Characterisation of the protein expression of the emerging immunotherapy targets VISTA, LAG-3 and PRAME in primary uveal melanoma: insights from a southern French patient cohort

Uveal melanoma (UM) is the most common intraocular tumour in adults, with dismal prognosis once metastases develop, since therapeutic options for the metastatic disease are ineffective. Over the past decade, novel cancer therapies based on immunotherapy have changed the landscape of treatment of different forms of cancer leading to many hopes of improvement in patient overall survival (OS). VISTA, LAG-3 and PRAME are novel promising targets of immunotherapy that have recently gained attention in different solid tumours, but whose relevance in UM remained to be comprehensively evaluated until now. Here, we studied the protein expression of VISTA, LAG-3 and PRAME using immunohistochemistry in representative whole tissue sections from primary UM cases in a cohort of 30 patients from a single centre (Nice University Hospital, Nice, France). The expression of each of these markers was correlated with different clinical and pathological parameters, including onset of metastases and OS. We demonstrated the protein expression of VISTA and LAG-3 in small lymphocytes infiltrating the tumour, while no expression of the proteins was detected in UM cells. For PRAME, nuclear expression was observed in UM cells, but no expression in tumour infiltrating immune cells was identified. Increased levels of VISTA expression in tumour infiltrating lymphocytes (TILs) were associated with nuclear BAP1 expression and better prognosis. Higher levels of LAG-3 in TILs were associated with higher levels of CD8-positive TILs. PRAME nuclear positivity in melanoma cells was associated with epithelioid cell dominant (>90%) UM histological subtype, higher mitotic numbers and a higher percentage of chromosome 8q gain. This study proposes VISTA as a novel relevant immune checkpoint molecule in primary UM and contributes to confirm LAG-3 and PRAME as potentially important immunotherapy targets in the treatment of UM patients, helping to expand the number of immunotherapy candidate molecules that are relevant to modulate in this aggressive cancer.

HIF-1 inactivation empowers HIF-2 to drive hypoxia adaptation in aggressive forms of medulloblastoma

Medulloblastoma (MB) is the most prevalent brain cancer in children. Four subgroups of MB have been identified; of these, Group 3 is the most metastatic. Its genetics and biology remain less clear than the other groups, and it has a poor prognosis and few effective treatments available. Tumor hypoxia and the resulting metabolism are known to be important in the growth and survival of tumors but, to date, have been only minimally explored in MB. Here we show that Group 3 MB tumors do not depend on the canonical transcription factor hypoxia-inducible factor-1α (HIF-1α) to mount an adaptive response to hypoxia. We discovered that HIF-1α is rendered inactive either through post-translational methylation, preventing its nuclear localization specifically in Group 3 MB, or by a low expression that prevents modulation of HIF-target genes. Strikingly, we found that HIF-2 takes over the role of HIF-1 in the nucleus and promotes the activation of hypoxia-dependent anabolic pathways. The exclusion of HIF-1 from the nucleus in Group 3 MB cells enhances the reliance on HIF-2's transcriptional role, making it a viable target for potential anticancer strategies. By combining pharmacological inhibition of HIF-2α with the use of metformin, a mitochondrial complex I inhibitor to block respiration, we effectively induced Group 3 MB cell death, surpassing the effectiveness observed in Non-Group 3 MB cells. Overall, the unique dependence of MB cells, but not normal cells, on HIF-2-mediated anabolic metabolism presents an appealing therapeutic opportunity for treating Group 3 MB patients with minimal toxicity.

BRCA1/2 Pathogenic Variants Are Not Common in Merkel Cell Carcinoma: Comprehensive Molecular Study of 30 Cases and Meta-Analysis of the Literature

Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous neuroendocrine cancer. Management of advanced MCC is mainly based on immune-checkpoint inhibitors. The high failure rate warrants an investigation of new therapeutic targets. The recent identification of BRCA1 or BRCA2 (BRCA1/2) mutations in some MCC raises the issue of the use of poly-(ADP-Ribose)-polymerase inhibitors in selected advanced cases. The main objective of our study is to determine the accurate frequency of BRCA1/2 pathogenic variants. We studied a series of 30 MCC and performed a meta-analysis of BRCA1/2 variants of published cases in the literature. In our series, we detected only one BRCA2 pathogenic variant. The low frequency of BRCA1/2 pathogenic variants in our series of MCC (3%) was confirmed by the meta-analysis of BRCA1/2 variants in the literature. Among the 915 MCC from 13 published series studied for molecular alterations of BRCA1/2, only 12 BRCA1/2 pathogenic mutations were identified (1-2% of MCC), whereas many other BRCA1/2 variants were variants of unknown significance or benign. BRCA1/2 pathogenic variants are uncommon in MCC. However, in BRCA-mutated MCC, poly-(ADP-Ribose)-polymerase inhibitors might be a valuable therapeutic option requiring validation by clinical trials.

Onychomatricoma: a clinicopathological, immunohistochemical, and molecular study of 10 cases highlighting recurrent RB1 deletion and the potential diagnostic value of LEF-1

AIMS

Onychomatricoma (OM), an uncommon benign fibroepithelial neoplasm of the nail unit, is sometimes diagnostically challenging for clinicians and pathologists. OM consistently expresses CD34, but no specific immunohistohemical markers or recurrent genetic alterations have been identified to date. Recent studies have suggested that Wnt signalling is a key molecular characteristic of OM.

METHODS AND RESULTS

Ten cases were analysed: four classical OM including two with pleomorphic cells; two superficial acral fibromyxoma-like variants of OM; three micropapilliferum variants of OM including one with pleomorphic cells; and one proliferating variant of OM. Immunohistochemically, the spindle cells were positive with CD34 (n = 10) and CD99 (n = 1), with focal reactivity for CD10 (n = 5). The epithelial component of the tumours expressed immunopositivity for LEF-1. Using array comparative genomic hybridization (aCGH), we demonstrated that all OM, including its variants that were tested (n = 8), harboured a few copy number alterations with losses of whole or part of chromosome 13 including the RB1 gene (n = 8) and chromosome 16 (n = 6).

CONCLUSION

We report a recurrent loss of RB1 (13q) as a possible driver molecular event in OM indicating a relationship between OM and other lesions of the spectrum of the so-called '13q/RB1' family of tumours. We did not identify a role for the Wnt/beta-catenin signalling pathway, as has been proposed in a recent study. LEF-1 could be a potential sensitive and specific marker of OM and should be used in the differential diagnosis between OM, superficial acral fibromyxoma, and the CD34-positive fibrosing family of tumours.

Vanished MDM2 amplification in multiple recurrences of an irradiated poorly differentiated sarcoma with amplified TRIO::TERT fusion gene

Among sarcomas, MDM2 amplification is usually a molecular hallmark of well-differentiated and dedifferentiated liposarcoma (WDLPS/DDLPS) and occasionally a secondary genetic anomaly in other sarcomas. Histological evaluation and FISH analysis showing MDM2 amplification led to the diagnosis of DDLPS for a tumor located on the left arm of a 71-year-old patient. The patient was treated by adjuvant radiotherapy (RT) but the tumor recurred soon after. Array-comparative genomic hybridization and targeted RNA/DNA Sequencing of the primary tumor and of four recurrences were done. Strikingly, the MDM2 amplification observed in the primary tumor had vanished in the recurrences. In contrast, other rearrangements, such as amplification of the genes TRIO and TERT as well as TRIO::TERT fusion were detected retrospectively in the primary tumor and in all the recurrences. The transitory nature of the MDM2 amplification raised the hypothesis that RT was active on cells that contained MDM2 amplification but not on other tumor cells with only the TERT and TRIO alterations. In contrast to MDM2 amplification, the TRIO::TERT amplified fusion was stable over time. The detection of this fusion was crucial in the analysis of the diagnostically challenging last tumor: it allowed to determine that it was a fourth recurrence, instead of a new independent tumor. It also suggested the diagnosis undifferentiated pleomorphic sarcoma rather than DDLPS. The TRIO::TERT fusion is not well explored. The current study shows that its role in sarcomas, with or without MDM2 amplification, should be more extensively researched.

AGAP3: A novel BRAF fusion partner in pediatric pancreatic-type acinar cell carcinoma

Most available molecular data on pancreatic acinar cell carcinoma (PACC) are provided by studies of adult cases. BRAF, RAF1, or RET rearrangements have been described in approximately 30% of cases. To the best of our knowledge, only seven cases with molecular data have been reported in pediatric PACC. We report here the comprehensive study of a pancreatic-type ACC from a 6-year-old patient. We detected an AGAP3::BRAF fusion. This result showing a BRAF rearrangement demonstrates a molecular link between adult and pediatric PACC. Moreover, it identifies AGAP3, a gene located at 7q36.1 that encodes a major component of the N-methyl-d-aspartate (NMDA) receptor signaling complex, as a partner gene of BRAF. The variability of BRAF partners is consistent with a driver role of BRAF alterations in PACC. The identification of such alterations is noteworthy for considering the use of MEK inhibitors in metastatic cases. We did not detect associated genomic instability. The better outcome of pediatric cases might be related to their stable genomic background.

Targeting of c-MET and AXL by cabozantinib is a potential therapeutic strategy for patients with head and neck cell carcinoma

Local or metastatic relapse following surgery, radiotherapy, and cisplatin is the leading cause of death in patients with head and neck squamous cell carcinoma (HNSCC). Our study shows overexpression of c-MET and AXL in HNSCC cells and patients resistant to radiotherapy and cisplatin. We demonstrate that cabozantinib, an inhibitor of vascular endothelial growth factor receptor (VEGFR), c-MET, and AXL, decreases migration, invasion, and proliferation and induces mitotic catastrophe and apoptotic cell death of naive and radiotherapy- and cisplatin-resistant HNSCC cells. Cabozantinib inhibits the growth and metastatic spread of experimental HNSCC in zebrafish and the growth of experimental HNSCC in mice by blocking tumor cell proliferation and angiogenesis. The efficacy of cabozantinib is also confirmed on viable sections of surgically removed specimens of human HNSCC and on a patient who relapses after five lines of treatment. These results suggest that cabozantinib is relevant for the treatment of patients with HNSCC after relapse under radiotherapy and cisplatin.

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AXL and c-MET are overexpressed in radiotherapy- and cisplatin-resistant HNSCC

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Overexpression of AXL and c-MET contributes to tumor aggressiveness and poor prognosis

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Cabozantinib has anti-tumor and anti-metastatic efficacy in mice and zebrafish models

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Cabozantinib efficacy is shown on HNSCC biopsies and in one patient after several relapses

Comprehensive study of 9 novel cases of TFEB-amplified renal cell carcinoma: an aggressive tumor with frequent PDL1 expression

BACKGROUND & OBJECTIVES

First described in 2014, renal cell carcinoma (RCC) with TFEB amplification (6p21) is a rare molecular subgroup whose diagnosis is challenging. The prognosis and therapeutic implications remain unclear.

METHODS

We report here the clinical, histological, immunohistochemical and genetic features of 9 novel cases. The pathological and immunohistochemical features were centrally reviewed by expert uropathologists. Fluorescence in situ hybridization (FISH) confirmed the diagnosis and comparative genomic hybridization (CGH) was performed to determine quantitative genomic alterations. We also performed an exhaustive review of the literature and compiled our data.

RESULTS

TFEB-amplified RCC were locally advanced with initial lymph node involvement in one case and liver metastasis in another case. They were high-grade eosinophilic tumors with papillary/pseudopapillary architecture, frequent positivity for melanocytic markers and frequent PDL1 expression. FISH demonstrated high-level TFEB amplification in 6 cases. One case showed concomitant TFEB translocation. CGH analysis identified complex alterations with frequent losses of 1p, 2q, 3p, 6p, and frequent 6p and 8q gains. VEGFA co-amplification was identified in all cases with a lower level than TFEB. The prognosis was poor with five patients having lymph node or distant metastases.

CONCLUSION

TFEB-amplified RCC is a rare molecular subgroup with variable morphology whose diagnosis is confirmed by FISH analysis. The complex alterations identified by CGH are consistent with an aggressive clinical behavior. The co-amplification of VEGFA and the expression of PDL1 could suggest a potential benefit from antiangiogenics and targeted immunotherapy in combination for these aggressive tumors.

RBM10-TFE3 fusions: A FISH-concealed anomaly in adult renal cell carcinomas displaying a variety of morphological and genomic features: Comprehensive study of six novel cases

The accurate diagnosis of Xp11-translocation renal cell carcinoma (RCC) in adults is challenging. TFE3 (located on chromosome X) fuses with a partner gene generally located on another chromosome. In rare cases TFE3 may fuse with a neighboring gene: RBM10. Because TFE3 false-positive immunostaining is a common pitfall in many laboratories, demonstration of the chromosomal rearrangement is required in order to ascertain the diagnosis. Fluorescence in situ hybridization (FISH)-that has been considered as the gold standard method-reaches its limits for detecting small Xp11 paracentric inversions. We performed a comprehensive clinical, histological and genomic study of six novel cases of RCC with RBM10-TFE3 fusion. Using FISH, TFE3 rearrangement was equivocal in one case and negative in others. RBM10-TFE3 fusion was discovered using targeted RNA sequencing (RNASeq). As all the previously reported cases (mean age: 50), the six patients were adults (mean age: 42), suggesting an epidemiologic difference between RBM10-TFE3 RCC and tumors harboring some other partner genes, such as ASPSCR1 that rather occur in children. Array-comparative genomic hybridization showed several alterations, notably a gain of 17q in four cases with papillary features and loss of 3p in one case with clear cells. Our study demonstrates that, though rare among adult cases of RCC, RBM10-TFE3 fusion is not exceptional and warrants appropriate molecular detection. Notably, it would be worthy to systemically investigate by RNASeq challenging RCC with type-2 papillary features and 17q gain.

Molecular follow-up of first-line treatment by osimertinib in lung cancer: Importance of using appropriate tools for detecting EGFR resistance mutation C797S

The C797S mutation encoded by EGFR exon 20 is classically observed as a tertiary event in EGFR-mutant non-small-cell lung carcinoma (NSCLC) primarily treated by first generation tyrosine kinase inhibitors (TKI) and secondarily treated by third-generation TKI, such as osimertinib, if the EGFR-T790M resistance mutation is detected. Recently, significant prolonged progression free survival has been observed following first-line osimertinib, in EGFR-mutant NSLC. While mechanisms of molecular resistance to first-generation TKI have been well studied, little is known about resistance induced by primary third-generation TKI treatments. We report the case of a 65 year-old female treated by first-line osimertinib for a multimetastatic exon 19-EGFR-mutant NSCLC. EGFR-C797S resistance mutation and PIK3CA mutation were detected together with the remaining EGFR-exon 19 deletion. This observation provides insights of acquired resistance to first line-osimertinib. It also highlights the importance of making molecular platforms which perform routine EGFR testing in lung cancer aware of the kind of therapeutic protocols given to the patient. Indeed, for rapid results or low-costs procedures, some targeted methods specifically targeting T790M may be used at relapse and may overlook alterations such as C797S or PIK3CA mutations. Targeted next generation sequencing is therefore a recommended option.

A Multicenter Phase II Study of Pazopanib in Patients with Unresectable Dermatofibrosarcoma Protuberans

Dermatofibrosarcoma protuberans (DFSP) is a soft-tissue sarcoma characterized by a high risk of local infiltration. The identification of the COL1A1-PDGFB t(17;22) translocation activating the PDGF pathway led to the use of imatinib in unresectable DFSP, with a response rate of 36-80%. Pazopanib is a multitarget tyrosine kinase inhibitor approved for soft-tissue sarcomas. We conducted a phase II study of patients with unresectable DFSP to evaluate the efficacy and safety of pazopanib. Patients received 800 mg of pazopanib daily. The primary endpoint was the objective response rate defined as the reduction of the largest diameter of the tumor by ≥30% at 6 months or at surgery. A total of 23 patients, including one pretreated with imatinib, were enrolled. With a median follow-up of 6.2 months (interquartile range = 5.6-7.8 months), five patients (22%, 95% confidence interval = 7-22%) had a partial response to pazopanib. The best objective response rate was 30% (95% confidence interval = 13-53%) using Response Evaluation Criteria in Solid Tumors. One patient with metastatic DFSP previously treated with imatinib died after 2.4 months. Nine patients (39%) discontinued the treatment owing to adverse events. Pharmacodynamics analyses of tumor samples were conducted: the enrichment of EGF and the EGFR-associated gene panel was associated with resistance, suggesting that EGFR-targeted therapies could be a therapeutic option to explore in DFSP. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01059656.

Abstract 5185: Analysis of the role of FGFR signaling in liposarcomas: Dual targeting of FGFR and MDM2 is synergistic

Clinical trials have shown the benefits of FGFR inhibitors; notably, the oral pan-FGFR inhibitor JNJ-42756493 (erdafitinib) has recently been the first FGFR kinase inhibitor to receive US FDA approval for the treatment of patients with advanced or metastatic urothelial carcinoma. Our objectives were to show that the FGFR pathway is involved in liposarcoma (LPS) pathogenesis and to investigate the therapeutic potential of erdafitinib for LPS patients.

LPS is the most common soft tissue sarcoma. Among LPS, well-differentiated/dedifferentiated LPS (WD/DDLPS) are the most frequent types. DDLPS have metastatic potential and a poor prognosis with a five-year mortality rate of 30%. Standard chemotherapies are inefficient and new therapeutic options are needed. FRS2, a crucial adaptor protein of the FGFR signaling pathway is overexpressed in most WD/DDLPS suggesting involvement of the FGFR pathway in LPS tumorigenesis.

Immunohistochemistry was used to perform an exhaustive analysis of the expression pattern of FGFR1-4 in WD/DDLPS both in a large collection of 421 primary tumors and in our in-house panel of validated human WDLPS and DDLPS cell lines. Cells were exposed to erdafitinib - as a single agent or in combination - and apoptosis and signalling pathway perturbations were monitored by flow cytometry and western blotting. Xenograft mouse models were used to confirm our in vitro results in the in vivo setting.

We have detected a high expression of FGFR1 and/or FGFR4 in a significant percentage of WDLPS and DDLPS and demonstrated that this expression is correlated with poor prognosis. Exposure of LPS cells to erdafitinib induced a decrease in cell viability, cell cycle arrest in G1 and apoptosis. Erdafitinib treatment had a strong inhibitory effect on the ERK1/2 pathway whereas the PI3K/AKT pathway was less affected. The PI3K/mTOR antagonist BEZ235 was not synergistic with erdafitinib in DDLPS cells. MDM2 overexpression being the hallmark of WD/DDLPS, we investigated the effects of the MDM2-TP53 interaction inhibitor RG7388 (idasanutlin) in combination with erdafitinib. Interestingly, we found that the combination of RG7388 and erdafitinib exerts a highly synergistic effect on both viability and apoptosis in all our WDLPS and DDLPS cell lines. We are currently investigating the mechanics of the synergy between the FGFR and the MDM2 antagonists.

We confirmed the inhibitory effect of erdafitinib on tumor growth using a DDLPS xenograft model.

Finally and importantly, we report the efficacy of FGFR inhibition in two metastatic DDLPS patients heavily pretreated and refractory to several lines of treatment with notably one patient on erdafitinib showing stable disease for 15 weeks.

In conclusion, we have shown that the FGFR pathway has therapeutic potential for a subset of DDLPS patients and that FGFR expression might constitute a powerful biomarker to select patients for clinical trials testing FGFR inhibitors.

Citation Format: Bérengère Dadone-Montaudié, Audrey Laroche-Clary, Aline Mongis, Vanessa Chaire, Ilaria Di Mauro, Renaud Schiappa, Emmanuel Chamorey, Bertucci François, Florence Pedeutour, Finetti Pascal, Jean-François Michiels, Antoine Italiano, Laurence Bianchini. Analysis of the role of FGFR signaling in liposarcomas: Dual targeting of FGFR and MDM2 is synergistic [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5185.

MDM2 amplification and fusion gene ss18-ssx in a poorly differentiated synovial sarcoma: A rare but puzzling conjunction

The detection of specific alterations by genetic analyses has been included in the diagnostic criterions of the World Health Organization's classification of soft tissues tumors since 2013. The presence of a SS18 rearrangement is pathognomonic of synovial sarcoma (SS). MDM2 amplification is strongly correlated to well-differentiated or dedifferentiated liposarcoma (DDLPS) in the context of sarcoma. We identified one case of poorly differentiated sarcoma harboring both SS18-SSX2 fusion and MDM2 amplification. The review of the literature showed high discrepancies, concerning the incidence of MDM2 amplification in SS: from 1.4% up to 40%. Our goal was to precisely determine the specific clinico-pathological features of this case and to estimate the frequency and characteristics of the association of SS18-SSX fusion/MDM2 amplification in sarcomas. We performed a retrospective and prospective study in 96 sarcomas, (56 SS and 40 DDLPS), using FISH and/or array-CGH to detect MDM2 amplification and SS18 rearrangement. None of the 96 cases presented both genetic alterations. Among the SS, only the index case (1/57: 1.7 %) presented the double anomaly. We concluded that MDM2 amplification in SS is a very rare event. The final diagnosis of the index case was a SS with SS18-SSX2 and MDM2 amplification as a secondary alteration. If the detection of MDM2 amplification is performed first in a poorly differentiated sarcoma, that may lead to not search other anomalies such as SS18 rearrangement and therefore to an erroneous diagnosis. This observation emphasizes the strong complementarity between histomorphology, immunohistochemistry and molecular studies in sarcoma diagnosis.

Detection of tetraploidization in chromophobe renal cell carcinoma: Insights and pitfalls

Chromosomal losses resulting in a marked hypodiploidy are a specificity of chromophobe renal cell carcinoma (ChRCC), the third most frequent type of kidney cancer. Its detection is useful in challenging cases. However some ChRCC, especially the eosinophilic variant, do not exhibit hypodiploidy and deserve to be better explored. Using comparative genomic hybridization (array-CGH) we observed chromosomal gains in five cases of nonmetastatic ChRCC. Our objective was to determine whether these apparent chromosomal gains were instead losses within a near-polyploid genome. We performed a retrospective and prospective molecular study of 26 cases of ChRCC retrieved among 643 renal tumors (2012-2019). All tumors were analyzed using array-CGH (Agilent) and array-CGH (Affymetrix) coupled to single nucleotide polymorphism analysis (array-SNP). In silico manual centralization of the fluorescence ratio, fluorescence in situ hybridization (FISH) and next generation sequencing were made in the five cases suspected of polyploidy. Tetraploidization was observed in 19% of our series of ChRCC. None of the methods used individually could identify both chromosomal losses and tetraploidy. Only the combination of manual recentring of array-CGH and FISH provided relevant results. B-allele frequency results indicated that tetraploidization occurred secondarily to chromosomal losses in four cases while it preceded losses in one case. Tetraploidization is a frequent but underestimated phenomenon in ChRCC that may be overlooked using the individual standard genomic methods. Its potential clinical consequences are not identified yet. Whether the mechanisms that induce chromosomal losses in ChRCC are the same that generate tetraploidization is not known.

Double minute chromosomes harboring MDM2 amplification in a pediatric atypical lipomatous tumor

Adipocytic tumors are rare in children and are mostly benign. Less than 25 cases of pediatric well-differentiated liposarcoma (WDLPS), atypical lipomatous tumors (ALT), and dedifferentiated liposarcoma (DDLPS) have been reported. Among them, only three cases were genetically analyzed. We describe the genetic features of a rapidly growing adipose tumor that occurred in the thigh of a 7-year-old girl. Histologically, it was composed of mature adipocytic cells with a few atypia. Molecular analysis showed high-level amplification of the 12q13-21 region including MDM2 among 64 amplified genes. MDM2 amplification is a diagnostic hallmark of ALT/WDLPS/DDLPS. In adult cases, it is typically located in ring or giant marker chromosomes. In the present case, extra-copies of MDM2 were located on double minute chromosomes (dmin). This raised the hypothesis of dmin being precursors of adult's rings and giant markers and may provide indications for a better understanding of the mechanisms of adipose tumor oncogenesis.

ALK-TPM3 rearrangement in adult renal cell carcinoma: Report of a new case showing loss of chromosome 3 and literature review

Seven cases of translocation-associated renal cell carcinoma involving ALK (ALK-tRCC) were referenced in the last World Health Organization's classification (2016), in a group of emerging/provisional RCC. The first three cases were pediatric, medullary-based, associated with sickle-cell trait and showed a fusion of ALK with VCL. Thirteen cases have been further described. They displayed clinical, morphological and genomic heterogeneity. Most of them occurred in adults. None of the patients was affected by sickle-cell disease. We report a new case of ALK-tRCC in a 55-year-old woman. Genomic profile showed losses of chromosomes 3, 9 and 14, anomalies often observed in clear cell RCC. VHL mutation or morphological features suggesting a clear cell RCC were not detected. We identified an unbalanced rearrangement of ALK and TPM3. Review of the literature identified similar features in our case and previously published cases: heterogeneous solid architecture, eosinophilic cells, mucinous cytoplasmic elements, rhabdoid cells and intracytoplasmic lumina. These elements may constitute the basis of a pathological definition of ALK-tRCC. Their observation in a RCC should lead to perform molecular detection of ALK rearrangement. This may have a crucial importance for metastatic patients treatment since ALK rearrangements confer sensitivity to tyrosine kinases inhibitors such as crizotinib.

[Detection of RAS genes mutation using the Cobas® method in a private laboratory of pathology: Medical and economical study in comparison to a public platform of molecular biology of cancer]

In France, determination of the mutation status of RAS genes for predictive response to anti-EGFR targeted treatments is carried out by public platforms of molecular biology of cancer created by the French National Cancer Institute. This study aims to demonstrate the feasibility of these analyses by a private pathology laboratory (MEDIPATH) as per the requirements of accreditation. We retrospectively studied the mutation status of KRAS and NRAS genes in 163 cases of colorectal metastatic cancer using the Cobas^® technique. We compared our results to those prospectively obtained through pyrosequencing and allelic discrimination by the genetic laboratory of solid tumors at the Nice University Hospital (PACA-EST regional platform). The results of both series were identical: 98.7% positive correlation; negative correlation of 93.1%; overall correlation of 95.7% (Kappa=0.92). This study demonstrates the feasibility of molecular analysis in a private pathology laboratory. As this practice requires a high level of guarantee, its accreditation, according to the NF-EN-ISO15189 quality compliance French standard, is essential. Conducting molecular analysis in this context avoids the steps of routing the sample and the result between the pathology laboratory and the platform, which reduces the overall time of rendering the result. In conclusion, the transfer of some analysis from these platforms to private pathology laboratories would allow the platforms to be discharged from a part of routine testing and therefore concentrate their efforts to the development of new analyses constantly required to access personalized medicine.

Association of Oncogenic Mutations in Patients With Advanced Cutaneous Squamous Cell Carcinomas Treated With Cetuximab

Importance

Cetuximab was recently proposed for advanced cutaneous squamous cell carcinomas (cSCC); however, its efficacy is inconsistent and identification of predictive biomarkers for response is necessary.

Objective

To search for somatic mutations of the HRAS, KRAS, NRAS, BRAF, and EGFR genes in patients with advanced cSCC treated with cetuximab; and to investigate the efficacy and tolerance of cetuximab according to these mutations.

Design, Setting, and Participants

A multicentric and retrospective study of 31 patients (22 men, 9 women) with histologically confirmed advanced cSCC carried out in 1 department of dermatology and 2 departments of medical oncology in France between January 2008 and December 2014. The median age of participants was 86 years (range, 48-96 years).

Interventions

Mutational status was determined by pyrosequencing method, allelic discrimination, or Sanger sequencing. Patients were treated by single-agent cetuximab.

Main Outcomes and Measures

The primary end point was the incidence of somatic mutations of the RAS, BRAF, and EGFR genes and association of cetuximab efficacy with these mutations was investigated by using Fisher test. Secondary end points were the disease control rate (DCR) at week 6, the progression free-survival (PFS), overall survival (OS), and safety profile of cetuximab.

Results

Thirty-one samples of cSCC from 31 patients were analyzed. Only 2 RAS mutated samples (6.5%) were identified. The first harbored a NRAS point mutation (c.35G>A) in codon 12, resulting in a p.G12D substitution. The second sample presented a HRAS point mutation (c.38G>T) in codon 13, resulting in a p.G13V substitution. No mutation of KRAS, BRAF, and EGFR genes at the investigated loci was found. Two patients with NRAS and HRAS mutations showed a partial and complete response to cetuximab, respectively. The mean duration of follow-up was 19 months. At week 6, the disease control rate was 67.8%. The median OS was 13 months and the median PFS was 9 months. All patients could continue cetuximab treatment without dose reduction.

Conclusions and Relevance

Even in elderly patients with advanced cSCC, cetuximab was efficacious and well-tolerated. This suggests that cetuximab is certainly warranted in the treatment of advanced cSCC. However, it is also important to identify tumor specific mutations that may determine response to treatment and prognosis for the disease. We have identified here that the incidence of RAS, BRAF, and EGFR mutations is low in cSCC.

PDGFRa amplification in multiple skin lesions of undifferentiated pleomorphic sarcoma: A clue for intimal sarcoma metastases

A 62-year-old human immunodeficiency virus-positive man was admitted for multiple cutaneous and subcutaneous nodules on his lower limbs, corresponding to an undifferentiated proliferation of spindle and pleomorphic cells, with irregular nuclei and numerous mitoses. The tumor cells were negative for a large panel of immunohistochemical markers, except CD10. MDM2 immunohistochemical staining was also negative, leading to the diagnosis of Fédération Nationale des Centres de Lutte contre le Cancer grade III undifferentiated pleomorphic sarcoma (UPS). Array-comparative genomic hybridization showed a highly complex karyotype, with amplification of the 4q12 region, an area that contains only the platelet-derived growth factor receptor α (PDGFRa) gene. This amplification of PDFGRa, molecular hallmark of intimal sarcoma (IS), led to the diagnosis of skin IS metastasis. A positron emission tomography showed a hypermetabolic mass protruding in the preaortic area, consistent with the diagnosis of aortic IS. Our study shows that a rare differential diagnosis in peripheral UPS can be IS skin metastasis, and underlines the importance of molecular analyses in UPS.

Peritoneal carcinomatosis of colorectal cancer: novel clinical and molecular outcomes

BACKGROUND

The objective of this study was to identify the prognostic impact of parameters in peritoneal carcinomatosis from colorectal cancer.

METHODS

We collected data from patients treated by cytoreductive surgery and Hyperthermic Intraperitoneal Chemotherapy for peritoneal carcinomatosis secondary to colorectal cancer.

RESULTS

Ninety-one procedures were performed. In univariate analysis, an increased peritoneal cancer index was associated with decreased survival (P < .001). The presence of signet ring cells was associated to a decrease in survival from 45.8 to 12.1 months (P < .001). Microsatellite sequences instability status was the only molecular prognostic factor correlated with an increase in median disease-free survival: 12.4 vs 24.9 months (P = .01). The presence of a mucinous component was associated with a decreased of survival from 51.9 to 35.1 months (P = .02).

CONCLUSIONS

Clinical factors were affecting the survival of patients. The absence of signet ring cells and mucinous component and the presence of microsatellite sequences instability may be favorable prognostic factors.

MET immunolabelling is a useful predictive tool for MET gene amplification in glioblastoma

AIMS

MET gene amplification is rare in glioblastoma (GBM) and represents a potential target for MET inhibitors. An immunohistochemical screening may be useful to identify MET amplification. The aim of our study was to establish how MET immunolabelling correlates with MET amplification.

METHODS

Three cohorts including 108 GBM (cohort 1, prospective), 104 GBM (cohort 2, retrospective) and 52 GBM (cohort 3, prospective) were investigated for MET expression by immunohistochemistry. MET amplification was assessed by comparative genomic hybridization on microarray (CGH-array) in all cohorts and by fluorescent in situ hybridization (FISH) in cohorts 2 and 3. Active form of MET was assessed using p-MET (Y1349) immunohistochemistry.

RESULTS

Diffuse MET amplification detectable by CGH-array was associated with diffuse, strong MET immunolabelling (four cases in cohort 1 and one case in cohort 2). Focal MET amplification detectable only by FISH was observed in small foci of strongly immunopositive cells in two GBM (cohort 2). In both cohorts, MET amplification was never detected in GBM devoid of strongly immunopositive cells. MET overexpression, observed in 23% of unamplified GBM, was associated with a predominant weak-to-moderate staining intensity and with necrosis (P < 0.005). p-MET was detected in all MET-amplified GBM and in perinecrotic areas of nonamplified GBM. A strong MET immunostaining intensity, at least focal and distant from necrosis, showed 100% sensitivity and 84% specificity for predicting MET amplification in cohort 3.

CONCLUSIONS

MET amplification is characterized by strongly immunopositive cells. Only GBM showing strong MET immunostaining is appropriate for the assessment of MET amplification.

Clinical effect of molecular methods in sarcoma diagnosis (GENSARC): a prospective, multicentre, observational study

BACKGROUND

Advances in molecular genetics of sarcoma have enabled the identification of type-specific aberrations. We aimed to assess the clinical effect of systematic implementation of molecular assays to improve sarcoma misdiagnosis.

METHODS

In this multicentre, observational study, we recruited patients from 32 centres of the French Sarcoma Group/Reference Network in Pathology of Sarcomas. Eligibility criteria included: biopsy or surgical resection; suspicion of: dermatofibrosarcoma protuberans (cohort 1), dedifferentiated liposarcoma (cohort 2), Ewing's sarcoma family of tumours (cohort 3), synovial sarcoma (cohort 4), alveolar rhabdomyosarcoma (cohort 5), and myxoid or round cell liposarcoma (cohort 6); review by one sarcoma-expert pathologist; availability of frozen material (except for cohort 1 of patients with dermatofibrosarcoma protuberans because anti-CD34 immunohistochemistry is performed on paraffin-embedded tissue); and patient information. For each case, the pathologist made one primary diagnosis followed by up to two differential diagnoses, based on histological characteristics only. Each diagnosis was classified as certain, probable, or possible. For each case to determine the molecular classification, we did fluorescence in-situ hybridisation on paraffin-embedded samples. We also did comparative genomic hybridisation and quantitative PCR (cohort 2) or reverse transcriptase PCR (cohorts 3-6) on frozen and paraffin-embedded samples. We made a final diagnosis based on the molecular results. The clinical effect of diagnosis correction was assessed by a board of experts.

FINDING

Between June 22, 2009, and Oct 30, 2012, 395 patients were enrolled in the study, of which 384 were eligible for inclusion. The diagnosis was eventually modified by molecular genetics for 53 patients: eight (16%) of 50 patients with dermatofibrosarcoma (cohort 1), seven (23%) of 30 patients with dedifferentiated liposarcoma (cohort 2), 13 (12%) of 112 with Ewing's sarcoma family of tumours (cohort 3), 16 (16%) of 97 patients with synovial sarcoma (cohort 4), seven (15%) of 46 patients with alveolar rhabdomyosarcoma (cohort 5), and two (4%) of 49 patients with myxoid or round cell liposarcoma (cohort 6), with an effect on primary management or prognosis assessment in 45 cases.

INTERPRETATION

Molecular genetic testing should be mandatory for diagnostic accuracy of sarcoma and appropriate clinical management, even when histological diagnosis is made by pathologist experts in this field.

FUNDING

French National Cancer Institute and Nice University Hospital.

HR23b expression is a potential predictive biomarker for HDAC inhibitor treatment in mesenchymal tumours and is associated with response to vorinostat

Histone deacetylases (HDAC) are key players in epigenetic regulation of gene expression and HDAC inhibitor (HDACi) treatment seems to be a promising anticancer therapy in many human tumours, including soft tissue sarcomas. HR23b has been shown to be a potential biomarker for sensitivity to HDACi therapy in cutaneous T‐cell lymphoma and hepatocellular carcinoma. We aimed to evaluate HR23b as a candidate biomarker for HDACi response in sarcomas and gastrointestinal stromal tumours (GIST). Therefore, HR23b expression was analysed comprehensively by western blot in sarcoma and GIST cell lines covering all major clinically relevant subtypes. MTT assay and ApoTox‐Glo^TM Triplex assay were performed after treatment with vorinostat, belinostat, mocetinostat and entinostat. HR23b protein expression was measured under HDACi treatment. Furthermore, HR23b expression levels were immunohistochemically determined in a large set of 523 clinical samples from sarcoma and GIST patients. Western blot analyses showed that sarcomas differ significantly in their expression of HR23b protein. All HDACi were able to regulate proliferation and apoptosis in vitro. Sensitivity to vorinostat correlated significantly with HR23b protein expression. Immunohistochemical prevalence screening in clinical samples of relevant adult‐type tumours revealed that 12.5% of sarcomas (among them malignant peripheral nerve sheath tumours, pleomorphic liposarcomas, leiomyosarcomas, dedifferentiated liposarcomas, synovial sarcomas and angiosarcomas) and 23.2% of GIST show high HR23b expression. Therefore, HDACi have antiproliferative and proapoptotic effects in sarcomas depending on the expression level of HR23b. These findings suggest that HR23b represents a candidate biomarker for HDACi sensitivity in certain sarcoma types and in GIST.

Spatio-temporal genetic heterogeneity of CTNNB1 mutations in sporadic desmoid type fibromatosis lesions

Desmoid type fibromatosis (DT) is a rare lesion of unclear pathogenesis that most often presents a mutation of the (β-catenin) gene. The natural history and clinical evolution are highly variable between patients and to date there is no consensus on optimal therapy. We report two cases of a patient with multiple DT lesions. Molecular investigations performed in both patients on multiple tumors at different anatomical sites revealed non-identical CTNNB1 mutations. The first patient was a 39-year-old man with a history of recurrent DT. In two of the DT lesions, three different mutations were found in codons 41 and 45, respectively. The lesions showed marked inflammatory features, characterized by IgG4 positive lymphoplasmacytic infiltrates and a foreign body reaction, which increased in intensity over time. The patient was eventually treated with a COX-2 inhibitor and the remaining mass was stabilized. In the two DT lesions of the second patient, CTNNB1 mutations S45P and T41A were found. The presence of different mutations in multiple focally recurrent sporadic DT lesions indicates that they do not have a clonal relationship. Our data suggest that a CTNNB1 mutation is a necessary event probably by providing a selective growth advantage. An IgG4 host antigen response is discussed as a potential predisposing factor for one of the patients.

Prognostic value of HMGA2, CDK4, and JUN amplification in well-differentiated and dedifferentiated liposarcomas

HMGA2, CDK4, and JUN genes have been described as frequently coamplified with MDM2 in atypical lipomatous tumor, well-differentiated liposarcoma, and dedifferentiated liposarcoma. We studied the frequency of amplification of these genes in a series of 48 dedifferentiated liposarcomas and 68 atypical lipomatous tumors/well-differentiated liposarcomas. We correlated their amplification status with clinicopathological features and outcomes. Histologically, both CDK4 (P=0.007) and JUN (P=0.005) amplifications were associated with dedifferentiated liposarcoma, whereas amplification of the proximal parts of HMGA2 (5'-untranslated region (UTR) and exons 1-3) was associated with atypical lipomatous tumor/well-differentiated liposarcoma (P=0.01). CDK4 amplification was associated with axial tumors. Amplification of 5'-UTR and exons 1-3 of HMGA2 was associated with primary status and grade 1. Shorter overall survival was correlated with: age >64 years (P=0.03), chemotherapy used in first intent (P<0.001), no surgery (P=0.003), grade 3 (P<0.001), distant metastasis (P<0.001), node involvement (P=0.006), and CDK4 amplification (P=0.07). In multivariate analysis, distant metastasis (HR=8.8) and grade 3 (HR=18.2) were associated with shorter overall survival. A shorter recurrence-free survival was associated with dedifferentiated liposarcoma (P<0.001), grade 3 (P<0.001), node involvement (P<0.001), distant metastasis (P=0.02), recurrent status (P=0.009), axial location (P=0.001), and with molecular features such as CDK4 (P=0.05) and JUN amplification (P=0.07). Amplification of 5'-UTR and exons 1-3 (P=0.08) and 3'-UTR (P=0.01) of HMGA2 were associated with longer recurrence-free survival. Distant metastasis was associated with shorter recurrence-free survival (HR=5.8) in multivariate analysis. Dedifferentiated liposarcoma type was associated with axial location, grade 3 and recurrent status. In conclusion, we showed that the amplification of HMGA2 was associated with the atypical lipomatous tumor/well-differentiated liposarcoma histological type and a good prognosis, whereas CDK4 and JUN amplifications were associated with dedifferentiated liposarcoma histology and a bad prognosis. In addition, we also provided the first description of the molecular evolution of a well-differentiated liposarcoma into four successive dedifferentiated liposarcoma relapses, which was consistent with our general observations.

SRC inhibition represents a potential therapeutic strategy in liposarcoma

Liposarcomas (LS) are the most common malignant mesenchymal tumors, with an overall long-term mortality rate of 60%. LS comprise three major subtypes, i.e., well-differentiated/dedifferentiated liposarcoma (WDLS/DDLS), myxoid/round cell liposarcoma (MLS) and pleomorphic liposarcoma (PLS). Aiming at the preclinical identification of novel therapeutic options, we here investigate the functional significance of SRC in primary human LS and in LS-derived cell lines. Immunohistochemical and Western blot analyses reveal relevant levels of activated p-(Tyr416)-SRC in LS of the different subtypes with particular activation in MLS and PLS. Dysregulation of the SRC modifiers CSK and PTP1B was excluded as major reason for the activation of the kinase. Consistent siRNA-mediated knockdown of SRC or inhibition by the SRC inhibitor Dasatinib led to decreased proliferation of LS cell lines of the different subtypes, with MLS cells reacting particularly sensitive in MTT assays. Flow cytometric analyses revealed that this effect was due to a significant decrease in mitotic activity and an induction of apoptosis. SRC inhibition by Dasatinib resulted in dephosphorylation of SRC itself, its interacting partners FAK and IGF-IR as well as its downstream target AKT. Consistent with a particular role of SRC in cell motility, Dasatinib reduced the migratory and invasive potential of MLS cells in Boyden chamber and Matrigel chamber assays. In summary, we provide evidence that SRC activation plays an important role in LS biology and therefore represents a potential therapeutic target, particularly in MLS and PLS.

Fluorescence in situ hybridization analysis is a helpful test for the diagnosis of dermatofibrosarcoma protuberans

Cytogenetically, most dermatofibrosarcoma protuberans are characterized by chromosomal rearrangements resulting in the collagen type-1 alpha 1 (COL1A1)-platelet-derived growth factor β (PDGFB) fusion gene. This abnormality can be detected by fluorescence in situ hybridization (FISH) analysis in routine practice. The aim of this study was to evaluate the role of the FISH analysis in the diagnosis of dermatofibrosarcoma protuberans. A FISH analysis was prospectively and systematically performed on a series of 448 consecutive tumor specimens. All cases were reviewed by two independent pathologists and classified in three categories according to the probability of a DFSP diagnosis before molecular analyses. Cases were classified as certain when dermatofibrosarcoma protuberans was the only possible diagnosis. Those cases for which dermatofibrosarcoma protuberans remained the first diagnosis, but other differential diagnosis existed, were regarded as probable. When dermatofibrosarcoma protuberans was considered a differential diagnosis, they were labeled as possible. The final diagnosis was supported by clinicopathological findings and results of FISH analyses. Immunohistochemical analysis of CD34 was systematically performed, and additional markers when necessary. The cases (n=37) with a non-interpretable FISH were excluded. For the 185 certain tumors specimens: 178 (96%) FISH analyses showed a PDGFB/COL1A1 rearrangement, 7 (4%) were negative. For the 114 probable tumors specimens: 104 (91%) FISH analyses were positive and 10 (9%) were negative leading to a new diagnosis in 8 cases. For the 112 possible cases: 91 (81%) FISH analyses were negative and 21 (19%) were positive. Of the 21 cases, initial diagnoses included unclassified sarcoma, myxofibrosarcoma, dermatofibroma, reactive lesion, solitary fibrous tumor, perineurioma, benign nerve sheath tumor, and undifferentiated spindle cell tumor without malignant evidence. FISH analysis has been helpful for confirming the diagnosis of dermatofibrosarcoma protuberans in 25% (104/411) of cases and necessary for the diagnosis of dermatofibrosarcoma protuberans in 5% (21/411) of cases.

The architecture and evolution of cancer neochromosomes

We isolated and analyzed, at single-nucleotide resolution, cancer-associated neochromosomes from well- and/or dedifferentiated liposarcomas. Neochromosomes, which can exceed 600 Mb in size, initially arise as circular structures following chromothripsis involving chromosome 12. The core of the neochromosome is amplified, rearranged, and corroded through hundreds of breakage-fusion-bridge cycles. Under selective pressure, amplified oncogenes are overexpressed, while coamplified passenger genes may be silenced epigenetically. New material may be captured during punctuated chromothriptic events. Centromeric corrosion leads to crisis, which is resolved through neocentromere formation or native centromere capture. Finally, amplification terminates, and the neochromosome core is stabilized in linear form by telomere capture. This study investigates the dynamic mutational processes underlying the life history of a special form of cancer mutation.

Syndecan-1 regulates adipogenesis: new insights in dedifferentiated liposarcoma tumorigenesis

Syndecan-1 (SDC1/CD138) is one of the main cell surface proteoglycans and is involved in crucial biological processes. Only a few studies have analyzed the role of SDC1 in mesenchymal tumor pathogenesis. In particular, its involvement in adipose tissue tumors has never been investigated. Dedifferentiated liposarcoma, one of the most frequent types of malignant adipose tumors, has a high potential of recurrence and metastastic evolution. Classical chemotherapy is inefficient in metastatic dedifferentiated liposarcoma and novel biological markers are needed for improving its treatment. In this study, we have analyzed the expression of SDC1 in well-differentiated/dedifferentiated liposarcomas and showed that SDC1 is highly overexpressed in dedifferentiated liposarcoma compared with normal adipose tissue and lipomas. Silencing of SDC1 in liposarcoma cells impaired cell viability and proliferation. Using the human multipotent adipose-derived stem cell model of human adipogenesis, we showed that SDC1 promotes proliferation of undifferentiated adipocyte progenitors and inhibits their adipogenic differentiation. Altogether, our results support the hypothesis that SDC1 might be involved in liposarcomagenesis. It might play a prominent role in the dedifferentiation process occurring when well-differentiated liposarcoma progress to dedifferentiated liposarcoma. Targeting SDC1 in these tumors might provide a novel therapeutic strategy.

The relevance of testing the efficacy of anti-angiogenesis treatments on cells derived from primary tumors: a new method for the personalized treatment of renal cell carcinoma

Despite the numerous available drugs, the most appropriate treatments for patients affected by common or rare renal cell carcinomas (RCC), like those associated with the Xp11.2 translocation/transcription factor for immunoglobulin heavy-chain enhancer 3 (TFE3) gene fusion (TFE3 RCC), are not clearly defined. We aimed to make a parallel between the sensitivity to targeted therapies on living patients and on cells derived from the initial tumor. Three patients diagnosed with a metastatic RCC (one clear cell RCC [ccRCC], two TFE3 RCC) were treated with anti-angiogenesis drugs. The concentrations of the different drugs giving 50% inhibition of cell proliferation (IC50) were determined with the Thiazolyl Blue Tetrazolium Bromide (MTT) assay on cells from the primary tumors and a reference sensitive RCC cell line (786-O). We considered the cells to be sensitive if the IC50 was lower or equal to that in 786-O cells, and insensitive if the IC50 was higher to that in 786-O cells (IC 50 of 6 ± 1 µM for sunitinib, 10 ± 1 µM for everolimus and 6 ± 1 µM for sorafenib). Based on this standard, the response in patients and in cells was equivalent. The efficacy of anti-angiogenesis therapies was also tested in cells obtained from five patients with non-metastatic ccRCC, and untreated as recommended by clinical practice in order to determine the best treatment in case of progression toward a metastatic grade. In vitro experiments may represent a method for evaluating the best first-line treatment for personalized management of ccRCC during the period following surgery.

Conservative multimodal management of a primitive neuroectodermal tumor of the thyroid

Abstract

Primitive neuroectodermal tumors (PNET) represent 1% of sarcomas. Head and neck peripheral PNETs have an intermediate prognosis between abdominopelvic disease and extremities. We here report the case of a 40-year old male who presented with primitive neuroectodermal tumor of the thyroid and was treated by multimodal treatment, including surgery, chemotherapy and intermediate dose radiotherapy. The patient is alive and fit with a functional larynx at 27 months. Multimodal treatments yield five-year survival rates of about 60%. Major drug regimens use vincristine, doxorubicin, ifosfamide or cyclophosphamide, dactinomycin and/or etoposide. Complete surgical excision is undertaken whenever possible to improve long-term survival. However, the relative radiosensitivity of tumors of the Ewing family, suggest multimodal treatment including adjuvant conformal radiotherapy in case of positive margins or poor response to chemotherapy rather than resection with 2-3 cm margins, which would imply laryngeal sacrifice for thyroid tumors. The role of expert rare tumor networks is crucial for optimal decision-making and management of such rare tumors on a case by case basis.

Autophagy plays a critical role in the degradation of active RHOA, the control of cell cytokinesis, and genomic stability

Degradation of signaling proteins is one of the most powerful tumor-suppressive mechanisms by which a cell can control its own growth. Here, we identify RHOA as the molecular target by which autophagy maintains genomic stability. Specifically, inhibition of autophagosome degradation by the loss of the v-ATPase a3 (TCIRG1) subunit is sufficient to induce aneuploidy. Underlying this phenotype, active RHOA is sequestered via p62 (SQSTM1) within autolysosomes and fails to localize to the plasma membrane or to the spindle midbody. Conversely, inhibition of autophagosome formation by ATG5 shRNA dramatically increases localization of active RHOA at the midbody, followed by diffusion to the flanking zones. As a result, all of the approaches we examined that compromise autophagy (irrespective of the defect: autophagosome formation, sequestration, or degradation) drive cytokinesis failure, multinucleation, and aneuploidy, processes that directly have an impact upon cancer progression. Consistently, we report a positive correlation between autophagy defects and the higher expression of RHOA in human lung carcinoma. We therefore propose that autophagy may act, in part, as a safeguard mechanism that degrades and thereby maintains the appropriate level of active RHOA at the midbody for faithful completion of cytokinesis and genome inheritance.

EGFR, KRAS, BRAF, and HER-2 molecular status in brain metastases from 77 NSCLC patients

The aim of this study was to determine the frequency of EGFR, KRAS, BRAF, and HER-2 mutations in brain metastases from non-small cell lung carcinomas (BM-NSCLC). A total of 77 samples of BM-NSCLC were included and 19 samples of BM from breast, kidney, and colorectal tumors were also studied as controls. These samples were collected from patients followed between 2008 and 2011 at Poitiers and Nice University Hospitals in France. The frequencies of EGFR, KRAS, BRAF, and HER-2 mutations in BM-NSCLC were 2.6, 38.5, 0, and 0% respectively. The incidence of KRAS mutation was significantly higher in female and younger patients (P < 0.05). No mutations of the four genes were found in BM from breast or kidney. However, among six BM from colorectal tumors, we identified KRAS mutations in three cases and BRAF mutations in two other cases. This study is the largest analysis on genetic alterations in BM-NSCLC performed to date. Our results suggest a low frequency of EGFR mutations in BM-NSCLC whereas KRAS mutations are as frequent in BM-NSCLC as in primitive NSCLC. These results raise the question of the variability of the brain metastatic potential of NSCLC cells in relation to the mutation pattern.

Identification of PPAP2B as a novel recurrent translocation partner gene of HMGA2 in lipomas

Most lipomas are characterized by translocations involving the HMGA2 gene in 12q14.3. These rearrangements lead to the fusion of HMGA2 with an ectopic sequence from the translocation chromosome partner. Only five fusion partners of HMGA2 have been identified in lipomas so far. The identification of novel fusion partners of HMGA2 is important not only for diagnosis in soft tissue tumors but also because these genes might have an oncogenic role in other tumors. We observed that t(1;12)(p32;q14) was the second most frequent translocation in our series of lipomas after t(3;12)(q28;q14.3). We detected overexpression of HMGA2 mRNA and protein in all t(1;12)(p32;q14) lipomas. We used a fluorescence in situ hybridization-based positional cloning strategy to characterize the 1p32 breakpoint. In 11 cases, we identified PPAP2B, a member of the lipid phosphate phosphatases family as the 1p32 target gene. Reverse transcription-polymerase chain reaction analysis followed by nucleotide sequencing of the fusion transcript indicated that HMGA2 3' untranslated region (3'UTR) fused with exon 6 of PPAP2B in one case. In other t(1;12) cases, the breakpoint was extragenic, located in the 3'region flanking PPAP2B 3'UTR. Moreover, in one case showing a t(1;6)(p32;p21) we observed a rearrangement of PPAP2B and HMGA1, which suggests that HMGA1 might also be a fusion partner for PPAP2B. Our results also revealed that adipocytic differentiation of human mesenchymal stem cells derived from adipose tissue was associated with a significant decrease in PPAP2B mRNA expression suggesting that PPAP2B might play a role in adipogenesis.