Human glycoprotein-2 expressed in Brunner glands - A putative autoimmune target and link between Crohn's and coeliac disease.

Glycoprotein 2 (GP2) is an autoantigen in Crohn's (CD) and coeliac disease (CeD). We assessed GP2-isoform (GP21-4)-expression in intestinal biopsies of paediatric patients with CD, CeD, ulcerative colitis (UC), and healthy children (HC). Transcription of GP21-4 was elevated in proximal small intestine in CeD and CD patients (only GP22/4) compared to jejunum (CeD/CD) and large bowel (CD). CeD patients demonstrated higher duodenal GP22/4-mRNA levels compared to HC/UC patients whereas CD patients showed higher GP24-mRNA levels compared to UC patients. Duodenal synthesis of only small GP2 isoforms (GP23/4) was demonstrated in epithelial cells in patients/HC and in Brunner glands (also large isoforms) with a more frequent apical location in CD/CeD patients. All four GP2 isoforms interacted with gliadin and phosphopeptidomannan. Gliadin digestion improved binding to GP2 isoforms. GP21-4 binding to CeD/CD-related antigens, elevated duodenal GP21-4-mRNA transcription, and GP2-protein secretion in Brunner glands of CeD/CD patients suggest an autoimmune CeD/CD link.

Update on quality assurance in neuropathology: Summary of the round robin trials on TERT promoter mutation, H3-3A mutation, 1p/19q codeletion, and KIAA1549::BRAF fusion testing in Germany in 2020 and 2021.

We previously reported on the first neuropathological round robin trials operated together with Quality in Pathology (QuIP) GmbH in 2018 and 2019 in Germany, i.e., the trials on IDH mutational testing and MGMT promoter methylation analysis [1]. For 2020 and 2021, the spectrum of round robin trials has been expanded to cover the most commonly used assays in neuropathological institutions. In addition to IDH mutation and MGMT promoter methylation testing, there is a long tradition for 1p/19q codeletion testing relevant in the context of the diagnosis of oligodendroglioma. With the 5th edition of the World Health Organization (WHO) classification of the central nervous system tumors, additional molecular markers came into focus: TERT promoter mutation is often assessed as a molecular diagnostic criterion for IDH-wildtype glioblastoma. Moreover, several molecular diagnostic markers have been introduced for pediatric brain tumors. Here, trials on KIAA1549::BRAF fusions (common in pilocytic astrocytomas) and H3-3A mutations (in diffuse midline gliomas, H3-K27-altered and diffuse hemispheric gliomas, H3-G34-mutant) were most desired by the neuropathological community. In this update, we report on these novel round robin trials. In summary, success rates in all four trials ranged from 75 to 96%, arguing for an overall high quality level in the field of molecular neuropathological diagnostics.

Epstein-Barr virus infection patterns in nodular lymphocyte-predominant Hodgkin lymphoma.

AIMS: To investigate Epstein-Barr virus (EBV) latency types in 19 cases of EBV-positive nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL), as such information is currently incomplete. METHODS AND RESULTS: Immunohistochemistry (IHC) for CD20, CD79a, PAX5, OCT2, CD30, CD15, CD3 and programmed cell death protein 1 was performed. For EBV detection, in-situ hybridisation (ISH) for EBV-encoded RNA (EBER) was employed combined with IHC for EBV-encoded latent membrane protein (LMP)-1, EBV-encoded nuclear antigen (EBNA)-2, and EBV-encoded BZLF1. In 95% of the cases, neoplastic cells with features of Hodgkin and Reed-Sternberg (HRS) cells were present, mostly showing expression of CD30. In all cases, the B-cell phenotype was largely intact, and delineation from classic Hodgkin lymphoma (CHL) was further supported by myocyte enhancer factor 2B (MEF2B) detection. All tumour cells were EBER-positive except in two cases. EBV latency type II was most frequent (89%) and type I was rare. Cases with latency type I were CD30-negative. Five cases contained some BZLF1-positive and/or EBNA-2-positive bystander lymphocytes. CONCLUSIONS: As HRS morphology of neoplastic cells and CD30 expression are frequent features of EBV-positive NLPHL, preservation of the B-cell transcription programme, MEF2B expression combined with NLPHL-typical architecture and background composition facilitate distinction from CHL. EBER ISH is the method of choice to identify these cases. The majority present with EBV latency type II, and only rare cases present with latency type I, which can be associated with missing CD30 expression. The presence of occasional bystander lymphocytes expressing BZLF1 and/or EBNA-2 and the partial EBV infection of neoplastic cells in some cases could indicate that EBV is either not primarily involved or is only a transient driver in the pathogenesis of EBV-positive NLPHL.

Assessment of gene expressions from squamous cell carcinoma of the head and neck to predict radiochemotherapy-related xerostomia and dysphagia.

PURPOSE: We tested the hypothesis that gene expressions from biopsies of locally advanced head and neck squamous cell carcinoma (HNSCC) patients can supplement dose-volume parameters to predict dysphagia and xerostomia following primary radiochemotherapy (RCTx). MATERIAL AND METHODS: A panel of 178 genes previously related to radiochemosensitivity of HNSCC was considered for nanoString analysis based on tumour biopsies of 90 patients with locally advanced HNSCC treated by primary RCTx. Dose-volume parameters were extracted from the parotid, submandibular glands, oral cavity, larynx, buccal mucosa, and lips. Normal tissue complication probability (NTCP) models were developed for acute, late, and for the improvement of xerostomia grade ≥2 and dysphagia grade ≥3 using a cross-validation-based least absolute shrinkage and selection operator (LASSO) approach combined with stepwise logistic regression for feature selection. The final signatures were included in a logistic regression model with optimism correction. Performance was assessed by the area under the receiver operating characteristic curve (AUC). RESULTS: NTCP models for acute and late xerostomia and the improvement of dysphagia resulted in optimism-corrected AUC values of 0.84, 0.76, and 0.70, respectively. The minimum dose to the contralateral parotid was selected for both acute and late xerostomia and the minimum dose to the larynx was selected for dysphagia improvement. For the xerostomia endpoints, the following gene expressions were selected: RPA2 (cellular response to DNA damage), TCF3 (salivary gland cells development), GBE1 (glycogen storage and regulation), and MAPK3 (regulation of cellular processes). No gene expression features were selected for the prediction of dysphagia. CONCLUSION: This hypothesis-generating study showed the potential of improving NTCP models using gene expression data for HNSCC patients. The presented models require independent validation before potential application in clinical practice.

Impact of Androgen Receptor Activity on Prostate-Specific Membrane Antigen Expression in Prostate Cancer Cells.

Prostate-specific membrane antigen (PSMA) is an essential molecular regulator of prostate cancer (PCa) progression coded by the FOLH1 gene. The PSMA protein has become an important factor in metastatic PCa diagnosis and radioligand therapy. However, low PSMA expression is suggested to be a resistance mechanism to PSMA-based imaging and therapy. Clinical studies revealed that androgen receptor (AR) inhibition increases PSMA expression. The mechanism has not yet been elucidated. Therefore, this study investigated the effect of activation and inhibition of androgen signaling on PSMA expression levels in vitro and compared these findings with PSMA levels in PCa patients receiving systemic therapy. To this end, LAPC4, LNCaP, and C4-2 PCa cells were treated with various concentrations of the synthetic androgen R1881 and antiandrogens. Changes in FOLH1 mRNA were determined using qPCR. Open access databases were used for ChIP-Seq and tissue expression analysis. Changes in PSMA protein were determined using western blot. For PSMA staining in patients' specimens, immunohistochemistry (IHC) was performed. Results revealed that treatment with the synthetic androgen R1881 led to decreased FOLH1 mRNA and PSMA protein. This effect was partially reversed by antiandrogen treatment. However, AR ChIP-Seq analysis revealed no canonical AR binding sites in the regulatory elements of the FOLH1 gene. IHC analysis indicated that androgen deprivation only resulted in increased PSMA expression in patients with low PSMA levels. The data demonstrate that AR activation and inhibition affects PSMA protein levels via a possible non-canonical mechanism. Moreover, analysis of PCa tissue reveals that low PSMA expression rates may be mandatory to increase PSMA by androgen deprivation.

[Detection of BRAF V600E mutation in metastatic colorectal carcinoma : A QuIP round robin test]. / Nachweis der BRAF-V600E-Mutation beim metastasierten kolorektalen Karzinom : Ein QuIP-Ringversuch.

Round robin testing is an important instrument for quality assurance. Increasingly, this also applies to the results of molecular diagnostics in pathology, which directly influence therapy decisions in precision oncology. In metastatic colorectal carcinoma (mCRC), the focus has been on detecting KRAS and NRAS mutations, whose absence allows therapy with EGFR blocking antibodies. Recently, BRAF has been added as another predictive marker, since mCRC patients with BRAF V600E mutation benefit significantly from treatment with encorafenib (a BRAF inhibitor) in combination with cetuximab (anti-EGFR antibody) after systemic therapy. Due to the approval of this treatment in 2020, it is a pre-requisite that BRAF V600E mutation detection in diagnostic pathologies is reliably performed. Therefore, this round robin test with BRAF V600E testing either by immunohistochemistry or molecular methods was performed. The round robin test results demonstrate that molecular BRAF V600E detection is currently clearly superior to immunohistochemical detection.

[Quality assurance in dMMR and MSI diagnostics]. / Qualitätssicherung in der dMMR- und MSI-Diagnostik.

Deficient mismatch repair (dMMR) and microsatellite instability (MSI) have therapeutic relevance not only for colorectal carcinomas but also for carcinomas of other entities (endometrium, biliary tract, pancreas). In order to guarantee the knowledge and good technical quality necessary for adequate implementation of the corresponding analyses in pathology institutes, the Pathology Quality Assurance Initiative ("Die Qualitätssicherung-Initiative Pathologie") has been offering proficiency tests (PT) for years. It has been shown for the dMMR PT that various antibody clones from different manufacturers provide comparable results in immunohistological examinations, except for slight variations. The difficulty lies in the staining protocol (intensity of staining) and the interpretation of the staining results. The molecular pathological MSI PT has shown a positive trend at a high-quality level over the last three years. Success rates increased from 89 (2018) to 97% (2019/2020). The choice of assay, whether commercial or in-house tests with the designated cutoffs for this purpose, has not been shown to have a significant impact on the PTs in the selected EQA samples.

MSI testing : What's new? What should be considered?

Based on new trial data regarding immune checkpoint inhibitors (ICIs), the detection of high-grade microsatellite instability (MSI-H) or underlying deficient mismatch repair protein (dMMR) is now becoming increasingly important for predicting treatment response. For the first time, a PD­1 ICI (pembrolizumab) has been approved by the European Medicines Agency (EMA) for first-line treatment of advanced (stage IV) dMMR/MSI­H colorectal cancer (CRC). Further indications, such as dMMR/MSI­H endometrial carcinoma (EC), have already succeeded (Dostarlimab, 2nd line treatment) and others are expected to follow before the end of 2021. The question of optimal testing in routine diagnostics should therefore be re-evaluated. Based on a consideration of the strengths and weaknesses of the widely available methods (immunohistochemistry and PCR), a test algorithm is proposed that allows quality assured, reliable, and cost-effective dMMR/MSI­H testing. For CRC and EC, testing is therefore already possible at the primary diagnosis stage, in line with international recommendations (NICE, NCCN). The clinician is therefore enabled from the outset to consider not only the predictive but also the prognostic and predispositional implications of such a test when counseling patients and formulating treatment recommendations. As a basis for quality assurance, participation in interlaboratory comparisons and continuous documentation of results (e.g., QuIP Monitor) are strongly recommended.

[MSI testing : What is new? What should be considered? German version]. / MSI-Testung : Was ist neu? Was ist zu beachten?

Based on new trial data regarding immune checkpoint inhibitors (ICIs), the detection of high-grade microsatellite instability (MSI-H) or underlying deficient mismatch repair protein (dMMR) is now becoming increasingly important for predicting treatment response. For the first time, a PD­1 ICI (pembrolizumab) has been approved by the European Medicines Agency (EMA) for first-line treatment of advanced (stage IV) dMMR/MSI­H colorectal cancer (CRC). Further indications, such as dMMR/MSI­H endometrial carcinoma (EC), have already succeeded (Dostarlimab, 2nd line treatment) and others are expected to follow before the end of 2021. The question of optimal testing in routine diagnostics should therefore be re-evaluated. Based on a consideration of the strengths and weaknesses of the widely available methods (immunohistochemistry and PCR), a test algorithm is proposed that allows quality assured, reliable, and cost-effective dMMR/MSI­H testing. For CRC and EC, testing is therefore already possible at the primary diagnosis stage, in line with international recommendations (NICE, NCCN). The clinician is therefore enabled from the outset to consider not only the predictive but also the prognostic and predispositional implications of such a test when counseling patients and formulating treatment recommendations. As a basis for quality assurance, participation in interlaboratory comparisons and continuous documentation of results (e.g., QuIP Monitor) are strongly recommended.

Favorable therapeutic response after anti-Mesothelin antibody-drug conjugate treatment requires high expression of Mesothelin in tumor cells.

PURPOSE: The cell surface glycoprotein Mesothelin is overexpressed in ovarian, fallopian tube, endometrial, cervical and primary peritoneal cancer and, therefore, might become a particular interesting tumor target in gynecologic oncology. However, even in malignant tumors of the same entity the level of Mesothelin expression varies between individuals, hence it can be expected that the response to Mesothelin-targeting therapies will be variable as well. In this study we explored the therapeutic potency of a novel anti-Mesothelin antibody-drug conjugate (Anetumab ravtansine) as a function of Mesothelin expression in the targeted tumor cells. METHODS: Anti-tumor activity studies were performed in human uterine xenograft tumor models that express Mesothelin at high, moderate or low levels. The antibody-drug conjugate (ADC) was applied in varying doses ranging from 2 to 15 mg/kg at variable intervals in tumor bearing SCID/beige mice and the impact on tumor growth was monitored. RESULTS: The therapeutic response to the anti-Mesothelin ADC correlated closely with the level of Mesothelin expression in tumor cells. Within the applied dose levels complete tumor regression was achieved only in tumors which expressed Mesothelin at particularly high levels (Hela cell tumors). The application of high anti-Mesothelin ADC doses less frequently was more efficious than giving lower doses at a higher frequency. CONCLUSION: The studies confirm the great therapeutic potential of Anetumab ravtansine. However, a favorable treatment outcome requires strong Mesothelin expression in tumor cells. Future clinical trials may benefit from a more rigorous selection of appropriate patients based on the level of Mesothelin expression in their tumor tissue. If, in addition, it is possible to better control side effects by introducing protective measures and by doing so to increase the maximum tolerated dose, Anetumab ravtansine has the potency to become a valuable therapeutic tool, especially in the field of gynecological oncology.

[Quality assurance in diagnostic in situ hybridization-experience of QuIP]. / Qualitätssicherung in der diagnostischen In-situ-Hybridisierung ­ Erfahrungen der QuIP.

The Quality Assurance Initiative Pathology (QuIP) gives pathologists the opportunity to check the methodological processes of immunohistological and molecular diagnostics in a result-oriented manner and obtain a certificate reflecting the quality. For in situ hybridization (ISH), 5 round robin tests were organized in 2019, two recurrent (HER2-ISH gastric carcinomas and HER2-ISH breast carcinomas) and three prototypical (ROS1-NSCLC, ALK1-NSCLC, NTRK). The different round robin tests, which were provided by QuIP, are based on the development in diagnostics and the importance of the therapeutic relevance of the molecules which are tested. The results of the round robin tests in 2019 showed a sensitivity of at least 94.4%, a specificity of at least 96.6%, and a success rate of 85-99%. This reflected the high standard of quality of the round robin test and the participating institutes.

Morphomolecular analysis of the immune tumor microenvironment in human head and neck cancer.

Immunotherapy is effective in head and neck squamous cell carcinoma (HNSCC), but only a minority of patients responds to immune checkpoint blockade (ICB). To contribute to a better understanding of the underlying immune biology, we combined histomorphological evaluation and molecular analysis of the HNSCC immune microenvironment in the TCGA cohort. Analyzing digital HE-stained slides, a method for classification of tumor infiltrating lymphocytes (TILs) in the intra-epithelial compartment (ieTILs, present vs. absent) and the stromal compartment (strTILs, high vs. low) was established. We also analyzed the abundance of eight immune cell populations (estimated from RNAseq data) and PD-L1 mRNA expression. Status of ieTILs and status of strTILs were concordant for 61%, but discordant for 39% of tumors. In univariate survival analysis, ieTILs were a positive prognostic marker for DFS in the study cohort (HR = 0.66, p = 0.015) and in the HPV- subcohort (HR = 0.68, p = 0.04), but not in the HPV + subcohort. T cells were a positive prognostic marker for DFS in the study cohort (HR = 0.80, p = 0.03) and in the HPV + subcohort (HR = 0.20, p = 0.001), but not in the HPV- subcohort. In univariate survival analysis, PD-L1 mRNA expression was neither associated with DFS nor with OS. However, in bivariate and multivariate analyses including both PD-L1 mRNA levels and T cells, PD-L1 was a negative prognostic marker of DFS and OS, while T cells remained a positive prognostic marker. In conclusion, ieTILs and strTILs were non-redundant biomarkers in HNSCC and should be evaluated separately. The identified prognostic markers should be evaluated for predictivity in ICB-treated patients.

B-cell receptor-driven MALT1 activity regulates MYC signaling in mantle cell lymphoma.

Mantle cell lymphoma (MCL) is a mature B-cell lymphoma characterized by poor clinical outcome. Recent studies revealed the importance of B-cell receptor (BCR) signaling in maintaining MCL survival. However, it remains unclear which role MALT1, an essential component of the CARD11-BCL10-MALT1 complex that links BCR signaling to the NF-κB pathway, plays in the biology of MCL. Here we show that a subset of MCLs is addicted to MALT1, as its inhibition by either RNA or pharmacologic interference induced cytotoxicity both in vitro and in vivo. Gene expression profiling following MALT1 inhibition demonstrated that MALT1 controls an MYC-driven gene expression network predominantly through increasing MYC protein stability. Thus, our analyses identify a previously unappreciated regulatory mechanism of MYC expression. Investigating primary mouse splenocytes, we could demonstrate that MALT1-induced MYC regulation is not restricted to MCL, but represents a common mechanism. MYC itself is pivotal for MCL survival because its downregulation and pharmacologic inhibition induced cytotoxicity in all MCL models. Collectively, these results provide a strong mechanistic rationale to investigate the therapeutic efficacy of targeting the MALT1-MYC axis in MCL patients.

Accuracy of diagnostic tests and a new algorithm for diagnosing cytomegalovirus colitis in inflammatory bowel diseases: a diagnostic study.

PURPOSE: The optimal method for detecting CMV colitis in patients with inflammatory bowel disease (IBD) has not been established. We wanted to investigate which diagnostic test would be most accurate when defining CMV colitis rather by the further clinical course than by using another diagnostic modality. METHODS: All consecutive patients with moderately or severely active IBD who had been tested for CMV by PCR, histology, or antigenemia assay at the two campuses CBF and CCM of the Charité - Universitätsmedizin Berlin between September 2006 and September 2009 were included in this retrospective study. During that time, in patients with a positive CMV test, immunosuppressive treatment of any kind was immediately reduced and antiviral treatment was started. This allowed identifying patients who responded to antiviral treatment and those who only responded to later escalation of immunosuppressive therapy. RESULTS: One hundred and nine patients were identified, out of whom nine were considered to have clinically relevant CMV colitis. Sensitivity and specificity were 1 and 0.94 for CMV PCR and 0.5 and 1 for pp65 antigen immunofluorescence assay from peripheral blood, 0.67 and 0.98 for immunohistochemistry, and 0.17 and 0.98 for hematoxylin-eosin staining. When using absence of leukocytosis, splenomegaly, and steroid refractory disease as clinical parameters to test for CMV colitis, blood CMV PCR and immunohistochemistry were able to exclude CMV colitis in negative patients with a 75% likelihood of positive patients to have clinically relevant CMV colitis. CONCLUSIONS: Blood-based CMV PCR together with simple clinical parameters can exclude clinically relevant CMV colitis at a high specificity.

Mesothelin as a target for cervical cancer therapy.

PURPOSE: The cell surface glycoprotein Mesothelin is overexpressed in several tumor entities and novel immune-based therapies are currently under the early clinical evaluation for the treatment of malignant pleura mesothelioma, ovarian cancer, and pancreatic cancer. Cervical cancer has not been recognized as a suitable target for Mesothelin-directed immune therapies so far. METHODS: To exploit a possible role of Mesothelin in cervical cancer treatment, we analysed Mesothelin expression in 79 cervical carcinomas and aligned expressions patterns with tumor growth parameters. A novel anti-Mesothelin drug conjugate (Anetumab Ravtansine) was applied for dose-efficiency studies in a Mesothelin positive tumor model for cervical cancer in Scid mice. RESULTS: In more than three-quarters (77%) of cervical adenocarcinomas, Mesothelin was expressed to high levels. Among squamous cell carcinomas of the cervix uteri expression levels were lower and expression patterns were less intense, but still ranged between 50-60% (57%). A significant correlation between Mesothelin expression levels and tumor grade, metastatic behaviour, and lymph- or hemangiosis was not found. The novel anti-Mesothelin-drug conjugate (Anetumab Ravtansine) showed a substantial dose-dependent therapeutic efficiency in a xenotransplant model for cervical cancer in SCID mice (hela cell tumors). Applying the ADC at a dose of 10 mg/kg twice weekly induced complete tumor regression in 88% of animals within 6 weeks. CONCLUSIONS: Mesothelin should be taken into account as a target in cervical cancer therapy and histological determination of Mesothelin expression should be considered in routine diagnostics of cervical carcinomas.

Immunohistochemical analysis of Bcl-2, nuclear S100A4, MITF and Ki67 for risk stratification of early-stage melanoma - A combined IHC score for melanoma risk stratification.

BACKGROUND AND OBJECTIVES: Overall survival (OS) in patients with early-stage malignant melanoma differs. To date, there are no established prognostic markers. We aimed to contribute to a better understanding of potential prognostic immunohistochemical markers for risk stratification. PATIENTS AND METHODS: 161 surgically resected early-stage malignant melanomas (stage pT1 and pT2) were analyzed for expression of 20 different proteins using immunohistochemistry. The results were correlated with OS. The cohort was randomly split into a discovery and a validation cohort. RESULTS: High Bcl-2 expression, high nuclear S100A4 expression as well as a Ki67 proliferation index of ≥ 20 % were associated with shorter OS. Strong MITF immunoreactivity was a predictor for favorable prognosis. A combination of these four markers resulted in a multi-marker score with significant prognostic value in multivariate survival analysis (HR: 3.704; 95 % CI 1.484 to 9.246; p = 0.005). Furthermore, the score was able to differentiate a low-risk group with excellent OS rates (five-year survival rate: 100 %), an intermediate-risk group (five-year survival rate: 81.8 %) and a high-risk group (five-year survival rate: 52.6 %). The prognostic value was confirmed within the validation cohort. CONCLUSIONS: Combined immunohistochemical analysis of Bcl-2, nuclear S100A4, Ki67 and MITF could contribute to better risk stratification of early-stage malignant melanoma patients.

T-cell repertoires in refractory coeliac disease.

OBJECTIVE: Refractory coeliac disease (RCD) is a potentially hazardous complication of coeliac disease (CD). In contrast to RCD type I, RCD type II is a precursor entity of enteropathy-associated T-cell lymphoma (EATL), which is associated with clonally expanding T-cells that are also found in the sequentially developing EATL. Using high-throughput sequencing (HTS), we aimed to establish the small-intestinal T-cell repertoire (TCR) in CD and RCD to unravel the role of distinct T-cell clonotypes in RCD pathogenesis. DESIGN: DNA extracted from duodenal mucosa specimens of controls (n=9), active coeliacs (n=10), coeliacs on a gluten-free diet (n=9), RCD type I (n=8), RCD type II (n=8) and unclassified Marsh I cases (n=3) collected from 2002 to 2013 was examined by TCRß-complementarity-determining regions 3 (CDR3) multiplex PCR followed by HTS of the amplicons. RESULTS: On average, 106 sequence reads per sample were generated consisting of up to 900 individual TCRß rearrangements. In RCD type II, the most frequent clonotypes (ie, sequence reads with identical CDR3) represent in average 42.6% of all TCRß rearrangements, which was significantly higher than in controls (6.8%; p<0.01) or RCD type I (6.7%; p<0.01). Repeat endoscopies in individual patients revealed stability of clonotypes for up to several years without clinical symptoms of EATL. Dominant clonotypes identified in individual patients with RCD type II were unique and not related between patients. CD-associated, gliadin-dependent CDR3 motifs were only detectable at low frequencies. CONCLUSIONS: TCRß-HTS analysis unravels the TCR in CD and allows detailed analysis of individual TCRß rearrangements. Dominant TCRß sequences identified in patients with RCD type II are unique and not homologous to known gliadin-specific TCR sequences, supporting the assumption that these clonal T-cells expand independent of gluten stimulation.

Interlaboratory concordance of PD-L1 immunohistochemistry for non-small-cell lung cancer.

AIMS: Programmed death ligand 1 (PD-L1) immunohistochemistry has become a mandatory diagnostic test in the treatment of lung cancer. Several research initiatives have started to harmonise the five PD-L1 immunohistochemistry assays that have been used in clinical trials. Here, we report data on interlaboratory and interassay concordance for commercial assays ('assays') and laboratory-developed tests (LDTs) at 10 German testing sites. METHODS AND RESULTS: To assess interlaboratory concordance, a tissue microarray containing 21 pulmonary carcinoma specimens was centrally prepared. Pre-cut sections were stained at 10 sites by the use of assays 28-8, 22C3, SP263, and SP142, as well as 11 LDTs. Assay performance was evaluated with a second tissue microarray containing 11 cell lines with defined PD-L1 expression. Quality control was centrally performed by manual and digital analyses. The assays yielded reproducible IHC staining patterns at all sites. In agreement with previous studies, 22C3, 28-8 and SP263 showed similar staining patterns, whereas SP142 was distinct. Among the LDTs, six of 11 protocols showed staining patterns similar to those of assays 22C3 and 28-8. Interlaboratory concordance of tumour cell scoring by use of a six-step system was moderate (Light's κ = 0.43-0.69), whereas the clinically approved cut-offs of ≥1% and ≥50% showed substantial concordance (κ = 0.73-0.89). Immune cell scoring by the use of SP142 yielded moderate concordance (κ = 0.42). CONCLUSIONS: The data confirm the previously described staining patterns of the assays, and show that they can be reproducibly employed at different sites. LDTs with staining results similar to those of the assays are implementable, but have to be carefully validated.

Intratumoral morphological heterogeneity can be an indicator of genetic heterogeneity in colorectal cancer.

Anti-EGFR-targeted therapy is used to treat metastatic colorectal cancers with RAS wild-type. However, resistance to targeted therapy is often observed and can be primary or acquired. One reason for primary resistance is the presence of mutations that are undetected due to genetic heterogeneity, which can be expressed by differences present in primary tumor and distant metastasis or recurrence or by an intratumoral heterogeneity (presence of different subclones in the investigated tumor sample). The aim of our study was to investigate if morphological heterogeneity can be an indicator of intratumoral heterogeneity. We analysed 13 samples with homogeneous and six samples with heterogeneous morphology with NGS. We were able to demonstrate that intratumoral genetic heterogeneity is present in all studied tumor samples, independent of homogeneous or heterogeneous morphology. Moreover, one sample of our cohort with morphological and genetic heterogeneity had a genetic wild-type profile in one tumor component. Therefore, we recommend to include each morphologically identifiable tumor component in the mutational analysis to not overlook resistance-inducing or potentially targetable mutations.