Publications by authors named "Wilko Weichert"

395 Publications

Comprehensive Genomic and Transcriptomic Analysis for Guiding Therapeutic Decisions in Patients with Rare Cancers.

Cancer Discov 2021 Jun 10. Epub 2021 Jun 10.

Omics IT and Data Management Core Facility, German Cancer Research Center.

The clinical relevance of comprehensive molecular analysis in rare cancers is not established. We analyzed the molecular profiles and clinical outcomes of 1,310 patients (rare cancers, 75.5%) enrolled in a prospective observational study by the German Cancer Consortium that applies whole-genome/exome and RNA sequencing to inform the care of adults with incurable cancers. Based on 472 single and six composite biomarkers, a cross-institutional molecular tumor board provided evidence-based management recommendations, including diagnostic reevaluation, genetic counseling, and experimental treatment, in 88% of cases. Recommended therapies were administered in 362 of 1,138 patients (31.8%) and resulted in significantly improved overall response and disease control rates (23.9% and 55.3%) compared to previous therapies, translating into a progression-free survival ratio >1.3 in 35.7% of patients. These data demonstrate the benefit of molecular stratification in rare cancers and represent a resource that may promote clinical trial access and drug approvals in this underserved patient population.
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http://dx.doi.org/10.1158/2159-8290.CD-21-0126DOI Listing
June 2021

Morphology Matters: A Critical Reappraisal of the Clinical Relevance of Morphologic Criteria From the 2019 WHO Classification in a Large Colorectal Cancer Cohort Comprising 1004 Cases.

Am J Surg Pathol 2021 Jul;45(7):969-978

Institute of Pathology.

The 2019 World Health Organization (WHO) classification of colorectal carcinoma (CRC) profoundly reclassified CRC subtypes and introduces tumor budding as a second major grading criterion, while condensing conventional grade into a 2-tiered system. So far it remains largely unexplored how these parameters interact with each other and whether they truly have an independent impact on patient prognosis. We reclassified a large single-center cohort of 1004 CRCs spanning 2 decades for adjusted WHO grade (low vs. high), tumor budding (Bd1/Bd2/Bd3), and CRC subtype (adenocarcinoma not otherwise specified, micropapillary, mucinous, serrated, medullary, adenoma-like, signet-ring cell, mixed adenoneuroendocrine carcinoma/neuroendocrine carcinoma, undifferentiated) according to the criteria of the 2019 WHO classification. We investigated the interaction of these parameters, their connection to stage/microsatellite status, and their significance for patient survival in the different subgroups. Specific subtypes other than adenocarcinoma not otherwise specified represented one third of all CRCs and were unevenly distributed throughout stage and microsatellite subgroups. Subtypes, WHO grade and tumor budding profoundly impacted all survival parameters (P<0.001 for all analyses), with CRC subtypes and tumor budding-but not WHO grade-being stage-independent prognosticators for all survival comparisons. WHO grade had very limited prognostic value in CRC subtypes, while tumor budding retained its strong prognostic impact in most scenarios. Accurate delineation of CRC subtypes introduced in the 2019 WHO classification provides strong stage-independent prognostic information, arguing that they should be considered in pathology reports and in clinical trials. Of the morphology-based grading schemes included in the 2019 WHO, tumor budding outperforms WHO grade.
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http://dx.doi.org/10.1097/PAS.0000000000001692DOI Listing
July 2021

[MSI testing : What is new? What should be considered? German version].

Pathologe 2021 May 27. Epub 2021 May 27.

Institut für Pathologie, Universitätsklinikum Köln, Kerpener Str. 62, 50937, Köln, Deutschland.

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 PD‑1 ICI (pembrolizumab) has been approved by the European Medicines Agency (EMA) for first-line treatment of advanced (stage IV) dMMR/MSI‑H colorectal cancer (CRC). Further indications, such as dMMR/MSI‑H 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/MSI‑H 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.
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http://dx.doi.org/10.1007/s00292-021-00944-7DOI Listing
May 2021

Implementation of Mass Spectrometry Imaging in Pathology: Advances and Challenges.

Clin Lab Med 2021 Jun 24;41(2):173-184. Epub 2021 Apr 24.

Institute of Pathology, Technical University of Munich, Trogerstr. 18, 81675 Munich, Germany. Electronic address:

Mass spectrometry imaging (MSI) combines the excellence in molecular characterization of mass spectrometry with microscopic imaging capabilities of hematoxylin- and eosin-stained samples, enabling the precise location of several analytes in the tissue. Especially in the field of pathology, MSI may have an impactful role in tumor diagnosis, biomarker identification, prognostic prediction, and characterization of tumor margins during tumor resection procedures. This article discusses the recent developments in the field that are paving the way for this technology to become accepted as an analytical tool in the clinical setting, its current limitations, and future directions.
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http://dx.doi.org/10.1016/j.cll.2021.03.001DOI Listing
June 2021

Conventional and semi-automatic histopathological analysis of tumor cell content for multigene sequencing of lung adenocarcinoma.

Transl Lung Cancer Res 2021 Apr;10(4):1666-1678

Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Background: Targeted genetic profiling of tissue samples is paramount to detect druggable genetic aberrations in patients with non-squamous non-small cell lung cancer (NSCLC). Accurate upfront estimation of tumor cell content (TCC) is a crucial pre-analytical step for reliable testing and to avoid false-negative results. As of now, TCC is usually estimated on hematoxylin-eosin (H&E) stained tissue sections by a pathologist, a methodology that may be prone to substantial intra- and interobserver variability. Here we the investigate suitability of digital pathology for TCC estimation in a clinical setting by evaluating the concordance between semi-automatic and conventional TCC quantification.

Methods: TCC was analyzed in 120 H&E and thyroid transcription factor 1 (TTF-1) stained high-resolution images by 19 participants with different levels of pathological expertise as well as by applying two semi-automatic digital pathology image analysis tools (HALO and QuPath).

Results: Agreement of TCC estimations [intra-class correlation coefficients (ICC)] between the two software tools (H&E: 0.87; TTF-1: 0.93) was higher compared to that between conventional observers (0.48; 0.47). Digital TCC estimations were in good agreement with the average of human TCC estimations (0.78; 0.96). Conventional TCC estimators tended to overestimate TCC, especially in H&E stainings, in tumors with solid patterns and in tumors with an actual TCC close to 50%.

Conclusions: Our results determine factors that influence TCC estimation. Computer-assisted analysis can improve the accuracy of TCC estimates prior to molecular diagnostic workflows. In addition, we provide a free web application to support self-training and quality improvement initiatives at other institutions.
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http://dx.doi.org/10.21037/tlcr-20-1168DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8107748PMC
April 2021

uPA-PAI-1 heteromerization promotes breast cancer progression by attracting tumorigenic neutrophils.

EMBO Mol Med 2021 Jun 16;13(6):e13110. Epub 2021 May 16.

Department of Otorhinolaryngology, University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany.

High intratumoral levels of urokinase-type plasminogen activator (uPA)-plasminogen activator inhibitor-1 (PAI-1) heteromers predict impaired survival and treatment response in early breast cancer. The pathogenetic role of this protein complex remains obscure. Here, we demonstrate that heteromerization of uPA and PAI-1 multiplies the potential of the single proteins to attract pro-tumorigenic neutrophils. To this end, tumor-released uPA-PAI-1 utilizes very low-density lipoprotein receptor and mitogen-activated protein kinases to initiate a pro-inflammatory program in perivascular macrophages. This enforces neutrophil trafficking to cancerous lesions and skews these immune cells toward a pro-tumorigenic phenotype, thus supporting tumor growth and metastasis. Blockade of uPA-PAI-1 heteromerization by a novel small-molecule inhibitor interfered with these events and effectively prevented tumor progression. Our findings identify a therapeutically targetable, hitherto unknown interplay between hemostasis and innate immunity that drives breast cancer progression. As a personalized immunotherapeutic strategy, blockade of uPA-PAI-1 heteromerization might be particularly beneficial for patients with highly aggressive uPA-PAI-1 tumors.
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http://dx.doi.org/10.15252/emmm.202013110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8185543PMC
June 2021

[Predictive diagnostics for checkpoint inhibitors].

Pathologe 2021 May 6. Epub 2021 May 6.

Institut für Pathologie, Technische Universität München, München, Deutschland.

Checkpoint inhibitors have revolutionized oncological treatment in many cancers and added a new immuno-oncological treatment pillar to the medicinal arsenal of conventional and molecularly targeted therapies. In monotherapy and in combination therapies, however, not all patients respond equally well, even in generally responsive tumor entities. Therefore, since the introduction of these therapies, a major focus has been the research on and implementation of predictive markers for patient selection. The first established biomarker, the expression of the target molecule PD-L1, has found its way into routine diagnostics in a large number of unfortunately very divergent diagnostic constellations in multiple entities. In addition, some molecular predictors, including the measurement of microsatellite instability and tumor mutational burden, have also been suggested and in some cases are already implemented into routine diagnostics. Additional molecular parameters have been proposed but most of them have not yet found their way into routine patient care. This review article discusses the current status and recent developments in the field of diagnostic response predictors in the context of an immune checkpoint blockade.
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http://dx.doi.org/10.1007/s00292-021-00939-4DOI Listing
May 2021

Prediction of Tumor Cellularity in Resectable PDAC from Preoperative Computed Tomography Imaging.

Cancers (Basel) 2021 Apr 25;13(9). Epub 2021 Apr 25.

Institute of Diagnostic and Interventional Radiology, School of Medicine, Technical University of Munich, 81675 Munich, Germany.

Background: PDAC remains a tumor entity with poor prognosis and a 5-year survival rate below 10%. Recent research has revealed invasive biomarkers, such as distinct molecular subtypes, predictive for therapy response and patient survival. Non-invasive prediction of individual patient outcome however remains an unresolved task.

Methods: Discrete cellularity regions of PDAC resection specimen ( = 43) were analyzed by routine histopathological work up. Regional tumor cellularity and CT-derived Hounsfield Units (HU, = 66) as well as iodine concentrations were regionally matched. One-way ANOVA and pairwise t-tests were performed to assess the relationship between different cellularity level in conventional, virtual monoenergetic 40 keV (monoE 40 keV) and iodine map reconstructions.

Results: A statistically significant negative correlation between regional tumor cellularity in histopathology and CT-derived HU from corresponding image regions was identified. Radiological differentiation was best possible in monoE 40 keV CT images. However, HU values differed significantly in conventional reconstructions as well, indicating the possibility of a broad clinical application of this finding.

Conclusion: In this study we establish a novel method for CT-based prediction of tumor cellularity for in-vivo tumor characterization in PDAC patients.
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http://dx.doi.org/10.3390/cancers13092069DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8123300PMC
April 2021

The Chemokine CX3CL1 Improves Trastuzumab Efficacy in HER2 Low-Expressing Cancer and .

Cancer Immunol Res 2021 Apr 27. Epub 2021 Apr 27.

Department of Gynecology and Obstetrics, Technical University of Munich, Munich, Germany.

A crucial mode of action of trastuzumab is the labeling of HER2-positive (HER2) tumor cells for the eradication by natural killer (NK) cells, a process called antibody-dependent cellular cytotoxicity (ADCC). However, despite widespread HER2 expression among cancer entities, only a fraction, with robust HER2 overexpression, benefits from trastuzumab therapy. ADCC requires both sufficient lymphocytic infiltration and close binding of the immune cells to the antibody-tagged tumor cells. We hypothesized that the chemokine CX3CL1 could improve both processes, as it is synthesized as a membrane-bound, adhesive form that is eventually cleaved into a soluble, chemotactic protein. Here, we show that CX3CL1 overexpression is a positive prognostic marker in breast cancer. CX3CL1 overexpression attracted tumor-suppressive lymphocytes, including NK cells, and inhibited tumor growth and lung metastasis in the syngeneic 4T1 breast cancer mouse model. In HER2 SKBR3, MDA-MB-453, and HT-29 tumor cells, CX3CL1 overexpression increased NK cell-mediated cytotoxicity and acted synergistically with trastuzumab. Even though CX3CL1 did not further improve trastuzumab efficacy in the trastuzumab-sensitive MDA-MB-453 model, it compensated for NK-cell depletion and prolonged survival. In the HER2 low-expressing HT-29 model, however, CX3CL1 overexpression not only prolonged survival time but also overcame trastuzumab resistance in a partly NK cell-dependent manner. Taken together, these findings identify CX3CL1 as a feasible pharmacologic target to enable trastuzumab therapy in HER2 low-expressing cancers and render it a potential predictive biomarker to determine therapy responders.
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http://dx.doi.org/10.1158/2326-6066.CIR-20-0327DOI Listing
April 2021

Sexual Difference Matters: Females with High Microsatellite Instability Show Increased Survival after Neoadjuvant Chemotherapy in Gastric Cancer.

Cancers (Basel) 2021 Mar 2;13(5). Epub 2021 Mar 2.

Institute of Pathology, TUM School of Medicine, Technical University of Munich, 81675 Munich, Germany.

We aimed to investigate patients with gastric/gastro-esophageal adenocarcinomas for sex- and age-specific differences regarding overall survival (OS) and response to neoadjuvant chemotherapy (CTx) under consideration of tumor specific molecular subtypes. Overall, 717 patients were analyzed, including 426 patients treated with and 291 treated without neoadjuvant CTx. Microsatellite instability (MSI) and Epstein-Barr virus positivity (EBV+) were determined previously. Females demonstrated a significantly increased OS ( 0.035), particularly in the subgroup treated with CTx ( 0.054). No significant differences regarding age were found. In the molecular subgroups, no sex-related differences were observed in the non-CTx group. However in the CTx group, females with MSI-high (H) tumors showed the best OS ( 0.043), followed by the male MSI-H ( 0.198) and female MSS ( 0.114) compared to the male MSS group as reference. The interaction between sex and MSI in this patient group was noticeable ( 0.053) and was included as a relevant factor in multivariable analyses. In conclusion, our results show an effect of sex on OS in gastric/gastro-esophageal cancer specifically for patients treated with neoadjuvant CTx. The superior survival of women with MSI-H tumors after neoadjuvant CTx implies that combined consideration of these factors could contribute to an individualized treatment of the patients.
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http://dx.doi.org/10.3390/cancers13051048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7958600PMC
March 2021

PALLD mutation in a European family conveys a stromal predisposition for familial pancreatic cancer.

JCI Insight 2021 Mar 25;6(8). Epub 2021 Mar 25.

Klinik und Poliklinik für Innere Medizin II, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.

BACKGROUNDPancreatic cancer is one of the deadliest cancers, with low long-term survival rates. Despite recent advances in treatment, it is important to identify and screen high-risk individuals for cancer prevention. Familial pancreatic cancer (FPC) accounts for 4%-10% of pancreatic cancers. Several germline mutations are related to an increased risk and might offer screening and therapy options. In this study, we aimed to identity of a susceptibility gene in a family with FPC.METHODSWhole exome sequencing and PCR confirmation was performed on the surgical specimen and peripheral blood of an index patient and her sister in a family with high incidence of pancreatic cancer, to identify somatic and germline mutations associated with familial pancreatic cancer. Compartment-specific gene expression data and immunohistochemistry were also queried.RESULTSThe identical germline mutation of the PALLD gene (NM_001166108.1:c.G154A:p.D52N) was detected in the index patient with pancreatic cancer and the tumor tissue of her sister. Whole genome sequencing showed similar somatic mutation patterns between the 2 sisters. Apart from the PALLD mutation, commonly mutated genes that characterize pancreatic ductal adenocarcinoma were found in both tumor samples. However, the 2 patients harbored different somatic KRAS mutations (G12D and G12V). Healthy siblings did not have the PALLD mutation, indicating a disease-specific impact. Compartment-specific gene expression data and IHC showed expression in cancer-associated fibroblasts (CAFs).CONCLUSIONWe identified a germline mutation of the palladin (PALLD) gene in 2 siblings in Europe, affected by familial pancreatic cancer, with a significant overexpression in CAFs, suggesting that stromal palladin could play a role in the development, maintenance, and/or progression of pancreatic cancer.FUNDINGDFG SFB 1321.
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http://dx.doi.org/10.1172/jci.insight.141532DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8119201PMC
March 2021

Therapy response and prognosis of patients with early breast cancer with low positivity for hormone receptors - An analysis of 2765 patients from neoadjuvant clinical trials.

Eur J Cancer 2021 May 18;148:159-170. Epub 2021 Mar 18.

German Breast Group (GBG Forschungs GmbH), Neu-Isenburg, Germany. Electronic address:

Aim: To evaluate HER2-negative breast cancer (BC) with a low hormone receptor (HR) expression, with regard to pathological complete response (pCR) and survival, in comparison to triple-negative BC (TNBC) and strong HR-positive BC.

Methods: We compared negative [oestrogen (ER) and progesterone receptor (PR) <1%], low-positive (ER and/or PR 1-9%) and strong-positive (ER or PR 10-100%) HR-expression in neoadjuvant clinical trial cohorts (n = 2765) of BC patients. End-points were disease-free survival (DFS), distant-disease free survival (DDFS) and overall survival (OS). We performed RNA sequencing on available tumour tissue samples from patients with low-HR expression (n = 38).

Results: Ninety-four (3.4%) patients had low HR-positive tumours, 1769 (64.0%) had strong HR-positive tumours, and 902 (32.6%) had TNBC. There were no significant differences in pCR rates between women with low HR-positive tumours (27.7%) and women with TNBC (35.5%). DFS and DDFS were also not different [for DFS, hazard ratio 1.26, 95%-CI (confidence interval) : 0.87-1.83, log-rank test p = 0.951; for DDFS, hazard ratio 1.17, 95%-CI: 0.78-1.76, log-rank test p = 0.774]. Patients with strong HR-positive tumours had a significantly lower pCR rate (pCR 9.4%; odds ratio 0.38, 95%-CI: 0.23-0.63), but better DFS (hazard ratio 0.48, 95%-CI: 0.33-0.70) and DDFS (hazard ratio 0.49, 95%-CI: 0.33-0.74) than patients with low HR-positive tumours. Molecular subtyping (RNA sequencing) of low HR-positive tumours classified these predominantly into a basal subtype (86.8%).

Conclusion: Low HR-positive, HER2-negative tumours have a similar clinical behaviour to TNBC showing high pCR rates and poor survival and also a basal-like gene expression signature. Patients with low HR-positive tumours should be regarded as candidates for therapy strategies targeting TNBC.
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http://dx.doi.org/10.1016/j.ejca.2021.02.020DOI Listing
May 2021

Differential Effects of Trp53 Alterations in Murine Colorectal Cancer.

Cancers (Basel) 2021 Feb 15;13(4). Epub 2021 Feb 15.

Department of Surgery, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany.

Background: Colorectal cancer (CRC) development is a multi-step process resulting in the accumulation of genetic alterations. Despite its high incidence, there are currently no mouse models that accurately recapitulate this process and mimic sporadic CRC. We aimed to develop and characterize a genetically engineered mouse model (GEMM) of Apc/Kras/Trp53 mutant CRC, the most frequent genetic subtype of CRC.

Methods: Tumors were induced in mice with conditional mutations or knockouts in Apc, Kras, and Trp53 by a segmental adeno-cre viral infection, monitored via colonoscopy and characterized on multiple levels via immunohistochemistry and next-generation sequencing.

Results: The model accurately recapitulates human colorectal carcinogenesis clinically, histologically and genetically. The Trp53 R172H hotspot mutation leads to significantly increased metastatic capacity. The effects of Trp53 alterations, as well as the response to treatment of this model, are similar to human CRC. Exome sequencing revealed spontaneous protein-modifying alterations in multiple CRC-related genes and oncogenic pathways, resulting in a genetic landscape resembling human CRC.

Conclusions: This model realistically mimics human CRC in many aspects, allows new insights into the role of TP53 in CRC, enables highly predictive preclinical studies and demonstrates the value of GEMMs in current translational cancer research and drug development.
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http://dx.doi.org/10.3390/cancers13040808DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7919037PMC
February 2021

Detection of gene fusions using targeted next-generation sequencing: a comparative evaluation.

BMC Med Genomics 2021 02 27;14(1):62. Epub 2021 Feb 27.

Institute of Pathology, University Hospital Cologne, Kerpener Str. 62, 50937, Cologne, Germany.

Background: Gene fusions represent promising targets for cancer therapy in lung cancer. Reliable detection of multiple gene fusions is therefore essential.

Methods: Five commercially available parallel sequencing assays were evaluated for their ability to detect gene fusions in eight cell lines and 18 FFPE tissue samples carrying a variety of known gene fusions. Four RNA-based assays and one DNA-based assay were compared; two were hybrid capture-based, TruSight Tumor 170 Assay (Illumina) and SureSelect XT HS Custom Panel (Agilent), and three were amplicon-based, Archer FusionPlex Lung Panel (ArcherDX), QIAseq RNAscan Custom Panel (Qiagen) and Oncomine Focus Assay (Thermo Fisher Scientific).

Results: The Illumina assay detected all tested fusions and showed the smallest number of false positive results. Both, the ArcherDX and Qiagen panels missed only one fusion event. Among the RNA-based assays, the Qiagen panel had the highest number of false positive events. The Oncomine Focus Assay (Thermo Fisher Scientific) was the least adequate assay for our purposes, seven fusions were not covered by the assay and two fusions were classified as uncertain. The DNA-based SureSelect XT HS Custom Panel (Agilent) missed three fusions and nine fusions were only called by one software version. Additionally, many false positive fusions were observed.

Conclusions: In summary, especially RNA-based parallel sequencing approaches are potent tools for reliable detection of targetable gene fusions in clinical diagnostics.
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http://dx.doi.org/10.1186/s12920-021-00909-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7912891PMC
February 2021

KRAS G12C-mutated advanced non-small cell lung cancer: A real-world cohort from the German prospective, observational, nation-wide CRISP Registry (AIO-TRK-0315).

Lung Cancer 2021 04 13;154:51-61. Epub 2021 Feb 13.

Pius-Hospital Oldenburg, Universitätsklinik für Innere Medizin, Oldenburg, Germany.

Objectives: After decades of unsuccessful efforts in inhibiting KRAS, promising clinical data targeting the mutation subtype G12C emerge. Since little is known about outcome with standard treatment of patients with G12C mutated non-small cell lung cancer (NSCLC), we analyzed a large, representative, real-world cohort from Germany.

Patients And Methods: A total of 1039 patients with advanced KRAS-mutant or -wildtype NSCLC without druggable alterations have been recruited in the prospective, observational registry CRISP from 12/2015 to 06/2019 by 98 centers in Germany. Details on treatment, best response, and outcome were analyzed for patients with KRAS wildtype, G12C, and non-G12C mutations.

Results: Within the study population, 160 (15.4 %) patients presented with KRAS G12C, 251 (24.2 %) with non-G12C mutations, 628 (60.4 %) with KRAS wildtype. High PD-L1 expression (Tumor Proportion Score, TPS > 50 %) was documented for 28.0 %, 43.5 %, and 28.9 % (wildtype, G12C, non-G12C) of the tested patients; 68.8 %, 89.3 %, and 87.7 % of the patients received first-line treatment combined with an immune checkpoint-inhibitor in 2019. TPS > 50 % vs. TPS < 1 % was associated with a significantly decreased risk of mortality in a multivariate Cox model (HR 0.39, 95 % CI 0.26-0.60, p=<0.001). There were no differences in clinical outcome between KRAS wildtype, G12C or non-G12C mutations and KRAS mutational status was not prognostic in the model.

Conclusion: Here we describe the so far largest prospectively recruited cohort of patients with advanced NSCLC and KRAS mutations, with special focus on the G12C mutation. These data constitute an extremely valuable historical control for upcoming clinical studies that employ KRAS inhibitors.
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http://dx.doi.org/10.1016/j.lungcan.2021.02.005DOI Listing
April 2021

Biomarker testing in non-small cell lung cancer in routine care: Analysis of the first 3,717 patients in the German prospective, observational, nation-wide CRISP Registry (AIO-TRK-0315).

Lung Cancer 2021 02 2;152:174-184. Epub 2020 Nov 2.

Onkologie der Thoraxtumore, Thoraxklinik Heidelberg gGmbH, German Center for Lung Research (DZL), Germany.

Objectives: An increasing number of treatment-determining biomarkers has been identified in non-small cell lung cancer (NSCLC) and molecular testing is recommended to enable optimal individualized treatment. However, data on implementation of these recommendations in the "real-world" setting are scarce. This study presents comprehensive details on the frequency, methodology and results of biomarker testing of advanced NSCLC in Germany.

Patients And Methods: This analysis included 3,717 patients with advanced NSCLC (2,921 non-squamous; 796 squamous), recruited into the CRISP registry at start of systemic therapy by 150 German sites between December 2015 and June 2019. Evaluated were the molecular biomarkers EGFR, ALK, ROS1, BRAF, KRAS, MET, TP53, RET, HER2, as well as expression of PD-L1.

Results: In total, 90.5 % of the patients were tested for biomarkers. Testing rates were 92.2 % (non-squamous), 70.7 % (squamous) and increased from 83.2 % in 2015/16 to 94.2% in 2019. Overall testing rates for EGFR, ALK, ROS1, and BRAF were 72.5 %, 74.5 %, 66.1 %, and 53.0 %, respectively (non-squamous). Testing rates for PD-L1 expression were 64.5 % (non-squamous), and 58.5 % (squamous). The most common testing methods were immunohistochemistry (68.5 % non-squamous, 58.3 % squamous), and next-generation sequencing (38.7 % non-squamous, 14.4 % squamous). Reasons for not testing were insufficient tumor material or lack of guideline recommendations (squamous). No alteration was found in 37.8 % (non-squamous), and 57.9 % (squamous), respectively. Most common alterations in non-squamous tumors (all patients/all patients tested for the respective biomarker): KRAS (17.3 %/39.2 %), TP53 (14.1 %/51.4 %), and EGFR (11.0 %/15.1 %); in squamous tumors: TP53 (7.0 %/69.1 %), MET (1.5 %/11.1 %), and EGFR (1.1 %/4.4 %). Median PFS (non-squamous) was 8.7 months (95 % CI 7.4-10.4) with druggable EGFR mutation, and 8.0 months (95 % CI 3.9-9.2) with druggable ALK alterations.

Conclusion: Testing rates in Germany are high nationwide and acceptable in international comparison, but still leave out a significant portion of patients, who could potentially benefit. Thus, specific measures are needed to increase implementation.
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http://dx.doi.org/10.1016/j.lungcan.2020.10.012DOI Listing
February 2021

The immunologic tumor microenvironment in endometrioid endometrial cancer in the morphomolecular context: mutual correlations and prognostic impact depending on molecular alterations.

Cancer Immunol Immunother 2021 Jun 19;70(6):1679-1689. Epub 2020 Dec 19.

Institute of Pathology, Technical University Munich, Trogerstrasse 18, 81675, Munich, Germany.

Objective: POLE-mutant, microsatellite-instable (MSI), p53-mutant and non-specific molecular profile (NSMP) are TCGA-defined molecular subgroups of endometrial cancer (EC). Hypothesizing that morphology and tumor immunology might differ depending on molecular background concerning composition and prognostic impact, we aimed to comprehensively interconnect morphologic, immunologic and molecular data.

Methods: TCGA-defined molecular groups were determined by immunohistochemistry and sequencing in n = 142 endometrioid EC. WHO-defined histopathological grading was performed. The immunologic microenvironment (iTME) was characterised by the quantification of intraepithelial and stromal populations of tumor-infiltrating lymphocytes (TIL: overall T-cells; T-Killer cells; regulatory T-cells (Treg)). Immunologic parameters were correlated with WHO-grading, TCGA-subgroups and prognosis.

Results: High density TIL were significantly more frequent in high-grade (G3) compared to low-grade (G1/2) EC in the whole cohort and in the subgroup of POLE-wildtype-/microsatellite-stable-EC. MSI was associated with high-level TIL-infiltration when taking into account the type of mismatch repair defect (MLH1/PMS2; MSH2/MSH6). Prognostic impact of biomarkers depended on molecular subgroups: In p53-mutant EC, Treg were independently prognostic, in NSMP, the unique independently prognostic biomarker was WHO-grading.

Conclusions: EC morphology and immunology differ depending on genetics. Our study delineated two molecularly distinct subgroups of immunogenic EC characterized by high-density TIL-infiltration: MSI EC and high-grade POLE-wildtype/microsatellite-stable-EC. Prognostic impact of TIL-populations relied on TCGA-subgroups indicating specific roles for TIL depending on molecular background. In NSMP, histopathological grading was the only prognostic biomarker demonstrating the relevance of WHO-grading in an era of molecular subtyping.
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http://dx.doi.org/10.1007/s00262-020-02813-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8139910PMC
June 2021

Do Canine Pancreatic Neuroendocrine Neoplasms Resemble Human Pancreatic Neuroendocrine Tumours? A Comparative Morphological and Immunohistochemical Investigation.

J Comp Pathol 2020 Nov 17;181:73-85. Epub 2020 Nov 17.

Institute of Pathology, School of Medicine, Technical University of Munich, Munich, Germany.

Although canine pancreatic neuroendocrine neoplasms (PanNENs) have been proposed as a model for the counterpart human neoplasms, the type or grade of human PanNEN that they resemble is unclear. PanNENs in animals are classified as adenoma or carcinoma, whereas in humans they are classified as pancreatic neuroendocrine tumour (PanNET) if well-differentiated, or as pancreatic neuroendocrine carcinoma (PanNEC) if poorly differentiated. We evaluated 16 canine primary PanNENs and two metastases histologically and immunohistochemically, and graded them using the animal and human grading systems. All neoplasms had local or vascular invasion and were classified as pancreatic islet cell carcinomas according to the current WHO classification. The Ki-67 index was low in all cases (0.01-1.50%). All had cytoplasmic expression of synaptophysin and insulin but were immunonegative for glucagon, confirming a functional diagnosis of canine insulinoma. Membranous expression of SSTR2A and nuclear expression of ATRX, but no p53 expression, was found in all neoplasms. One primary tumour was diagnosed as a mixed neuroendocrine-non-neuroendocrine neoplasm, which is the first report of this neoplasm in dogs. The other 15 primary tumours and both metastatic tumours were graded as PanNET G1, according to the human WHO classification. We conclude that canine PanNENs share well-differentiated histomorphology, SSTR2A expression and absence of nuclear p53 immunolabelling with human PanNETs G1. However, they differ in ATRX gene expression and functionality, and seem to have a worse prognosis than human PanNETs G1, although their generally low Ki-67 index precludes more precise assessment of prognosis. Membranous SSTR2A expression renders canine PanNENs potentially amenable to treatment with somatostatin analogues or SSTR targeted in-vivo imaging methods.
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http://dx.doi.org/10.1016/j.jcpa.2020.10.001DOI Listing
November 2020

[Impact of the novel in vitro diagnostic regulation (IVDR) of the European Union on pathology laboratories. What's important?]

Pathologe 2020 Dec;41(Suppl 2):129-133

Institut für Pathologie, Technische Universität München, München, Deutschland.

In 2022 the new in vitro diagnostic regulation (IVDR) of the European Union will come into full effect. This complex regulatory framework aims at a stricter regulation and monitoring of industrial diagnostic assay production. The IVDR defines many new methodological requirements and includes an additional entirely new focus on the clinical validity of diagnostic assays as well as a novel tighter vigilance system. Although not the core of the regulation, the whole field of laboratory developed tests (LDTs) is also subject to fundamental restructuring within this regulatory framework. The respective requirements are broad and will pose many challenges to assay developers and users in pathology. The many new aspects of LDT production and use must be properly addressed to avoid a bottleneck in diagnostic assay availability. In this article, the impact of the different aspects of the IVDR on European pathology laboratories will be discussed.
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http://dx.doi.org/10.1007/s00292-020-00867-9DOI Listing
December 2020

[Diagnosis and therapy of tumors with NTRK gene fusion].

Pathologe 2021 Feb;42(1):103-115

Klinik für Innere Medizin I, Universitätsklinikum Ulm, Ulm, Deutschland.

NTRK gene fusions are sporadic genetic alterations that can occur across tumor entities. Whereas they are quite rare in most solid tumors they are present at much higher frequencies in certain rare tumors such as infantile fibrosarcoma, congenital mesoblastic nephroma, secretory breast, or salivary gland carcinoma. NTRK gene fusions or TRK fusion proteins are considered strong oncogenic drivers. If NTRK gene fusions are detected, TRK inhibitors such as entrectinib and larotrectinib can be used regardless of the tumor entity. So far only larotrectinib is approved in the European Union. Both drugs have been shown to be effective and well tolerated in phase I and phase II studies. The low prevalence of TRK fusion-positive cancers poses challenges for diagnostic and clinical work-flows. On one hand, patients with NTRK gene fusions should be identified; on the other hand, epidemiological, histological, and resource-related aspects have to be taken into account. Based on these premises, we suggest a diagnostic algorithm for TRK fusion cancers and present current data on TRK inhibitors.
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http://dx.doi.org/10.1007/s00292-020-00864-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7858552PMC
February 2021

Circulating Interleukin-4 Is Associated with a Systemic T Cell Response against Tumor-Associated Antigens in Treatment-Naïve Patients with Resectable Non-Small-Cell Lung Cancer.

Cancers (Basel) 2020 Nov 24;12(12). Epub 2020 Nov 24.

Regensburg Center for Interventional Immunology and Regensburg University Hospital, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany.

Spontaneous T cell responses to tumor-associated antigens (TAs) in the peripheral blood of patients with non-small-cell lung cancer (NSCLC) may be relevant for postoperative survival. However, the conditions underlying these T cell responses remain unclear. We quantified the levels of 27 cytokines in the peripheral blood and tumor tissues from treatment-naïve patients with NSCLC ( = 36) and analyzed associations between local and systemic cytokine profiles and both TA-specific T cell responses and clinical parameters. We defined T cell responders as patients with circulating T cells that were reactive to TAs and T cell nonresponders as patients without detectable TA-specific T cells. TA-specific T cell responses were correlated with serum cytokine levels, particularly the levels of interleukin(IL)-4 and granulocyte colony-stimulating factor (G-CSF), but poorly correlated with the cytokine levels in tumor tissues. Nonresponders showed significantly higher serum IL-4 levels than responders ( = 0.03); the predicted probability of being a responder was higher for individuals with low serum IL-4 levels. In multivariable Cox regression analyses, in addition to IL-4 (hazard ratio (HR) 2.8 (95% confidence interval (CI): 0.78-9.9); = 0.116), the age-adjusted IL-8 level (HR 3.9 (95% CI: 1.05-14.5); = 0.042) predicted tumor recurrence. However, this study included data for many cytokines without adjustment for multiple testing; thus, the observed differences in IL-4 or IL-8 levels might be incidental findings. Therefore, additional studies are necessary to confirm these results.
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http://dx.doi.org/10.3390/cancers12123496DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7761081PMC
November 2020

Single-Nucleus and In Situ RNA-Sequencing Reveal Cell Topographies in the Human Pancreas.

Gastroenterology 2021 Mar 16;160(4):1330-1344.e11. Epub 2020 Nov 16.

Center for Digital Health, Berlin Institute of Health and Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany. Electronic address:

Background & Aims: Molecular evidence of cellular heterogeneity in the human exocrine pancreas has not been yet established because of the local concentration and cascade of hydrolytic enzymes that can rapidly degrade cells and RNA upon pancreatic resection. We sought to better understand the heterogeneity and cellular composition of the pancreas in neonates and adults in healthy and diseased conditions using single-cell sequencing approaches.

Methods: We innovated single-nucleus RNA-sequencing protocols and profiled more than 120,000 cells from pancreata of adult and neonatal human donors. We validated the single-nucleus findings using RNA fluorescence in situ hybridization, in situ sequencing, and computational approaches.

Results: We created the first comprehensive atlas of human pancreas cells including epithelial and nonepithelial constituents, and uncovered 3 distinct acinar cell types, with possible implications for homeostatic and inflammatory processes of the pancreas. The comparison with neonatal single-nucleus sequencing data showed a different cellular composition of the endocrine tissue, highlighting the tissue dynamics occurring during development. By applying spatial cartography, involving cell proximity mapping through in situ sequencing, we found evidence of specific cell type neighborhoods, dynamic topographies in the endocrine and exocrine pancreas, and principles of morphologic organization of the organ. Furthermore, similar analyses in chronic pancreatitis biopsy samples showed the presence of acinar-REG cells, a reciprocal association between macrophages and activated stellate cells, and a new potential role of tuft cells in this disease.

Conclusions: Our human pancreas cell atlas can be interrogated to understand pancreatic cell biology and provides a crucial reference set for comparisons with diseased tissue samples to map the cellular foundations of pancreatic diseases.
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http://dx.doi.org/10.1053/j.gastro.2020.11.010DOI Listing
March 2021

Loss of RNF43 Function Contributes to Gastric Carcinogenesis by Impairing DNA Damage Response.

Cell Mol Gastroenterol Hepatol 2021 11;11(4):1071-1094. Epub 2020 Nov 11.

Institute for Medical Microbiology, Immunology and Hygiene, School of Medicine, Technical University of Munich, Munich, Germany. Electronic address:

Background & Aims: RING finger protein 43 (RNF43) is a tumor suppressor that frequently is mutated in gastric tumors. The link between RNF43 and modulation of Wingless-related integration site (WNT) signaling has not been shown clearly in the stomach. Because mutations in RNF43 are highly enriched in microsatellite-unstable gastric tumors, which show defects in DNA damage response (DDR), we investigated whether RNF43 is involved in DDR in the stomach.

Methods: DDR activation and cell viability upon γ-radiation was analyzed in gastric cells where expression of RNF43 was depleted. Response to chemotherapeutic agents 5-fluorouracil and cisplatin was analyzed in gastric cancer cell lines and xenograft tumors. In addition, involvement of RNF43 in DDR activation was analyzed upon Helicobacter pylori infection in wild-type and Rnf43 mice. Furthermore, a cohort of human gastric biopsy specimens was analyzed for RNF43 expression and mutation status as well as for activation of DDR.

Results: RNF43 depletion conferred resistance to γ-radiation and chemotherapy by dampening the activation of DDR, thereby preventing apoptosis in gastric cells. Upon Helicobacter pylori infection, RNF43 loss of function reduced activation of DDR and apoptosis. Furthermore, RNF43 expression correlated with DDR activation in human gastric biopsy specimens, and RNF43 mutations found in gastric tumors conferred resistance to DNA damage. When exploring the molecular mechanisms behind these findings, a direct interaction between RNF43 and phosphorylated H2A histone family member X (γH2AX) was observed.

Conclusions: We identified a novel function for RNF43 in the stomach as a regulator of DDR. Loss of RNF43 function in gastric cells confers resistance to DNA damage-inducing radiotherapy and chemotherapy, suggesting RNF43 as a possible biomarker for therapy selection.
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http://dx.doi.org/10.1016/j.jcmgh.2020.11.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7898035PMC
November 2020

Next-generation diagnostics for precision oncology: Preanalytical considerations, technical challenges, and available technologies.

Semin Cancer Biol 2020 Nov 7. Epub 2020 Nov 7.

Institute of Pathology, Technical University Munich, Germany; German Cancer Consostium (DKTK), Partner Site Munich, Germany. Electronic address:

Molecular diagnostics as the centrepiece of precision oncology has gone through revolutionary developments over the last decade, becoming tremendously broad, deep and precise with still ongoing advancements. In the majority of scenarios, treatment selection for cancer patients without any type of molecular characterization is no longer conceivable. Considering the impact of sample quality on the reliability of molecular analyses and the importance of the results for the fate of an individual patient, it is surprising how sparsely preanalytical and analytical requirements are addressed scientifically. Standardization and rigorous quality assessment continue to play only a marginal role in the field. Within this review, we will systematically discuss influencing preanalytic parameters and technology setups affecting molecular test results. We will shed light on the specifics of different analytes, technical modalities, and analysis pipelines. The review will have a certain focus on broad molecular genetic tumour testing with next generation sequencing but will go beyond that including other molecular diagnostic modalities and will give a glimpse into the future of molecular testing.
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http://dx.doi.org/10.1016/j.semcancer.2020.10.015DOI Listing
November 2020

Tracking a TGF-β activator in vivo: sensitive PET imaging of αvβ8-integrin with the Ga-68-labeled cyclic RGD octapeptide trimer Ga-68-Triveoctin.

EJNMMI Res 2020 Oct 31;10(1):133. Epub 2020 Oct 31.

Institut für Pathologie Und Pathologische Anatomie, Technische Universität München, Trogerstraße 18, 81675, Munich, Germany.

Purpose: As a major activator of transforming growth factor β (TGF-β), the RGD receptor αvβ8-integrin is involved in pathogenic processes related to TGF-β dysregulation, such as tumor growth, invasion, and radiochemoresistance, metastasis and tumor cell stemness, as well as epithelial-mesenchymal transition. The novel positron emission tomography (PET) radiopharmaceutical Ga-68-Triveoctin for in vivo mapping of αvβ8-integrin expression might enhance the prognosis of certain tumor entities, as well as support and augment TGF-β-targeted therapeutic approaches.

Methods: Monomeric and trimeric conjugates of cyclo(GLRGDLp(NMe)K(pent-4-ynoic amide)) were synthesized by click chemistry (CuAAC), labeled with Ga-68, and evaluated in MeWo (human melanoma) xenografted SCID mice by means of PET and ex-vivo biodistribution. αvβ8-integrin expression in murine tissues was determined by β8-IHC. A human subject received a single injection of 173 MBq of Ga-68-Triveoctin and underwent 3 subsequent PET/CT scans at 25, 45, and 90 min p.i..

Results: The trimer Ga-68-Triveoctin exhibits a 6.7-fold higher αvβ8-integrin affinity than the monomer (IC of 5.7 vs. 38 nM, respectively). Accordingly, biodistribution showed a higher tumor uptake (1.9 vs. 1.0%IA/g, respectively) but a similar baseline upon blockade (0.25%IA/g for both). IHC showed an intermediate β8-expression in the tumor while most organs and tissues were found β8-negative. Low non-target tissue uptakes (< 0.4%IA/g) confirmed a low degree of unspecific binding. Due to its hydrophilicity (log D = - 3.1), Ga-68-Triveoctin is excreted renally and shows favorable tumor/tissue ratios in mice (t/blood: 6.7; t/liver: 6.8; t/muscle: 29). A high kidney uptake in mice (kidney-to-blood and -to-muscle ratios of 126 and 505, respectively) is not reflected by human PET (corresponding values are 15 and 30, respectively), which furthermore showed notable uptakes in coeliac and choroid plexus (SUVmean 6.1 and 9.7, respectively, 90 min p.i.).

Conclusion: Ga-68-Triveoctin enables sensitive in-vivo imaging αvβ8-integrin expression in murine tumor xenografts. PET in a human subject confirmed a favorable biodistribution, underscoring the potential of Ga-68-Triveoctin for mapping of αvβ8-integrin expression in a clinical setting.
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http://dx.doi.org/10.1186/s13550-020-00706-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7603442PMC
October 2020

3D histopathology of human tumours by fast clearing and ultramicroscopy.

Sci Rep 2020 10 19;10(1):17619. Epub 2020 Oct 19.

Department of Bioelectronics, TU Wien, Vienna, Austria.

Here, we describe a novel approach that allows pathologists to three-dimensionally analyse malignant tissues, including the tumour-host tissue interface. Our visualization technique utilizes a combination of ultrafast chemical tissue clearing and light-sheet microscopy to obtain virtual slices and 3D reconstructions of up to multiple centimetre sized tumour resectates. For the clearing of tumours we propose a preparation technique comprising three steps: (a) Fixation and enhancement of tissue autofluorescence with formalin/5-sulfosalicylic acid. (b) Ultrafast active chemical dehydration with 2,2-dimethoxypropane and (c) refractive index matching with dibenzyl ether at up to 56 °C. After clearing, the tumour resectates are imaged. The images are computationally post-processed for contrast enhancement and artefact removal and then 3D reconstructed. Importantly, the sequence a-c is fully reversible, allowing the morphological correlation of one and the same histological structures, once visualized with our novel technique and once visualized by standard H&E- and IHC-staining. After reverting the clearing procedure followed by standard H&E processing, the hallmarks of ductal carcinoma in situ (DCIS) found in the cleared samples could be successfully correlated with the corresponding structures present in H&E and IHC staining. Since the imaging of several thousands of optical sections is a fast process, it is possible to analyse a larger part of the tumour than by mechanical slicing. As this also adds further information about the 3D structure of malignancies, we expect that our technology will become a valuable addition for histological diagnosis in clinical pathology.
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http://dx.doi.org/10.1038/s41598-020-71737-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7572501PMC
October 2020

Pathological RANK signaling in B cells drives autoimmunity and chronic lymphocytic leukemia.

J Exp Med 2021 Feb;218(2)

Institut für Klinische Chemie und Pathobiochemie, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.

Clinical evidence suggests alterations in receptor activator of NF-κB (RANK) signaling are key contributors to B cell autoimmunity and malignancy, but the pathophysiological consequences of aberrant B cell-intrinsic RANK signaling remain unknown. We generated mice that express a human lymphoma-derived, hyperactive RANKK240E variant in B lymphocytes in vivo. Forced RANK signaling disrupted B cell tolerance and induced a fully penetrant systemic lupus erythematosus-like disease in addition to the development of chronic lymphocytic leukemia (CLL). Importantly, RANKK240E transgenic CLL cells as well as CLL cells of independent murine and of human origin depend on microenvironmental RANK ligand (RANKL) for tumor cell survival. Consequently, inhibition of the RANKL-RANK axis with anti-RANKL antibodies killed murine and human CLL cells in vitro and in vivo. These results establish pathological B cell-intrinsic RANK signaling as a potential driver of autoimmunity and B cell malignancy, and they suggest the exploitation of clinically available anti-RANKL compounds for CLL treatment.
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http://dx.doi.org/10.1084/jem.20200517DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7868734PMC
February 2021

Aggressive PDACs Show Hypomethylation of Repetitive Elements and the Execution of an Intrinsic IFN Program Linked to a Ductal Cell of Origin.

Cancer Discov 2021 Mar 15;11(3):638-659. Epub 2020 Oct 15.

German Cancer Consortium (DKTK), Heidelberg, Germany.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by extensive desmoplasia, which challenges the molecular analyses of bulk tumor samples. Here we FACS-purified epithelial cells from human PDAC and normal pancreas and derived their genome-wide transcriptome and DNA methylome landscapes. Clustering based on DNA methylation revealed two distinct PDAC groups displaying different methylation patterns at regions encoding repeat elements. Methylation tumors are characterized by higher expression of endogenous retroviral transcripts and double-stranded RNA sensors, which lead to a cell-intrinsic activation of an interferon signature (IFNsign). This results in a protumorigenic microenvironment and poor patient outcome. Methylation/IFNsign and Methylation/IFNsign PDAC cells preserve lineage traits, respective of normal ductal or acinar pancreatic cells. Moreover, ductal-derived / mouse PDACs show higher expression of IFNsign compared with acinar-derived counterparts. Collectively, our data point to two different origins and etiologies of human PDACs, with the aggressive Methylation/IFNsign subtype potentially targetable by agents blocking intrinsic IFN signaling. SIGNIFICANCE: The mutational landscapes of PDAC alone cannot explain the observed interpatient heterogeneity. We identified two PDAC subtypes characterized by differential DNA methylation, preserving traits from normal ductal/acinar cells associated with IFN signaling. Our work suggests that epigenetic traits and the cell of origin contribute to PDAC heterogeneity..
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http://dx.doi.org/10.1158/2159-8290.CD-20-1202DOI Listing
March 2021

Mesenchymal Plasticity Regulated by Prrx1 Drives Aggressive Pancreatic Cancer Biology.

Gastroenterology 2021 01 30;160(1):346-361.e24. Epub 2020 Sep 30.

Klinik und Poliklinik für Innere Medizin II, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany; German Cancer Consortium, Partner Site Munich, Germany. Electronic address:

Background & Aims: Pancreatic ductal adenocarcinoma (PDAC) is characterized by a fibroblast-rich desmoplastic stroma. Cancer-associated fibroblasts (CAFs) have been shown to display a high degree of interconvertible states including quiescent, inflammatory, and myofibroblastic phenotypes; however, the mechanisms by which this plasticity is achieved are poorly understood. Here, we aim to elucidate the role of CAF plasticity and its impact on PDAC biology.

Methods: To investigate the role of mesenchymal plasticity in PDAC progression, we generated a PDAC mouse model in which CAF plasticity is modulated by genetic depletion of the transcription factor Prrx1. Primary pancreatic fibroblasts from this mouse model were further characterized by functional in vitro assays. To characterize the impact of CAFs on tumor differentiation and response to chemotherapy, various coculture experiments were performed. In vivo, tumors were characterized by morphology, extracellular matrix composition, and tumor dissemination and metastasis.

Results: Our in vivo findings showed that Prrx1-deficient CAFs remain constitutively activated. Importantly, this CAF phenotype determines tumor differentiation and disrupts systemic tumor dissemination. Mechanistically, coculture experiments of tumor organoids and CAFs showed that CAFs shape the epithelial-to-mesenchymal phenotype and confer gemcitabine resistance of PDAC cells induced by CAF-derived hepatocyte growth factor. Furthermore, gene expression analysis showed that patients with pancreatic cancer with high stromal expression of Prrx1 display the squamous, most aggressive, subtype of PDAC.

Conclusions: Here, we define that the Prrx1 transcription factor is critical for tuning CAF activation, allowing a dynamic switch between a dormant and an activated state. This work shows that Prrx1-mediated CAF plasticity has significant impact on PDAC biology and therapeutic resistance.
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http://dx.doi.org/10.1053/j.gastro.2020.09.010DOI Listing
January 2021