PURPOSE: To evaluate proton fat-water chemical shift fast low-angle shot magnetic resonance (MR) imaging for differentiation of fat-containing hyperechoic liver nodules from hyperechoic liver nodules without a fatty component. MATERIALS AND METHODS: T1-weighted fast low-angle shot fat-water chemical shift gradient-echo MR imaging was performed in 96 patients without cirrhosis with 138 hyperechoic liver nodules. In-phase and opposed-phase breath-hold images were acquired. The percentage of signal intensity variation between in-phase and opposed-phase images and the spleen-to-lesion contrast ratio were used to differentiate liver nodules. RESULTS: Chemical shift MR images showed fat in 15 (11%) hyperechoic nodules (two angiomyolipomas and 13 nodular fatty infiltrations of the liver). The mean percentage of signal intensity variation between in-phase and opposed-phase images was 156% (standard error, 43.5%) in nodules with fat and -0.16% (standard error, 0.96%) in nodules without fat (P = .003). Spleen-to-lesion contrast was similar on in- and opposed-phase images in lesions without fat (mean difference, -0.0107; standard error, 0.012), whereas the mean difference in fat-containing nodules was 0.805 (standard error, 0.225; P = .003). The area under the receiver operating characteristic curve was 0.97 for signal intensity variation. CONCLUSION: Hyperechogenicity in certain liver nodules is caused by fat. Chemical shift MR imaging allows accurate differentiation between these and other hyperechoic lesions with no fat component.

9718 Background: Epidermal growth factor receptor (EGFR) is a protoncogen that is found overexpressed in colorectal carcinomas (CRC) and it correlates with a worse prognosis. The aim was to describe EGFR overexpression patterns in non-metastatic CRC and to correlate these data with follow-up. Methods: We analyzed a series of 56 CRC. Inclusion criteria were: a) resected primary adenocarcinoma; b) curative surgery; c) pT3 N0–2 M0 without progression during the first 6 months post surgery; d) minimum follow-up over 3 years. EGFR overexpression was analyzed by immunohistochemistry (IHC) using the Dako PharmaDx kit (Glostrup, Denmark). As positive control the Dako slides and a bloc cell of A431-AAM cells were used. Presence of cytoplasmic and membrane patterns (intensity 1(+), 2(+) and 3(+)) were evaluated as well as the percentage of positive cells. Statistical analysis: association between qualitative variables was analyzed by Fisher's exact test. Disease-free and overall survival distributions were estimated by the Kaplan-Meier method and were analyzed with the log rank test. All P values are from two-sided statistical tests. Results: Characteristics of the patients (pts) were as follows: mean age: 68,4 years (range: 28–91); sex: 24 male and 32 female; location: 19 right colon and 37 left colon; follow-up: 44 pts alive without disease (78,5%), 9 died of disease (16,5%) and 3 died of other causes (5%). 10 pts had metastasis in the follow-up. IHC: Forty-two cases were positive (75%) and were classified as follows: 17 with >50% of positive cells (30%), 7 with 25–50% of positive cells (13%) and 18 cases with < 25% of positive cells. Patterns of staining were cytoplasmic predominance in 27 cases (48%) and 15 with membrane predominance (27%): 4 with intensity 1(+), 9 with 2(+) and 2 with 3(+). Only those patients with tumors harboring membrane positivity 2(+) and 3(+) had more probability to present metastasis (p= 0.067). Conclusions: EGFR overexpression evaluated as a membrane pattern with 2(+) and 3(+) intensity is related with metastatic development in colon carcinoma. Suported by a grant of C.I.R. Hospital de Sabadell. Consorci Sanitari Parc Taulí. Sabadell. Spain No significant financial relationships to disclose.

e15041 Background: Resistance to oxaliplatin is one of the main problems of colorectal cancer (CRC) treatment success. It is not clear if intrinsic and acquired resistance processes are developed by related mechanisms. In a previous work (Martinez-Cardús et al. Mol Cancer Ther, January 2009), we determined a profile of oxaliplatin-acquired resistance related genes by using an in vitro model. In the present work, we analyzed this genetic profile in paraffin-embedded primary adenocarcinomas from CRC patients treated with oxaliplatin-fluoropyrimidine. mRNA expression data was correlated with response rate and time to progression (TTP) in order to determine the role of these genes as markers of resistance to oxaliplatin-based treatment. Material and Method: mRNA levels were analyzed by using Real Time PCR. β-actin and 18s were used as housekeeping genes and, as a reference sample, we used commercial pool of mRNA from different human tumours. Chi- square and Fisher test were used in order to value differences in response rate to treatment. TTP was studied by using Kaplan Meyer curves and Log rank test. Median and percentile 33 and 66 were used as threshold values to determine both high and low expression level groups for each gene analyzed. We considered statistically significant a two-sided p-value lower than 0.05. Results: Forty-four advanced CRC patients treated with fluoropyrimidine plus oxaliplatin were analyzed. 54.5% of them were males; primary tumour was localized in colon in a 65.9% of cases. According to qRT-PCR analysis, the in vitro oxaliplatin acquired resistance related genes could be detected in the tumours but the expression of any of them correlated significantly with in vivo resistance to oxaliplatin-based treatment by using the three different threshold values to define groups. Conclusions: According to our results, these genes could not be used as markers of resistance to oxaliplatin-based treatment in non-treated tumours. Thereby, oxaliplatin resistance acquisition genes seems not to be involved in intrinsic drug resistance probably due to the fact that acquired and intrinsic oxaliplatin resistance are not related mechanisms. Further studies to typify oxaliplatin intrinsic resistance potential markers are guaranteed. No significant financial relationships to disclose.

BACKGROUND: Primary renal cell carcinoma (RCC) is the most frequent kidney cancer. In renal transplant patients, RCC more commonly arise in the native kidneys, whereas allograft involvement has been just occasionally reported. In these latter cases, a graft origin of tumor cells should be considered and other recipients from the same donor should be investigated. So far, genetic studies to trace the origin of cancer cells have always confirmed the donor origin of these tumors. METHODS: A 58-year-old man developed an RCC in the grafted kidney 14 years after transplantation. Histologic and immunohistochemical studies diagnosed a clear cell RCC with sarcomatoid changes. A nine microsatellite DNA assay was used to compare renal tumor cells with donor's (graft parenchyma) and recipient's (lymph nodes and blood) cells. RESULTS: Of the nine microsatellites analyzed, four turned out to be noninformative and the other five (D1S2734, D1S214, D1S199, D19S219, and Humara) showed different band profiles in donor's and recipient's cells DNA. Tumor and blood profile matching confirmed the recipient origin of neoplastic cells. CONCLUSIONS: We report the first case of a grafted-kidney RCC whose recipient's cell origin has been proved by microsatellite analysis. An origin from the recipient's kidney or bone marrow stem cells is proposed as the more plausible hypothesis.

In recent years, an increasing number of studies have shown that elevated expression of cyclin dependent kinase (Cdk5) contributes to the oncogenic initiation and progression of many types of cancers. In this study, we investigated the expression pattern of Cdk5 in colorectal cancer (CRC) cell lines and in a large number of tumor samples in order to evaluate its relevance in this pathogenesis and possible use as a prognostic marker. We found that Cdk5 is highly expressed and activated in CRC cell lines and that silencing of the kinase decreases their migration ability. In tumor tissues, Cdk5 is overexpressed compared to normal tissues due to a copy number gain. In patients with localized disease, we found that high Cdk5 levels correlate with poor prognosis, while in the metastatic setting, this was only the case for patients receiving an oxaliplatin-based treatment. When exploring the Cdk5 levels in the consensus molecular subtypes (CMS), we found the lowest levels in subtype 1, where high Cdk5 again was associated with a poorer prognosis. In conclusion, we confirm that Cdk5 is involved in CRC and disease progression and that it could serve as a prognostic and predictive biomarker in this disease.

One of the most striking epigenetic alterations that occurs at the level of the nucleosome is the complete exchange of the canonical H2A histones for the macroH2A variant. Here, we provide insight into the poorly recognized function of macroH2A in transcriptional activation and demonstrate its relevance in embryonic and adult stem cells. Knockdown of macroH2A1 in mouse embryonic stem (mES) cells limited their capacity to differentiate but not their self-renewal. The loss of macroH2A1 interfered with the proper activation of differentiation genes, most of which are direct target genes of macroH2A. Additionally, macroH2A1-deficient mES cells displayed incomplete inactivation of pluripotency genes and formed defective embryoid bodies. In vivo, macroH2A1-deficient teratomas contained a massive expansion of malignant, undifferentiated carcinoma tissue. In the heterogeneous culture of primary human keratinocytes, macroH2A1 levels negatively correlated with the self-renewal capacity of the pluripotent compartment. Together these results establish macroH2A1 as a critical chromatin component that regulates the delicate balance between self-renewal and differentiation of embryonic and adult stem cells.

Purpose: This work addresses the detection of Helicobacter pylori (H. pylori) in histological images with immunohistochemical staining. This analysis is a time demanding task, currently done by an expert pathologist that visually inspects the samples. Given the effort required to localise the pathogen in images, a limited number of annotations might be available in an initial setting. Our goal is to design an approach that, using a limited set of annotations, is capable of obtaining results good enough to be used as a support tool. Methods: We propose to use autoencoders to learn the latent patterns of healthy patches and formulate a specific measure of the reconstruction error of the image in HSV space. ROC analysis is used to set the optimal threshold of this measure and the percentage of positive patches in a sample that determines the presence of H. pylori. Results: Our method has been tested on an own database of 245 Whole Slide Images (WSI) having 117 cases without H. pylori and different density of the bacteria in the remaining ones. The database has 1211 annotated patches, with only 163 positive patches. This dataset of positive annotations was used to train a baseline thresholding and an SVM using the features of a pre-trained RedNet18 and ViT models. A 10-fold cross-validation shows that our method has better performance with 91% accuracy, 86% sensitivity, 96% specificity and 0.97 AUC in the diagnosis of H. pylori. Conclusion: Unlike classification approaches, our shallow autoencoder with threshold adaptation for the detection of anomalous staining is able to achieve competitive results with a limited set of annotated data. This initial approach is good enough to be used as a guide for fast annotation of infected patches.

Abstract Background Reliable biomarkers for precision medicine in metastatic colorectal cancer (mCRC) are needed. Blood biomarkers like chemokines may offer insights into overall tumor burden, yet, few prospective studies explore chemokine dynamics during treatment. This study investigates the behavior of a chemokine panel in mCRC patients during first-line oxaliplatin-based treatment, aiming to identify predictive and prognostic biomarkers. Methods Blood from oxaliplatin-treated mCRC patients was collected at three time points: before treatment (PRET), at response evaluation (EVAR), and at disease progression or last follow-up (LFUP). A custom 11-chemokine panel assessed serum chemokine levels by Luminex®, correlating them with treatment response, overall survival (OS), and progression-free survival (PFS) using the Cox proportional hazards models with the inverse probability weighting (IPW) approach. Additionally, immune system-associated gene expression was studied by Nanostring® in 15 primary tumor samples and correlated with CXCL13 expression, OS, and PFS. In silico analysis of 119 liver metastases from CRC patients, post neoadjuvant oxaliplatin-based treatment or untreated, evaluated CXCL13 expression’s correlation with immune cell infiltration, tertiary lymphoid structure (TLS) presence, OS, and PFS. Additionally, CXCL13 dynamics was studied by ELISA in 36 mCRC patients from the METIMMOX study control arm. Results Responders exhibited increased CXCL13 at EVAR, contrasting with non-responders whose levels decreased at EVAR and LFUP. Increased CXCL13 independently associated with improved PFS (median 14.5 vs. 8.9 months; HR = 0.34, p = 0.003) and OS (median 39.7 vs. 15.3 months; HR = 0.34, p = 0.003). CXCL13 expression correlated positively with an immunogenic tumor microenvironment, increased B cells, T cells (mainly CD8+) and enhanced OS. In silico , higher CXCL13 expression associated significantly with increased immune infiltration and improved OS. High CXCL13 expression was linked to the presence of TLSs, also associated with enhanced OS, especially in neoadjuvant-treated patients. Similar trends were obtained using the METIMMOX cohort. Conclusion The increase of CXCL13 levels in peripheral blood and its association with the formation of TLSs within the metastatic lesions, emerges as a potential biomarker indicative of the therapeutic efficacy in metastatic CRC patients undergoing oxaliplatin-based treatment.