fusion transcripts are inspected visually, and the fusions are selected based on relevance to diagnostic classification or therapy to be validated by an orthogonal method. Results: 41 tumor samples were sequenced and analyzed for gene fusions. A total of 203 candidate fusions were detected by two or more fusion callers. Based on functional annotations and potential impact on diagnosis or therapeutic approaches, 12 fusion transcripts of interest were identified, 10 of which were validated by either pre-enrollment testing or an orthogonal method. Of 16 mesenchymal cases, 6 validated fusions had diagnostic relevance and 3 validated fusions had therapeutic implications (ERC1-BRAF, RBPMS-NTRK2, and VCAN-IL23R). Two patients responded to matched targeted therapy. In one case, diagnostic classification was revised. Conclusions: Whole-transcriptome sequencing in this selected patient population identified some fusion transcripts with clinical relevance. Determining the biologic significance of previously unreported fusions will require orthogonal sequencing such as whole genome, functional studies, and analysis of larger patient populations. Improved accuracy and scalability of methods for large-scale gene fusion analysis in the growing public datasets are likely to expand the landscape of gene fusions in cancer. Citation Format: Alma Imamovic, Alanna J. Church, Laura B. Corson, Deirdre Reidy, Navin Pinto, Luke Maese, Theodore W. Laetsch, AeRang Kim, Susan I. Vear, Margaret E. Macy, Mark A. Applebaum, Rochelle Bagatell, Amit J. Sabnis, Daniel A. Weiser, Julia L. Glade-Bender, Gianna R. Strand, Lobin A. Lee, R. Seth Pinches, Catherine M. Clinton, Brian D. Crompton, Neal I. Lindeman, Steven G. DuBois, Katherine A. Janeway, Eliezer M. Van Allen. Leveraging cloud-based computational resources for gene fusion discovery with potential clinical implications for pediatric solid tumor patients [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr B13.