Deciphering resistance mechanisms in cancer: final report of MATCH-R study with a focus on molecular drivers and PDX development.

BACKGROUND: Understanding the resistance mechanisms of tumor is crucial for advancing cancer therapies. The prospective MATCH-R trial (NCT02517892), led by Gustave Roussy, aimed to characterize resistance mechanisms to cancer treatments through molecular analysis of fresh tumor biopsies. This report presents the genomic data analysis of the MATCH-R study conducted from 2015 to 2022 and focuses on targeted therapies. METHODS: The study included resistant metastatic patients (pts) who accepted an image-guided tumor biopsy. After evaluation of tumor content (TC) in frozen tissue biopsies, targeted NGS (10 < TC < 30%) or Whole Exome Sequencing and RNA sequencing (TC > 30%) were performed before and/or after the anticancer therapy. Patient-derived xenografts (PDX) were established by implanting tumor fragments into NOD scid gamma mice and amplified up to five passages. RESULTS: A total of 1,120 biopsies were collected from 857 pts with the most frequent tumor types being lung (38.8%), digestive (16.3%) and prostate (14.1%) cancer. Molecular targetable driver were identified in 30.9% (n = 265/857) of the patients, with EGFR (41.5%), FGFR2/3 (15.5%), ALK (11.7%), BRAF (6.8%), and KRAS (5.7%) being the most common altered genes. Furthermore, 66.0% (n = 175/265) had a biopsy at progression on targeted therapy. Among resistant cases, 41.1% (n = 72/175) had no identified molecular mechanism, 32.0% (n = 56/175) showed on-target resistance, and 25.1% (n = 44/175) exhibited a by-pass resistance mechanism. Molecular profiling of the 44 patients with by-pass resistance identified 51 variants, with KRAS (13.7%), PIK3CA (11.8%), PTEN (11.8%), NF2 (7.8%), AKT1 (5.9%), and NF1 (5.9%) being the most altered genes. Treatment was tailored for 45% of the patients with a resistance mechanism identified leading to an 11 months median extension of clinical benefit. A total of 341 biopsies were implanted in mice, successfully establishing 136 PDX models achieving a 39.9% success rate. PDX models are available for EGFR (n = 31), FGFR2/3 (n = 26), KRAS (n = 18), ALK (n = 16), BRAF (n = 6) and NTRK (n = 2) driven cancers. These models closely recapitulate the biology of the original tumors in term of molecular alterations and pharmacological status, and served as valuable models to validate overcoming treatment strategies. CONCLUSION: The MATCH-R study highlights the feasibility of on purpose image guided tumor biopsies and PDX establishment to characterize resistance mechanisms and guide personalized therapies to improve outcomes in pre-treated metastatic patients.

Dual alcohol and metabolic-related liver disease: Results from a population of liver transplant patients.

BACKGROUND & AIMS: If alcohol-related liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD) are now the two main indications for liver transplantation (LT), it has been recognized that both conditions can coexist in varying degrees and the concept of dual-aetiology fatty liver disease (DAFLD) has been proposed. This retrospective study aimed to evaluate, in a cohort of patients transplanted for ALD and NAFLD, the prevalence of DAFLD before LT and the impact on liver graft outcome. METHODS: From 1990 to 2010, all patients who underwent LT for the so-called ALD or NAFLD in our centre were included. Before LT, DAFLD was defined as patients with a history of excessive alcohol consumption and obesity associated with either diabetes or hypertension. Before LT, patients were separated into three groups: DAFLD, ALD, and NAFLD. Fatty liver graft disease was classified according to the FLIP algorithm. RESULTS: Out of 907, adult LT recipients were identified: 33 DAFLD patients, 333 ALD patients, and 24 NAFLD patients. After LT, ALD patients experienced significantly more alcohol relapse than DAFLD patients, who had twice more post-LT metabolic syndrome. Out of 926, post-LT biopsies, DAFLD patients had significantly more fatty liver graft disease due to metabolic syndrome features than ALD patients. CONCLUSION: Our results support that DAFLD recently emerged as an indication of LT. In the future, this particular population needs to be identified as a specific entity since post-LT outcome on the graft is different from ALD and more similar to NAFLD patients.

A novel fusion variant LSM14A::NR4A3 in extraskeletal myxoid chondrosarcoma.

Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft tissue neoplasm of uncertain lineage characterized by the pathognomonic rearrangement of the NR4A3 gene, which in most cases is fused with EWSR1. Other NR4A3 fusion partners have been described, namely TAF15, FUS, TCF12, and TGF. Some studies suggest that EMCs with non-EWSR1 variant fusion are associated with high-grade morphology and worst clinical behavior compared to EWSR1::NR4A3 tumors, supporting the potential significance of particular fusion variant in EMC. We report a case of a 34-year-old male who presented with calf EMC and subsequently developed a slowly progressive metastatic disease 3 years after diagnosis. Whole-transcriptome analysis with total RNA sequencing enabled identification of a novel fusion transcript LSM14A::NR4A3, expanding the molecular spectrum of EMC.

Bevacizumab plus FOLFIRI after failure of platinum-etoposide first-line chemotherapy in patients with advanced neuroendocrine carcinoma (PRODIGE 41-BEVANEC): a randomised, multicentre, non-comparative, open-label, phase 2 trial.

BACKGROUND: There is no standard second-line treatment after platinum-etoposide chemotherapy for gastroenteropancreatic neuroendocrine carcinoma. We aimed to evaluate the efficacy of FOLFIRI plus bevacizumab, and FOLFIRI alone, in this setting. METHODS: We did a randomised, non-comparative, open-label, phase 2 trial (PRODIGE 41-BEVANEC) at 26 hospitals in France. We included patients aged 18 years or older with locally advanced or metastatic gastroenteropancreatic neuroendocrine carcinoma or neuroendocrine carcinoma of unknown primary origin, documented progressive disease during or after first-line platinum-etoposide chemotherapy, and an Eastern Cooperative Oncology Group performance status of 0-2. Patients were randomly assigned (1:1; block size of three), without stratification, to receive FOLFIRI (irinotecan 180 mg/m2, calcium folinate 400 mg/m2 or levofolinate 200 mg/m2, and fluorouracil 400 mg/m2 bolus then 2400 mg/m2 over 46 h) plus bevacizumab 5 mg/kg or FOLFIRI alone, intravenously, every 2 weeks until disease progression or unacceptable toxicity. Neither patients nor investigators were masked to group assignment. The primary outcome was overall survival at 6 months after randomisation, evaluated in the modified intention-to-treat population (all enrolled and randomly assigned patients who received at least one cycle of FOLFIRI). This study is now complete and is registered with ClinicalTrials.gov, NCT02820857. FINDINGS: Between Sept 5, 2017, and Feb 8, 2022, 150 patients were assessed for eligibility and 133 were enrolled and randomly assigned: 65 to the FOLFIRI plus bevacizumab group and 68 to the FOLFIRI group. 126 patients (59 in the FOLFIRI plus bevacizumab group and 67 in the FOLFIRI group) received at least one cycle of FOLFIRI and were included in the modified intention-to-treat population, 83 (66%) of whom were male and 43 (34%) were female, and the median age of the patients was 67 years (IQR 58-73). The primary tumour location was colorectal in 38 (30%) of 126 patients, pancreatic in 34 (27%), gastro-oesophageal in 22 (17%), and unknown in 23 (18%). After a median follow-up of 25·7 months (95% CI 22·0-38·2), 6-month overall survival was 53% (80% CI 43-61) in the FOLFIRI plus bevacizumab group and 60% (51-68) in the FOLFIRI group. Grade 3-4 adverse events that occurred in at least 5% of patients were neutropenia (eight [14%] patients), diarrhoea (six [10%]), and asthenia (five [8%]) in the FOLFIRI plus bevacizumab group, and neutropenia (seven [10%]) in the FOLFIRI group. One treatment-related death (ischaemic stroke) occurred in the FOLFIRI plus bevacizumab group. INTERPRETATION: The addition of bevacizumab did not seem to increase the benefit of FOLFIRI with regard to overall survival. FOLFIRI could be considered as a standard second-line treatment in patients with gastroenteropancreatic neuroendocrine carcinoma. FUNDING: French Ministry of Health and Roche SAS.

Standardized Pathology Screening of Mature Tertiary Lymphoid Structures in Cancers.

Mature tertiary lymphoid structures (mTLSs) are organized lymphoid structures containing B lymphocytes admixed to CD23+ follicular dendritic cells. Their presence has been linked to improved survival and sensitivity to immune checkpoint inhibitors in several cancers, emerging as a promising pancancer biomarker. However, the requirements for any biomarker are clear methodology, proven feasibility, and reliability. In 357 patients' samples, we studied tertiary lymphoid structures (TLSs) parameters using multiplex immunofluorescence (mIF), hematoxylin-eosin-saffron (HES) staining, double CD20/CD23 staining, and single CD23 immunohistochemistry. The cohort included carcinomas (n = 211) and sarcomas (n = 146), gathering biopsies (n = 170), and surgical specimens (n = 187). mTLSs were defined as TLSs containing either a visible germinal center on HES staining or CD23+ follicular dendritic cells. Focusing on 40 TLSs assessed using mIF, double CD20/CD23 staining was less sensitive than mIF to assess maturity in 27.5% (n = 11/40) but was rescued by single CD23 staining in 90.9% (n = 10/11). In 97 patients, several samples (n = 240) were reviewed to characterize TLS distribution. The likelihood of finding TLSs in surgical material was 6.1 higher than in biopsy and 2.0 higher in primary samples than in metastasis after adjustment with a type of sample. Interrater agreement rates over 4 examiners were 0.65 (Fleiss kappa, 95% CI [0.46, 0.90]) for the presence of TLS and 0.90 for maturity (95% CI [0.83, 0.99]). In this study, we propose a standardized method to screen mTLSs in cancer samples using HES staining and immunohistochemistry that can be applied to all specimens.

Are protocol graft biopsies after pediatric liver transplantation useful? Experience in a single center over 20 years.

BACKGROUND: The role of protocol liver biopsies (PLB) in the follow-up of pediatric liver transplant recipients remains questionable. This single-center retrospective study aimed to evaluate their clinical impact on the long-term management of pediatric liver transplant recipients. METHODS: We described histopathological lesions and clinical consequences for patient management of PLB performed 1, 5, 10, 15, 20, and 25 years after pediatric liver transplantation (LT). RESULTS: A total of 351 PLB performed on 133 patients between 1992 and 2021 were reviewed. PLB found signs of rejection in 21.7% of cases (76/351), and moderate to severe fibrosis in 26.5% of cases (93/351). Overall, 264 PLB (75.2%) did not cause any changes to patient care. Immunosuppression was enhanced after 63 PLB, including 23 cases of occult rejection. The 1-year PLB triggered significantly more changes, while biopsies at 15, 20, and 25 years produced the lowest rates of subsequent modifications. PLB had a significantly higher probability of inducing therapeutic changes if the patient had abnormal biological or imaging results (odds ratio [OR] 2.82 and 2.06), or a recent history of rejection or bacterial infection (OR 2.22 and 2.03). CONCLUSION: Our results suggest that, although it often does not prompt any treatment changes, PLB could be performed because of its ability to detect silent rejection requiring an increase in immunosuppression. PLB could be carried out 1, 5, and 10 years after LT and then every 10 years in patients with normal biological and imaging results and no recent complications, while other patients could be kept on a 5-year protocol.

De novo generation of the NPM-ALK fusion recapitulates the pleiotropic phenotypes of ALK+ ALCL pathogenesis and reveals the ROR2 receptor as target for tumor cells.

BACKGROUND: Anaplastic large cell lymphoma positive for ALK (ALK+ ALCL) is a rare type of non-Hodgkin lymphoma. This lymphoma is caused by chromosomal translocations involving the anaplastic lymphoma kinase gene (ALK). In this study, we aimed to identify mechanisms of transformation and therapeutic targets by generating a model of ALK+ ALCL lymphomagenesis ab initio with the specific NPM-ALK fusion. METHODS: We performed CRISPR/Cas9-mediated genome editing of the NPM-ALK chromosomal translocation in primary human activated T lymphocytes. RESULTS: Both CD4+ and CD8+ NPM-ALK-edited T lymphocytes showed rapid and reproducible competitive advantage in culture and led to in vivo disease development with nodal and extra-nodal features. Murine tumors displayed the phenotypic diversity observed in ALK+ ALCL patients, including CD4+ and CD8+ lymphomas. Assessment of transcriptome data from models and patients revealed global activation of the WNT signaling pathway, including both canonical and non-canonical pathways, during ALK+ ALCL lymphomagenesis. Specifically, we found that the WNT signaling cell surface receptor ROR2 represented a robust and genuine marker of all ALK+ ALCL patient tumor samples. CONCLUSIONS: In this study, ab initio modeling of the ALK+ ALCL chromosomal translocation in mature T lymphocytes enabled the identification of new therapeutic targets. As ROR2 targeting approaches for other cancers are under development (including lung and ovarian tumors), our findings suggest that ALK+ ALCL cases with resistance to current therapies may also benefit from ROR2 targeting strategies.

Drug-induced bile duct injury: new agents, new mechanisms.

PURPOSE OF REVIEW: Drug-induced bile duct injury can be caused by a long list of agents. In most cases, damage is because of T-cell-mediated idiosyncratic reactions. Recently, a number of new agents, including not only drugs but also herbal supplements, have been incriminated and new mechanisms of bile duct injury have emerged. This review will focus on these new data. RECENT FINDINGS: New members of drug families already known to be responsible for bile duct injury have been incriminated. New players have been identified, such as herbal supplements, like kratom, and recreational drugs, such as ketamine used outside the medical setting. Anticytokine monoclonal antibodies are rarely involved. In contrast, antineoplastic treatments are of growing concern, especially immune checkpoint inhibitors, which induce immune-related adverse effects because of the excessive stimulation of the immune system and its lack of regulation. SUMMARY: Two patterns of bile duct injury are recognized. Drug-induced small-duct cholangiopathies target the smaller bile ducts; acute injuries eventually progress to chronic disease in the form of the vanishing bile duct syndrome. Drug-induced sclerosing cholangitis target large bile ducts, with a protracted chronic course; the onset of symptoms may be delayed after drug discontinuation; potentially severe, life-threatening complications can occur.

Posttransplant immune-mediated cholangiopathies.

PURPOSE OF REVIEW: Liver transplantation (LT) is the treatment of end-stage chronic liver diseases, mainly decompensated cirrhosis and hepatocellular carcinoma. Biliary complications can be schematically classified into macroscopic versus microscopic lesions. Immune-related cholangiopathies include rejection, graft-versus-host disease (GVHD) and recurrence of pre-LT auto-immune biliary diseases, i.e. primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC). Here, we review the various types of posttransplant immune-related cholangiopathies, and discuss their clinical implications, especially diagnostic issues. RECENT FINDINGS: Recurrence of PBC and PSC after LT is increasingly well described in large cohorts and long-term follow-up. In this setting, the preventive effect of ursodeoxycholic acid on PBC recurrence, as well as the deleterious role of tacrolimus are now well documented. In addition, the significant negative impact of recurrent PBC on survival after LT has recently been demonstrated. With respect to rejection-associated biliary injury, a growing body of evidence is emerging on the role of anti-HLA antibody-mediated rejection. SUMMARY: Immune-mediated cholangiopathies occurring after LT can be divided in two main nosologic groups: biliary lesions due to recurrence of PBC or PSC, or in the context of rejection, either acute or chronic, T-cell- or antibody-mediated. GVHD is very rare. Final diagnosis is strongly based on clinical context (indication for LT, delay since transplantation, biological abnormalities, imaging) but also and to an even greater extent on biopsy of liver graft. Clinico-pathological discussions are recommended, hearing in mind that diseases can be intertwined.

Laminin 332 in cancer: When the extracellular matrix turns signals from cell anchorage to cell movement.

Laminin 332 is crucial in the biology of epithelia. This large extracellular matrix protein consists of the heterotrimeric assembly of three subunits - α3, ß3, and γ2 - and its multifunctionality relies on a number of extracellular proteolytic processing events. Laminin 332 is central to normal epithelium homeostasis by sustaining cell adhesion, polarity, proliferation, and differentiation. It also supports a major function in epithelial tissue formation, repair, and regeneration by buttressing cell migration and survival and basement membrane assembly. Interest in this protein increased after the discovery that its expression is perturbed in tumor cells, cancer-associated fibroblasts, and the tumor microenvironment. This review summarizes current knowledge regarding the established involvement of the laminin 332 γ2 chain in tumor invasiveness and discusses the role of its α3 and ß3 subunits.

Perspectives in pathomics in head and neck cancer.

PURPOSE OF REVIEW: Pathology is the cornerstone of cancer care. Pathomics, which represents the use of artificial intelligence in digital pathology, is an emerging and promising field that will revolutionize medical and surgical pathology in the coming years. This review provides an overview of pathomics, its current and future applications and its most relevant applications in Head and Neck cancer care. RECENT FINDINGS: The number of studies investigating the use of artificial intelligence in pathology is rapidly growing, especially as the utilization of deep learning has shown great potential with Whole Slide Images. Even though numerous steps still remain before its clinical use, Pathomics has been used for varied applications comprising of computer-assisted diagnosis, molecular anomalies prediction, tumor microenvironment and biomarker identification as well as prognosis evaluation. The majority of studies were performed on the most frequent cancers, notably breast, prostate, and lung. Interesting results were also found in Head and Neck cancers. SUMMARY: Even if its use in Head and Neck cancer care is still low, Pathomics is a powerful tool to improve diagnosis, identify prognostic factors and new biomarkers. Important challenges lie ahead before its use in a clinical practice, notably the lack of information on how AI makes its decisions, the slow deployment of digital pathology, and the need for extensively validated data in order to obtain authorities approval. Regardless, pathomics will most likely improve pathology in general, including Head and Neck cancer care in the coming years.

Post-Radiation Grade 3 Neuroendocrine Carcinoma: A New Entity?

BACKGROUND: Cancer survivors have a 14% increased risk of developing a malignancy compared with the general population. Second radiation-induced malignancies with different histologies have been described in different organs. Based on individual observations, we hypothesized that neuroendocrine carcinoma (NEC) could arise in irradiated organs. METHODS: In a retrospective analysis of Gustave Roussy database of NEC patients (small cell lung cancer excluded) diagnosed as a second cancer, we looked for the frequency of grade 3 NEC that arose in patients who had received previous radiation therapy for a first cancer. Radiation therapy for the first cancer, dose, location of radiation therapy, pathological characteristics, overall survival, and response to treatment of secondary NEC were analyzed. RESULTS: From January 1995 to December 2017, 847 cases of NEC were seen at Gustave Roussy. Among them, 95 (11.2%) patients had a history of previous malignancy of which 36 (4%) had been treated with radiation therapy. Out of these 36 patients, 12 (1.4% of all NEC patients) developed a NEC within the previous irradiated organ (median dose of 50 Gy, range 36-67.5). Most frequent first cancers were breast cancer (n = 4) and Hodgkin lymphoma (n = 3). NEC arose within a median time of 21.7 years (range 5.1-36.4) from radiation in the thorax (n = 5), digestive tract (n = 3), and other sites. Five large cell NEC, 3 small cell NEC, 1 mixed neuroendocrine neoplasm and 3 not otherwise specified NEC were diagnosed. Ten patients had stage IV disease at diagnosis; median overall survival was 37.8 months (95% CI [17.6 to NA]). Three patients (25%) achieved complete response with multimodal treatment. CONCLUSIONS: NEC can arise from previously irradiated organs and may have a better outcome in this setting. Other risk factors should be investigated to explain the high rate of previous cancer in this population of neuroendocrine neoplasm.

Long-Term Results after Surgical Resection of Peritoneal Metastasis from Neuroendocrine Tumors.

INTRODUCTION: Peritoneal metastases from neuroendocrine tumors are associated with a bad prognosis. The objective of our study was to evaluate whether surgical resection could lead to prolonged survival in selected patients. This survival was compared to that of patients operated for liver metastasis. METHODS: From our prospectively maintained database we included 88 patients who underwent the complete resection of peritoneal and/or liver metastasis between January 1995 and December 2016 in Gustave-Roussy. Three resection groups were compared: peritoneal metastasis alone, liver metastasis alone, and the combined resection of liver and peritoneal metastases. RESULTS: The median peritoneal cancer index was 10 in the peritoneal group and 11 in the peritoneal + liver group. The 5-year overall survival was 81% (60-100) in the peritoneal group compared to 78% (65.2-92.8) in the liver group, and 72% (58.7-89.7) in the peritoneal + liver group (p = 0.71). The 3-year disease-free survival reached 26.9% (16.1-45.1) in the liver group, 12.5% (2.3-68.2) in the peritoneal group, and 32.4% (19.9-52.6) in the combined liver + peritoneal group (p = 0.45). In the univariate analysis, the prognosis factors for a longer survival were: small bowel primary tumor origin, low preoperative chromogranin A level, and tumor grade ≤1. CONCLUSION: Despite a high recurrence rate, long-term overall survival can be achieved after the resection of peritoneal metastasis in selected patients. This survival is comparable to that of patients operated for liver metastasis only. Surgery should stand as a standard treatment for peritoneal metastases in patients with resectable disease.

Specific Genomic Alterations in High-Grade Pulmonary Neuroendocrine Tumours with Carcinoid Morphology.

INTRODUCTION: High-grade lung neuroendocrine tumours with carcinoid morphology have been recently reported; they may represent the thoracic counterparts of grade 3 digestive neuroendocrine tumours. We aimed to study their genetic landscape including analysis of tumoral heterogeneity. METHODS: Eleven patients with high-grade (>20% Ki-67 and/or >10 mitoses) lung neuroendocrine tumours with a carcinoid morphology were included. We analysed copy number variations, somatic mutations, and protein expression in 16 tumour samples (2 samples were available for 5 patients allowing us to study spatial and temporal heterogeneity). RESULTS: Genomic patterns were heterogeneous ranging from "quiet" to tetraploid, heavily rearranged genomes. Oncogene mutations were rare and most genetic alterations targeted tumour suppressor genes. Chromosomes 11 (7/11), 3 (6/11), 13 (4/11), and 6-17 (3/11) were the most frequently lost. Altered tumour suppressor genes were common to both carcinoids and neuroendocrine carcinomas, involving different pathways including chromatin remodelling (KMT2A, ARID1A, SETD2, SMARCA2, BAP1, PBRM1, KAT6A), DNA repair (MEN1, POLQ, ATR, MLH1, ATM), cell cycle (RB1, TP53, CDKN2A), cell adhesion (LATS2, CTNNB1, GSK3B) and metabolism (VHL). Comparative spatial/temporal analyses confirmed that these tumours emerged from clones of lower aggressivity but revealed that they were genetically heterogeneous accumulating "neuroendocrine carcinoma-like" genetic alterations through progression such as TP53/RB1 alterations. CONCLUSION: These data confirm the importance of chromatin remodelling genes in pulmonary carcinoids and highlight the potential role of TP53 and RB1 to drive the transformation in more aggressive high-grade tumours.

A Consensus-Developed Morphological Re-Evaluation of 196 High-Grade Gastroenteropancreatic Neuroendocrine Neoplasms and Its Clinical Correlations.

High-grade gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are classified according to morphology as well-differentiated neuroendocrine tumours (NETs) G3 or poorly differentiated neuroendocrine carcinomas (NECs). Little data exist concerning which morphological criteria this subdivision should be based on. Uncertainty exists if the NEC group should be further subdivided according to proliferation rate. Clinical data on NET G3 and NEC with a lower Ki-67 range are limited. A total of 213 patients with high-grade GEP-NEN (Ki-67 >20%) were included from the Nordic NEC Registries. Four experienced NET pathologists re-evaluated the cases to develop the best morphological criteria to separate NET G3 from NEC, assuming longer survival in NET G3. Organoid growth pattern, capillary network in direct contact to tumour cells, and absence of desmoplastic stroma were found to best separate NET G3 from NEC. Of 196 patients with metastatic disease, NET G3 was found in 12.3%, NEC with a Ki-67 <55% (NEC < 55) in 29.6%, and NEC with a Ki-67 ≥55% (NEC ≥ 55) in 56.6%. Only in 1.5%, the morphology was ambiguous. Of 164 patients receiving first-line chemotherapy, 88% received platinum/etoposide treatment. Response rate was higher for NEC ≥ 55 (44%) than that of NEC < 55 (25%) and NET G3 (24%) (p = 0.025 and p = 0.026). Median progression-free survival was 5 months for all groups. Median overall survival was 33 months for NET G3 compared to 11 months for both NEC < 55 and NEC ≥ 55 (p = 0.004 and 0.003). Specific morphological criteria can separate NET G3 from NECs and show prognostic significance. High-grade GEP-NEN patients stratified by morphology and proliferation rate demonstrate significant differences in response to chemotherapy and survival.

PAX3-NCOA1 alveolar rhabdomyosarcoma of the tongue: A rare entity with challenging diagnosis and management.

Alveolar rhabdomyosarcoma (ARMS) is associated with PAX3/PAX7-FOXO1 fusion, which confers specific clinic and biologic characteristics with inferior outcomes. A minority of tumors still histologically classified as "true" ARMS lack the canonical PAX-FOXO1 fusion but have new molecular alterations. We present the first case of PAX3-NCOA1 ARMS with clinical data and follow-up in a two-year-old girl with ARMS of the tongue and nodal extension, treated with chemotherapy, hemi glossectomy, lymph node dissection, and brachytherapy to conserve oral function and limit long-term sequelae. Given the rarity of such variant fusion in ARMS, international collaboration is required to evaluate its prognostic value.

[Gastric bacterial overgrowth: An unusual histological observation, not to be overlooked]. / Pullulation bactérienne gastrique : une observation histologique inhabituelle, à ne pas méconnaître.

Gastric bacterial overgrowth is a rare situation, which may be associated with short- and long-term complications. It must be known from pathologists, since it might be detected incidentally at histological examination of gastric biopsies. We report here the case of a 74-year old woman, obese, without significant medical history, apart from a gastro-esophageal reflux treated by the long-term administration of proton pump inhibitors (PPI). In this patient, gastric bacterial overgrowth was detected at histological examination of gastric biopsies performed after colectomy for left colon adenocarcinoma. Large clusters of small, round, "coccoid" bacteria were present in the gastric mucus. Their characteristics were suggestive of enterobacteria. Bacterial proliferation was associated with severe and diffuse lesions of active gastritis. The course was rapidly unfavorable, and the patient rapidly deceased with multiple infections and multi-organ failure. In our observation, the pathogenesis of gastric bacterial overgrowth was probably multifactorial. It might have been facilitated by long-term PPI treatment and obesity, which are known risk factors, and promoted, in the post-operative setting, by multiple infections and immune failure. Our observation underlines that gastric bacterial overgrowth might be associated with severe gastritis, which might justify antibiotherapy. Other consequences of prolonged gastric dysbiosis cannot be excluded, such as the promotion of neoplastic lesions.

EWSR1-PATZ1 fusion sarcoma - A new case report and review of the literature / Sarcome avec transcrit de fusion EWSR1-PATZ1 - Une nouvelle observation avec revue de la littérature.

Sarcoma with EWSR1-PATZ1 gene fusion is an exceedingly rare and newly described Ewing-like sarcoma harboring EWSR1 rearrangements involving fusion partners other than ETS family genes. The clinical, histopathologic and immunophenotypic features of cases reported in literature are fairly diverse and not specific. We report a new case report posing real challenges for histological and molecular diagnosis.

Clinical utility of SMARCA4 testing by immunohistochemistry in rare ovarian tumours.

BACKGROUND: Ovarian small cell carcinoma, hypercalcaemic type (SCCOHT) is a rare and lethal disease affecting young women. As histological diagnosis is challenging and urgent, there is a clear need for a robust diagnostic test. While mutations in the chromatin-remodelling gene, SMARCA4, appear to be typical, it may not be feasible routinely to be clinically relevant. METHODS: Previous studies have described the value of SMARCA4 IHC to differentiate SCCOHT from ovarian neoplasms (ON), with similar histologic appearances. We aimed to evaluate its clinical utility among a cohort of 44 SCCOHT and 94 rare ON frequently misdiagnosed as SCCOHT. RESULTS: Forty-three percent (16/36) of SCCOHT had been classified locally as non-SCCOHT confirming the diagnosis challenge. Sensitivity and specificity of SMARCA4 IHC were excellent at 88% and 94%, respectively. In a community setting with a much lower prevalence of the disease, estimated PPV is 40% while NPV remained high at 99%. Finally, among the 16 SCCOHT misclassified locally, SMARCA4 IHC testing would have resulted in corrected diagnosis in 88% of cases. CONCLUSIONS: SMARCA4 IHC is a highly sensitive, and specific test for the diagnosis of SCCOHT and is of huge clinical utility in providing a timely and accurate diagnosis of this challenging disease.

BAP1 mutations define a homogeneous subgroup of hepatocellular carcinoma with fibrolamellar-like features and activated PKA.

BACKGROUND & AIMS: DNAJB1-PRKACA fusion is a specific driver event in fibrolamellar carcinoma (FLC), a rare subtype of hepatocellular carcinoma (HCC) that occurs in adolescents and young adults. In older patients, molecular determinants of HCC with mixed histological features of HCC and FLC (mixed-FLC/HCC) remain to be discovered. METHODS: A series of 151 liver tumors including 126 HCC, 15 FLC, and 10 mixed-FLC/HCC were analyzed by RNAseq and whole-genome- or whole-exome sequencing. Western blots were performed to validate genomic discoveries. Results were validated using the TCGA database. RESULTS: Most of the mixed-FLC/HCC RNAseq clustered in a robust subgroup of 17 tumors, which all had mutations or translocations inactivating BAP1, the gene encoding BRCA1-associated protein-1. Like FLC, BAP1-HCC were significantly enriched in females, patients with a lack of chronic liver disease, and fibrotic tumors compared to non-BAP1 HCC. However, patients were older and had a poorer prognosis than those with FLC. BAP1 tumors were immune hot, showed progenitor features and did not show DNAJB1-PRKACA fusion, while almost none of these tumors had mutations in CTNNB1, TP53 and TERT promoter. In contrast, 80% of the BAP1 tumors showed a chromosome gain of PRKACA at 19p13, combined with a loss of PRKAR2A (coding for the inhibitory regulatory subunit of PKA) at 3p21, leading to a high PRKACA/PRKAR2A ratio at the mRNA and protein levels. CONCLUSION: We have characterized a subgroup of BAP1-driven HCC with fibrolamellar-like features and a dysregulation of the PKA pathway, which could be at the root of the clinical and histological similarities between BAP1 tumors and DNAJB1-PRKACA FLCs. LAY SUMMARY: Herein, we have defined a homogeneous subgroup of hepatocellular carcinomas in which the BAP1 gene is inactivated. This leads to the development of cancers with features similar to those of fibrolamellar carcinoma. These tumors more frequently develop in females without chronic liver disease or cirrhosis. The presence of PKA activation and T cell infiltrates suggest that these tumors could be treated with PKA inhibitors or immunomodulators.