Die komplizierte Gicht

Ein 57-jähriger Patient wurde aus der internistischen Abteilung einer auswärtigen Klinik übernommen, mit zahlreichen Gichttophi und einer Überwärmung des rechten Knies und des rechten Ellenbogens. Seit 20 Tagen bestand eine probatorische parenterale Antibiotikatherapie. Durch eine sofortige Punktion des rechten Kniegelenks konnte die Diagnose einer bakteriellen Arthritis gestellt werden. Es erfolgte umgehend eine Operation mit Spülung und ausführlichem Debridement unter der Weiterführung der Antibiotikatherapie. Bei Patienten mit Gicht und Verdacht auf eine zusätzliche Infektion muss immer eine vollständige und konsequente Fokussuche und ggf. eine operative Focussanierung durchgeführt werden.

Lateral Fasciectomy Sparing the Superficial Peroneal Nerve with Simultaneous Mesh Graft in Non-healing Lateral Leg Ulcers of Diverse Vascular Origins: Surgical Technique, Short- and Long-term Results from 44 Legs

OBJECTIVES

The technique of lateral fasciectomy (LF) sparing the superficial peroneal nerve with mesh graft coverage is a novel treatment of non-healing lateral leg ulcers of various vascular origin affecting the fascia. We report short- and long-term results of LF for recalcitrant lateral leg ulcers.

DESIGN

This study is a single center, retrospective case series of consecutive patients treated by LF.

MATERIALS

From 827 ulcers treated at our institution, 44 recalcitrant lateral leg ulcers affecting the fascia (41 patients) underwent lateral fasciectomy between 2006 and 2013.

METHODS

Preoperative indications, step-by-step surgical procedures, and perioperative care methodologies are presented. Long-term effects of healing and recurrence were clinically investigated or obtained through telephone interviews with relatives and local practitioners.

RESULTS

Three discrete etiologies were identified: venous ulcers (n = 24), arterial-venous/mixed ulcers (n = 11), and arteriolar Martorell hypertensive leg ulcers (n = 9). Complete healing was achieved in 40 legs (91%) after 3 months, and in 43 of the affected legs (98%) in total. The median duration to complete healing was 64 days. There was no difference between the healing times of different etiologies. No local recurrence was observed during the follow-up period, which ranged from 1.8 to 8.7 years (median: 5.11, mean: 5.12). Twelve patients (27%) died within this period due to multimorbidity.

CONCLUSIONS

Following lateral fasciectomy and mesh graft coverage, 43 legs (98%) healed in previously treatment resistant lateral leg ulcers.

[Brain stem infarction, temporal headache, and elevated inflammatory parameters in a 74-year-old man]

We report the case of a 74 year old man with a brain stem infarction, temporal headache and elevated inflammatory parameters. Giant cell arteritis with involvement of the temporal and vertebral arteries was proven by histology, duplex sonography and MRI. Although intensive immunosuppressive therapy was started, the patient developed two brain infarcts within 6 months. Initially, C‑reactive protein and erythrocyte sedimentation rate were significantly elevated, but normalized over time. Involvement of the vertebral artery in giant cell arteritis is thought to be rare; steroid refractory courses are very rare. Brain stem infarction might be the consequence.

[Speech Ability and Psychological Outcome After Treatment of Oral Cancer]

BACKGROUND

In recent years interactions between surgical treatment of oral carcinoma and incidence of anxiety or depression have become a subject of discussions. This prospective study is a comparison between the extent of loss of speech intelligibility and presence of depressive symptoms or anxiety as a result of oral carcinoma.

MATERIAL AND METHODS

One year after surgical therapy for oral carcinoma, 90 patients of an average age of 60±12 years were examined. Their speech intelligibility degree was measured using standardized automatic speech recognition (word recognition rate, WR). Symptoms of anxiety and depression were detected by use of HAD-Scales (HADS). Next to the relationship between WR and HADS other influential variables related to WR and HADS were statistically evaluated.

RESULTS

The WR average was 53.2±17.2. Female WR was better than male. The difference between tumor classifications T1 and T4 compared to the WR reached statistical significance. Significant differences were detected between WR and "tumor localization", "graft donor site", "graft morphology", "tongue motility", and "tracheostoma" groups. There was a relationship between tongue motility and graft morphology, graft donor site and tumor localization. HAD-Scores in the mean were elevated: HADS-Total=43.3%, HADS-A=43.3% und HADS-D= 51.1%. WR correlates with HADS-D-Subscale, but not with HADS-A-Subscale.

CONCLUSION

Communication disorders as a result of neoplasmic orofacial surgery may be related to extent of the treatment and to affective impairments. This should receive attention in the concept of rehabilitation.

Bacaryolanes A-C, Rare Bacterial Caryolanes from a Mangrove Endophyte

Caryolanes are known as typical plant-derived sesquiterpenes. Here we describe the isolation and full structure elucidation of three caryolanes, bacaryolane A-C (1-3), that are produced by a bacterial endophyte (Streptomyces sp. JMRC:ST027706) of the mangrove plant Bruguiera gymnorrhiza. By 2D NMR, analysis of the first X-ray crystallographic data of a caryolane (bacaryolane C), CD spectroscopy, and comparison with data for plant-derived caryolanes, we rigorously established the absolute configuration of the bacaryolanes and related compounds from bacteria. Bacterial caryolanes appear as the mirror images of typical plant caryolanes. Apparently plant and bacteria harbor stereodivergent biosynthetic pathways, which may be used as metabolic signatures. The discovery of plant-like volatile terpenes in endophytes not only is an important addition to the bacterial terpenome but may also point to complex molecular interactions in the plant-microbe association.

Patient-bounded extrapolation using low-dose priors for volume-of-interest imaging in C-arm CT

PURPOSE

Three-dimensional (3D) volume-of-interest (VOI) imaging with C-arm systems provides anatomical information in a predefined 3D target region at a considerably low x-ray dose. However, VOI imaging involves laterally truncated projections from which conventional reconstruction algorithms generally yield images with severe truncation artifacts. Heuristic based extrapolation methods, e.g., water cylinder extrapolation, typically rely on techniques that complete the truncated data by means of a continuity assumption and thus appear to be ad-hoc. It is our goal to improve the image quality of VOI imaging by exploiting existing patient-specific prior information in the workflow.

METHODS

A necessary initial step prior to a 3D acquisition is to isocenter the patient with respect to the target to be scanned. To this end, low-dose fluoroscopic x-ray acquisitions are usually applied from anterior-posterior (AP) and medio-lateral (ML) views. Based on this, the patient is isocentered by repositioning the table. In this work, we present a patient-bounded extrapolation method that makes use of these noncollimated fluoroscopic images to improve image quality in 3D VOI reconstruction. The algorithm first extracts the 2D patient contours from the noncollimated AP and ML fluoroscopic images. These 2D contours are then combined to estimate a volumetric model of the patient. Forward-projecting the shape of the model at the eventually acquired C-arm rotation views gives the patient boundary information in the projection domain. In this manner, we are in the position to substantially improve image quality by enforcing the extrapolated line profiles to end at the known patient boundaries, derived from the 3D shape model estimate.

RESULTS

The proposed method was evaluated on eight clinical datasets with different degrees of truncation. The proposed algorithm achieved a relative root mean square error (rRMSE) of about 1.0% with respect to the reference reconstruction on nontruncated data, even in the presence of severe truncation, compared to a rRMSE of 8.0% when applying a state-of-the-art heuristic extrapolation technique.

CONCLUSIONS

The method we proposed in this paper leads to a major improvement in image quality for 3D C-arm based VOI imaging. It involves no additional radiation when using fluoroscopic images that are acquired during the patient isocentering process. The model estimation can be readily integrated into the existing interventional workflow without additional hardware.

The Added Value of Volume-of-Interest C-Arm CT Imaging during Endovascular Treatment of Intracranial Aneurysms

BACKGROUND AND PURPOSE

Successful endovascular treatment of intracranial aneurysms requires understanding the exact relationship of implanted devices to the aneurysm, parent artery, and other branch vessels during the treatment. Intraprocedural C-arm CT imaging has been shown to provide such information. However, its repeated use is limited due to increasing radiation exposure to the patient. The goal of this study was to evaluate a new volume-of-interest C-arm CT imaging technique, which would provide device-specific information through multiple 3D acquisitions of only the region of interest, thus reducing cumulative radiation exposure to the patient.

MATERIALS AND METHODS

VOI C-arm CT images were obtained in 28 patients undergoing endovascular treatment of intracranial aneurysms. VOI images were acquired with the x-ray source collimated around the deployed device, both horizontally and vertically. The images were reconstructed by using a novel prototype robust reconstruction algorithm to minimize truncation artifacts from double collimation. The reconstruction accuracy of VOI C-arm CT images was assessed quantitatively by comparing them with the full-head noncollimated images.

RESULTS

Quantitative analysis showed that the quality of VOI C-arm CT images is comparable with that of the standard Feldkamp, Davis, and Kress reconstruction of noncollimated C-arm CT images (correlation coefficient = 0.96 and structural similarity index = 0.92). Furthermore, 91.5% reduction in dose-area product was achieved with VOI imaging compared with the full-head acquisition.

CONCLUSIONS

VOI imaging allows multiple 3D C-arm CT acquisitions and provides information related to device expansion, parent wall apposition, and neck coverage during the procedure, with very low additional radiation exposure to the patient.

Abstract B70: High-throughput analysis of 3D tumor colony formation of primary cell suspensions derived from xenografts to identify efficacy of anti-tumor agents in single agent or combination therapy

Recent experience in anti-cancer research has demonstrated that three-dimensional (3D) tumor cell culture models represent a biological assay system, being more relevant than two-dimensional (2D) monolayer cell cultures. Anchorage-independent 3D growth is one of the hallmarks of cell transformation and performance of 3D colony formation assays in semi-solid media is considered as an accurate and stringent measure for detecting growth of malignant, transformed cells.

Here, we describe the high-throughput application of a 3D soft-agar clonogenic assay using primary cell suspensions of patient-derived (PDX) and cell line-derived (CDX) xenografts in a 96 well microplate format, using targeted anti-tumor agents, such as Braf, Wnt pathway, and telomerase inhibitors. Colony formation was determined by automated image analysis. Our data show that this is a more appropriate read-out compared to indirect measurements, such as determination of metabolic activity by measuring intracellular ATP.

Specificity of the assay was demonstrated by testing Braf inhibitors vemurafenib and dabrafenib, which potently inhibited colony formation of V600E mutated tumors of melanoma and colon carcinoma (MEXF 1732, MEXF 672, MEXF 989, HT-144, and Colo 205), whereas Braf wildtype tumors of the same histotypes were less sensitive (MEXF 1792, MEXF 1870, MEXF 535, MEXF 622, and HCT-116). Moreover, anti-tumor activity was determined for several standard of care agents. Erlotinib, for example, exhibited differential in vitro activity, which closely matched results obtained for xenografts when tested in vivo, and EGFR was overexpressed in sensitive tumor models.

The 3D soft-agar clonogenic assay is customizable for different treatment layouts, which makes it a valuable tool for efficacy determinations of single drug treatments in broad screens or drug combinations. By using a 5×5 matrix combination approach, we identified synergistic interactions between Wnt pathway (XAV-939) and telomerase (RHPS4) inhibitors using Bliss independence analysis. These results are in line with a postulated molecular link between Wnt/β-catenin signalling and telomerase expression (Hoffmeyer et al. Science 336, 1549, 2012).

In conclusion, the 3D assay platform provides a fast and robust method for the assessment of anti-tumor agents using primary cell suspensions in vitro without needing to establish permanent cell lines. Screening approaches with single agents and combinations in broad tumor panels are of high value for investigating cytotoxic and new targeted anti-tumor agents, as well as for hypothesis generation and selection of development or treatment strategies.

Citation Format: Armin Maier, Sumeer Dhar, Andreas Maunz, Bruno Zeitouni, Anne-Lise Peille, Torsten Giesemann, Heinz-Herbert Fiebig. High-throughput analysis of 3D tumor colony formation of primary cell suspensions derived from xenografts to identify efficacy of anti-tumor agents in single agent or combination therapy. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B70.

Abstract 1705: Classification of colorectal PDX into transcriptomic subtypes associated with distinct genomic alteration profiles and in vivo response patterns to therapies

Recently, unsupervised gene expression-based signatures with prognostic and potential predictive implications were proposed for colorectal cancer (CRC) classification. The challenge is now to characterize the genomic alterations of CRC subtypes and their sensitivity to therapies. Patient derived xenograft models (PDX) may be a valuable tool for this purpose, as they retain the molecular features and drug response patterns of their parental patient tumors. In this study, we classified our collection of colon PDX into transcriptomic subtypes and investigated the associations with genomic alterations and in vivo responses to cetuximab (CTX), oxaliplatin (OXT) and irinotecan (IR). We determined expression profiles of 67 PDX models using Affymetrix HGU133 Plus2.0 arrays and applied the CRC assigner-786 gene expression signature reported by Sadanandam et al. to classify our PDX into 5 subtypes. We identified 34 (51%) transit-amplifying (TA), 15 (22%) goblet-like (GL), 10 (15%) inflammatory (IF), 7 (10%) enterocyte (ET) and 1 (1%) stem-like (SL) PDX models. TA showed a gene signature of WNT pathway activation whereas GL, ET and IF PDX subtypes harbored gene signatures of KRAS pathway activation. As analyzed by whole exome sequencing and Affymetrix SNP6.0 array, the GL, ET and IF subtypes were found to display different signatures of mutational processes, mutations and chromosomal rearrangement patterns than TA and SL. Of particular note, mutations in BRAF, PIK3CA/PTEN, TGFBR2/SMAD4 or NOTCH1 were mainly found in GL, ET or IF while mutations in APC, TP53 and KRAS were not associated with a given subtype. Regarding PDX drug sensitivity, 10/11 TA/SL PDX with unaltered KRAS/PIK3CA/PTEN/HER2 status were sensitive to CTX whereas 9/12 models with alterations were resistant. TA and SL PDX were also frequently sensitive to IR and OXT (6/10 and 4/10, respectively). In the IF subtype, 6/6 PDX showing KRAS, PIK3CA or PTEN alterations were resistant to CTX. Of interest, 5/5 IF PDX were sensitive to IR treatment. As in IF PDX, GL and ET often had alterations in KRAS/PIK3CA/PTEN/HER2 and were resistant to CTX. Moreover, these subtypes were resistant to both IR and OXT. Furthermore, the frequent KRAS pathway activation and the presence of actionable mutations in GL, ET and IF would advocate the testing of inhibitors (as monotherapy or in combination) of BRAF, PI3K or MEK in tumors of these subtypes while WNT inhibitors should be tested in TA models.Molecular classification of our colon PDX collection confirmed their similarities with patient tumors. Investigation of drug sensitivity resulted in the identification of PDX subtypes which respond poorly to standard therapies and which require different treatment options. Testing alternative and combined therapies in PDX may be a valuable approach to optimize personalized medicine.

Citation Format: Anne-Lise Peille, Christina Gredy, Bruno Zeitouni, Armin Maier, Kerstin Klingner, Tim Kees, Julia Schüler, Thomas Metz, Heinz. Herbert Fiebig, Vincent Vuaroqueaux. Classification of colorectal PDX into transcriptomic subtypes associated with distinct genomic alteration profiles and in vivo response patterns to therapies. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1705. doi:10.1158/1538-7445.AM2015-1705

Abstract 4472: Plitidepsin shows antitumor activity in patient-derived tumor xenografts and hematologic malignancies

Plitidepsin is a new marine-derived anti-tumor agent, originally isolated from the tunicate Aplidium albicans that is now fully obtained by total chemical synthesis. The compound is currently being evaluated in a pivotal phase III trial in patients with refractory/relapsed multiple myeloma. Previous in vitro studies in 26 hematological cell lines demonstrated that plitidepsin was more active in multiple myeloma and non-Hodgkin lymphoma compared to CML, AML and ALL derived cell lines as determined in a 4 day proliferation assay in suspension cultures. We have recently shown that plitidepsin interacts selectively with eEF1A2 (eukaryotic translation elongation factor 1 alpha 2) in tumor cells, which results in apoptotic cell death. To identify target tumor types for future clinical studies, the inhibition of colony formation of plitidepsin was assessed in vitro in 116 established patient derived xenografts tumor models from 23 different tumor types, including solid tumors and hematological malignancies such as myeloma, leukemia and lymphoma. The anti-tumor activity of plitidepsin varied depending on the concentration used, achieving a mean IC70 (inhibitory concentration of 70%) value of 3 nM (range between 0.03 nM and >1 μM), which can be also achieved in patients treated using the clinical recommended dose or less. 39 out of 116 tumors showed above average sensitivity (IC70 < 1nM) and IC70 values in these tumors were about 9-fold lower than the mean of all tumors as tested. Sensitive tumor types were seen among different tumor types, such as hematological malignancies, pleuramesothelioma, melanoma, small cell and non-small cell lung cancer (both adeno and large cell), as well as renal cancer. In conclusion plitidepsin showed a broad differential antitumor activity in vitro in hematological malignancies and in solid tumors. Bioinformatic analyses are currently underway to identify biomarkers and/or gene signatures that can predict sensitivity or resistance to plitidepsin for selecting patients being responsive to the drug.

Citation Format: Armin Maier, Gerhard Kelter, Vincent Vuaroquaux, Pablo M. Avilés Marin, Carmen Cuevas, Carlos M. Galmarini, Heinz H. Fiebig. Plitidepsin shows antitumor activity in patient-derived tumor xenografts and hematologic malignancies. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4472. doi:10.1158/1538-7445.AM2015-4472

Composition and uses of anaerobic digestion derived biogas from wastewater treatment facilities in North America

A study was conducted to determine the current knowledge of biogas production and its use at municipal wastewater treatment plants (WWTPs) across North America. Information was provided by municipal WWTPs across Canada and the US. It was determined that hydrogen sulfide (H2S) and silicon (Si) compounds had sufficient variability to be of concern. The only biogas production trend that could be identified was a possible seasonal relationship with sludge input and biogas production. Secondary analysis was performed to observe trends in biogas usage in urban areas larger than 150,000 in the US and 50,000 in Canada; 66% of facilities had anaerobic digestion systems and, of those, only 35% had an energy recovery system. Climatic, population, and socio-political influences on the trends were considered. The primary conclusion was that more data is required to perform significant analyses on biogas production and composition variation.

Piggy-back Hepatic Transplant Technique and Veno-venous Bypass Without Cardiac Arrest: A Multidisciplinary Approach in Borderline T3b/T3c Renal Tumors

Surgery for renal cell carcinomas with tumor thrombus extending in the Inferior Vena Cava (IVC) can be particularly challenging, especially in the retrohepatic and intraatrial situations (T3b and T3c). Classically, these tumors require the intraoperative use of cardio-pulmonary by-pass (CPB) and deep hypothermic circulatory arrest (DHCA), that can result in specific complications (stroke, platelet dysfunction), with increased postoperative morbidity rates.

In urological practice, a particular IVC preparation method is currently in use, allowing full control both upon the IVC and its tributaries. It is derived from the “piggy-back” liver transplantation technique and implies the resection of all hepatic ligaments, leaving the hepatic vascular connections intact. This procedure is joined by a form of veno-venous bypass (between the right atrium and the infrarenal IVC) that allows a constant central venous pressure (by assuring blood return), with less bleeding and without the need for CPB and DHCA (avoiding, in this way, their inherent complications). All in all, these recently-introduced procedures can offer better thrombus control, improved oncologic outcomes and smaller complication rates. We aim to present a case of borderline T3b/T3c renal tumor that was successfully treated in our university center using these techniques.

Anti-tumor activity of the TGF-β receptor kinase inhibitor galunisertib (LY2157299 monohydrate) in patient-derived tumor xenografts

Purpose

The transforming growth factor-beta (TGF-β) signaling pathway is known to play a critical role in promoting tumor growth. Consequently, blocking this pathway has been found to inhibit tumor growth. In order to achieve an optimal anti-tumor effect, however, it remains to be established whether blocking the TGF-β signaling pathway alone is sufficient, or whether the tumor microenvironment plays an additional, possibly synergistic, role.

Methods

To investigate the relevance of blocking TGF-β signaling in tumor cells within the context of their respective tissue microenvironments, we treated a panel of patient-derived xenografts (PDX) with the selective TGF-β receptor kinase inhibitor LY2157299 monohydrate (galunisertib) and assessed both the in vitro and in vivo effects.

Results

Galunisertib was found to inhibit the growth in an in vitro clonogenic assay in 6.3 % (5/79) of the examined PDX. Evaluation of the expression profiles of a number of genes, representing both canonical and non-canonical TGF-β signaling pathways, revealed that most PDX exhibited expression changes affecting TGF-β downstream signaling. Next, we subjected 13 of the PDX to an in vivo assessment and, by doing so, observed distinct response patterns. These results suggest that, next to intrinsic, also extrinsic or microenvironmental factors can affect galunisertib response. pSMAD2 protein expression and TGF-βRI mRNA expression levels were found to correlate with the in vivo galunisertib effects.

Conclusions

From our data we conclude that intrinsic, tumor-dependent TGF-β signaling does not fully explain the anti-tumor effect of galunisertib. Hence, in vivo xenograft models may be more appropriate than in vitro clonogenic assays to assess the anti-tumor activity of TGF-β inhibitors such as galunisertib.

Electronic supplementary material

The online version of this article (doi:10.1007/s13402-014-0210-8) contains supplementary material, which is available to authorized users.

Aggregate Exposure and Cumulative Risk Assessment--Integrating Occupational and Non-occupational Risk Factors

Occupational exposure limits have traditionally focused on preventing morbidity and mortality arising from inhalation exposures to individual chemical stressors in the workplace. While central to occupational risk assessment, occupational exposure limits have limited application as a refined disease prevention tool because they do not account for all of the complexities of the work and non-occupational environments and are based on varying health endpoints. To be of greater utility, occupational exposure limits and other risk management tools could integrate broader consideration of risks from multiple exposure pathways and routes (aggregate risk) as well as the combined risk from exposure to both chemical and non-chemical stressors, within and beyond the workplace, including the possibility that such exposures may cause interactions or modify the toxic effects observed (cumulative risk). Although still at a rudimentary stage in many cases, a variety of methods and tools have been developed or are being used in allied risk assessment fields to incorporate such considerations in the risk assessment process. These approaches, which are collectively referred to as cumulative risk assessment, have potential to be adapted or modified for occupational scenarios and provide a tangible path forward for occupational risk assessment. Accounting for complex exposures in the workplace and the broader risks faced by the individual also requires a more complete consideration of the composite effects of occupational and non-occupational risk factors to fully assess and manage worker health problems. Barriers to integrating these different factors remain, but new and ongoing community-based and worker health-related initiatives may provide mechanisms for identifying and integrating risk from aggregate exposures and cumulative risks from all relevant sources, be they occupational or non-occupational.

The Scientific Basis of Uncertainty Factors Used in Setting Occupational Exposure Limits

The uncertainty factor concept is integrated into health risk assessments for all aspects of public health practice, including by most organizations that derive occupational exposure limits. The use of uncertainty factors is predicated on the assumption that a sufficient reduction in exposure from those at the boundary for the onset of adverse effects will yield a safe exposure level for at least the great majority of the exposed population, including vulnerable subgroups. There are differences in the application of the uncertainty factor approach among groups that conduct occupational assessments; however, there are common areas of uncertainty which are considered by all or nearly all occupational exposure limit-setting organizations. Five key uncertainties that are often examined include interspecies variability in response when extrapolating from animal studies to humans, response variability in humans, uncertainty in estimating a no-effect level from a dose where effects were observed, extrapolation from shorter duration studies to a full life-time exposure, and other insufficiencies in the overall health effects database indicating that the most sensitive adverse effect may not have been evaluated. In addition, a modifying factor is used by some organizations to account for other remaining uncertainties-typically related to exposure scenarios or accounting for the interplay among the five areas noted above. Consideration of uncertainties in occupational exposure limit derivation is a systematic process whereby the factors applied are not arbitrary, although they are mathematically imprecise. As the scientific basis for uncertainty factor application has improved, default uncertainty factors are now used only in the absence of chemical-specific data, and the trend is to replace them with chemical-specific adjustment factors whenever possible. The increased application of scientific data in the development of uncertainty factors for individual chemicals also has the benefit of increasing the transparency of occupational exposure limit derivation. Improved characterization of the scientific basis for uncertainty factors has led to increasing rigor and transparency in their application as part of the overall occupational exposure limit derivation process.

Setting Occupational Exposure Limits for Chemical Allergens--Understanding the Challenges

Chemical allergens represent a significant health burden in the workplace. Exposures to such chemicals can cause the onset of a diverse group of adverse health effects triggered by immune-mediated responses. Common responses associated with workplace exposures to low molecular weight (LMW) chemical allergens range from allergic contact dermatitis to life-threatening cases of asthma. Establishing occupational exposure limits (OELs) for chemical allergens presents numerous difficulties for occupational hygiene professionals. Few OELs have been developed for LMW allergens because of the unique biological mechanisms that govern the immune-mediated responses. The purpose of this article is to explore the primary challenges confronting the establishment of OELs for LMW allergens. Specific topics include: (1) understanding the biology of LMW chemical allergies as it applies to setting OELs; (2) selecting the appropriate immune-mediated response (i.e., sensitization versus elicitation); (3) characterizing the dose (concentration)-response relationship of immune-mediated responses; (4) determining the impact of temporal exposure patterns (i.e., cumulative versus acute exposures); and (5) understanding the role of individual susceptibility and exposure route. Additional information is presented on the importance of using alternative exposure recommendations and risk management practices, including medical surveillance, to aid in protecting workers from exposures to LMW allergens when OELs cannot be established.

The Global Landscape of Occupational Exposure Limits--Implementation of Harmonization Principles to Guide Limit Selection

Occupational exposure limits (OELs) serve as health-based benchmarks against which measured or estimated workplace exposures can be compared. In the years since the introduction of OELs to public health practice, both developed and developing countries have established processes for deriving, setting, and using OELs to protect workers exposed to hazardous chemicals. These processes vary widely, however, and have thus resulted in a confusing international landscape for identifying and applying such limits in workplaces. The occupational hygienist will encounter significant overlap in coverage among organizations for many chemicals, while other important chemicals have OELs developed by few, if any, organizations. Where multiple organizations have published an OEL, the derived value often varies considerably-reflecting differences in both risk policy and risk assessment methodology as well as access to available pertinent data. This article explores the underlying reasons for variability in OELs, and recommends the harmonization of risk-based methods used by OEL-deriving organizations. A framework is also proposed for the identification and systematic evaluation of OEL resources, which occupational hygienists can use to support risk characterization and risk management decisions in situations where multiple potentially relevant OELs exist.

Abstract 3699: Molecular profiling of BRAFi-resistance in melanoma cancer models using high-throughput sequencing in patient-derived xenografts

Patients with metastatic V600E mutant melanomas treated with BRAF inhibitors (BRAFi) frequently develop resistant tumors with aggressive phenotypes. Furthermore, approximately 20-40% of V600E mutant tumors are intrinsically resistant to BRAFi. Suitable models for studying mechanisms of acquired and intrinsic resistance to BRAFi are therefore necessary. In the present study, we applied deep sequencing techniques to identify possible mechanisms of intrinsic and acquired resistance in our collection of melanoma patient-derived xenograft models (MEXFs) treated with BRAFi.

Mutational and expression profiles in MEXFs were characterized by whole-exome sequencing (WES) and HG-U133 Plus 2.0 Affymetrix chips and correlated with BRAFi efficacy data from 3D Tumor Clonogenic Assays (TCA). In addition, four resistant cell lines were created by continuously treating 2D monolayer cultures of tumor cells with Vemurafenib, all of which were initially sensitive to BRAFi and carry the BRAF V600E mutation. Expression profiles and mutations of these cell lines were analyzed from RNA-seq data. Potential gene candidates responsible for conferring resistance were further investigated by Q-PCR and Western-blot experiments.

WES data revealed that the number of mutations per model was highly variable. Some MEXFs showed a hyper-mutated profile (>2000 mutations) and were characterized by specific mutational signatures in agreement with those found in melanoma (Alexandrov et al, Nature, 2013). Mutation frequencies of genes typically mutated in melanoma are very similar to those found in The Cancer Genome Atlas. We observed a high correlation of mutations between our MEXFs and their respective cell lines. Among the models with a V600E mutation, only one (MEXF 462) showed resistance to BRAFi-treatment as identified by 3D TCA analyses. In this model, we identified gene point mutations and a high over-expression of EGFR, MEK1, PDGFRA and NF1 in contrast to the other models, suggesting a specific regulation of the RTK signaling pathways. In 2D assays, synergistic interaction of Vemurafenib and Erlotinib was shown. RNA-seq analysis of the cell line established from MEXF 276, in which resistance to Vemurafenib was induced, revealed around 20% of genes being differentially expressed (FC>2) between sensitive and resistant cell lines. An up-regulation of EGFR was also found in this resistant cell line and was confirmed by Western-blot. In addition, an overexpression of PLAU, a biomarker of invasiveness, was identified. We currently perform expression profiling of three other models resistant to BRAFi. Preliminary results suggest different patterns of gene regulation involved in acquisition of resistance. A precise map of transcriptomic and mutational profiles of the four cell lines will be generated and we are investigating if invasiveness is increased upon acquisition of resistance.

Citation Format: Bruno Zeitouni, Gerhard Kelter, Armin Maier, Florian Kiefer, Frederic Foucault, Anne-Lise Peille, Tim Kees, Torsten Giesemann, Vincent Vuaroqueaux, Thomas Metcalfe, Heinz-Herbert Fiebig. Molecular profiling of BRAFi-resistance in melanoma cancer models using high-throughput sequencing in patient-derived xenografts. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3699. doi:10.1158/1538-7445.AM2014-3699

Abstract 1231: In vitro anticancer activity of imidazo-acridinone (HKH40A) in panels of human patient-derived tumor xenografts (PDXs) and human leukemia and lymphoma cell lines

HKH40A is a synthetic, DNA-intercalating (Kosakowska-Cholody et al., 2009) anticancer agent consisting of an imidazo-acridinone linked to a 1,8-naphthalimide moiety via a 1,4-dipropylpiperazine linker. It displayed strong inhibitory activity in the NCI-60 tumor cell line panel in vitro with an IC50 of about 1 nM in selected tumor cell lines (Hariprakasha et al. 2007). In addition, anticancer activity was observed in hepatoma models both in vitro and in vivo. We have investigated the in vitro anticancer activity of HKH40A in 3D cultures, using panels of 206 PDXs and 11 human leukemia and lymphoma cell lines. The 3D clonogenic assay was performed in a 96 well format using a metabolic readout as an equivalent for colony formation. PDXs and hematologic cell lines were propagated in immunedeficient mice.

HKH40A proved to be very potent with a mean IC50 of 6 nM and a mean IC70 of 12 nM. Overall, the hematological cell lines were more sensitive than the solid tumor models. Selective activity (definition: IC50 < 1/3 of mean IC50) was seen in 4 out of 6 acute myeloid leukaemias (AMLs), in 1 out of 1 chronic lymphocytic leukemia (CLL) and in 1 out of 3 non-Hodgkin lymphomas (NHLs). Among the solid tumors, pleural mesotheliomas were most sensitive followed by soft tissue sarcomas and anal cancer. Selective activity was observed in a subset of 8 out of 30 colon cancer models, which presented IC50 values < 1/3 of the mean IC50 of all tumors. The drug sensitivity data will be correlated to mutational and transcriptomic (Whole Exome Sequencing and Affymetrix HG-U133 plus 2.0 array profiles) characteristics of the PDXs to identify predictive biomarkers of drug response and resistance.

Overall, HKH40A is a novel imidazo-acridinone with high in vitro activity mainly in AMLs and NHLs as well as in pleural mesotheliomas, soft tissue sarcomas and in a subset of colon cancer models. The identification of predictive biomarkers is ongoing.

*Deceased during an NCI retreat

Citation Format: Heinz H. Fiebig, Armin Maier, Gerhard Kelter, Vincent Vuaroqueaux, Humcha K. Hariprakasha, Christopher Michejda. In vitro anticancer activity of imidazo-acridinone (HKH40A) in panels of human patient-derived tumor xenografts (PDXs) and human leukemia and lymphoma cell lines. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1231. doi:10.1158/1538-7445.AM2014-1231

Abstract LB-314: Whole exome sequencing analyses of gastric cancers reveal two distinct genomic alteration patterns with implications in drug sensitivity

Gastric cancer is the fourth most common cancer diagnosed and the second most frequent cause of cancer-related death worldwide. Multiple factors can contribute to the development of gastric cancer, including H. pylori infection, dietary behaviour and life style, possibly resulting in distinct cancer subtypes with different drug sensitivity profiles. In the present study we searched for gastric cancer mutation patterns in the dataset of the “The Cancer Genome Atlas” (TCGA) and in our collection of patient derived xenografts (PDX). In a second part, we evaluated gene alteration patterns for their implications for drug sensitivity.

In both TCGA and our PDX datasets, Whole Exome Sequencing analyses revealed two subsets of gastric tumors characterized by specific mutation signatures, with different types and numbers of genomic alterations. The first subset (60% and 75% of samples) contained lower levels of mutations and was characterized by increased numbers of large chromosomal rearrangements resulting in gene loss or amplifications. The second subset of tumors (25%-40% of samples) revealed higher levels of mutations that were predominantly nucleic acid substitutions and small indels linked to mismatch repair genes including MLH1 or MSH3 and to high microsatellite instability. In both subsets, the mutation spectrum was dominated by C>T transitions with an increase of small indels in the subset of highly-mutated tumors.

At the gene level, the genes which were mutated in our gastric PDX collection overlapped to great extent with the mutations found in TCGA tumors, especially regarding the most frequently mutated genes. In the first subset, high levels of gene amplifications and deletions were found, including growth factor receptor amplifications in EGFR and HER2. Furthermore, the mutation frequency in genes associated with drug resistance such as KRAS was decreased. The tumors with growth factor receptor amplification responded consistently to therapies such as Cetuximab or Trastuzumab. In contrast, an increased frequency of mutations in oncogenes and tumor suppressors, including KRAS (n=5/10), PIK3CA (n=5/10) and PTEN (n=7/10), was found in the second subset. The mutational profile of these tumors suggest the use of compounds targeting downstream molecules, such as PIK3CA, or targeting effectors of DNA repair, such as PARP, for anti-cancer therapy. Of note, no association was found between the mutation groups and sensitivity to chemotherapeutic agents such as 5FU, Cisplatin or Paclitaxel.

In conclusion, we identified two subsets of gastric tumors both in the TCGA dataset and in our collection of PDX models, characterized by distinct genomic alteration profiles suggesting different therapeutic approaches. Currently, we are assessing drug sensitivity profiles within the two subsets in our PDX models.

Citation Format: Anne-Lise Peille, Swee-Seong Wong, Florian Kiefer, Bruno Zeitouni, Armin Maier, Frederic Foucault, Tim Kees, Vincent Vuaroqueaux, Amit Aggarwal, Christoph Reinhard, Heinz Herbert Fiebig. Whole exome sequencing analyses of gastric cancers reveal two distinct genomic alteration patterns with implications in drug sensitivity. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-314. doi:10.1158/1538-7445.AM2014-LB-314

Abdominal wall non-clostridian gas cellulitis: a rare complication of a colostoma

The authors report the case of a 69 year-old patient, with obesity, having a left colostomy that has been made for rectal cancer (12 years ago) and who developed a non-clostridian gascellulitis of the abdominal wall as a result of intraparietal traumatic tract perforation of the colostomy. The presence of the peristomal hernia favoured the posttraumatic injury of the colostomy. Repeated surgical inteventions and the antibiotic treatment determined a favourable evolution. Despite the wound contamination with excrement, transit stoma relocation was not necessary. Some clinical and therapeutic aspects of abdominal wall infections are presented.