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.

The combination of bevacizumab/Avastin and erlotinib/Tarceva is relevant for the treatment of metastatic renal cell carcinoma: the role of a synonymous mutation of the EGFR receptor.

Metastatic clear cell renal cell carcinomas (mRCC) over-express the vascular endothelial growth factor (VEGF). Hence, the anti-VEGF antibody bevacizumab/Avastin (BVZ) combined with interferon alpha (IFN) was approved for the treatment of mRCC. However, approval was lost in July 2016 due to the absence of sustained efficacy. We previously showed that BVZ accelerates tumor growth in experimental models of mRCC in mice, results in part explained by down-regulation of the phospho tyrosine phosphatase receptor kappa (PTPRκ) in tumor cells. The epidermal growth factor receptor (EGFR) is a direct target of PTPRκ. Its down-regulation leads to constitutive activation of EGFR, an observation which prompted us to test the effect of the EGFR inhibitor erlotinib/Tarceva (ERLO) in addition to BVZ/IFN. The influence of the long non-coding RNA, EGFR-AS1, on ERLO efficacy was also addressed. Methods: The effect of BVZ/IFN/ERLO was tested on the growth of experimental tumors in nude mice. The presence of germline mutation in the EGFR was evaluated on cell lines and primary RCC cells. In vitro translation and transfections of expression vectors coding the wild-type or the EGFR mutated gene in HEK-293 cells were used to test the role of EGFR mutation of the ERLO efficacy. Correlation between EGFR/EGFR-AS1 expression and survival was analyzed with an online available data base (TCGA). Results: Tumor growth was strongly reduced by the triple combination BVZ/IFN/ERLO and linked to reduced levels of pro-angiogenic/pro-inflammatory cytokines of the ELR+CXCL family and to subsequent inhibition of vascularization, a decreased number of lymphatic vessels and polarization of macrophages towards the M1 phenotype. Cells isolated from surgical resection of human tumors presented a range of sensitivity to ERLO depending on the presence of a newly detected mutation in the EGFR and to the presence of EGFR-AS1. Conclusions: Our results point-out that the BVZ/IFN/ERLO combination deserves testing for the treatment of mRCC that have a specific mutation in the EGFR.

Dismantling papillary renal cell carcinoma classification: The heterogeneity of genetic profiles suggests several independent diseases.

Papillary renal cell carcinoma (pRCC) is the second most frequent renal cell carcinoma (RCC) after clear cell RCC. In contrast to clear cell RCC, there is no consensual protocol using targeted therapy for metastatic pRCC. Moreover, diagnosis of some pRCC, especially pRCC of type 2 (pRCC2) may be challenging. Our aim was to identify molecular biomarkers that could be helpful for the diagnosis and treatment of pRCC. We studied the clinical, histological, immunohistological, and comprehensive genetic features of a series of 31 pRCC including 15 pRCC1 and 16 pRCC2. We aimed to determine whether pRCC represents a unique entity or several diseases. In addition, we compared the genetic features of pRCC2 to those of eight RCC showing various degrees of tubulo-papillary architecture, including three TFE-translocation RCC and five unclassified RCC. We demonstrate that pRCC is a heterogeneous group of tumors with distinct evolution. While most pRCC2 had genetic profiles similar to pRCC1, some shared genomic features, such as loss of 3p and loss of chromosome 14, with clear cell RCC, TFE-translocation RCC, and unclassified RCC. We identified variants of the MET gene in three pRCC1. A mutation in the BRAF gene was also identified in one pRCC1. In addition, using next-generation sequencing (NGS), we identified several variant genes. Genomic profiling completed by NGS allowed us to classify pRCC2 in several groups and to identify novel mutations. Our findings provide novel information on the pathogenesis of pRCC that allow insights for personalized treatment.

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.

[Data quality of cancer registration by Adicap codes, used by French pathologists from Paca, 2005-2006]. / Evaluation de la qualité du recueil des codes Adicap de tumeurs invasives et in situ par le Crisap de Paca Est, 2005-2006.

AIM: To assess the reliability of systematic and exhaustive cancer Adicap code registration by French pathology laboratories within the Crisap of Paca East network. METHODS: The Adicap code includes tumour site, histology and pathology technique. A quality control programme was applied to malignant and in situ tumours with an Adicap code to assess data quality, correct errors and supply missing data, based on IARC recommendations. RESULTS: In 2005 and 2006, 45,980 pathology examinations were entered in the Crisap of Paca East database. There was at least one Adicap code per examination, patients, surgeons and pathologists were identified and date of diagnosis was completed, as recommended by the HAS-Afaqap 2005 French pathologist professional quality control. Discrepancies between histopathology tissue and tumour site were found in 0.32% of cases (n=147), between age and histopathology in 0.04% of cases (n=19), and between genital tumour and sex in 0.01% of cases (n=3). In 2006, within 9535 subjects, dates of birth and postcodes of residence were missing, respectively, in 0.39% (n=37) and 22.46% (n=2142) of cases. CONCLUSION: Data quality for the Adicap code database may be considered satisfactory. Extended to Paca in 2007, Crisap Paca database can now be exploited for Paca regional cancer control strategy.

Cetuximab shows activity in colorectal cancer patients with tumors for which FISH analysis does not detect an increase in EGFR gene copy number.

BACKGROUND: EGFR (epidermal growth factor receptor) gene gain assessed by FISH (fluorescence in situ hybridization) has been shown to be predictive of response to EGFR-targeted therapies in patients with non-small cell lung cancer. The aim or our study was to relate the EGFR gene copy number to therapeutic results in patients with metastatic colorectal cancer (CRC) treated with a cetuximab-containing regimen. METHODS: Forty-seven patients with metastatic CRC treated with a cetuximab-containing regimen between August 2004 and September 2006 were included in our study. EGFR status was assessed by immunohistochemistry (IHC) and by FISH on fixed paraffin-embedded sections of tumor specimens. RESULTS: By IHC (n = 47), 39 patients (83%) had EGFR-positive tumors. EGFR gene copy gain was detected in 8 (19.5%) of 41 tumors. Neither EGFR expression assessed by IHC nor EGFR gene copy gain assessed by FISH were statistically significantly correlated with objective response rate, disease control rate, progression-free survival, and overall survival. Of the 33 patients whose tumors were FISH negative, 8 patients (24.2%) had a partial response, and 10 (30.3%) had stable disease. CONCLUSIONS: EGFR FISH analysis does not seem to be a sufficiently robust test for selecting candidate CRC patients for cetuximab therapy.