Genetic Heterogeneity in Cellular Angiofibromas.

BACKGROUND: Cellular angiofibroma, a rare benign mesenchymal neoplasm, is classified within the 13q/RB1 family of tumors due to morphological, immunohistochemical, and genetic similarities with spindle cell lipoma. Here, genetic data reveal pathogenetic heterogeneity in cellular angiofibroma. METHODS: Three cellular angiofibromas were studied using G-banding/Karyotyping, array comparative genomic hybridization, RNA sequencing, and direct cycling sequencing. RESULTS: The first tumor carried a del(13)(q12) together with heterozygous loss and minimal expression of the RB1 gene. Tumors two and three displayed chromosome 8 abnormalities associated with chimeras of the pleomorphic adenoma gene 1 (PLAG1). In tumor 2, the cathepsin B (CTSB) fused to PLAG1 (CTSB::PLAG1) while in tumor 3, the mir-99a-let-7c cluster host gene (MIR99AHG) fused to PLAG1 (MIR99AHG::PLAG1), both leading to elevated expression of PLAG1 and insulin growth factor 2. CONCLUSION: This study uncovers two genetic pathways contributing to the pathogenetic heterogeneity within cellular angiofibromas. The first aligns with the 13q/RB1 family of tumors and the second involves PLAG1-chimeras. These findings highlight the diverse genetic landscape of cellular angiofibromas, providing insights into potential diagnostic strategies.

Cytoreductive Surgery With Hyperthermic Intraperitoneal Chemotherapy and Liver Resection is a Treatment Option for Patients With Peritoneal and Liver Metastases From Colorectal Cancer.

BACKGROUND: Colorectal cancer frequently metastasize to the liver and peritoneum, and is associated with a poor prognosis. In selected patients, a benefit in overall survival (OS) was shown for both peritoneal metastases (PM-CRC) offered cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC), and colorectal liver metastases (CLM) treated with surgical resection. However, the presence of CLM was considered a relative contraindication to CRS-HIPEC, causing a paucity in outcome data in this patient group. STUDY DESIGN: Patient with PM-CRC having CRS-HIPEC at a single national center between 2007 and 2023, with additional intervention for CLM, were included (previous curative treatment for extra-peritoneal and extra-hepatic metastases was allowed). Three groups were defined: CLM before CRS-HIPEC (preCRS-HIPEC); CLM resected simultaneously with CRS-HIPEC (simCRS-HIPEC); CLM after CRS-HIPEC (postCRS-HIPEC), aiming to retrospectively analyze outcomes. RESULTS: Fifty-seven patients were included and classified as: preCRS-HIPEC (n=11), simCRS-HIPEC (n=29), and postCRS-HIPEC (n=17). Median peritoneal cancer index (PCI) was 8, 13 patients had severe complications (Clavien-Dindo ≥3), and no 90-day mortality. Median OS was 48 months after CRS-HIPEC. PCI was a predictor of OS (HR 1.11, P<0.001). We observed no difference in short or long-term outcomes between intervention groups. DISCUSSION: This study demonstrate that patients with CLM having CRS-HIPEC had comparable OS to reports on CRS-HIPEC only, likely explained by a low PCI. Simultaneous CLM resection did not increase the risk of severe complications. CONCLUSION: In this national cohort, CRS-HIPEC and CLM intervention offers long-term survival, suggesting that this treatment may be offered to selected patients with PM-CRC and CLM.

Molecular testing for personalized therapy is underutilized in patients with borderline resectable and locally advanced pancreatic cancer - real world data from the NORPACT-2 study.

BACKGROUND: International guidelines currently recommend the use of molecular testing in patients with advanced pancreatic cancer. The rate of actionable molecular alterations is low. The utility of molecular testing in patients with borderline resectable (BRPC) or locally advanced (LAPC) pancreatic cancer in real world clinical practice is unclear. METHODS: 188 consecutive patients included in a prospective, population-based study (NORPACT-2) in patients with BRPC and LAPC (2018-2020) were reviewed. Molecular testing was performed at the discretion of the treating oncologist and was not recommended as a routine investigation by the national guidelines. All patients were considered fit to undergo primary chemotherapy and potential surgical resection. The frequency and the results of molecular testing (microsatellite instability (MSI) and/or KRAS status) were assessed. RESULTS: Thirty patients (16%) underwent molecular testing. MSI tumour was detected in one (3.6%) of 28 tested patients. The patient received immunotherapy and subsequently underwent surgical resection. Histological assessment of the resected specimen revealed a complete response. KRAS wild type was detected in one (14.3%) of seven tested patient. Patients who initiated FOLFIRINOX as the primary chemotherapy regimen (p = 0.022), or were being treated at one of the eight hospital trusts (p = 0.001) were more likely to undergo molecular testing. CONCLUSIONS: Molecular testing was rarely performed in patients with BRPC or LAPC. Routine molecular testing for all patients with BRPC and LAPC should be considered to increase identification of targetable mutations and improve outcomes.

Accurate and comprehensive evaluation of O6-methylguanine-DNA methyltransferase promoter methylation by nanopore sequencing.

AIMS: The methylation status of the O6-methylguanine-DNA methyltransferase (MGMT) promoter region is essential in evaluating the prognosis and predicting the drug response in patients with glioblastoma. In this study, we evaluated the utility of using nanopore long-read sequencing as a method for assessing methylation levels throughout the MGMT CpG-island, compared its performance to established techniques and demonstrated its clinical applicability. METHODS: We analysed 165 samples from CNS tumours, focusing on the MGMT CpG-island using nanopore sequencing. Oxford Nanopore Technologies (ONT) MinION and PromethION flow cells were employed for single sample or barcoded assays, guided by a CRISPR/Cas9 protocol, adaptive sampling or as part of a whole genome sequencing assay. Methylation data obtained through nanopore sequencing were compared to results obtained via pyrosequencing and methylation bead arrays. Hierarchical clustering was applied to nanopore sequencing data for patient stratification. RESULTS: Nanopore sequencing displayed a strong correlation (R2 = 0.91) with pyrosequencing results for the four CpGs of MGMT analysed by both methods. The MGMT-STP27 algorithm's classification was effectively reproduced using nanopore data. Unsupervised hierarchical clustering revealed distinct patterns in methylated and unmethylated samples, providing comparable survival prediction capabilities. Nanopore sequencing yielded high-confidence results in a rapid timeframe, typically within hours of sequencing, and extended the analysis to all 98 CpGs of the MGMT CpG-island. CONCLUSIONS: This study presents nanopore sequencing as a valid and efficient method for determining MGMT promotor methylation status. It offers a comprehensive view of the MGMT promoter methylation landscape, which enables the identification of potentially clinically relevant subgroups of patients. Further exploration of the clinical implications of patient stratification using nanopore sequencing of MGMT is warranted.

UV1 telomerase vaccine with ipilimumab and nivolumab as second line treatment for pleural mesothelioma - A phase II randomised trial.

PURPOSE: The NIPU-trial investigates the effect of adding the telomerase vaccine UV1 to treatment with ipilimumab and nivolumab for patients with pleural mesothelioma (PM). METHODS: In this phase 2 open-label trial, patients with PM progressing after first-line chemotherapy were randomised to receive ipilimumab and nivolumab alone (arm B) or combined with UV1 (arm A). The primary endpoint was progression-free survival (PFS) as determined by BICR. It was estimated that 69 PFS events were needed to detect a hazard ratio (HR) of 0.60 with 80% power and a one-sided alpha level of 0.10. RESULTS: 118 patients were randomised. The median PFS determined by blinded independent central review (BICR) was 4.2 months (95%CI 2.9-9.8) in arm A and 4.7 months (95%CI 3.9-7.0) in arm B (HR 1.01, 80%CI 0.75-1.36 P = 0.979), after a median follow-up of 12.5 months (95%CI 9.7-15.6). The investigator-determined median PFS was 4.3 months (95%CI 3.0-6.8) in arm A and 2.9 months (95%CI 2.4-5.5) in arm B (HR 0.60, 80%CI 0.45-0.81 P = 0.025). Confirmed objective response rate (ORR) by BICR was 31% in arm A and 16% in arm B (odds ratio 2.44 80%CI 1.35-4.49 P = 0.056). After a median follow-up time of 17.3 months (95%CI 15.8-22.9), the OS was 15.4 months (95%CI 11.1-22.6) in arm A and 11.1 months (95%CI 8.8-18.1) in arm B, (HR 0.73, 80%CI 0.53-1.0, P = 0.197). CONCLUSION: The primary endpoint was not met. Predefined analyses of response rates are in favour of adding the vaccine.

Genetic characterization of intramuscular myxomas.

Introduction: Intramuscular myxomas are benign tumors that are challenging to diagnose, especially on core needle biopsies. Acquired chromosomal aberrations and pathogenic variants in codon 201 or codon 227 in GNAS complex locus gene (GNAS) have been reported in these tumors. Here we present our genetic findings in a series of 22 intramuscular myxomas. Materials and methods: The tumors were investigated for the presence of acquired chromosomal aberrations using G-banding and karyotyping. Pathogenic variants in codon 201 or codon 227 of GNAS were assessed using direct cycle Sanger sequencing and Ion AmpliSeq Cancer Hotspot Panel v2 methodologies. Results: Eleven tumors carried chromosomal abnormalities. Six tumors had numerical, four had structural, and one had both numerical and structural chromosomal aberrations. Gains of chromosomes 7 and 8 were the most common abnormalities being found in five and four tumors respectively. Pathogenic variants in GNAS were detected in 19 myxomas (86%) with both methodologies. The detected pathogenic variants were p.R201H in nine cases (seven with abnormal and two with normal karyotypes), p.R201C in five cases, all with normal karyotypes, p.R201S in three cases (two with abnormal and one with normal karyotype), p.R201G in one case with a normal karyotype, and p.Q227E in one case with a normal karyotype. Conclusion: Firstly, our data indicate a possible association between chromosomal abnormalities and GNAS pathogenic variants in intramuscular myxomas. Secondly, the presence of the rare pathogenic variants R201S, p.R201G and p.Q227E in 26% (5 out of 19) of myxomas with GNAS pathogenic variants shows that methodologies designed to detect only the common "hotspot" of p.R201C and p.R201H will give false negative results. Finally, a comparison between Ion AmpliSeq Cancer Hotspot Panel v2 and direct cycle Sanger sequencing showed that direct cycle Sanger sequencing provides a quick, reliable, and relatively cheap method to detect GNAS pathogenic variants, matching even the most cutting-edge sequencing methods.

Evaluation of NTRK expression and fusions in a large cohort of early-stage lung cancer.

Tropomyosin receptor kinases (TRK) are attractive targets for cancer therapy. As TRK-inhibitors are approved for all solid cancers with detectable fusions involving the Neurotrophic tyrosine receptor kinase (NTRK)-genes, there has been an increased interest in optimizing testing regimes. In this project, we wanted to find the prevalence of NTRK fusions in a cohort of various histopathological types of early-stage lung cancer in Norway and to investigate the association between TRK protein expression and specific histopathological types, including their molecular and epidemiological characteristics. We used immunohistochemistry (IHC) as a screening tool for TRK expression, and next-generation sequencing (NGS) and fluorescence in situ hybridization (FISH) as confirmatory tests for underlying NTRK-fusion. Among 940 cases, 43 (4.6%) had positive TRK IHC, but in none of these could a NTRK fusion be confirmed by NGS or FISH. IHC-positive cases showed various staining intensities and patterns including cytoplasmatic or nuclear staining. IHC-positivity was more common in squamous cell carcinoma (LUSC) (10.3%) and adenoid cystic carcinoma (40.0%), where the majority showed heterogeneous staining intensity. In comparison, only 1.1% of the adenocarcinomas were positive. IHC-positivity was also more common in men, but this association could be explained by the dominance of LUSC in TRK IHC-positive cases. Protein expression was not associated with differences in time to relapse or overall survival. Our study indicates that NTRK fusion is rare in early-stage lung cancer. Due to the high level of false positive cases with IHC, Pan-TRK IHC is less suited as a screening tool for NTRK-fusions in LUSC and adenoid cystic carcinoma.

Genetic Pathways in Peritoneal Mesothelioma Tumorigenesis.

BACKGROUND/AIM: Mesotheliomas are tumors similar to, and probably derived from, mesothelial cells. They carry acquired chromosomal rearrangements, deletions affecting CDKN2A, pathogenetic polymorphisms in NF2, and fusion genes which often contain the promiscuous EWSR1, FUS, and ALK as partner genes. Here, we report the cytogenomic results on two peritoneal mesotheliomas. MATERIALS AND METHODS: Both tumors were examined using G-banding with karyotyping and array comparative genomic hybridization (aCGH). One of them was further investigated with RNA sequencing, reverse transcription polymerase chain reaction (RT-PCR), Sanger sequencing, and fluorescence in situ hybridization (FISH). RESULTS: In the first mesothelioma, the karyotype was 25∼26,X,+5,+7,+20[cp4]/50∼52,idemx2[cp7]/46,XX[2]. aCGH detected gains of chromosomes 5, 7, and 20 with retained heterozygosity on these chromosomes. In the second tumor, the karyotype was 46,XX,inv(10)(p11q25)[7]/46,XX[3]. aCGH did not detect any gains or losses and showed heterozygosity for all chromosomes. RNA sequencing, RT-PCR/Sanger sequencing, and FISH showed that the inv(10) fused MAP3K8 from 10p11 with ABLIM1 from 10q25. The MAP3K8::ABLIM1 chimera lacked exon 9 of MAP3K8. CONCLUSION: Our data, together with information on previously described mesotheliomas, illustrate two pathogenetic mechanisms in peritoneal mesothelioma: One pathway is characterized by hyperhaploidy, but with retained disomies for chromosomes 5, 7, and 20; this may be particularly prevalent in biphasic mesotheliomas. The second pathway is characterized by rearrangements of MAP3K8 from which exon 9 of MAP3K8 is lost. The absence of exon 9 from oncogenetically rearranged MAP3K8 is a common theme in thyroid carcinoma, lung cancer, and spitzoid as well as other melanoma subtypes.

"Evaluation of ROS1 expression and rearrangements in a large cohort of early-stage lung cancer".

BACKGROUND: ROS1 fusion is an infrequent, but attractive target for therapy in patients with metastatic non- small-cell lung cancer. In studies on mainly late-stage disease, the prevalence of ROS1 fusions is about 1-3%. In early-stage lung cancer ROS1 might also provide a fruitful target for neoadjuvant or adjuvant therapy. In the present study, we investigated the prevalence of ROS1 fusion in a Norwegian cohort of early-stage lung cancer. We also explored whether positive ROS1 immunohistochemical (IHC) stain was associated with certain mutations, clinical characteristics and outcomes. METHODS: The study was performed using biobank material from 921 lung cancer patients including 542 patients with adenocarcinoma surgically resected during 2006-2018. Initially, we screened the samples with two different IHC clones (D4D6 and SP384) targeting ROS1. All samples that showed more than weak or focal staining, as well as a subgroup of negative samples, were analyzed with ROS1 fluorescence in situ hybridization (FISH) and next-generation sequencing (NGS) with a comprehensive NGS DNA and RNA panel. Positive ROS1-fusion was defined as those samples positive in at least two of the three methods (IHC, FISH, NGS). RESULTS: Fifty cases were IHC positive. Of these, three samples were both NGS and FISH-positive and considered positive for ROS1 fusion. Two more samples were FISH positive only, and whilst IHC and NGS were negative. These were also negative with Reverse Transcription quantitative real time Polymerase Chain Reaction (RT-qPCR). The prevalence of ROS1 fusion in adenocarcinomas was 0.6%. All cases with ROS1 fusion had TP53 mutations. IHC-positivity was associated with adenocarcinoma. Among SP384-IHC positive cases we also found an association with never smoking status. There was no association between positive IHC and overall survival, time to relapse, age, stage, sex or pack-year of smoking. CONCLUSIONS: ROS1 seems to be less frequent in early-stage disease than in advanced stages. IHC is a sensitive, but less specific method and the results need to be confirmed with another method like FISH or NGS.

Fusion of the High-mobility Group AT-Hook 2 (HMGA2) and the Gelsolin (GSN) Genes in Lipomas With t(9;12)(q33;q14) Chromosomal Translocation.

BACKGROUND/AIM: Lipomas are benign tumors composed of mature fat cells. They are common soft tissue tumors that often carry chromosome aberrations involving 12q14 resulting in rearrangements, deregulation, and generation of chimeras of the high-mobility group AT-hook 2 gene (HMGA2) which maps in 12q14.3. In the present study, we report the finding of t(9;12)(q33;q14) translocation in lipomas and describe its molecular consequences. MATERIALS AND METHODS: Four lipomas from two male and two female adult patients were selected because their neoplastic cells carried a t(9;12)(q33;q14) as the sole karyotypic aberration. The tumors were investigated using RNA sequencing, reverse transcription polymerase chain reaction (RT-PCR), and Sanger sequencing techniques. RESULTS: RNA sequencing of a t(9;12)(q33;q14)-lipoma detected an in-frame fusion of HMGA2 with the gelsolin gene (GSN) from 9q33. RT-PCR together with Sanger sequencing confirmed the presence of an HMGA2::GSN chimera in the tumor as well as in two other tumors from which RNA was available. The chimera was predicted to code for an HMGA2::GSN protein which would contain the three AT-hook domains of HMGA2 and the entire functional part of GSN. CONCLUSION: t(9;12)(q33;q14) is a recurrent cytogenetic aberration in lipomas and generates an HMGA2::GSN chimera. Similar to what is seen in other rearrangements of HMGA2 in mesenchymal tumors, the translocation physically separates the part of HMGA2 encoding AT-hook domains from the gene's 3'-terminal part which contains elements that normally regulate HMGA2 expression.

Recurrent 8q11-13 Aberrations Leading to PLAG1 Rearrangements, Including Novel Chimeras HNRNPA2B1::PLAG1 and SDCBP::PLAG1, in Lipomatous Tumors.

BACKGROUND/AIM: Structural abnormalities of chromosome bands 8q11-13, resulting in rearrangement of the pleomorphic adenoma gene 1 (PLAG1), are known to characterize lipoblastoma, a benign fat cell tumor, found mainly in children. Here, we describe 8q11-13 rearrangements and their molecular consequences on PLAG1 in 7 lipomatous tumors in adults. MATERIALS AND METHODS: The patients were 5 males and 2 females between 23 and 62 years old. The tumors, namely five lipomas, one fibrolipoma and one spindle cell lipoma, were examined using G-banding with karyotyping, fluorescence in situ hybridization (FISH; three tumors), RNA sequencing, reverse transcription (RT) PCR, and Sanger sequencing analyses (two tumors). RESULTS: All 7 tumors had karyotypic aberrations which included rearrangements of chromosome bands 8q11-13 (the criterion for selection into this study). FISH analyses with a PLAG1 break apart probe showed abnormal hybridization signals in both interphase nuclei and on metaphase spreads indicating PLAG1 rearrangement. RNA sequencing detected fusion between exon 1 of heterogeneous nuclear ribonucleoprotein A2/B1 (HNRNPA2B1) and exon 2 or 3 of PLAG1 in a lipoma and fusion between exon 2 of syndecan binding protein (SDCBP) and exon 2 or 3 of PLAG1 in a spindle cell lipoma. The HNRNPA2B1::PLAG1 and SDCBP::PLAG1 fusion transcripts were confirmed using RT-PCR/Sanger sequencing analyses. CONCLUSION: As 8q11-13 aberrations/PLAG1-rearrangements/PLAG1-chimeras may evidently be a defining pathogenetic feature of lipogenic neoplasms of several histological types and not just lipoblastomas, we suggest that the term "8q11-13/PLAG1-rearranged lipomatous tumors" be generally adopted for this tumor subset.

Astrocytoma (CNS WHO grade 4), IDH-mutant with co-occurrence of BRAF p.V600E mutation, and homozygous loss of CDKN2A.

Molecular alterations nowadays play a crucial role in the diagnosis of brain tumors. Some of these alterations are associated with outcome and/or response to treatment, including sequence variants of isocitrate dehydrogenase (IDH) at position p.R132 or p.R172. Such IDH variants have so far been described in histone H3-wildtype primary brain tumors only in adult-type diffuse gliomas and are associated with a better outcome compared to their IDH-wildtype counterpart, the glioblastoma. Moreover, homozygous loss of CDKN2A and/or CDKN2B in IDH-mutant astrocytomas shortens the median overall survival regardless of histological features of malignancy. Such tumors are therefore considered to be aggressive and graded as WHO central nervous system (CNS) grade 4 lesions. The coexistence of an IDH-sequence variation and a BRAF p.V600E alteration has only rarely been described in diffuse astrocytomas. Due to the small number of cases, little is known about such neoplasms in terms of clinical behavior and response to treatment. Herein we describe the first case, to our knowledge, of an astrocytoma (CNS WHO grade 4), IDH-mutant, and BRAF p.V600E-mutant with homozygous deletion of CDKN2A. Pathologists should be aware that such an expression profile does exist even in WHO CNS grade 4 astrocytomas, IDH-mutant, and are encouraged to test for the BRAF p.V600E sequence variant as such an alteration may provide additional treatment options.

Presence of a t(12;18)(q14;q21) Chromosome Translocation and Fusion of the Genes for High-mobility Group AT-Hook 2 (HMGA2) and WNT Inhibitory Factor 1 (WIF1) in Infrapatellar Fat Pad Cells from a Patient With Hoffa's Disease.

BACKGROUND/AIM: Hoffa's disease is anterior knee pain presumably stemming from inflammatory fibrous hyperplasia of the infrapatellar fat pad (Hoffa's pad). The etiology and pathogenesis are unclear, however, and no genetic information about the disease has been published. We report the genetic findings in cells from the fat pad of a patient with Hoffa's disease. MATERIALS AND METHODS: Infrapatellar fat pad cells from a patient with Hoffa's disease were examined using cytogenetic, RNA sequencing, reverse transcription-polymerase chain reaction, and Sanger sequencing techniques. RESULTS: Cytogenetic examination of short-term cultured cells from the Hoffa's pad revealed a balanced t(12;18)(q14;q21) translocation as the sole chromosomal aberration. RNA sequencing detected an out-of-frame fusion of exon 3 of the gene coding for high mobility group AT-hook 2 (HMGA2) with exon 9 of the gene coding for WNT inhibitory factor 1 (WIF1). The fusion was subsequently verified by reverse transcription-polymerase chain reaction together with Sanger sequencing. CONCLUSION: Our data indicate that Hoffa's disease is a neoplastic process with acquired genetic aberrations similar to those found in many benign tumors of connective tissues. The genetic aberrations are presumably acquired by mesenchymal stem cells of the infrapatellar fat pad inducing proliferation and differentiation into adipocytes or other mature connective tissue cells.

Chromosomal Translocation t(5;12)(p13;q14) Leading to Fusion of High-mobility Group AT-hook 2 Gene With Intergenic Sequences From Chromosome Sub-Band 5p13.2 in Benign Myoid Neoplasms of the Breast: A Second Case.

BACKGROUND/AIM: Recently, we reported a myoid hamartoma carrying a t(5;12)(p13;q14) karyotypic aberration leading to fusion of the high-mobility group AT-hook 2 (HMGA2) gene with a sequence from chromosome sub-band 5p13.2. We describe here another benign myoid tumor of the breast with identical genetic aberrations. MATERIALS AND METHODS: A mammary leiomyomatous tumor found in a 45-year-old woman was studied using cytogenetics, fluorescence in situ hybridization, RNA sequencing, reverse transcription-polymerase chain reaction and Sanger sequencing. RESULTS: The karyotype of the tumor cells was 46,XX,t(5;12) (p13;q14)[14]. Fluorescence in situ hybridization showed rearrangement of HMGA2, RNA sequencing detected fusion of HMGA2 with a sequence from 5p13.2, whereupon reverse transcription-polymerase chain reaction together with Sanger sequencing verified the HMGA2-fusion transcript. The results were identical to those obtained by us previously in a myoid hamartoma of the breast. CONCLUSION: The translocation t(5;12)(p13;q14) and fusion of HMGA2 with sequences from sub-band 5p13.2 appear to be recurrent events in benign mammary myoid neoplasms.

Factors affecting outcome in resected EGFR-mutated lung cancer.

INTRODUCTION: Long-term data on disease trajectory of EGFR-mutated early-stage non-small cell lung cancer (NSCLC) is still limited. This is relevant in the context of the recently approved introduction of adjuvant EGFR-targeting therapy, specifically osimertinib in resected stage II-III EGFR-mutated NSCLC. METHODS: Long-term data on patients with resected adenocarcinoma of the lung and known EGFR-status were analysed with focus on site of relapse and detailed cause of death. Patients resected in the period 2006 to 2018 were included. RESULTS: Of 503 patients (286 (57%) females, median age 67.3 years), 62 (12%) harboured an EGFR-mutation, 286 (57%) were in stage I. After a median follow-up of 8.0 years, 241 (48%) patients relapsed. Recurrence occurred in 30% and 53% of EGFR-positive stage IA and IB patients, respectively. Median overall survival was longer in EGFR-mutated versus non-mutated patients (128 versus 88 months). The recurrence rate, time to recurrence and rate of brain metastases was not different between EGFR-mutated and non-mutated groups. Median time from recurrence to death was longer in EGFR-mutated patients (31 months) compared with non-mutated patients (15 months). More patients without EGFR-mutation succumbed to non-cancer related death (18%) compared to patients with EGFR-mutations (8%). CONCLUSIONS: The recurrence pattern in EGFR-mutated and non-mutated NSCLC-patients is similar and the rate is high in early stages. Time from recurrence to death and overall survival is longer in the EGFR-mutated group, due to lower risk of non-lung cancer deaths, and efficient treatment upon relapse.

Recurrent Fusion of the Genes for High-mobility Group AT-hook 2 (HMGA2) and Nuclear Receptor Co-repressor 2 (NCOR2) in Osteoclastic Giant Cell-rich Tumors of Bone.

BACKGROUND/AIM: Chimeras involving the high-mobility group AT-hook 2 gene (HMGA2 in 12q14.3) have been found in lipomas and other benign mesenchymal tumors. We report here a fusion of HMGA2 with the nuclear receptor co-repressor 2 gene (NCOR2 in 12q24.31) repeatedly found in tumors of bone and the first cytogenetic investigation of this fusion. MATERIALS AND METHODS: Six osteoclastic giant cell-rich tumors were investigated using G-banding, RNA sequencing, reverse transcription polymerase chain reaction, Sanger sequencing, and fluorescence in situ hybridization. RESULTS: Four tumors had structural chromosomal aberrations of 12q. The pathogenic variant c.103_104GG>AT (p.Gly35Met) in the H3.3 histone A gene was found in a tumor without 12q aberration. In-frame HMGA2-NCOR2 fusion transcripts were found in all tumors. In two cases, the presence of an HMGA2-NCOR2 fusion gene was confirmed by FISH on metaphase spreads. CONCLUSION: Our results demonstrate that a subset of osteoclastic giant cell-rich tumors of bone are characterized by an HMGA2-NCOR2 fusion gene.

Fusion of the Paired Box 3 (PAX3) and Myocardin (MYOCD) Genes in Pediatric Rhabdomyosarcoma.

BACKGROUND/AIM: Fusions of the paired box 3 gene (PAX3 in 2q36) with different partners have been reported in rhabdomyosarcomas and biphenotypic sinonasal sarcomas. We herein report the myocardin (MYOCD on 17p12) gene as a novel PAX3-fusion partner in a pediatric tumor with adverse clinical outcome. MATERIALS AND METHODS: A rhabdomyo-sarcoma found in a 10-year-old girl was studied using a range of genetic methodologies. RESULTS: The karyotype of the tumor cells was 48,XX,add(2)(q11),+del(2)(q35),add(3)(q?25),-7, del(8)(p 21),-15, add(17)(p 11), + 20, +der(?) t(?; 15) (?;q15),+mar[8]/46,XX[2]. Fluorescence in situ hybridization detected PAX3 rearrangement whereas array comparative genomic hybridization revealed genomic imbalances affecting hundreds of genes, including MYCN, MYC, FOXO3, and the tumor suppressor gene TP53. A PAX3-MYOCD fusion transcript was found by RNA sequencing and confirmed by Sanger sequencing. CONCLUSION: The investigated rhabdomyosarcoma carried a novel PAX3-MYOCD fusion gene and extensive additional aberrations affecting the allelic balance of many genes, among them TP53 and members of MYC and FOXO families of transcription factors.

The Prognostic Effect of KRAS Mutations in Non-Small Cell Lung Carcinoma Revisited: A Norwegian Multicentre Study.

BACKGROUND: due to emerging therapeutics targeting KRAS G12C and previous reports with conflicting results regarding the prognostic impact of KRAS and KRAS G12C in non-small cell lung cancer (NSCLC), we aimed to investigate the frequency of KRAS mutations and their associations with clinical characteristics and outcome. Since mutation subtypes have different preferences for downstream pathways, we also aimed to investigate whether there were differences in outcome according to mutation preference for the Raf, PI3K/Akt, or RalGDS/Ral pathways. METHODS: retrospectively, clinicopathological data from 1233 stage I-IV non-squamous NSCLC patients with known KRAS status were reviewed. KRAS' associations with clinical characteristics were analysed. Progression free survival (PFS) and overall survival (OS) were assessed for the following groups: KRAS wild type (wt) versus mutated, KRAS wt versus KRAS G12C versus KRAS non-G12C, among KRAS mutation subtypes and among mutation subtypes grouped according to preference for downstream pathways. RESULTS: a total of 1117 patients were included; 38% had KRAS mutated tumours, 17% had G12C. Among KRAS mutated, G12C was the most frequent mutation in former/current smokers (45%) and G12D in never smokers (46%). There were no significant differences in survival according to KRAS status, G12C status, among KRAS mutation subtypes or mutation preference for downstream pathways. CONCLUSION: KRAS status or KRAS mutation subtype did not have any significant influence on PFS or OS.

Monosomy 13 in Mammary Myofibroblastoma.

BACKGROUND/AIM: Myofibroblastoma of the breast is a rare benign mesenchymal tumor whose morphology is similar to that of spindle-cell lipoma. The few hitherto genetically investigated mammary myofibroblastomas have been shown to have had loss of material from chromosome 13, changes that are also common in spindle-cell lipoma. Our aim was to add to the existing knowledge of genetic aberrations in mammary myofibroblastoma by investigating another such tumor. MATERIALS AND METHODS: Cytogenetic and array comparative genome hybridization (aCGH) analyses were performed on a surgically removed mammary myofibroblastoma from a 76-year-old man. RESULTS: Short-term cultured cells from the tumor showed the karyotype 45,XY,-13[3]/44~45,idem,add(19)(q13)[cp2]. aCGH detected loss of one entire chromosome 13 and heterozygous loss from 19q between sub-band 19q13.12 and 19qter. CONCLUSION: These findings add to the evidence that loss of 13q material is typical of mammary myofibroblastomas.

Low Concordance Between T-Cell Densities in Matched Primary Tumors and Liver Metastases in Microsatellite Stable Colorectal Cancer.

BACKGROUND: The subtype, density and location of tumor infiltrating T-cells are being explored as prognostic and predictive biomarkers in primary colorectal cancer (pCRC) and colorectal liver metastases (CLM). Very limited data exist comparing findings in pCRC and matched CLM. PATIENTS AND METHODS: Fifty-eight patients with available pCRC and matched CLM (57/58 microsatellite stable) were included in this OSLO-COMET substudy. In immunohistochemically stained sections, total (Ttot), helper (TH), cytotoxic (CTL), and regulatory (Treg) T-cells were manually counted in hotspots from the invasive margin (IM), intratumor (IT), and tumor adjacent regions to determine T-cell densities. RESULTS: A striking accumulation of T-cells was found in IM of both pCRC and CLM with much lower densities in the IT region, exemplified by Ttot of 2838 versus 340 cells/mm2, respectively, in CLM. The correlation at the individual level between T-cell densities in pCRC and corresponding CLM was poor for all regions and T-cell subtypes; for instance, the correlation coefficient (R2) for IM Ttot was 0.07. The IT TH : CTL and Treg : TH ratios were 2.94 and 0.44, respectively, in pCRC, and 1.84 and 0.24, respectively, in CLM. CONCLUSION: The observed accumulation of T-cells in the IM regions of pCRC and CLM with low penetration to the IT regions, combined with high TH : CTL and Treg : TH ratios, point to the presence of an immune suppressive microenvironment. T-cell densities of CLM differed markedly from the matched pCRC, indicating that to evaluate T-cell biomarkers in metastasis, the commonly available pCRC cannot serve as a surrogate for the metastatic tumor.