Non-linear QED approach for betatron radiation in a laser wakefield accelerator

Laser plasma-based accelerators provide an excellent source of collimated, bright, and adequately coherent betatron-type x-ray pulses with potential applications in science and industry. So far the laser plasma-based betatron radiation has been described within the concept of classical Liénard-Wiechert potentials incorporated in particle-in-cell simulations, a computing power-demanding approach, especially for the case of multi-petawatt lasers. In this work, we describe the laser plasma-based generation of betatron radiation at the most fundamental level of quantum mechanics. In our approach, photon emission from the relativistic electrons in the plasma bubble is described within a nonlinear quantum electrodynamics (QED) framework. The reported QED-based betatron radiation results are in excellent agreement with similar results using Liénard-Wiechert potentials, as well as in very good agreement with betatron radiation measurements, obtained with multi-10-TW lasers interacting with He and multielectron N[Formula: see text] gas targets. Furthermore, our QED approach results in a dramatic reduction of the computational runtime demands, making it a favorable tool for designing betatron radiation experiments, especially in multi-petawatt laser facilities.

Design, manufacturing, evaluation, and performance of a 3D-printed, custom-made nozzle for laser wakefield acceleration experiments

Laser WakeField Acceleration (LWFA) is extensively used as a high-energy electron source, with electrons achieving energies up to the GeV level. The produced electron beam characteristics depend strongly on the gas density profile. When the gaseous target is a gas jet, the gas density profile is affected by parameters, such as the nozzle geometry, the gas used, and the backing pressure applied to the gas valve. An electron source based on the LWFA mechanism has recently been developed at the Institute of Plasma Physics and Lasers. To improve controllability over the electron source, we developed a set of 3D-printed nozzles suitable for creating different gas density profiles according to the experimental necessities. Here, we present a study of the design, manufacturing, evaluation, and performance of a 3D-printed nozzle intended for LWFA experiments.

Inter-Rater Agreement for Diagnosing Adenomyosis Using Magnetic Resonance Imaging and Transvaginal Ultrasonography

Our aim was to compare the inter-rater agreement about transvaginal ultrasonography (TVS) with magnetic resonance imaging (MRI) with regard to diagnosing adenomyosis and for assessing various predefined imaging features of adenomyosis, in the same set of women. The study cohort included 51 women, prospectively, consecutively recruited based on a clinical suspicion of adenomyosis. MRIs and TVS videoclips and 3D volumes were retrospectively assessed by four experienced radiologists and five experienced sonographers, respectively. Each rater subjectively evaluated the presence or absence of adenomyosis, as well as imaging features suggestive of adenomyosis. Fleiss kappa (κ) was used to reflect inter-rater agreement for categorical data, and the intraclass correlation coefficient (ICC) was used to reflect the reliability of quantitative data. Agreement between raters for diagnosing adenomyosis was higher for TVS than for MRI (κ = 0.42 vs. 0.28). MRI had a higher inter-rater agreement in assessing wall asymmetry, irregular junctional zone (JZ), and the presence of myometrial cysts, while TVU had a better agreement for assessing globular shape. MRI showed a moderate to good reliability for measuring the JZ (ICC = 0.57-0.82). For TVS, the JZ was unmeasurable in >50% of cases, and the remaining cases had low reliability (ICC = -0.31-0.08). We found that inter-rater agreement for diagnosing adenomyosis was higher for TVS than for MRI, despite the fact that MRI showed a higher inter-rater agreement in most specific features. Measurements of JZ in the coronal plane with 3D TVS were unreliable and thus unlikely to be useful for diagnosing adenomyosis.

Efficient plasma electron accelerator driven by linearly chirped multi-10-TW laser pulses

The temporal rearrangement of the spectral components of an ultrafast and intense laser pulse, i.e., the chirp of the pulse, offers significant possibilities for controlling its interaction with matter and plasma. In the propagation of ultra-strong laser pulses within the self-induced plasma, laser pulse chirp can play a major role in the dynamics of wakefield and plasma bubble formation, as well as in the electron injection and related electron acceleration. Here, we experimentally demonstrate the control of the generation efficiency of a relativistic electron beam, with respect to maximum electron energy and current, by accurately varying the chirp value of a multi-10-TW laser pulse. We explicitly show that positively chirped laser pulses, i.e., pulses with instantaneous frequency increasing with time, accelerate electrons in the order of 100 MeV much more efficiently in comparison to unchirped or negatively chirped pulses. Corresponding Particle-In-Cell simulations strongly support the experimental results, depicting a smoother plasma bubble density distribution and electron injection conditions that favor the maximum acceleration of the electron beam, when positively chirped laser pulses are used. Our results, aside from extending the validity of similar studies reported for PW laser pulses, provide the ground for understanding the subtle dynamics of an efficient plasma electron accelerator driven by chirped laser pulses.

Paraduodenal pancreatitis - problem in the groove

BACKGROUND

Paraduodenal pancreatitis (PDP) is a particular form of chronic pancreatitis (CP) occurring in and around the duodenal wall. Despite its low prevalence, this rare condition presents a significant challenge in clinical practice.

METHODS

We retrospectively analysed the electronic medical charts of all patients with a diagnosis of chronic pancreatitis and identified those with PDP, between January 1999 and December 2020.

RESULTS

There were 35 patients diagnosed with PDP (86% males and 14% females); median age of 56 ± 11 (range 38-80). Alcohol overconsumption was reported in 81% and smoking in 90% of patients. Abdominal pain was the leading symptom (71%), followed by weight loss, nausea and vomiting, jaundice, and diarrhoea. In 23 patients (66%), recurrent acute pancreatitis attacks were noted. Focal duodenal wall thickening was present in 34 patients (97%), cystic lesions in 80%, pancreatic duct dilatation in 54% and common bile duct dilatation in 46%. Endoscopic treatment was performed on nine patients (26%) and five patients (14%) underwent surgery. Complete symptom relief was reported in 12 patients (34%), partial symptom relief in three (9%), there was no improvement in five (14%), data were not available in three (9%) and 12 (34%) patients died before data analysis.

CONCLUSIONS

PDP is a rare form of pancreatitis, most commonly occurring in the 5th or 6th decade of life, with a predominance in males and patients with a history of smoking and high alcohol consumption. Focal thickening and cystic lesions of the duodenal wall are the most common imaging findings, followed by pancreatic duct and common bile duct dilatation. A minority of patients requires surgery.

Assessment of structural chromosomal instability phenotypes as biomarkers of carboplatin response in triple negative breast cancer: the TNT trial

BACKGROUND

In the TNT trial of triple negative breast cancer (NCT00532727), germline BRCA1/2 mutations were present in 28% of carboplatin responders. We assessed quantitative measures of structural chromosomal instability (CIN) to identify a wider patient subgroup within TNT with preferential benefit from carboplatin over docetaxel.

PATIENTS AND METHODS

Copy number aberrations (CNAs) were established from 135 formalin-fixed paraffin-embedded primary carcinomas using Illumina OmniExpress SNP-arrays. Seven published [allelic imbalanced CNA (AiCNA); allelic balanced CNA (AbCNA); copy number neutral loss of heterozygosity (CnLOH); number of telomeric allelic imbalances (NtAI); BRCA1-like status; percentage of genome altered (PGA); homologous recombination deficiency (HRD) scores] and two novel [Shannon diversity index (SI); high-level amplifications (HLAMP)] CIN-measurements were derived. HLAMP was defined based on the presence of at least one of the top 5% amplified cytobands located on 1q, 8q and 10p. Continuous CIN-measurements were divided into tertiles. All nine CIN-measurements were used to analyse objective response rate (ORR) and progression-free survival (PFS).

RESULTS

Patients with tumours without HLAMP had a numerically higher ORR and significantly longer PFS in the carboplatin (C) than in the docetaxel (D) arm [56% (C) versus 29% (D), PHLAMP,quiet = 0.085; PFS 6.1 months (C) versus 4.1 months (D), Pinteraction/HLAMP = 0.047]. In the carboplatin arm, patients with tumours showing intermediate telomeric NtAI and AiCNA had higher ORR [54% (C) versus 20% (D), PNtAI,intermediate = 0.03; 62% (C) versus 33% (D), PAiCNA,intermediate = 0.076]. Patients with high AiCNA and PGA had shorter PFS in the carboplatin arm [3.4 months (high) versus 5.7 months (low/intermediate); and 3.8 months (high) versus 5.6 months (low/intermediate), respectively; Pinteraction/AiCNA = 0.027, Padj.interaction/AiCNA = 0.125 and Pinteraction/PGA = 0.053, Padj.interaction/PGA = 0.176], whilst no difference was observed in the docetaxel arm.

CONCLUSIONS

Patients with tumours lacking HLAMP and demonstrating intermediate CIN-measurements formed a subgroup benefitting from carboplatin relative to docetaxel treatment within the TNT trial. This suggests a complex and paradoxical relationship between the extent of genomic instability in primary tumours and treatment response in the metastatic setting.

Clinical features and MRI progression of small duct primary sclerosing cholangitis (PSC)

PURPOSE

First, to evaluate and describe the clinical and MRI progression of patients with small duct primary sclerosing cholangitis (sdPSC), and second, to look for MRI features associated with disease progression to large duct PSC.

METHOD

16 patients (7 female, 9 male; median age 27 years) with diagnosis of sdPSC and available MR imaging were included in this retrospective dual-center study. Liver function tests (LFTs) and imaging was reviewed in consensus by two radiologists at baseline and follow-up, and compared by means of non-parametric tests, with p < 0.05 deemed significant.

RESULTS

At baseline and follow-up patients had a cholestatic liver profile with elevated LFTs. Progressive liver deformity, heterogeneous enhancement and hilar lymphadenopathy were common findings. In 9 patients follow-up MRI was available with a mean interval between imaging of 10.6 years (range 3.6-15.3 years). 5 patients (55.5 %) developed cholangiographic changes diagnostic of large duct PSC. No correlation was observed between MRI findings or LFTs at baseline and the endpoint of developing PSC typical cholangiographic changes at follow-up imaging (p > 0.05).

CONCLUSIONS

More than half of sdPSC patients developed cholangiographic changes, supporting that sdPSC may be an early stage of large duct PSC rather than an entity of its own. Larger studies are needed to address the value of MRI for prediction of sdPSC disease progression.

Inter-reader agreement of interpretation of radiological course of bile duct changes between serial follow-up magnetic resonance imaging/3D magnetic resonance cholangiopancreatography of patients with primary sclerosing cholangitis

Objectives: Interpretation of MRI/MRCP in primary sclerosing cholangitis (PSC) at a single time point has low inter-reader agreement. Agreement of interpretation of the dynamic course of duct changes in follow-up MRI/MRCP is of clinical importance but remains unknown. Our aims are therefore to assess the inter-reader agreement of interpretation of the course of duct changes in PSC and investigate if elimination of 3 D MRCP affects inter-reader agreement.Materials and Methods: We studied 40 consecutive PSC-patients who underwent two liver MRI/MRCPs at two time points. Two readers independently evaluated the course of duct changes between the two time points in two imaging sets, one with and one without 3 D MRCP. The intraclass correlation coefficient (ICC) was calculated for evaluation of inter-reader and intra-reader agreement between the two time points and two imaging sets accordingly.Results: Inter-reader agreement of the interpretation of the course of duct changes between the two time points was poor (ICC up to 0.224). Elimination of 3 D MRCP neither improved inter-reader agreement which was again poor (ICC up to 0.26) nor did it change considerably the way readers interpret the course of ducts changes (ICC for intra-reader agreement between 0.809 and 0.978).Conclusions: Inter-reader agreement of the interpretation of radiological course of duct changes is poor in serial follow-up MRI/MRCP of PSC-patients. Elimination of 3 D MRCP does not increase inter-reader agreement but maintains an excellent intra-reader agreement for the interpretation of the dynamic course of bile duct changes.Key pointsInter-reader agreement of interpretation of radiological course of bile duct changes between serial follow-up MRI/MRCP examinations of patients with PSC is poor.Absence of 3D MRCP does not affect considerably the way readers interpret the radiological course of bile ducts changes.When MRCP is absent or of low quality, utilization of other sequences seems to be helpful as an alternative for bile duct evaluation.

Abstract P1-06-07: Characterization of chromosomal instability in the TNT trial: A randomized phase III trial of carboplatin compared with docetaxel for patients with metastatic or recurrent locally advanced triple negative or BRCA1/2 breast cancer (CRUK/07/012)

Background

A distinctive trait of triple negative breast cancer (TNBC) is the acquisition of genome wide highly aberrant copy number states, which is more evident in metastatic settings. The level of copy number alterations can be characterized by quantitative estimates of chromosomal instability, such as allelic imbalanced copy number aberrations, telomeric allelic imbalance (NtAI), homologous recombination deficiency (HRD) score, referred here as genomic scars. Several of these scars are reported as being indicative of BRCAness and potential predictive and/or prognostic biomarkers of chemotherapy response, currently mostly demonstrated in neoadjuvant settings in TNBC.

Aims

Using several genomic scar measures, we aim to capture chromosomal instability and test their predictive and prognostic value in metastatic or recurrent locally advanced triple negative or BRCA1/2 mutated breast cancer in the TNT trial.

Methods

Patients recruited to TNT (n=376) had ER-/PR-/Her2- breast cancer or were germline BRCA mutation carriers. Genome-wide copy numbers (CN) were derived from FFPE samples including primary tumours and positive lymph nodes (n=183, docetaxel=93, carboplatin=90; BRCA1 mut=25). Genomic scars were generated using ASCAT (Van loo et al., PNAS 2010) CN profiles. HRD scores were established by Myriad Genetics, Inc. assay (n=272). BRCA1-like classifier was applied as described in Schouten et al., Mol Onc 2015. Shannon diversity index was calculated using ASCAT raw CN profiles. Association of genomic scars with PAM50 subtypes and BRCA1 deficiency status were evaluated using Kruskal-Wallis test; p-values were adjusted for multiple comparisons (Dunn's test). Statistical significance was defined as p&lt;0.05. Association of genomic scars with objective tumour response rate (ORR) and Progression Free Survival (PFS) was assessed using logistic regression and restricted mean survival analysis, respectively.

Results

HRD and NtAI scores were higher in basal like samples compared to non-basal like (median diff. HRD=11.5, p=0.005; NtAI=3, p=0.04). HRD (p=2e-14) and NtAI (p=0.003) scores were also higher in BRCA1 deficient (BRCA1 germline/somatic mutant or BRCA1 methylated) samples compared to non-deficient. Using the BRCA1-like classifier, 42 out of 50 BRCA1 deficient samples and 93 out of 133 BRCA1 non-deficient/undetermined samples were identified as BRCA1-like. The Shannon diversity index, measuring CN heterogeneity, clustered samples into 3 groups. Analysis of ORR showed non-significant trends to preferential response rates with docetaxel in cluster 1 and 3. Membership of cluster 2 predicted higher ORR to carboplatin over docetaxel (interaction p=0.017). PFS indicated a treatment effect in cluster 2, but not in cluster 1 or 3; there was no evidence of interaction between subgroups and treatment (p=0.15).

Conclusions

Our results suggest that the overall heterogeneity of the copy number landscape is a promising area for seeking predictive/prognostic biomarkers in metastatic TNBC, and combined with other modalities of high-dimensional omics data could provide essential treatment response information.

Citation Format: Sipos O, Tovey H, Quist J, Haider S, Nowinski S, Gazinska P, Kernaghan S, Toms C, Timms KM, Lanchbury JS, Linn SC, Pinder SE, Bliss JM, Tutt A, Cheang MC, Grigoriadis A, On behalf of the TNT Trial Management Group and Investigators. Characterization of chromosomal instability in the TNT trial: A randomized phase III trial of carboplatin compared with docetaxel for patients with metastatic or recurrent locally advanced triple negative or BRCA1/2 breast cancer (CRUK/07/012) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-06-07.

Utility of VS38c in the diagnostic and prognostic assessment of osteosarcoma and other bone tumours/tumour-like lesions

Background

VS38c is a monoclonal antibody that recognises a rough endoplasmic reticulum (rER) intracellular antigen termed cytoskeleton-linking membrane protein 63. rER is typically found in viable tumour cells and is abundant in osteosarcoma cells. The aim of this study was to determine the diagnostic and prognostic utility of VS38c in the histological assessment of osteosarcoma and other bone tumours/tumour-like leisons.

Methods

Immunohistochemical staining with VS38c was carried out on formalin-fixed specimens of osteosarcoma (pre/post-chemotherapy) and a wide range of benign and malignant bone lesions. In addition, VS38c staining of cultures of MG63 and Sa0S2 osteosarcoma cell cultures. (±cisplatin and actinomycin D-treatment) was analysed.

Results

VS38c strongly stained tumour cells in all low-grade and high-grade osteosarcomas and in undifferentiated sarcomas and high-grade chondrosarcomas. There was little or no VS38c staining of low-grade chondrosarcomas or chordomas and variable staining of Ewing sarcomas. Osteoblasts in benign bone-forming tumours and mononuclear stromal cells in chondroblastomas, giant cell tumours and non-ossifying fibromas strongly stained for VS38c. VS38c staining was absent in cisplatin and actinomycin D treated Sa0S2 and MG63 cells. In specimens of osteosarcoma post-neoadjuvant therapy, VS38c staining was absent in most morphologically necrotic areas of tumor although some cells with pyknotic nuclei stained for VS38c in these areas. Most tumour cells exhibiting atypical nuclear forms were not stained by VS38c.

Conclusions

Our findings show that VS38c is a sensitive but not specific diagnostic marker of osteosarcoma. Staining with VS38c identifies viable osteosarcoma cells, a feature which may be useful in the assessment of percentage tumour necrosis post-neoadjuvant chemotherapy.

Functional redundancy between Apc and Apc2 regulates tissue homeostasis and prevents tumorigenesis in murine mammary epithelium

Aberrant Wnt signaling within breast cancer is associated with poor prognosis, but regulation of this pathway in breast tissue remains poorly understood and the consequences of immediate or long-term dysregulation remain elusive. The exact contribution of the Wnt-regulating proteins adenomatous polyposis coli (APC) and APC2 in the pathogenesis of human breast cancer are ill-defined, but our analysis of publically available array data sets indicates that tumors with concomitant low expression of both proteins occurs more frequently in the 'triple negative' phenotype, which is a subtype of breast cancer with particularly poor prognosis. We have used mouse transgenics to delete Apc and/or Apc2 from mouse mammary epithelium to elucidate the significance of these proteins in mammary homeostasis and delineate their influences on Wnt signaling and tumorigenesis. Loss of either protein alone failed to affect Wnt signaling levels or tissue homeostasis. Strikingly, concomitant loss led to local disruption of β-catenin status, disruption in epithelial integrity, cohesion and polarity, increased cell division and a distinctive form of ductal hyperplasia with 'squamoid' ghost cell nodules in young animals. Upon aging, the development of Wnt activated mammary carcinomas with squamous differentiation was accompanied by a significantly reduced survival. This novel Wnt-driven mammary tumor model highlights the importance of functional redundancies existing between the Apc proteins both in normal homeostasis and in tumorigenesis.

Abstract P1-07-03: Mesenchymal subtype negatively associates with the presence of immune infiltrates within a triple negative breast cancer classifier

Introduction: Lehmann and colleagues (Lehmann et al., 2011) devised a gene expression classification system for triple negative breast cancer (TNBC) consisting of seven subtypes—IM, BL1, BL2, LAR, M, MSL, and UNS (unselected). We (Ring et al., 2016) recently modified this original algorithm of 2188 gene subtyping into a 101-gene algorithm. In addition to a reduction of genes, the 101-gene algorithm has two methodological differences: first, the immunomodulatory (IM) signature was treated not as a subtype but rather as a binary feature of one of the other subtypes (e.g. BL1/IM+, LAR/IM-); second, when tumors—by a predefined correlation coefficient—showed traits of more than one subtype, both subtypes were reported as “dual subtypes.”

Aim: Our aim was to apply the 101-gene algorithm for TNBC subtyping and to establish the relation of TNBC subtypes with their IM-status across several independent data sets.

Methods: 951 patients from four independent TNBC cohorts with available gene expression data were analyzed by the 101-gene algorithm. Of these 848 were classified with at least one subtype.

Results: The distribution of the 5 TNBC subtypes in both single and dual subtypes was 47%,10%,15%,18%,11%, for BL1, BL2, LAR, M, and MSL respectively. The majority of cases gave only one subtype (572, 67%) with M (Mesenchymal) being 9% (n=54) of these. Given this frequency of 9% of M as a baseline, in the remaining 276 (33%) cases with dual subtypes, the expectation that M would be one of the two is 11% (64 subtype calls). However, M is one of the two of the dual subtypes at a much higher frequency of 40% (222 subtype calls, Chi-Squared, P&lt;0.0001). IM+ is a common feature across these cohorts (n=310 or 37%). When examining the IM feature within the patients exhibiting the M subtype as either a single subtype or one of the two dual subtypes (n=276, 33%), IM positive tumors are never of the M phenotype (Chi-Squared, p&lt;0.0001).

Conclusions: We further have confirmed with the 101-gene algorithm that the IM signature inversely associates with the M subtype as it has been observed with the 2188 gene algorithm (Lehmann et al., 2016). Moreover, the M signature is occasionally a confounder of other subtypes however still identifies those tumors negative for immune infiltrates. This raises important opportunities to understand the relationships between intrinsic tumor biology reflected in TNBC subtypes and their interaction with variable immune cell stroma which are the subject of ongoing analyses.

Citation Format: Grigoriadis A, Quist J, Mirza H, Cheang MC, Ring BZ, Hout DR, Bailey DB, Seitz RS, Tutt AN. Mesenchymal subtype negatively associates with the presence of immune infiltrates within a triple negative breast cancer classifier [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-07-03.

Abstract P1-05-14: Copy number aberration-induced gene breakage analysis identifies recurrent FOXP1 fusions in breast cancer

Background: Genomic instability is a critical feature of breast cancers, which manifests in genome-wide copy number aberrations (CNA), often causing “gene breakage” and the generation of fusion genes. We aimed to identify aborted transcripts with underlying CNAs and to investigate the molecular landscape of breast cancers harbouring such events.

Methods: A walking student's t-test algorithm was applied to Affymetrix Exon 1.0ST array data of 123 breast cancers to identify regions of aborted transcription and overlaid with DNA breakpoints derived from matched Affymetrix SNP6 ASCAT-segmented copy number. Aborted transcripts were investigated as potential fusion gene partners through RNA-seq analysis of 151 breast cancer samples (TCGA) and 51 breast cancer cell lines (BCCL) using ChimeraScan. Clinical correlates were established for clinicopathological features, genomic instability measures, and gene expression-based molecular classifiers including PAM50, TNBCtype, IntClust subtypes and immune signatures.

Results: One hundred and six genes with recurrent CNA-induced aborted transcription were identified. Aborted transcription showed hormone receptor subtype-specificity for 7 genes (nTNBC=1, nNon-TNBC=6) and was less prevalent in samples of IntClust 2 and IntClust 4 subtypes (p: 0.0043, 0.0011). Aborted transcripts were more frequently observed in samples with greater copy-neutral loss of heterozygosity (p=0.012), while aborted transcription of 54/106 genes significantly affected enrichment of 27 tumor-infiltrating lymphocyte subpopulations.14 aborted transcripts were found as a fusion gene with one partner in RNA-seq of TCGA and BCCL, while 19 were involved in multiple fusion events (range=1-6, median=2). Nine of 106 genes displayed gene breakage and fusion events exclusively in samples with an enriched tandem duplication phenotype. Notably, FOXP1, localised to a tumour suppressor locus at 3p14.1, reported the highest number of fusion configurations (n=6) with concurrent aborted transcription across all RNA-seq datasets (nPRADA=9, nTCGA=38, nBCCL=6).

Conclusion: CNA-induced gene breakage affects the molecular landscape of breast cancers and is linked with many genomic configurations of interest including copy-neutral loss of heterozygosity and tandem duplications. In particular, the role of recurrent gene fusions of the tumour suppressor, FOXP1, in tumourigenesis warrants further investigation.

Citation Format: Mohd Noor A, Maguire S, Watkins J, Quist J, Mirza H, Tutt A, Gillett C, Natrajan R, Grigoriadis A. Copy number aberration-induced gene breakage analysis identifies recurrent FOXP1 fusions in breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-05-14.

Multidetector CT of pancreatic ductal adenocarcinoma: Effect of tube voltage and iodine load on tumour conspicuity and image quality

OBJECTIVES

To compare a low-tube-voltage with or without high-iodine-load multidetector CT (MDCT) protocol with a normal-tube-voltage, normal-iodine-load (standard) protocol in patients with pancreatic ductal adenocarcinoma (PDAC) with respect to tumour conspicuity and image quality.

METHODS

Thirty consecutive patients (mean age: 66 years, men/women: 14/16) preoperatively underwent triple-phase 64-channel MDCT examinations twice according to: (i) 120-kV standard protocol (PS; 0.75 g iodine (I)/kg body weight, n = 30) and (ii) 80-kV protocol A (PA; 0.75 g I/kg, n = 14) or protocol B (PB; 1 g I/kg, n = 16). Two independent readers evaluated tumour delineation and image quality blindly for all protocols. A third reader estimated the pancreas-to-tumour contrast-to-noise ratio (CNR). Statistical analysis was performed with the Chi-square test.

RESULTS

Tumour delineation was significantly better in PB and PA compared with PS (P = 0.02). The evaluation of image quality was similar for the three protocols (all, P > 0.05). The highest CNR was observed with PB and was significantly better compared to PA (P = 0.02) and PS (P = 0.0002).

CONCLUSION

In patients with PDAC, a low-tube-voltage, high-iodine-load protocol improves tumour delineation and CNR leading to higher tumour conspicuity compared to standard protocol MDCT.

KEY POINTS

• Low-tube-voltage high-iodine-load MDCT improves pancreatic cancer conspicuity compared to a standard protocol. • The pancreas-to-tumour attenuation difference increases significantly by reducing the tube voltage. • The radiation exposure dose decreases by reducing the tube voltage.

Perfusion computed tomography for detection of hepatocellular carcinoma in patients with liver cirrhosis

PURPOSE

To evaluate the diagnostic performance of dynamic perfusion CT (P-CT) for detection of hepatocellular carcinoma (HCC) in the cirrhotic liver.

MATERIALS AND METHODS

Twenty-six cirrhotic patients (19 men, aged 69 ± 10 years) with suspicion of HCC prospectively underwent P-CT of the liver using the 4D spiral-mode (100/80 kV; 150/175mAs/rot) of a dual-source system. Two readers assessed: (1) arterial liver-perfusion (ALP), portal-venous liver-perfusion (PLP) and hepatic perfusion-index (HPI) maps alone; and (2) side-by-side with maximum-intensity-projections of arterial time-points (art-MIP) for detection of HCC using histopathology and imaging follow-up as standard of reference. Another reader quantitatively assessed perfusion maps of detected lesions.

RESULTS

A total of 48 HCCs in 21/26 (81%) patients with a mean size of 20 ± 10 mm were detected by histopathology (9/48, 19%) or imaging follow-up (39/48, 81%). Detection rates (Reader1/Reader2) of HPI maps and side-by-side analysis of HPI combined with arterial MIP were 92/88% and 98/96%, respectively. Positive-predictive values were 63/63% and 68/71%, respectively. A cut-off value of ≥85% HPI and ≥99% HPI yielded a sensitivity and specificity of 100%, respectively, for detection of HCC.

CONCLUSION

P-CT shows a high sensitivity for detection of HCC in the cirrhotic liver. Quantitative assessment has the potential to reduce false-positive findings improving the specificity of HCC diagnosis.

KEY POINTS

• Visual analysis of perfusion maps shows good sensitivity for detection of HCC. • Additional assessment of anatomical arterial MIPs further improves detection rates of HCC. • Quantitative perfusion analysis has the potential to reduce false-positive findings. • In cirrhotic livers, a hepatic-perfusion-index ≥ 9 9% might be specific for HCC.

Abstract P3-04-05: Amplification driven expression of KIAA0020, a PARP1 interacting gene, facilitates repair of replication associated DNA damage in triple-negative breast cancers

Approximately 25% of triple-negative breast cancers display increased copy number in the region of 9p24. Since several genes mapping to this genomic locus have been shown to be involved in the biology of triple-negative breast cancers, a copy number-dependent transcriptional influence of genes at 9p24 on the malignant phenotypes has been suggested. Given the limited options of targeted therapy for triple-negative breast cancer patients, further studies of genes located at this locus could therefore provide potential novel targets or companion biomarkers for this disease.

By integrating microarray-based DNA copy number and gene expression of genes located on 9p24 in 111 triple-negative breast cancers, we identified among a wider set of genes three hypothetical genes, KIAA0020, KIAA1432 and KIAA2026 whose expression was highly correlated with their copy number status. External validation through analysis of several comprehensive breast cancer cohorts, confirmed KIAA0020 as being highly abundant in basal-like/ triple-negative breast cancers. Involvement of KIAA0020 in PARP1 activity and the DNA damage response has previously been suggested. To elucidate KIAA0020's functional involvement in cell growth, cell cycle progression, apoptosis and DNA damage response in this subtype of breast cancer, breast cancer cell lines with and without increased 9p24 copy number levels were used as in vitro models. In cell lines with increased DNA copy number at 9p24, depletion of KIAA0020 expression selectively impaired growth causing an accumulation in S-phase and a decrease in cell proliferation. Furthermore, KIAA0020-silencing in such cell lines resulted in decreased repair of hydroxyurea induced replication associated DNA damage, accumulation of DNA double strand breaks and decreased occurrence of RAD51 and PAR foci, all pointing to a decreased repair of inactivated replication forks.

Taken together, our data supports the notion that genes of unknown function, residing in the 9p24 copy number aberrant region are involved in DNA repair and may thereby also contribute to the tumourigenesis of triple-negative breast cancers. A subset of such triple-negative tumours seemed to have developed a dependency on the expression of KIAA0020, a PARP1 interacting gene, for replication fork associated repair. Thus, greater understanding of KIAA0020's molecular function may provide additional information for patient selection with regards to DNA damaging chemotherapeutics or PARP inhibitors within triple-negative breast cancers.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-04-05.

Abstract P5-01-01: Lymphoid tissue inducer cells: Identification of a novel immune cell within the breast tumour microenvironment and its role in promoting tumour cell invasion

Within breast cancers, trans-endothelial migration of tumour cells through lymphatic vessels is the first step to tumour dissemination and lympho-vascular invasion has been shown to stratify breast cancer phenotypes into distinct prognostic groups. The exact molecular mechanisms mediating tumor cell entry and persistence within the lymphatic system remain unclear. Lymphoid tissue inducer (LTi) cells are members of the emerging family of retinoic acid related orphan receptor (ROR)gt+ innate lymphoid cells (ILCs), and their interaction with stromal cells induces production by the stromal cells of VEGF-C and “lymphoid” chemokines, essential for lymphoid organogenesis. We hypothesized that tumour cells manipulate the normal processes that govern chemokine-dependent, trans-lymphatic migration of immune cells, including LTi cells; shaping its microenvironment. Results: We analyzed the expression of lymphoid chemokines genes (CXCL12, CXCL13, CCL19, CCL20 and CCL21) and their corresponding receptors (CXCR4, CXCR5, CCR6 and CCR7) within the METABRIC (Molecular Taxonomy of Breast Cancer International Consortium) Tissue Bank. An unsupervised hierarchical cluster analysis revealed co-expression of these genes, categorizing breast tumors as relatively high/low expressors. Tumors exhibiting relatively high expression of these genes were found to be enriched for “basal-like” breast cancers according to PAM50 intrinsic subtype assignments. Immunofluorescence of the primary tumour sections identified cells that were comparable in phenotype to LTi cells. In a blinded study, we observed that patients with high LTi counts within the tumour microenvironment were also likely to have a gene expression corresponding to high expression for the lymphoid chemokines. IHC for the lymphatic marker, podoplanin found that the LTi count correlated with both an increased lymphatic vessel density and tumor invasion into lymphatic vessels. Within the basal and HER2+ve subtypes, patients with more than 4 lymph nodes were found to exhibit higher numbers of intratumoural LTi cells. In vitro studies, alongside multi-photon in vivo imaging were performed to investigate the interaction between intra-tumoural LTi and mesenchymal stromal cells. CXCL13 was shown to be essential for LTi clustering around stromal cells in vitro, and, the administration of a blocking antibody in vivo delayed the onset of lymph node metastasis in a murine mammary tumour (4T1.2) model. CXCLl3 has been identified as having independent prognostic significance in breast cancer, but we and others report that breast cancer cell lines are not the source of CXCL13. We show that an increase in stromal CXCL13 concentration within the tumour microenvironment following LTi recruitment promotes an EMT phenotype in the 4T1.2 cancer cell line, possibly via activation of the RANKL/RANK axis promoting tumorigenesis. We report for the first time, the identification of LTi cells within the human breast cancer tumour microenvironment and propose a pivotal role for these cells, through stromal cell interactions in the tumour microenvironment, in facilitating lymphatic invasion of tumour cells by modulation of the local lymphoid chemokine profile.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-01-01.

Distinctive Expression of Cancer/Testis-X Antigens in a Subset of ER Negative Breast Carcinomas

Background: Cancer/testis-X antigens are a multigene family that are predominantly expressed in human germ line cells, with little or no expression in somatic adult tissues, but become aberrantly activated in various malignancies. Some such CT-X antigens represent ideal targets for cancer immunotherapy and have already been used in clinical testing. In contrast to melanomas, bladder, lung, ovarian and hepatocellular carcinomas which show higher levels of CT-X antigen expression, the reports in breast cancers have been inconclusive to date and a comprehensive gene expression and clinicopathological analysis has yet to be performed.Material and Methods: Using sequencing data as well as nine publicly available gene expression data sets, we analyzed the expression of Cancer/testis-X antigens in more than 1900 primary breast cancers. Complementary analysis was performed on three tissue microarrays comprising a total of 201 primary breast carcinomas and 53 brain metastases. Clinical information on the ER-, PR-, HER2, Ki67, p53, EGFR and basal markers was available for statistical analysis.Results: A significantly higher expression of Cancer/testis-X antigens was found in ER negative breast carcinomas over different data sets with a concordant gene expression pattern of several Cancer/testis-X antigens. Members of the MAGEA family and NY-ESO-1/CTAG1B were consistently the most prevalent. Immunohistochemical analyses confirmed a significant correlation of MAGEA family and NY-ESO-1/CTAG1B with ER negative (pValue &lt; 0.0001), PR negative (pValue &lt; 0.01) and Ki67 staining (pValue &lt; 0.0001). Many of these tumors were also positive for basal markers.Discussion: Previous studies of Cancer/testis-X antigens in breast have focused on ER positive cancers, in smaller subsets and provided inconclusive results. Using comprehensive gene expression data sets and tissue microarrays, we have demonstrated a significant association of MAGEA family and NY-ESO-1/CTAG1B with ER/PR negative breast cancer. Since these cancers represent a subgroup for which less therapeutic modalities are available, we propose the use of MAGEA and NY-ESO-1/CTAG1B cancer vaccines in the adjuvant setting as an approach to restricting tumor growth and metastases. Clinical trails using MAGEA and NY-ESO-1/CTAG1B are warranted.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3139.

Array CGH profiling of favourable histology Wilms tumours reveals novel gains and losses associated with relapse

Despite the excellent survival of Wilms tumour patients treated with multimodality therapy, approximately 15% will suffer from tumour relapse, where response rates are markedly reduced. We have carried out microarray-based comparative genomic hybridisation on a series of 76 Wilms tumour samples, enriched for cases which recurred, to identify changes in DNA copy number associated with clinical outcome. Using 1Mb-spaced genome-wide BAC arrays, the most significantly different genomic changes between favourable histology tumours that did (n = 37), and did not (n = 39), subsequently relapse were gains on 1q, and novel deletions at 12q24 and 18q21. Further relapse-associated loci included losses at 1q32.1, 2q36.3-2q37.1, and gain at 13q31. 1q gains correlated strongly with loss of 1p and/or 16q. In 3 of 11 cases with concurrent 1p(-)/1q(+), a breakpoint was identified at 1p13. Multiple low-level sub-megabase gains along the length of 1q were identified using chromosome 1 tiling-path arrays. One such recurrent region at 1q22-q23.1 included candidate genes RAB25, NES, CRABP2, HDGF and NTRK1, which were screened for mRNA expression using quantitative RT-PCR. These data provide a high-resolution catalogue of genomic copy number changes in relapsing favourable histology Wilms tumours.

Expression of interstitial collagenase during skeletal development of the mouse is restricted to osteoblast-like cells and hypertrophic chondrocytes

We determined the expression pattern of the matrix metalloproteinase interstitial collagenase (MMP-1) during mouse embryo development using in situ hybridization and immunohistochemistry. Localized MMP-1 mRNA was first detected at 14.5 days postconceptus. The spatial and temporal expression was restricted to areas of endochondral and intramembranous bone formation, such as in the mandibula, maxilla, clavicle, scapula, in the vertebrae, and in the dorsal, but not the ventral part of the ribs. The highest levels of MMP-1 transcripts and MMP-1 protein were found in the metaphyses and diaphyses of the long bones. MMP-1 was expressed by hypertrophic chondrocytes and by osteoblastic cells localized along the newly formed bone trabeculae. No expression was detected in osteoclasts. Two other related members of the MMP family, stromelysin-1 (MMP-3) and stromelysin-2 (MMP-10), were not expressed during days 7.5 and 16.5 of mouse embryogenesis. The tissue-specific expression of MMP-1 and the exclusive ability of interstitial collagenase to digest native collagen of types I, II, III, and X, the major components of bone, cartilage, and tendon, strongly suggests an important and specific function of this enzyme in bone development and remodeling.

The evaluation of cerebral atrophy in renal dialysis patients by computerized tomography

Thirty nine patients undergoing chronic hemodialysis, were submitted to brain computerized tomography in order to investigate the probable existence of brain atrophy. Evaluation was done by measuring the size of brain ventricles by means of a planimeter. An enlargement of the ventricles ranging from 1.43 to 3.13 times the normal was found in all patients. No relation was observed between the degree of the ventricular enlargement and the EEG findings, the clinical neurological picture and the duration of hemodialysis.