Performances of the Idylla GeneFusion Assay: contribution to a rapid diagnosis of targetable gene fusions in tumour samples.

AIMS: We aimed to evaluate the performances of the Idylla GeneFusion Assay (IGFA) designed to detect, in a single, rapid and fully automated assay, ALK, ROS1, RET, NTRK1, NTRK2 and NTRK3 gene fusions and MET exon 14 skipping in cancer samples. METHODS: Based on a set of tumours enriched in cases with gene fusions, we applied the IGFA to tumour areas of various sizes and tumour cell contents. IGFA results were compared with those obtained with other methods (immunohistochemistry, fluorescent in situ hybridisation, DNA and RNA next-generation sequencing). RESULTS: We selected 68 tumours: 49 cases with known gene fusions (8 ALK, 8 ROS1, 5 RET, 7 NTRK1, 3 NTRK2 and 6 NTRK3 ones) or MET exon 14 skipping mutations (12 cases) and 19 cases with no fusion and no MET mutation. We performed 128 IGFA tests on distinct tissue areas. The global sensitivity and specificity of the IGFA were, respectively, 62.82% and 99.2% with variations between molecular targets and tissue areas. Of note, 72.5% sensitivity and 98.79% specificity were obtained in 37 tissue areas fulfilling the manufacturer's recommendations (ie, at least 10% of tumour cells in at least 20 mm² of tissue area). The rate of non-conclusive results was higher in small samples with low percentages of tumour cells. CONCLUSIONS: The IGFA could contribute to the rapid detection of targetable gene fusions and mutations, especially in context of rapidly growing cancers requiring urgent therapeutic choices.

Ultrafast Gene Fusion Assessment for Nonsquamous NSCLC.

Introduction: Gene fusion testing of ALK, ROS1, RET, NTRK, and MET exon 14 skipping mutations is guideline recommended in nonsquamous NSCLC (NS-NSCLC). Nevertheless, assessment is often hindered by the limited availability of tissue and prolonged next-generation sequencing (NGS) testing, which can protract the initiation of a targeted therapy. Therefore, the development of faster gene fusion assessment is critical for optimal clinical decision-making. Here, we compared two ultrafast gene fusion assays (UFGFAs) using NGS (Genexus, Oncomine Precision Assay, Thermo Fisher Scientific) and a multiplex reverse-transcriptase polymerase chain reaction (Idylla, GeneFusion Assay, Biocartis) approach at diagnosis in a retrospective series of 195 NS-NSCLC cases and five extrapulmonary tumors with a known NTRK fusion. Methods: A total of 195 NS-NSCLC cases (113 known gene fusions and 82 wild-type tumors) were included retrospectively. To validate the detection of a NTRK fusion, we added five NTRK-positive extrathoracic tumors. The diagnostic performance of the two UFGFAs and standard procedures was compared. Results: The accuracy was 92.3% and 93.1% for Idylla and Genexus, respectively. Both systems improved the sensitivity for detection by including a 5'-3' imbalance analysis. Although detection of ROS1, MET exon 14 skipping, and RET was excellent with both systems, ALK fusion detection was reduced with sensitivities of 87% and 88%, respectively. Idylla had a limited sensitivity of 67% for NTRK fusions, in which only an imbalance assessment was used. Conclusions: UFGFA using NGS and reverse-transcriptase polymerase chain reaction approaches had an equal level of detection of gene fusion but with some technique-specific limitations. Nevertheless, UFGFA detection in routine clinical care is feasible with both systems allowing faster initiation of therapy and a broad degree of screening.

Molecular profile of non-small cell lung cancer in reunion Island.

BACKGROUND: In recent years, the discovery of predictive biomarkers has enabled the development of targeted therapies that have improved the prognosis of patients with non-small cell lung cancer (NSCLC). No data are available at present on the molecular profile of NSCLC in Reunion Island, a French overseas department located in the Indian Ocean and characterized by an ethnically-mixed population. METHOD: This observational, retrospective, and multicenter study included all patients who were diagnosed with NSCLC in Reunion Island during 2 years and whose tumor specimens were sent for molecular analysis at Bordeaux University Hospital. The aim of the study was to determine the molecular profile of NSCLC in the Reunionese population, including the frequency of epidermal growth factor receptor (EGFR) mutation. RESULTS: A total of 310 patients with NSCLC were screened for genetic mutations. Of these, 281 (91%) had adenocarcinoma, 207 (66%) were born in Reunion Island, 79 (25%) were never-smokers, and 109 (35%) were women. One hundred and seventy-eight (57%) patients had a genetic mutation. An EGFR mutation was detected in 69 patients (22%) of the 310 included patients. This mutation was detected in 23% of patients with adenocarcinoma, 40% of women, 55% of never-smokers, and 23% of patients born in Reunion Island. CONCLUSION: The frequency of EGFR mutation is high in the Reunionese population. This frequency is similar to that reported in Asia and may be explained by the history of migrations and ethnic mixing in Reunion Island. These findings suggest complex interactions between genetic and environmental factors in the carcinogenesis of NSCLC.

Clinical impact of STK11 mutation in advanced-stage non-small cell lung cancer.

BACKGROUND: Mutations in STK11/LKB1 gene present a negative impact on tumour immune microenvironment, especially with concomitant activating KRAS mutation. These recent data may explain a decreased response to immunotherapy treatment in STK11 mutant non-small cell lung cancer (NSCLC). OBJECTIVE: The primary objective is to evaluate, in a real-life setting, overall survival (OS) in patients with NSCLC according to the presence of STK11 mutation. The secondary objective is to assess time to treatment failure (TTF) for the first-line chemotherapy or immunotherapy. METHODS: This observational multicentric study was conducted in Nouvelle-Aquitaine (France), for 24 months. Clinical, histopathological and imagery data were collected in each centre while the next-generation sequencing analysis was performed in Bordeaux Hospital University. Patient's data were longitudinally followed from NSCLC diagnosis date to the occurrence of censoring events (therapeutic failure or death, as applicable) or until the study end date. RESULTS: median OS from the first drug administration was significantly longer for STK11wt patients than STK11mut patients (16.2 months [11 - nr] versus 4.7 months [2.5-9.4]; Log-rank test P < 0.001). The Presence of STK11 mutation was significantly associated with shortened OS (RR = 2.26 [1.35-3.79], P = 0.002). First-line TTF was significantly shorter in STK11mut population and the presence of the mutation was significantly associated with an increase in treatment failures (RR = 1.87 [1.21-2.89], P = 0.005). The type of treatment (chemotherapy, immunotherapy) does not influence the amplitude of reduced TTF in patients with STK11mut. CONCLUSION: The presence of STK11 mutation is associated with poor prognosis in NSCLC.

An EZH2 blocker sensitizes histone mutated diffuse midline glioma to cholesterol metabolism inhibitors through an off-target effect.

Background: Diffuse Midline Glioma, H3K27M-mutant (DMG) is a rare, highly aggressive pediatric tumor affecting the brainstem, and is one of the deadliest cancers. Currently available treatment options such as chemotherapy and radiotherapy do only modestly prolong survival. In this pathology, H3K27 mutations deregulate Polycomb Repressive Complex 2 (PRC2), including enzymatic activity of EZH2, which is therefore under investigation as a therapeutic target. Methods: We used a chemical EZH2 inhibitor, GSK126, small interfering RNAs, and a CRISPR/Cas9 knockout approaches in a series of DMG tumor cell lines to investigate metabolic treatment responses by proteomic analysis. A combination strategy was elaborated and studied in primary and established DMG cells, spheroid 3D cultures, and in vivo in a chick chorio-allantoic membrane DMG assay and an orthotopic intracranial DMG mouse model. Results: GSK126 shows significant (P < .05-.001) inhibitory effects in in vitro cell proliferation assays and induces apoptosis. Chemical targeting of EZH2 induced expression of proteins implicated in cholesterol metabolism. Low-dose GSK126 treatment together with statins revealed strong growth inhibition in combinatorial treatments, but not in single treatments, both in DMG cells in vitro, in DMG spheroid cultures, and in chick and mouse in vivo models (P < .05). All statistical tests were two-sided. Conclusions: Our results reveal an unexpected GSK126-inducible sensitivity to cholesterol biosynthesis inhibitors in highly aggressive pediatric glioma that warrants further evaluation as treatment strategy. This combinatorial therapy should have few side effects because of the low doses used to achieve significant anti-tumor activity.

Detection of NTRK fusions in glioblastoma: fluorescent in situ hybridisation is more useful than pan-TRK immunohistochemistry as a screening tool prior to RNA sequencing.

Glioblastomas are frequent malignant brain tumours with a very poor prognosis and a need for new and efficient therapeutic strategies. With the approval of anti-TRK targeted therapies to treat patients with advanced NTRK-rearranged cancers, independent of the type of cancer, potential new treatment opportunities are available for the 0.5-5% of patients with NTRK-rearranged glioblastomas. Identification of these rare NTRK-rearranged glioblastomas requires efficient diagnostic tools and strategies which are evaluated in this study. We compared the results of NTRK1, NTRK2 and NTRK3 fluorescent in situ hybridisation (FISH) assays to those of pan-TRK immunohistochemistry (IHC) using two EPR17341 and A7H6R clones in a set of 196 patients with glioblastomas. Cases with at least 15% of positive nuclei using FISH analyses were further analysed using RNA sequencing. Above the 15% threshold, seven positive glioblastomas (3.57%) were identified by FISH assays (4 NTRK1, 3 NTRK2, no NTRK3). NTRK rearrangements were confirmed by RNA sequencing analyses in four cases [1 LMNA-NTRK1, 1 PRKAR2A-NTRK2, 1 SPECC1L-NTRK2 and 1 NACC2-NTRK2 fusions, i.e., 4/196 (2%) of NTRK-rearranged tumours in our series] but no rearrangement was detected in three samples with less than 30% of positive tumour nuclei as determined by NTRK1 FISH. Pan-TRK immunostaining showed major discrepancies when using either the EPR17341 or the A7H6R clones for the following criteria: main intensity, H-Score based scoring and homogeneity/heterogeneity of staining (Kappa values <0.2). This led to defining adequate criteria to identify NTRK-rearranged gliomas exhibiting strong and diffuse immunostaining contrasting to the variable and heterogeneous staining in non-NTRK-rearranged gliomas (p<0.0001). As assessing NTRK rearrangements has become crucial for glioma therapy, FISH seems to be a valuable tool to maximise access to TRK testing in patients with glioblastomas. In contrast to other cancers, pan-TRK IHC appears of limited interest in this field because there is no 'on/off' IHC positivity criterion to distinguish between NTRK-rearranged and non-NTRK-rearranged gliomas. RNA sequencing analyses are necessary in FISH positive cases with less than 30% positive nuclei, to avoid false positivity when scoring is close to the detection threshold.

Novel findings of splenic extramedullary hematopoiesis during primary myelofibrosis, post-essential thrombocythemia, and post-polycythemia vera myelofibrosis.

BCR-ABL-fusion-negative myeloproliferative neoplasms (MPNs) with myelofibrosis (MF) include primary MF, post-polycythemia vera MF and post-essential thrombocythemia MF. Clonal extramedullary hematopoiesis (EMH) can occur during MPN pathogenesis. Although histopathological bone-marrow (BM) features during clonal EMH have been investigated, those of the spleen have been poorly described. We analyzed splenectomy samples from 28 patients with MF and BM samples from 20 of them. Slides were stained with hematoxylin and eosin, reticulin, and trichrome, with immunohistochemical labeling of glycophorin A, myeloperoxidase, CD61, CD34, and CD117. We also subjected splenectomy and BM samples from six patients and spleen samples from seven patients to next-generation sequencing (NGS). Megakaryocyte-rich spleen nodules (MRSNs), seen in seven of the 28 patients, were significantly associated with megakaryocyte proliferation in the spleen (p = 0.04). We devised a grading system for spleen fibrosis (SF) and found that SF was increased in 20 of 28 patients. Notably, patients with SF were more likely to have MRSNs, suggesting that megakaryocytes might participate in SF, as previously described in BM. Comparisons of spleen and BM NGS findings of six patients' specimens revealed identical mutational status in the two organs for half of the patients. We observed additional mutations in the spleen of two patients. However, the meaning of this finding remains unknown since there was a long interval between BM and spleen samplings (68 and 82 months, respectively).

MSI-High RAS-BRAF wild-type colorectal adenocarcinomas with MLH1 loss have a high frequency of targetable oncogenic gene fusions whose diagnoses are feasible using methods easy-to-implement in pathology laboratories.

Targetable kinase fusions are extremely rare (<1%) in colorectal cancers (CRCs), making their diagnosis challenging and often underinvestigated. They have been shown particularly frequently among MSI-High, BRAF/KRAS/NRAS wild-type CRCs with MLH1 loss (MLH1loss MSI-High wild-type). We searched for NTRK1, NTRK2, NTRK3, ALK, ROS1, BRAF, RET, and NRG1 kinase fusions in CRCs using methods easy-to-implement in pathology laboratories: immunohistochemistry (IHC), fluorescent in situ hybridization (FISH), and fully automated real-time PCR targeted analyses. RNA-sequencing analyses were used for confirmation. Among 84 selected MLH1 deficient (IHC) CRCs cases, MLH1loss MSI-High wild-type CRCs consisted first in 19 cases after Idylla™ analyses and finally in 18 cases (21%) after RNA-sequencing (detection of one additional KRASG12D mutation). FISH (and when relevant, IHC) analyses concluded in 5 NTRK1, 3 NTRK3, 1 ALK, 2 BRAF, and 2 RET FISH positive tumors. ALK and NTRK1 rearranged tumors were IHC positive, but pan-TRK IHC was negative in the 3 NTRK3 FISH positive tumors. RNA-sequencing analyses confirmed 12 of 13 fusions with only one false positive RET FISH result. Finally, 12/18 (67%) of MLH1loss MSI-High wild-type CRCs contained targetable kinase fusions. Our study demonstrates the feasibility, but also the cost-effectiveness, of a multistep but rapid diagnostic strategy based on nonsequencing methods to identify rare and targetable kinase fusions in patients with advanced CRCs, as well as the high prevalence of these kinase fusions in MLH1loss MSI-High wild-type CRCs. Nevertheless, confirmatory RNA-sequencing analyses are necessary in case of low FISH positive nuclei percentage to rule out FISH false-positive results.

Positive Association Between Location of Melanoma, Ultraviolet Signature, Tumor Mutational Burden, and Response to Anti-PD-1 Therapy.

Emerging evidence suggests a correlation between the tumor mutational burden (TMB) and the response to programmed cell death-1 protein (PD-1) monotherapy across multiple cancer types. In skin cancers, as high TMB is mostly because of ultraviolet (UV) exposure, we hypothesized a correlation between the primary melanoma cutaneous location according to sun exposure and response to anti-PD-1 monotherapy. METHODS: The aim of this study was to analyze, in advanced melanoma, the relationship between TMB, locations according to sun exposure, and response to PD-1 inhibitors. We conducted a prospective multicentric analysis, by sequencing the most recent metastatic sample before PD-1 inhibitors using FoundationOne assay. RESULTS: One hundred two patients were included, with TMB available for 94 cases. In univariate and multivariate linear regression, TMB was significantly associated with sun-exposed areas of the primary melanoma location and with age (coefficients of the association with log-TMB: non-UV location, -1.05; chronic sun-exposed area, 1.12; P value for the location, < 10-5; age, 0.021 per year, P value for age, .002). Molecular UV signature present on the metastatic site was associated with higher TMB (P = .003). Melanomas bearing a high TMB had a higher probability of response to PD-1 inhibitors compared with melanomas with a low TMB, with a dose-dependent effect following an exponential curve and a negative odds ratio of 0.40 (95% CI, 0.20 to 0.72, P = .004) between log-TMB and 6-month progression. CONCLUSION: Cumulative sun exposure related to skin location and molecular UV signature present on the metastatic site appear to be relevant biomarkers directly linked to TMB. Because TMB is not yet available to all for routine clinical use, the location of the primary melanoma in a sun-exposed area may play an important role in clinical decisions regarding therapeutic choice.

CD63-GPC1-Positive Exosomes Coupled with CA19-9 Offer Good Diagnostic Potential for Resectable Pancreatic Ductal Adenocarcinoma.

Tumor-released extracellular vesicles (EVs) contain tumor-specific cargo distinguishing them from healthy EVs, and making them eligible as circulating biomarkers. Glypican 1 (GPC1)-positive exosome relevance as liquid biopsy elements is still debated. We carried out a prospective study to quantify GPC1-positive exosomes in sera from pancreatic ductal adenocarcinoma (PDAC) patients undergoing up-front surgery, as compared to controls including patients without cancer history and patients displaying pancreatic preneoplasic lesions. Sera were enriched in EVs, and exosomes were pulled down with anti-CD63 coupled magnetic beads. GPC1-positive bead percentages determined by flow cytometry were significantly higher in PDAC than in the control group. Diagnosis accuracy reached 78% (sensitivity 64% and specificity 90%), when results from peripheral and portal blood were combined. In association with echo-guided-ultrasound-fine-needle-aspiration (EUS-FNA) negative predictive value was 80% as compared to 33% for EUS-FNA only. This approach is clinically relevant as a companion test to the already available diagnostic tools, since patients with GPC1-positive exosomes in peripheral blood showed decreased tumor free survival.

High Clinical Value of Liquid Biopsy to Detect Circulating Tumor Cells and Tumor Exosomes in Pancreatic Ductal Adenocarcinoma Patients Eligible for Up-Front Surgery.

PURPOSE: Expediting the diagnosis of pancreatic ductal adenocarcinoma (PDAC) would benefit care management, especially for the start of treatments requiring histological evidence. This study evaluated the combined diagnostic performance of circulating biomarkers obtained by peripheral and portal blood liquid biopsy in patients with resectable PDAC. EXPERIMENTAL DESIGN: Liquid biopsies were performed in a prospective translational clinical trial (PANC-CTC #NCT03032913) including 22 patients with resectable PDAC and 28 noncancer controls from February to November 2017. Circulating tumor cells (CTCs) were detected using the CellSearch® method or after RosetteSep® enrichment combined with CRISPR/Cas9-improved KRAS mutant alleles quantification by droplet digital PCR. CD63 bead-coupled Glypican-1 (GPC1)-positive exosomes were quantified by flow cytometry. RESULTS: Liquid biopsies were positive in 7/22 (32%), 13/22 (59%), and 14/22 (64%) patients with CellSearch® or RosetteSep®-based CTC detection or GPC1-positive exosomes, respectively, in peripheral and/or portal blood. Liquid biopsy performance was improved in portal blood only with CellSearch®, reaching 45% of PDAC identification (5/11) versus 10% (2/22) in peripheral blood. Importantly, combining CTC and GPC1-positive-exosome detection displayed 100% of sensitivity and 80% of specificity, with a negative predictive value of 100%. High levels of GPC1+-exosomes and/or CTC presence were significantly correlated with progression-free survival and with overall survival when CTC clusters were found. CONCLUSION: This study is the first to evaluate combined CTC and exosome detection to diagnose resectable pancreatic cancers. Liquid biopsy combining several biomarkers could provide a rapid, reliable, noninvasive decision-making tool in early, potentially curable pancreatic cancer. Moreover, the prognostic value could select patients eligible for neoadjuvant treatment before surgery. This exploratory study deserves further validation.

Assessment of BRAFV600E mutation in pulmonary Langerhans cell histiocytosis in tissue biopsies and bronchoalveolar lavages by droplet digital polymerase chain reaction.

The neoplastic nature of pulmonary Langerhans cell histiocytosis (PLCH) is still debated. As the detection of BRAF V600E and MAP2K1 mutations in patients with PCLH is now considered for such assessment, the aim of our study was to evaluate digital droplet polymerase chain reaction (ddPCR) in PCLH diagnosis. We retrospectively analyzed BRAFV600E detection in a cohort of 42 PCLH tissues and 18 bronchoalveolar lavages (BALs) by ddPCR, immunohistochemistry, high-resolution melting PCR (HRM), and next-generation sequencing (NGS). The presence of BRAFV600E mutation was assessed by at least two concordant techniques to further evaluate specificity and sensitivity of each method. The BRAF V600E mutation prevalence was detected in 18 out of 41 cases by ddPCR, 10 out of 36 cases by HRM PCR, and 16 out of 31 cases by NGS. BRAFV600E immunohistochemistry sensitivity was 94%, and specificity was 79%. HRM PCR sensitivity was only 59%, and specificity was 100%. NGS sensitivity and specificity were 100% for interpretable cases (n = 31), but in 11 cases, this technique was non-contributive. The analysis of BAL samples by ddPCR revealed a BRAFV600E mutation both in tissue and in BAL samples in one patient, a wild-type status both in tissue and in BAL samples in two patients, and a wild-type BRAF status in BAL and a BRAFV600E mutation in tissue samples in four patients. The study supports the usefulness of ddPCR for BRAF status assessment in either tissue or BAL samples to increase the accuracy of PLCH diagnosis.

Evaluation of a fast and fully automated platform to diagnose EGFR and KRAS mutations in formalin-fixed and paraffin-embedded non-small cell lung cancer samples in less than one day.

AIMS: Searching for EGFR and KRAS mutations within non-small cell lung carcinoma (NSCLC) samples remains time-consuming and can delay treatment choices in patients with acute deterioration. We evaluated the performances of the fully automated Idylla platform to quickly detect these mutations in NSCLC samples. METHODS: We used the Idylla EGFR Mutation Assay and the Idylla KRAS Mutation Test to analyse 18 formalin-fixed paraffin-embedded NSCLC tumour samples with known EGFR and KRAS mutation status according to next-generation sequencing (NGS) and droplet digital PCR (ddPCR) for EGFRT790M mutations. RESULTS: Idylla assays identified KRAS and EGFR activating mutations in 4 and 10 NSCLC samples, respectively. EGFRT790M resistance mutations were identified in only 1 sample using Idylla but in 4 and 14 samples using NGS and ddPCR, respectively. No false-positive result was noted with Idylla assays. Mutation written report was obtained after 130 min (KRAS assays) to 140 min (EGFR assays). CONCLUSIONS: The Idylla platform is an interesting ancillary first-line fast and fully automated tool to detect EGFR and KRAS mutations in NSCLC samples allowing rapid treatment choices in patients with acute deterioration.

Neuroendocrine phenotype as an acquired resistance mechanism in ALK-rearranged lung adenocarcinoma.

A 63-year-old caucasian woman, presenting with metastatic primitive lung adenocarcinoma was treated with ALK inhibitor crizotinib treatment for six month. After rapid regression of all known lesions, tumor progression appeared six month later on all the already known lesions. A biopsy of subclavicular lymphadenopathy revealed a carcinoma with neuroendocrine phenotype with both immunohistochemical expression of ALK protein and ALK-rearrangement. It was associated with acquired resistance to crizotinib with ALK-rearrangement but without point mutation or amplification of the ALK gene. We herein report the first case of histological neuroendocrine transformation after ALK inhibitor crizotinib treatment, associated with acquired resistance to crizotinib.

Primary digestive melanoma in association with tubular adenoma: a case report illustrating the distinction from metastatic colonic melanoma.

We report here an exceptional pattern of atypical lentiginous melanocytic proliferation within an adenoma, leading to focal lamina propria infiltration and pulmonary metastasis, which was considered as primary colonic mucosal melanoma (MM) in a Caucasian patient. Such case illustrates the diagnosis criteria required to differentiate primary MM from colonic metastasis of melanoma, including the absence of past history of other primary melanoma, a unique colonic and abdominal lesion with predominant features of in situ lentiginous MM and a very focal and unique invasive area without other digestive tract or abdominal localization. This tumor displayed a KIT exon 11 mutation leading to a unique combination of p.I571M and p.D572G deleterious amino acid changes. Such pattern also favors the diagnosis as KIT appears as a master oncogenic player in MM oncogenesis.

Two cases of opportunistic parasite infections in patients receiving alemtuzumab.

Two cases are reported of rare digestive opportunistic parasites in patients being treated with alemtuzumab for lymphoid haematological malignancies. In both patients, classical biological examinations were insufficient to reach the diagnosis. Only specific parasitological techniques enabled diagnoses of cryptosporidiosis and microsporidiosis, respectively. In both cases, cellular immune reconstitution was sufficient to eradicate these opportunistic infections. In this context, parasitological diagnosis is often underestimated by medical practitioners, so immunologists and oncohaematologists need to be aware of this kind of opportunistic pathogen.