Detection of Crimean-Congo haemorrhagic fever virus in Hyalomma marginatum ticks, southern France, May 2022 and April 2023

Crimean-Congo haemorrhagic fever (CCHF), a potentially severe zoonotic viral disease causing fever and haemorrhagic manifestations in humans. As the Crimean-Congo haemorrhagic fever virus (CCHFV) has been detected in ticks in Spain and antibodies against the virus in ruminant sera in Corsica, it was necessary to know more about the situation in France. In 2022-2023, CCHFV was detected in 155 ticks collected from horses and cattle in southern France.

Innovation in Radionuclide Therapy for the Treatment of Prostate Cancers: Radiochemical Perspective and Recent Therapeutic Practices

Prostate cancer represents the second cause of death by cancer in males in western countries. While early-stage diseases are accessible to surgery and/or external radiotherapy, advanced metastatic prostate cancers are primarily treated with androgen deprivation therapy, to which new generation androgen receptor antagonists or taxane-based chemotherapies are added in the case of tumor relapse. Nevertheless, patients become invariably resistant to castration with a median survival that rarely exceeds 3 years. This fostered the search for alternative strategies, independent of the androgen receptor signaling pathway. In this line, radionuclide therapies may represent an interesting option as they could target either the microenvironment of sclerotic bone metastases with the use of radiopharmaceuticals containing samarium-153, strontium-89 or radium-223 or tumor cells expressing the prostate-specific membrane antigen (PSMA), a protein found at the surface of prostate cancer cells. This review gives highlights the chemical properties of radioligands targeting prostate cancer cells and recapitulates the clinical trials evaluating the efficacy of radionuclide therapies, alone or in combination with other approved treatments, in patients with castration-resistant prostate tumors. It discusses some of the encouraging results obtained, especially the benefit on overall survival that was reported with [¹⁷⁷Lu]-PSMA-617. It also addresses the specific requirements for the use of this particular class of drugs, both in terms of medical staff coordination and adapted infrastructures for efficient radioprotection.

Improving the response to oxaliplatin by targeting chemotherapy-induced CLDN1 in resistant metastatic colorectal cancer cells

BACKGROUND

Tumor resistance is a frequent cause of therapy failure and remains a major challenge for the long-term management of colorectal cancer (CRC). The aim of this study was to determine the implication of the tight junctional protein claudin 1 (CLDN1) in the acquired resistance to chemotherapy.

METHODS

Immunohistochemistry was used to determine CLDN1 expression in post-chemotherapy liver metastases from 58 CRC patients. The effects of oxaliplatin on membrane CLDN1 expression were evaluated by flow cytometry, immunofluorescence and western blotting experiments in vitro and in vivo. Phosphoproteome analyses, proximity ligation and luciferase reporter assays were used to unravel the mechanism of CLDN1 induction. RNAseq experiments were performed on oxaliplatin-resistant cell lines to investigate the role of CLDN1 in chemoresistance. The "one-two punch" sequential combination of oxaliplatin followed by an anti-CLDN1 antibody-drug conjugate (ADC) was tested in both CRC cell lines and murine models.

RESULTS

We found a significant correlation between CLDN1 expression level and histologic response to chemotherapy, CLDN1 expression being the highest in resistant metastatic residual cells of patients showing minor responses. Moreover, in both murine xenograft model and CRC cell lines, CLDN1 expression was upregulated after exposure to conventional chemotherapies used in CRC treatment. CLDN1 overexpression was, at least in part, functionally related to the activation of the MAPKp38/GSK3β/Wnt/β-catenin pathway. Overexpression of CLDN1 was also observed in oxaliplatin-resistant CRC cell lines and was associated with resistance to apoptosis, suggesting an anti-apoptotic role for CLDN1. Finally, we demonstrated that the sequential treatment with oxaliplatin followed by an anti-CLDN1 ADC displayed a synergistic effect in vitro and in in vivo.

CONCLUSION

Our study identifies CLDN1 as a new biomarker of acquired resistance to chemotherapy in CRC patients and suggests that a "one-two punch" approach targeting chemotherapy-induced CLDN1 expression may represent a therapeutic opportunity to circumvent resistance and to improve the outcome of patients with advanced CRC.

Abstract 4930: Foldamers mimicking the B-DNA surface as a new class of DNA topoisomerase I inhibitors

DNA mimicry has been the subject of intensive research and resulted in the development of DNA analogues such as PNAs and LNAs. There are also examples of proteins with structural and/or charge distribution analogies with respect to the DNA double helix which allow them to interfere with other DNA-binding proteins and modulate the biological processes in which they are involved. We previously characterized a new class of DNA-surface mimic molecules constituted by repetitions of dimeric units of 8-amino-2-quinolinecarboxylic acid (Q) and 8-aminomethyl-2-quinolinecarboxylic acid (mQ). The helical folding of these entities can mimic a B-DNA molecule, displaying a minor and a major groove that can be modulated depending on the dimers and of the nature of their side chains. In vitro, these DNA mimics could inhibit, in a relative selective manner, the catalytic activity of DNA topoisomerase I (Top1), whereas they had no effect on the activity of DNA polymerases or DNAses. Inhibition of Top1-mediated relaxation of supercoiled DNA plasmid increased with the length of the DNA mimics. Here, we further characterized the mechanism of Top1 inhibition by these DNA mimics. We found that, conversely to camptothecin (CPT) and its derivatives that poison Top1 via the inhibition or the re-ligation step of the reaction, DNA mimics inhibited Top1-mediated DNA cleavage in vitro by preventing the binding of the enzyme to its substrate, a mechanism of Top1 competitive inhibition that was formerly referred to as catalytic inhibition. We also found that co-incubation of DNA mimics with CPT had an additive effect on the inhibition of Top1-mediated relaxation of supercoiled DNA, further suggesting a mechanism that is different from CPT. Because transfection of DNA mimics could inhibit the growth of various cancer cell lines, we further investigated whether Top1 could play a role in this cytotoxicity. We found that Top1 knock-down in OVCAR4 ovarian cancer cells resulted in decreased sensitivity to the (mQQ4)8 DNA mimic as compared to OVCAR4 control cells, suggesting that Top1 is a target of DNA mimics in cells and is involved in their cytotoxic effects. Conversely to CPT, transfection of HCT116 cells with the (mQQ4)8 DNA mimic was not associated with an increase in γH2AX, suggesting that DNA mimics do not induce DNA breakage. We are currently analyzing whether the (mQQ4)8 can have an impact on CPT-induced Top1-DNA complexes formation. Interestingly, we also showed that several SN38-resistant HCT116 cell clones characterized by specific Top1 mutations were still sensitive to the (mQQ4)8 DNA mimic. Together our results demonstrate that DNA mimics can be considered as a new class of competitive inhibitors of Top1. Further studies are ongoing to identify the structural features that are essential for Top1 inhibition in order to generate more potent derivatives that could be used to counteract resistance to CPT derivatives used in the clinic.

Citation Format: Aurélie Garcin, Valentina Corvaglia, Madeleine Bossaert, Marie-Jeanne Pillaire, Ivan Huc, Sébastien Britton, Vincent Parissi, Philippe Pourquier. Foldamers mimicking the B-DNA surface as a new class of DNA topoisomerase I inhibitors. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4930.

Seroprevalence of Crimean-Congo Hemorrhagic Fever Among Small Ruminants from Southern Romania

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease that can be contracted by direct contact with viremic animals or humans. Domestic animals are accidental hosts and contribute to the spread and amplification of the virus. The main objective of this study was to provide updated information related to CCHF virus (CCHFV) infection in Southern Romania by assessing the seroprevalence of CCHF in small ruminants (sheep and goats) using a double-antigen sandwich enzyme-linked immunosorbent assay and by detection of CCHFV in engorged ticks and serum samples using real-time RT-PCR. The overall seroprevalence of CCHF in small ruminants was 37.7% (95% CI 31.7 to 43.7). No statistical seroprevalence difference was observed between the two species of ruminants (p = 0.76), but a significant difference was established between the locations (p < 0.01). No CCHFV RNA was detected in tick pools and small ruminant's sera tested by real-time RT-PCR, although the high seroprevalence to CCHFV among ruminants indicates that CCHV or a closely related virus circulates in Southern Romania.

SARS-CoV-2 antibodies seroprevalence in dogs from France using ELISA and an automated western blotting assay

Dogs are occasionally susceptible to SARS-CoV-2, developing few or no clinical signs. Epidemiological surveillance of SARS-CoV-2 in dogs requires testing to distinguish it from other canine coronaviruses. In the last year, significant advances have been made in the diagnosis of SARS-CoV-2, allowing its surveillance in both human and animal populations. Here, using ELISA and automated western blotting (AWB) assays, we performed a longitudinal study on 809 apparently healthy dogs from different regions of France to investigate anti-SARS-CoV-2 antibodies. There were three main groups: (i) 356 dogs sampled once before the pandemic, (ii) 235 dogs sampled once during the pandemic, and (iii) 218 dogs, including 82 dogs sampled twice (before and during the pandemic), 125 dogs sampled twice during the pandemic and 11 dogs sampled three times (once before and twice during the pandemic). Using ELISA, seroprevalence was significantly higher during the pandemic [5.5% (25/453)] than during the pre-pandemic period [1.1% (5/449)]. Among the 218 dogs sampled twice, at least 8 ELISA-seroconversions were observed. ELISA positive pre-pandemic sera were not confirmed in serial tests by AWB, indicating possible ELISA cross-reactivity, probably with other canine coronaviruses. A significant difference was observed between these two serological tests (Q = 88, p = 0.008). A clear correlation was observed between SARS-CoV-2 seroprevalence in dogs and the incidence of SARS-CoV-2 infection in human population from the same area. AWB could be used as a second line assay to confirm the doubtful and discrepant ELISA results in dogs. Our results confirm the previous experimental models regarding the susceptibility of dogs to SARS-CoV-2, suggesting that viral transmission from and between dogs is weak or absent. However, the new variants with multiple mutations could adapt to dogs; this hypothesis cannot be ruled out in the absence of genomic data on SARS-CoV-2 from dogs.

PXR Modulates the Prostate Cancer Cell Response to Afatinib by Regulating the Expression of the Monocarboxylate Transporter SLC16A1

Simple Summary

Many kinase inhibitors have been tested as potential alternatives for the treatment of castration-resistant prostate cancers. However, none of these clinical trials led to drug approval despite interesting responses. Our study reveals that genes involved in drug metabolism and their master regulator PXR (Pregnane X Receptor) could be responsible, at least in part, for these disappointing results as they can modulate tumor cell response to specific kinase inhibitors. We found that stable expression of PXR sensitized prostate cancer cells to erlotinib, dabrafenib, and afatinib, while it rendered cells resistant to dasatinib and had no effect for other inhibitors tested. We also report for the first time that sensitization to afatinib is due to an alteration in drug transport that involves the SLC16A1 monocarboxylate transporter. Together, our results further indicate that PXR might be considered as a biomarker of response to kinase inhibitors in castration-resistant prostate cancers.

Abstract

Resistance to castration is a crucial issue in the treatment of metastatic prostate cancer. Kinase inhibitors (KIs) have been tested as potential alternatives, but none of them are approved yet. KIs are subject of extensive metabolism at both the hepatic and the tumor level. Here, we studied the role of PXR (Pregnane X Receptor), a master regulator of metabolism, in the resistance to KIs in a prostate cancer setting. We confirmed that PXR is expressed in prostate tumors and is more frequently detected in advanced forms of the disease. We showed that stable expression of PXR in 22Rv1 prostate cancer cells conferred a resistance to dasatinib and a higher sensitivity to erlotinib, dabrafenib, and afatinib. Higher sensitivity to afatinib was due to a ~ 2-fold increase in its intracellular accumulation and involved the SLC16A1 transporter as its pharmacological inhibition by BAY-8002 suppressed sensitization of 22Rv1 cells to afatinib and was accompanied with reduced intracellular concentration of the drug. We found that PXR could bind to the SLC16A1 promoter and induced its transcription in the presence of PXR agonists. Together, our results suggest that PXR could be a biomarker of response to kinase inhibitors in castration-resistant prostate cancers.

Internalization of Foldamer-Based DNA Mimics through a Site-Specific Antibody Conjugate to Target HER2-Positive Cancer Cells

Inhibition of protein-DNA interactions represents an attractive strategy to modulate essential cellular functions. We reported the synthesis of unique oligoamide-based foldamers that adopt single helical conformations and mimic the negatively charged phosphate moieties of B-DNA. These mimics alter the activity of DNA interacting enzymes used as targets for cancer treatment, such as DNA topoisomerase I, and they are cytotoxic only in the presence of a transfection agent. The aim of our study was to improve internalization and selective delivery of these highly charged molecules to cancer cells. For this purpose, we synthesized an antibody-drug conjugate (ADC) using a DNA mimic as a payload to specifically target cancer cells overexpressing HER2. We report the bioconjugation of a 16-mer DNA mimic with trastuzumab and its functional validation in breast and ovarian cancer cells expressing various levels of HER2. Binding of the ADC to HER2 increased with the expression of the receptor. The ADC was internalized into cells and was more efficient than trastuzumab at inhibiting their growth in vitro. These results provide proof of concept that it is possible to site-specifically graft high molecular weight payloads such as DNA mimics onto monoclonal antibodies to improve their selective internalization and delivery in cancer cells.

Multiplexed Droplet Digital PCR Assays for the Simultaneous Screening of Major Genetic Alterations in Tumors of the Central Nervous System

The increased integration of molecular alterations to define tumor type or grade in central nervous system (CNS) tumor classification brings new challenges for the pathologist to make the best use of a precious limited tissue specimen for molecular studies. Within the different methods available to identify gene alterations, the droplet digital PCR (dPCR) constitutes a rapid, cost-effective, and very sensitive tool. In this study, we describe the development and validation of five multiplexed dPCR assays to detect major CNS biomarkers by using only small amounts of DNA extracted from formalin-fixed paraffin-embedded specimens. When compared to HRM-sequencing, NGS-sequencing, RNA-sequencing, or simplex digital PCR assays used as “gold standard” methods, these multiplexed dPCR assays displayed 100% specificity and sensitivity for the simultaneous detection of: 1/BRAF V600E mutation and KIAA1549:BRAF fusion; 2/FGFR1 N546K and K656E mutations and FGFR1 duplication; 3/H3F3A K27M and G34R/V mutations; 4/IDH1 R132X and IDH2 R172X mutations; and 5/TERT promoter mutations C228T and C250T. In light of the increased integration of molecular alteration, we believe that such strategies might help laboratories to optimize their screening strategies for routine diagnosis of pediatric and adult CNS tumors.

The Anti-Cancer Drug Dabrafenib Is a Potent Activator of the Human Pregnane X Receptor

The human pregnane X receptor (hPXR) is activated by a large set of endogenous and exogenous compounds and plays a critical role in the control of detoxifying enzymes and transporters regulating liver and gastrointestinal drug metabolism and clearance. hPXR is also involved in both the development of multidrug resistance and enhanced cancer cells aggressiveness. Moreover, its unintentional activation by pharmaceutical drugs can mediate drug–drug interactions and cause severe adverse events. In that context, the potential of the anticancer BRAF inhibitor dabrafenib suspected to activate hPXR and the human constitutive androstane receptor (hCAR) has not been thoroughly investigated yet. Using different reporter cellular assays, we demonstrate that dabrafenib can activate hPXR as efficiently as its reference agonist SR12813, whereas it does not activate mouse or zebrafish PXR nor hCAR. We also showed that dabrafenib binds to recombinant hPXR, induces the expression of hPXR responsive genes in colon LS174T-hPXR cancer cells and human hepatocytes and finally increases the proliferation in LS174T-hPXR cells. Our study reveals that by using a panel of different cellular techniques it is possible to improve the assessment of hPXR agonist activity for new developed drugs.

First detection and genome sequencing of SARS-CoV-2 in an infected cat in France

After its first description in Wuhan (China), SARS-CoV-2 the agent of coronavirus disease 2019 (COVID-19) rapidly spread worldwide. Previous studies suggested that pets could be susceptible to SARS-CoV-2. Here, we investigated the putative infection by SARS-CoV-2 in 22 cats and 11 dogs from owners previously infected or suspected of being infected by SARS-CoV-2. For each animal, rectal, nasopharyngeal swabs and serum were taken. Swabs were submitted to RT-qPCR assays targeting 2 genes of SARS-CoV-2. All dogs were tested SARS-CoV-2 negative. One cat was tested positive by RT-qPCR on rectal swab. Nasopharyngeal swabs from this animal were tested negative. This cat showed mild respiratory and digestive signs. Serological analysis confirms the presence of antibodies against the SARS-CoV-2 in both serum samples taken 10 days apart. Genome sequence analysis revealed that the cat SARS-CoV-2 belongs to the phylogenetic clade A2a like most of the French human SARS-CoV-2. This study reports for the first time the natural infection of a cat in France (near Paris) probably through their owners. There is currently no evidence that cats can spread COVID-19 and owners should not abandon their pets or compromise their welfare.

High Content Screening Using New U2OS Reporter Cell Models Identifies Harmol Hydrochloride as a Selective and Competitive Antagonist of the Androgen Receptor

Prostate cancer is the most commonly diagnosed malignancy in men. Its growth mainly relies on the activity of the androgen receptor (AR), justifying the use of androgen deprivation therapy as a gold standard treatment for the metastatic disease. Inhibition of the androgen axis using second generation antagonists has improved patients’ survival, but is systematically confronted to resistance mechanisms, leading to a median survival that does not exceed 5 years. Counteracting this resistance has been the object of a large number of investigations, with a particular emphasis towards the identification of new AR inhibitors, whether they antagonize the receptor by a competitive or a non-competitive binding. To this end, many high content screens have been performed, to identify new non-steroidal AR antagonists, using a variety of approaches, but reported somewhat controversial results, depending on the approach and on the cell model that was used for screening. In our study, we used the U2OS osteosarcoma cells stably transfected with AR or ARv7 and a luciferase reporter as a previously validated model to screen the Prestwick Phytochemical library. The results of our screen identified ellipticine, harmol, and harmine hydrochloride as confirmed hits. Surprisingly, we could demonstrate that harmol hydrochloride, previously identified as a non-competitive inhibitor of AR or a weak inhibitor of androgen signaling, was actually a competitive antagonist of AR, which inhibits the growth of VCaP prostate cancer line, at concentrations for which it did not affect the growth of the AR negative DU145 and PC3 cells. Interestingly, we also report for the first time that harmol hydrochloride was selective for AR, as it could not alter the activity of other nuclear receptors, such as the glucocorticoid receptor (GR), the progesterone receptor (PR), or the mineralocorticoid receptor (MR). Additionally, we demonstrate that, conversely to enzalutamide, harmol hydrochloride did not show any agonistic activity towards the pregnane X receptor (PXR), a master regulator of drug metabolism. Together, our results shed light on the importance of the cellular context for the screening of new AR antagonists. They further indicate that some of the potential hits that were previously identified may have been overlooked.

Evaluation of a commercial ELISA for detection of epizootic haemorrhagic disease antibodies in domestic and wild ruminant sera

Bluetongue (BT) and epizootic haemorrhagic disease (EHD) are vector-borne viral diseases affecting domestic and wild ruminants. Both are notifiable under OIE rules. BT and EHD viruses (BTV and EHDV) are closely related Orbiviruses with structural, antigenic and molecular similarities. Both viruses can produce analogous clinical signs in susceptible animals. Serological tests are commonly used for BT and EHD diagnosis and surveillance. Competitive ELISA (c-ELISA) is the most widely used serological test for the specific detection of BTV or EHDV viral protein 7 (VP7) antibodies (Abs). The specificity and sensitivity of the BTV c-ELISA kits available on the market are recognized for the detection of BTV Abs. Concerning EHD, a single commercial EHDV c-ELISA kit (ELISA A kit) commonly used for diagnosis in Europe and Africa was available between 2011 and 2018 but is now no longer on the market. In this study, we evaluated a new commercial c-ELISA to detect ruminant EHDV VP7 Abs in 2,199 serum samples from cattle, sheep, goats, wild deer and zoo animals. The results showed that this ELISA kit is specific and can detect the presence of IgG anti-EHDV VP7 with a very good diagnostic specificity and a satisfactory sensitivity in domestic ruminants, zoo animals and wild deer. Therefore, the evaluated c-ELISA can detect the introduction of EHDV into an area where BTV-seropositive domestic animals are present. The performance of this kit is similar to that of the c-ELISA A kit and can thus be used for diagnosis.

Carboxylate-functionalized foldamer inhibitors of HIV-1 integrase and Topoisomerase 1: artificial analogues of DNA mimic proteins

Inspired by DNA mimic proteins, we have introduced aromatic foldamers bearing phosphonate groups as synthetic mimics of the charge surface of B-DNA and competitive inhibitors of some therapeutically relevant DNA-binding enzymes: the human DNA Topoisomerase 1 (Top1) and the human HIV-1 integrase (HIV-1 IN). We now report on variants of these anionic foldamers bearing carboxylates instead of phosphonates. Several new monomers have been synthesized with protecting groups suitable for solid phase synthesis (SPS). Six hexadecaamides have been prepared using SPS. Proof of their resemblance to B-DNA was brought by the first crystal structure of one of these DNA-mimic foldamers in its polyanionic form. While some of the foldamers were found to be as active as, or even more active than, the original phosphonate oligomers, others had no activity at all or could even stimulate enzyme activity in vitro. Some foldamers were found to have differential inhibitory effects on the two enzymes. These results demonstrate a strong dependence of inhibitory activity on foldamer structure and charge distribution. They open broad avenues for the development of new classes of derivatives that could inhibit the interaction of specific proteins with their DNA target thereby influencing the cellular pathways in which they are involved.

Prospective assessment of the predictive value of the BRCA1 gene status in sarcoma patients treated with trabectedin: an updated analysis of the EORTC 62091 trial

We describe the predictive value of BRCA1 gene status on trabectedin efficacy and found no correlation despite the mechanisms of action of this drug that rely on DNA repair systems.

Single helically folded aromatic oligoamides that mimic the charge surface of double-stranded B-DNA

Numerous essential biomolecular processes require the recognition of DNA surface features by proteins. Molecules mimicking these features could potentially act as decoys and interfere with pharmacologically or therapeutically relevant protein-DNA interactions. Although naturally occurring DNA-mimicking proteins have been described, synthetic tunable molecules that mimic the charge surface of double-stranded DNA are not known. Here, we report the design, synthesis and structural characterization of aromatic oligoamides that fold into single helical conformations and display a double helical array of negatively charged residues in positions that match the phosphate moieties in B-DNA. These molecules were able to inhibit several enzymes possessing non-sequence-selective DNA-binding properties, including topoisomerase 1 and HIV-1 integrase, presumably through specific foldamer-protein interactions, whereas sequence-selective enzymes were not inhibited. Such modular and synthetically accessible DNA mimics provide a versatile platform to design novel inhibitors of protein-DNA interactions.

Safety and efficacy of temsirolimus as second line treatment for patients with recurrent bladder cancer

BACKGROUND

Bladder cancer is the 7th cause of death from cancer in men and 10th in women. Metastatic patients have a poor prognosis with a median overall survival of 14 months. Until recently, vinflunine was the only second-line chemotherapy available for patients who relapse. Deregulation of the PI3K/AKT/mTOR pathway was observed in more than 40% of bladder tumors and suggested the use of mTOR as a target for the treatment of urothelial cancers.

METHODS

This trial assessed the efficacy of temsirolimus in a homogenous cohort of patients with recurrent or metastatic bladder cancer following first-line chemotherapy. Efficacy was measured in terms of non-progression at two months according to the RECIST v1.1 criteria. Based on a two-stage optimal Simon's design, 15 non-progressions out of 51 evaluable patients were required to claim efficacy. Patients were treated at a weekly dose of 25 mg IV until progression, unacceptable toxicities or withdrawal.

RESULTS

Among the 54 patients enrolled in the study between November 2009 and July 2014, 45 were assessable for the primary efficacy endpoint. A total of 22 (48.9%) non-progressions were observed at 2 months with 3 partial responses and 19 stable diseases. Remarkably, 4 patients were treated for more than 30 weeks. Fifty patients experienced at least a related grade1/2 (94%) and twenty-eight patients (52.8%) a related grade 3/4 adverse event. Eleven patients had to stop treatment for toxicity. This led to recruitment being halted by an independent data monitoring committee with regard to the risk-benefit balance and the fact that the primary objective was already met.

CONCLUSIONS

While the positivity of this trial indicates a potential benefit of temsirolimus for a subset of bladder cancer patients who are refractory to first line platinum-based chemotherapy, the risk of adverse events associated with the use of this mTOR inhibitor would need to be considered when such an option is envisaged in this frail population of patients. It also remains to identify patients who will benefit the most from this targeted therapy.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01827943 (trial registration date: October 29, 2012); Retrospectively registered.

A novel double-antigen sandwich ELISA for the species-independent detection of Crimean-Congo hemorrhagic fever virus-specific antibodies

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease in humans caused by the CCHF virus (CCHFV). The detection of anti-CCHFV antibodies in animals is used to reveal infection risk areas. Therefore a simple, quick and reliable multispecies assay for the detection of CCHFV-specific antibodies is needed. This work presents the development and validation of a novel CCHF double-antigen ELISA for the detection of anti-CCHFV nucleoprotein antibodies. The test requires 30 μl of serum, and results are obtained within 90 min. As the ELISA is based on recombinant N-protein of the IbAr10200 virus, it can be run under standard biosafety conditions. For assay validation, sera from 95 cattle and 176 small ruminants from CCHF-endemic regions (origin: Albania, Cameroon, Kosovo, Former Yugoslav Republic of Macedonia, Mauritania, Pakistan, Turkey) served as a positive reference serum panel. The CCHF antibody status of the positive reference samples had been previously confirmed by two serological assays (species-adapted VectorBest ELISA and Euroimmun IFA). CCHFV strains belonging to three different clades are known to circulate in the countries where the positive samples originated. Sera from 402 cattle and 804 small ruminants from Germany and France served as the negative serum panel, as both countries are considered outside of the CCHFV endemic zone. Sera from monkeys, camels, rats, ferrets, raccoon dogs, raccoons, foxes, hares, pigs and humans were also tested, to determine the suitability of this novel ELISA for these species. All negative reference sera were confirmed by the CCHF double-antigen ELISA, indicating a specificity of 100%. 268 of 271 positive reference sera tested positive for CCHFV-specific antibodies, 8sensitivity of 99%9. Further analysis are needed to ensure a recognition of the IbAr10200 nucleoprotein by antibodies directed against all known CCHFV clades. This is planned to be realized with sera from other regions covering the three missing clades.

Association of NR1I2, CYP3A5 and ABCB1 genetic polymorphisms with variability of temsirolimus pharmacokinetics and toxicity in patients with metastatic bladder cancer

PURPOSE

Temsirolimus is a mammalian target of rapamycin (mTOR) inhibitor that exhibits antitumor activity in renal cell carcinoma and mantle cell lymphoma. The metabolism of temsirolimus and its active metabolite sirolimus mainly depends on cytochrome P450 3A4/5 (CYP3A4/A5) and the ABCB1 transporter. Differently from sirolimus, no pharmacogenetic study on temsirolimus has been conducted. Therefore, the aim of this pilot study was to identify genetic determinants of the inter-individual variability in temsirolimus pharmacokinetics and toxicity.

METHODS

Pharmacokinetic profiles were obtained for 16 patients with bladder cancer after intravenous infusion of 25 mg temsirolimus. Non-compartmental analysis was performed to calculate the pharmacokinetic parameters of temsirolimus and sirolimus, its main metabolite. The presence of single nucleotide polymorphisms (SNPs) in CYP3A5, ABCB1 and in their transcriptional regulator NR1I2 (PXR) was assessed by genotyping. Non-parametric statistical tests were used to assess associations between candidate SNPs and temsirolimus pharmacokinetics and toxicity.

RESULTS

The ratio between sirolimus AUC and temsirolimus AUC was 1.6-fold higher in patients who experienced serious toxic events (p = 0.034). The frequency of adverse events was significantly higher in patients homozygous for the NR1I2-rs6785049 A allele (OR = 0.065, p = 0.04) or NR1I2-rs3814055 C allele (OR = 0.032, p = 0.006). These NR1I2 SNPs were also predictive of temsirolimus half-life and global exposure to temsirolimus and sirolimus. Finally, the effect of the ABCB1-rs1128503, ABCB1-rs2032582 and CYP3A5*3 SNPs on sirolimus pharmacokinetics was confirmed.

CONCLUSIONS

Our findings suggest that SNPs of NR1I2 and its target genes CYP3A5 and ABCB1 are genetic determinants of temsirolimus pharmacokinetics and toxicity in patients with bladder cancer.

Diagnostic evaluation of assays for detection of antibodies against porcine epidemic diarrhea virus (PEDV) in pigs exposed to different PEDV strains

Porcine epidemic diarrhea virus (PEDV) has caused economic losses in the Americas, Asia and Europe in recent years. Reliable serological assays are essential for epidemiological studies and vaccine evaluation. The objective of this study was to compare the ability of five enzyme-linked immunosorbent assays (ELISAs) to detect antibodies against different PEDV strains in pig serum. A total of 732 serum samples from North American or European pigs were tested. Samples included experimental samples from pigs infected with classical (G1a PEDV) or variant genogroup 1 PEDV (G1b PEDV), pandemic genogroup 2 PEDV (G2b PEDV) or non-infected controls. Field samples from herds with confirmed or unknown PEDV exposure were also used. Three indirect ELISAs based on G2b antigens (ELISAs 1, 2 and 3), a competitive ELISA based on the G2b antigen (ELISA 4) and a competitive ELISA based on the G1a antigen (ELISA 5) were compared. Overall, the tests had a moderate agreement (κ = 0.61). G1a PEDV infected pigs were earliest detected by ELISA 3, G1b PEDV infected pigs were earliest detected by ELISAs 4 and 5 and the performance of all tests was similar for the G2b PEDV group. ELISA 1 showed the overall lowest detection on experimentally and field derived samples. Diagnostic sensitivity and specificity with a 95% probability interval were estimated to be 68.2% (62.1–74.4%) and 97.5% (95.2–99.0%) for ELISA 1, 73.7% (71.5–79.6%) and 98.4% (96.6–99.5%) for ELISA 2, 86.2% (81.1–90.6%) and 91.6% (87.7–94.8%) for ELISA 3, 78.3% (72.8–83.5%) and 99.7% (98.2–100%) for ELISA 4, and 93.5% (90.3–96.0%) and 91.2% (83.8–97.9%) for ELISA 5. Differences in detection among assays seem to be more related to intrinsic factors of an assay than to the PEDV antigen used.

Development of a Double-Antigen Microsphere Immunoassay for Simultaneous Group and Serotype Detection of Bluetongue Virus Antibodies

Bluetongue viruses (BTV) are arboviruses responsible for infections in ruminants. The confirmation of BTV infections is based on rapid serological tests such as enzyme-linked immunosorbent assays (ELISAs) using the BTV viral protein 7 (VP7) as antigen. The determination of the BTV serotype by serological analyses could be only performed by neutralization tests (VNT) which are time-consuming and require BSL3 facilities. VP2 protein is considered the major serotype-defining protein of BTV. To improve the serological characterization of BTV infections, the recombinant VP7 and BTV serotype 8 (BTV-8) VP2 were synthesized using insect cells expression system. The purified antigens were covalently bound to fluorescent beads and then assayed with 822 characterized ruminant sera from BTV vaccinations or infections in a duplex microsphere immunoassay (MIA). The revelation step of this serological duplex assay was performed with biotinylated antigens instead of antispecies conjugates to use it on different ruminant species. The results demonstrated that MIA detected the anti-VP7 antibodies with a high specificity as well as a competitive ELISA approved for BTV diagnosis, with a better efficiency for the early detection of the anti-VP7 antibodies. The VP2 MIA results showed that this technology is also an alternative to VNT for BTV diagnosis. Comparisons between the VP2 MIA and VNT results showed that VNT detects the anti-VP2 antibodies in an early stage and that the VP2 MIA is as specific as VNT. This novel immunoassay provides a platform for developing multiplex assays, in which the presence of antibodies against multiple BTV serotypes can be detected simultaneously.

Abstract 4794: Oligoamide-based mimics of double-stranded B-DNA as a new class of DNA topoisomerase I catalytic inhibitors

Since the discovery of Topoisomerase I as a specific target for the treatment of cancers more than 30 years ago, only two inhibitors derived from the natural compound camptothecin (CPT) have been approved in the clinic for the treatment of colon, lung and ovarian cancers: topotecan and irinotecan. The cytotoxicity of these Top1 poisons relies on their capability to stabilize covalent Top1-DNA complexes, leading to replication-mediated DNA double-strand breaks. However tumor cells develop multiple resistance mechanisms that are limiting their efficacy. Though new CPT derivatives and other Top1 poisons with various chemical structures have been developed, they share the same resistance mechanisms. Aside from conventional approaches focus on compounds with higher potency to stabilize Top1-DNA complexes, we investigated the possibility to inhibit Top1 binding to DNA and/or DNA cleavage by using DNA mimics that would act as decoys, a strategy that was never explored before. To this aim, single chain oligoamides composed by iteration of mQQ units (Q: 8-amino-2-quinoline carboxylic acid; mQ: 8-aminomethyl-2-quinoline carboxylic acid) were synthesized. These molecules fold into helices that are stabilized by electrostatic repulsions and hydrogen bonds between the amide functions and endocyclic nitrogen atoms at adjacent residues. When Q and mQ precursors are functionalized by negatively charged residues, the positions of these residues in the folded structure match the position of phosphate residues in duplex B-DNA. Because distances between residues in mQQ and QmQ units are slightly different, it is possible to define a major groove and a minor groove, as in B-DNA, with the possibility to impact on groove width by changing the positions of the substituents (Q4 or Q5 for substitution in position 4 or 5 of the quinoline monomer, respectively), clearly establishing (mQQ5)n and (mQQ4)n as potential DNA-mimics of an unprecedented kind.

We found that both (mQQ5)n and (mQQ4)n oligomers inhibited the activity of Top1-mediated relaxation of supercoiled DNA in vitro. Inhibition increased with the length of the oligoamide to reach an IC50 value (concentration inhibiting 50% of Top1-mediated DNA relaxation) around the nM range for the longest oligomer that was tested i.e. (mQQ4)16, corresponding to a double-strand DNA of 16 base pairs. By comparison, CPT had an IC50 of ∼10 μM in the same conditions. Top1 inhibition was rather selective as a (mQQ4)8 oligomer moderately inhibited Top2-mediated activity and did not affect the activity of various DNA interacting enzymes such as restriction enzymes XhoI and NdeI or nucleases such as DNAse I, S1 nuclease, benzonase or Flap-endonuclease I. Because these oligomers are resistant to proteases and nucleases and can be synthesized rapidly by solid phase synthesis with the possibility to modify its substituents without altering their helicity, they represent good candidates for drug development.

Citation Format: Philippe Pourquier, Krzysztof Ziach, Céline Chollet, Vincent Parissi, Mathieu Marchivie, Panchami Prabhakaran, Partha P. Bose, Katta Laxmi-Reddy, Frédéric Godde, Stéphane Chaignepain, Jean Marie Schmitter, Ivan Huc. Oligoamide-based mimics of double-stranded B-DNA as a new class of DNA topoisomerase I catalytic inhibitors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4794.

Early objective response may not be a prognostic factor of survival for patients with metastatic urothelial carcinoma: from a retrospective analysis of a cohort of 113 patients

BACKGROUND

This study aims to better define prognostic factors for patients with metastatic urothelial carcinoma (mUC), and to identify patients who will benefit from first-line cisplatin-based chemotherapy. We test the hypothesis that early objective response (EOR), defined as the occurrence of an objective response following 2 or 3 courses of chemotherapy, could be a prognostic factor for overall survival (OS) and thus be used to guide treatment decisions. Data from 113 patients with evaluable mUC receiving first-line cisplatin-based treatment between January 2004 and December 2006 was collected retrospectively from prospectively-maintained databases across seven French cancer centers. Clinical factors potentially associated with survival and EOR were analyzed in univariate and multivariate analysis.

RESULTS

One hundred three patient records were complete and available for inclusion in the multivariate model. Four factors were independently associated with OS: Performance status 1 and 2 (HR 2.3 [95 % CI 1.3-3.9], p = 0.002; HR 3.4 [95 % CI 1.6-7.2], p = 0.001 respectively); presence of visceral metastases (HR 2.2 [95 % CI 1.3-3.9], p = 0.004); abnormal hemoglobin levels (HR 1.7 [95 % CI 1.01-2.8], p = 0.045); disease progression (HR 10.1 [95 % CI 4.2-24.1], p < 0.001).

CONCLUSIONS

This study confirms the prognostic factors previously reported in first-line chemotherapy for mUC. However, we failed to demonstrate that EOR was an independent predictive factor of OS. Nevertheless, an early response evaluation is recommended since early progression is an important parameter that can be used to decide whether treatment should be interrupted and changed for alternative strategies integrating the concept of personalized medicine or new immune therapies.

Polymorphisms in SLCO1B3 and NR1I2 as genetic determinants of hematotoxicity of carboplatin and paclitaxel combination

Aim: The goal of our study was to assess the impact of patients’ genetic background on their sensitivity to carboplatin/paclitaxel hematotoxicity. Patients & methods: Parameters describing sensitivity to neutropenia and to thrombocytopenia of 201 patients were extracted from a previous pharmacokinetic/pharmacodynamics analysis, in order to assess their association with 52 candidates SNPs in 18 genes. Results: Carriers of a T allele of SLCO1B3-rs4149117 were 19% less sensitive to thrombocytopenia than the homozygotes for the G allele (p = 0.00279). Carriers of two copies of the ATG haplotypes of NR1I2-rs1523130, rs3814055 and rs1523127 were 19% less sensitive to thrombocytopenia than those harboring other haplotypes (p = 0.025). Conclusion: Our results revealed the importance of SLCO1B3 and NR1I2 in the sensitivity to carboplatin/paclitaxel thrombocytopenia.

Safety and efficacy of temsirolimus as second-line treatment for patients with recurrent bladder cancer

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Background: Bladder cancer is the 7th cause of death from cancer in men and 10th in women. For metastatic patients, prognosis is poor with a median overall survival of 15 months that remained unchanged for the past 15 years. No standard second-line chemotherapy is available for patients who relapse. Acquired mutations leading to a deregulation of the PI3K/AKT/mTOR pathway have been reported in more than 40% of bladder cancers suggesting the use of the mTOR (mammalian target of rapamycin) signalling pathway as an attractive target for the treatment of urothelial tumors. Methods: The main objective of this study was to assess the efficacy of temsirolimus, an mTOR inhibitor that is already used for the treatment of renal cancers, in patients with recurrent or metastatic bladder cancer who already received a first line chemotherapy. Efficacy was measured in terms of non-progression of the disease at two months of treatment following the RECIST v1.1 criteria. Based on a two-stage optimal Simon’s design, a total of 15 non-progressions out of 51 eligible and assessable patients were required to claim efficacy. Patients were treated at a weekly dose of 25 mg until progression, unacceptable toxicities or withdrawal. Results: Fifty-four patients were enrolled in the study between November 2009 and July 2014 in seven French centres. At the end of the first stage, six patients out of 17 were progression-free at 2 months leading to the inclusion of additional 37 patients in the second stage of the study. Thirty-six patients were eligible and assessable for the primary efficacy endpoint. A total of 18 (50%) non-progressions were observed at 2 months. Among them, partial response was documented for two patients and stable disease for 16. Twenty-five related adverse events were observed in 19 (35.2%) of the patients. Conclusions: Our study is providing the first clinical evidence of a potential benefit of temsirolimus for the treatment of relapsed bladder cancers. Ancillary study is ongoing to investigate the mutational status of genes which are involved in the PI3K/AKT/mTOR signalling pathway in order to identify a predictive signature of response to temsirolimus in bladder cancer. Clinical trial information: NCT0187943NCT0187943.

BRCA1 haplotype and clinical benefit of trabectedin in soft-tissue sarcoma patients

Background:

This study aimed to determine whether the BRCA1 haplotype was associated with trabectedin efficacy in soft-tissue sarcoma (STS) patients.

Methods:

We analysed BRCA1 single-nucleotide polymorphisms (SNPs) in tumour specimens from 135 advanced STS patients enrolled in published phase 2 trials or in a compassionate-use programme of trabectedin. Forty-four advanced STS patients treated with doxorubicin and 85 patients with localised STS served as controls. The 6-month nonprogression rate and overall survival (OS) were analysed according to BRCA1 haplotype using log-rank tests.

Results:

A favourable BRCA1 haplotype (presence of at least one AAAG allele) was significantly associated with an improved 6-month nonprogression rate. It was the only variable significantly associated with OS. No correlations were found between outcomes for patients with localised or advanced STS treated with doxorubicin.

Conclusions:

The BRCA1 haplotype represents a potential DNA repair biomarker that can be used for the prediction of response to trabectedin in STS patients.

Abstract 3813: Role of the ERG transcription factor in the resistance of prostate cancer cells to the topoisomerase I inhibitor camptothecin

Prostate cancer (PCa) is a major public health issue as it is the second cause of death among cancers in industrialized countries, and its incidence is rising. Surgery is the main option for the curative treatment of localized forms of PCa and recurrences are managed with androgen deprivation strategies. In the case of advanced metastatic PCa and when tumors become resistant to castration (mCRPC), chemotherapy with taxanes is initiated. However, response rates remain low with a restricted number of alternatives due to the intrinsic resistance of CRPC to a wide range of cytotoxic agents. Advanced PCa are particularly resistant to topoisomerase I (Top1) inhibitors from the camptothecin (CPT) family, but the mechanistic bases of this resistance have not been investigated in details. Top1 is a nuclear enzyme that induces transient single strand breaks in duplex DNA to ensure the removal of torsional constraints associated with crucial DNA transactions such as replication, transcription, chromosome segregation or DNA recombination. We have previously shown that interaction of Top1 with DNA-PKcs, a kinase involved in non-homologous end-joining, could regulate the cellular response to CPT independently of DNA repair. This was further confirmed by the fact that NU7441, a specific inhibitor of the kinase activity of DNA-PKcs, had no effect on Hela cell sensitivity to CPT. Recently, it was shown that, in PCa cells, DNA-PKcs could interact with ERG, a transcription factor of the ETS family. As advanced PCa are often characterized by a TMPRSS2-ERG fusion leading to wild-type ERG overexpression, we investigated whether ERG could play a role in the resistance of PCa cells to CPT by regulating Top1/DNA-PKcs interaction. We showed that VCaP cells harboring the TMPRSS2-ERG fusion resulting in a 6-fold increase of ERG protein as compared to ERG fusion-negative (control) DU145 or PC3 cells were &gt;100-fold more resistant to CPT. RWPE-1 stably overexpressing low levels of wild-type ERG (2-fold increase) did not show a major change in resistance to CPT as compared to control RWPE-1 cells stably expressing lacZ. Using two specific siRNA, we also showed that transient downregulation of ERG drastically reduced the sensitivity of VCaP cells to CPT, this effect being dependent on the efficacy of ERG repression. Interestingly, this effect was not due to a change in Top1 levels, suggesting that ERG downregulation may affect Top1-DNA-PKcs interaction. We detected this interaction in VCaP cells by immunoprecipitation in the presence of ethidium bromide, indicating that it was independent of DNA and it remains to be seen whether it is disrupted following ERG repression. Our preliminary findings provide evidences for a new mechanism by which ERG and its interaction with DNA-PKcs could explain, at least in part, the intrinsic resistance of PCa to Top1 inhibitors by the regulation of Top1-DNA-PKcs interaction.

Citation Format: Emmanuel Roche, Danièle Montaudon, Samer Kayali, Nadine Houédé, Philippe Pourquier. Role of the ERG transcription factor in the resistance of prostate cancer cells to the topoisomerase I inhibitor camptothecin. [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 3813. doi:10.1158/1538-7445.AM2014-3813

Targeting the genetic alterations of the PI3K-AKT-mTOR pathway: its potential use in the treatment of bladder cancers

Urothelial carcinoma of the bladder is the most frequent tumor of the urinary tract and represents the fifth cause of death by cancer worldwide. The current first line chemotherapy is a combination of cisplatin and gemcitabine with median survival not exceeding 15months. Vinflunine is the only drug approved by EMEA as second-line treatment and few progresses have been made for the past 20years to increase the survival of metastatic patients, especially those who are not eligible for cisplatin-based regimen. The recent studies characterizing the genetic background of urothelial cancers of the bladder, revealed chromosomal alterations that are not seen at the same level in other types of cancers. This is especially the case for mutations of genes involved in the PI3K/AKT/mTOR signaling pathway that occupies a major place in the etiology of these tumors. Here, we describe the mutations leading to constitutive activation of the PI3K/AKT/mTOR pathway and discuss the potential use of the different classes of PI3K/AKT/mTOR inhibitors in the treatment of urothelial bladder cancers. Despite the recent pivotal study evidencing specific mutations of TSC1 in bladder cancer patients responding to everolimus and the encouraging results obtained with other derivatives than rapalogs, few clinical trials are ongoing in bladder cancers. Because of the genetic complexity of these tumors, the cross-talks of the PI3K/AKT/mTOR pathway with other pathways, and the small number of eligible patients, it will be of utmost importance to carefully choose the drugs or drug combinations to be further tested in the clinic.

Abstract 4478: SHMT2 modulates DNA methylation and differentially affects prostate cancer cell response to platinum derivatives

Prostate cancer (PCa) is one of the leading causes of death from cancer in men. Several prognostic factors allow differentiating low-grade from high-grade PCa that are often refractory to chemical castration but are still treated with hormone therapy to which docetaxel or cabazitaxel are added when they become resistant to the anti-androgen. Despite many clinical trials with other chemotherapeutic agents, response rates remain low, pointing towards the need for new alternative therapies to treat these aggressive tumors. Using a rational in silico approach based on the NCI60-cell line panel, we recently identified a signature of 6 genes, the expression of which could predict at the functional level, sensitivity to oxaliplatin but not to cisplatin in DU145, LNCaP and C42B prostate cancer cell lines (Puyo et al. Mol. Pharmacol, 2012). Among them, we focused on SHMT2, the mitochondrial isoform of serine hydroxymethyl transferase involved in the biosynthesis of purines. Downregulation of SHMT2 or absence of SHMT2 catalytic activity was associated with a resistance to oxaliplatin, whereas it had no effect on cisplatin sensitivity, a selectivity that was attributed to the DACH moiety of platinum derivatives. Here, we investigated the role of DNA methylation in this selective response to platinum compounds since SHMTs can indirectly regulate the methylation status of DNA. Variations in global level of methylation as measured by the methylation status of LINE-1 retrotransposon, was associated with differences in sensitivity of PCa cells to platinum compounds. Using our in silico approach, we found significant correlations between SHMT2 expression and cell sensitivity to both demethylating agents azacytidine and decitabine. We also found that treatment of DU145 cells, with high level of global DNA methylation, sensitized cells to platinum compounds. In order to evaluate whether methylation could impair the formation of Pt-adducts in vitro, we used purified oligonucleotides containing a unique site of platination. We show that methylation at specific CpG in the vicinity of the platination site could reduce the kinetics of DNA adducts formation. This inhibition was more pronounced for DACH platin than for cisplatin. We also assessed the effect of transient repression of SHMT2 in LNCaP cells on the methylation status of ∼450,000 CpG sites using the Infinium Meth450K beadchip from Illumina. Preliminary results show that significant changes in methylation status was only observed in a reduced number of CpGs which were not located in genes that are known to be involved in cell response to Pt adducts formation. Together our results demonstrate that SHMT2-mediated specific response to oxaliplatin can be due to both methylation in the vicinity of the platination site and the modulation of the expression of genes that are not directly linked to the processing of DNA-adducts.

Citation Format: Stéphane Puyo, Nadine Houédé, Marina Hamant, Pierre Richaud, Jacques Robert, Philippe Pourquier. SHMT2 modulates DNA methylation and differentially affects prostate cancer cell response to platinum derivatives. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4478. doi:10.1158/1538-7445.AM2013-4478

Abstract 18: Predictive value of BRCA1 haplotype for trabectedin efficacy in patients with advanced soft-tissue sarcoma

Background: Trabectedin (T) has shown objective response and disease stabilisation in 5%-10% and 30-40% of unselected patients with advanced soft tissue sarcoma (STS) failing prior anthracyclines and/or ifosfamide chemotherapy. Although the precise mechanism of action of T is not fully elucidated, this drug has been found to be more active in tumor cells with a deficient homologous recombination (HR) repair system. BRCA1 is a key player of the HER system. Our aim was to determine whether the status of 4 single nucleotide polymorphims (SNPs) was associated with clinical activity of T in advanced STS patients. Methods: We analyzed SNPs (rs16941, rs16942, rs 1799966, and rs 799917) of BRCA1 in two independent cohort of patients (training cohort: 113 patients, validation cohort: 84 patients) with advanced STS from nine major referral European centres for STS. All patients were treated between 1999 and 2011 in phase I-II clinical trials or in the context of a compassionate-use programme that was open to advanced STS patients who had failed conventional chemotherapy. T was given at different doses (0.5-3 mg/m2) with the use of two different schedules: a 3-h infusion or a 24-h continuous infusion. Results: Median age of the patients in the training set was 49 years (range 17-77). The two most frequent histological subtypes were: leiomyosarcoma (non-uterine: 21, uterine: 10) and liposarcoma (myxoid round cell: 21, other: 17). 632 cycles of T were administered, with a median of 4 cycles per patient (range 1-25). The median follow-up was 10 months (range,

0.6-96 months). One complete response, 18 partial responses, and 26 disease stabilizations that lasted for &gt;6 months were observed. The median PFS was

3.5 months (95% confidence interval [CI], 2.7-4.4 months). The median OS was 13.6 months (95% CI, 8.7-18.5 months). PFS was significantly higher for patients who had at least 1 allele of the most frequent

BRCA1 AAAG haplotype (median PFS: 5.6 months [95% CI, 1.4-9.8 months] vs 2.5 months [95% CI, 1.3-3.6 months]; P =

.03). The same trend was observed for OS (median OS: 14.1 months [95% CI,

4.4-23.8 months] vs 5.4 months [95% CI, 1.7-9.0 months]; P = .0095). We observed a similar association between BRCA1 haptlotype and PFS in the independent validation cohort (median PFS: 5.2 vs 2.7 months, P = .02). Conclusion:

BRCA1 haplotype may represent a predictive DNA-based biomarker for trabectedin efficacy in advanced STS patients. Such a biomarker assessable form paraffin-embedded tumor material could be easily used into routine practice provided it is validated in a prospective setting.

Citation Format: Audrey Laroche-Clary, Vanessa Chaire, Valérie Le Morvan, Agnès Neuville, Sébastien Salas, François Bertucci, Philippe Pourquier, Antoine Italiano. Predictive value of BRCA1 haplotype for trabectedin efficacy in patients with advanced soft-tissue sarcoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 18. doi:10.1158/1538-7445.AM2013-18

Validation of a commercially available indirect ELISA using a nucleocapside recombinant protein for detection of Schmallenberg virus antibodies

A newly developed Enzym Like Immuno Sorbant Assay (ELISA) based on the recombinant nucleocapsid protein (N) of Schmallenberg virus (SBV) was evaluated and validated for the detection of SBV-specific IgG antibodies in ruminant sera by three European Reference Laboratories. Validation data sets derived from sheep, goat and bovine sera collected in France and Germany (n = 1515) in 2011 and 2012 were categorized according to the results of a virus neutralization test (VNT) or an indirect immuno-flurorescence assay (IFA). The specificity was evaluated with 1364 sera from sheep, goat and bovine collected in France and Belgium before 2009. Overall agreement between VNT and ELISA was 98.9% and 98.3% between VNT and IFA, indicating a very good concordance between the different techniques. Although cross-reactions with other Orthobunyavirus from the Simbu serogroup viruses might occur, it is a highly sensitive, specific and robust ELISA-test validated to detect anti-SBV antibodies. This test can be applied for SBV sero-diagnostics and disease-surveillance studies in ruminant species in Europe.

Gene expression signature predicting high-grade prostate cancer responses to oxaliplatin

Prostate cancer is one of the leading causes of cancer-related deaths among men. Several prognostic factors allow differentiation of low-grade tumors from high-grade tumors with high metastatic potential. High-grade tumors are currently treated with hormone therapy, to which taxanes are added when the tumors become resistant to castration. Clinical trials with other anticancer agents did not take into account the genetic backgrounds of the tumors, and most trials demonstrated low response rates. Here we used an in silico approach to screen for drug candidates that might be used as alternatives to taxanes, on the basis of a published expression signature involving 86 genes that could distinguish high-grade and low-grade tumors (Proc Natl Acad Sci USA 103:10991-10996, 2006). We explored the National Cancer Institute databases, which include data on the gene expression profiles of 60 human tumor cell lines and the in vitro sensitivities of the cell lines to anticancer drugs, and we identified several genes in the signature for which expression levels were correlated with chemosensitivity. As an example of the validation of this in silico approach, we identified a set of six genes for which expression levels could predict cell sensitivity to oxaliplatin but not cisplatin. This signature was validated in vitro through silencing of the genes in DU145, LNCaP, and C4-2B prostate cancer cells, which was accompanied by changes in oxaliplatin but not cisplatin cytotoxicity. These results demonstrate the relevance of our approach for the identification of both alternative treatments for high-grade prostate cancers and new biomarkers to predict clinical tumor responses.

The polyphenolic ellagitannin vescalagin acts as a preferential catalytic inhibitor of the α isoform of human DNA topoisomerase II

Polyphenolic ellagitannins are natural compounds that are often associated with the therapeutic activity of plant extracts used in traditional medicine. They display cancer-preventing activity in animal models by a mechanism that remains unclear. Potential targets have been proposed, including DNA topoisomerases II (Top2). Top2α and Top2β, the two isoforms of the human Top2, play a crucial role in the regulation of replication, transcription, and chromosome segregation. They are the target of anticancer agents used in the clinic such as anthracyclines (e.g., doxorubicin) or the epipodophyllotoxin etoposide. It was recently shown that the antitumor activity of etoposide was due primarily to the inhibition of Top2α, whereas inhibition of Top2β was responsible for the development of secondary malignancies, pointing to the need for more selective Top2α inhibitors. Here, we show that the polyphenolic ellagitannin vescalagin preferentially inhibits the decatenation activity of Top2α in vitro, by a redox-independent mechanism. In CEM cells, we also show that transient small interfering RNA-mediated down-regulation of Top2α but not of Top2β conferred a resistance to vescalagin, indicating that the α isoform is a preferential target. We further confirmed that Top2α inhibition was due to a catalytic inhibition of the enzyme because it did not induce DNA double-strand breaks in CEM-treated cells but prevented the formation of Top2α- rather than Top2β-DNA covalent complexes induced by etoposide. To our knowledge, vescalagin is the first example of a catalytic inhibitor for which cytotoxicity is due, at least in part, to the preferential inhibition of Top2α.

Abstract 2665: Oxaliplatin as an alternative for the treatment of high grade prostate cancers. Identification of serine hydroxymethyl transferases (SHMT) as selective biomarkers of oxaliplatin sensitivity via the modulation of DNA methylation

Prostate cancer (PCa) is one of the leading causes of death from cancer in men. High Gleason grade PCa are characterized by aggressive tumors with poorly differentiated cells and a high metastatic potential. They are often refractory to chemical castration but still treated with hormone therapy to which docetaxel or cabazitaxel are added when they become resistant to the anti-androgen. Despite many clinical trials with other chemotherapeutic agents, response rates remain low pointing towards the need for new alternative therapies. Using an in silico approach based on a 86 genes signature which could distinguish between low-grade and high-grade tumors, we identified 9 genes (PCCB, SHMT2, DPM1, RHOT2, RPL13, CD59, EIF4AI, CDKN2C, JUN) for which expression levels across the NCI-60 cell lines panel was significantly correlated (p&lt; 0.05) to oxaliplatin but not to cisplatin sensitivity. Among them, SHMT2 which is overexpressed in high grade PCa, encodes the mitochondrial isoform of serine hydroxymethyl transferase, which converts glycine to serine, which is then exported to the cytoplasm to generate the one-carbon units that are required for the biosynthesis of purines. SiRNA-mediated donwregulation of SHMT2 in DU145 or LNCaP prostate tumor cell lines rendered cells resistant to oxaliplatin but not to cisplatin. CHO 51-11 cells which express a catalytically inactive SHMT2 were also resistant to oxaliplatin but not to cisplatin as compared to CHO K1 control cells. The selective resistance to oxaliplatin was not due to the oxalate moiety since addition of oxalate to cisplatin could not restore the level of sensitivity of CHO cells to oxaliplatin. Selectivity could however be attributed to the diamino cyclohexane (DACH) moiety of oxaliplatin since CHO 51-11 cells were also resistant to dichloro(1,2-diaminocyclohexane)-platinum(II). Resistance to oxaliplatin could also be achieved by SHMT1 downregulation (the cytoplasmic form of SHMT) or by an alteration of the pool of glycine and serine. SHMTs can indirectly regulate the methylation status of DNA, and we showed that siRNA-mediated downregulation of SHMTs in hypomethylated LNCaP cells increased the global level of DNA methylation, as measured by 4 CpGs methylation status of LINE-1. Interestingly, increased level of global methylation status was associated with increased resistance to oxaliplatin. Altogether, our results identified oxaliplatin as a potential alternative for the treatment of high grade prostate cancers and SHMT2 (and SHMT1) as selective markers of oxaliplatin sensitivity which involves, at least in part, the regulation of global levels of DNA methylation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2665. doi:1538-7445.AM2012-2665

A gene expression signature to predict high-grade prostate cancer response to oxaliplatin

150

Background: Prostate cancer (PCa) is one of the leading causes of death from cancer in men. High Gleason grade prostate cancers are characterized by aggressive tumors with poorly differentiated cells and a high metastatic potential. They are often refractory to chemical castration but still treated with hormone therapy to which docetaxel or cabazitaxel are added when they become resistant to the anti-androgen. Despite many clinical trials with other chemotherapeutic agents, response rates remain low. Moreover, none of these trials took into account the tumor grade.

Methods: We used an in silico approach to screen for drug candidates that could be used as an alternative to taxanes, based on a 86 genes signature which could distinguish between low-grade and high-grade tumors. We extracted from the NCI60 panel databases the expression profiles of the 86 genes across 60 human tumor cell lines and the corresponding in vitro cytotoxicity data of 152 drugs and looked for correlation between their expression level and cell sensitivity to each of these drugs.

Results: Among the 86 genes, we identified 9 genes (PCCB, SHMT2, DPM1, RHOT2, RPL13, CD59, EIF4AI, CDKN2C, JUN) for which expression levels across the 60 cell lines was significantly correlated (p< 0.05) to oxaliplatin but not to cisplatin sensitivity. This signature was validated at the functional level since repression of each of these genes conferred a significant change in the sensitivity of PCa cell lines to oxaliplatin but not cisplatin.

Conclusions: Our results provide a proof of concept that gene expression signature specific from high grade PCa could be used for the identification of alternative therapies to taxanes. They could also be used to select patients for further clinical trials and as predictive markers of response to these drugs, which represents a further step forward towards personalized therapy of PCa.

New Topoisomerase I mutations are associated with resistance to camptothecin

Background

Topoisomerase I (TOP1) is a nuclear enzyme that catalyzes the relaxation of supercoiled DNA during DNA replication and transcription. TOP1 is the molecular target of camptothecin and related drugs such as irinotecan and SN38 (irinotecan's active metabolite). Irinotecan is widely used as an anti-cancer agent in the treatment of metastatic colon cancer. However, its efficacy is often limited by the development of resistance.

Methods

We previously established several SN38 resistant HCT116-derived clones to study the mechanisms underlying resistance to SN38. Here, we investigated whether resistance to SN38 in these cell lines could be linked to the presence of TOP1 mutations and changes in its expression and activity. Functional analyses were performed on these cell lines challenged with SN38 and we specifically monitored the double strands breaks with γH2AX staining and replication activity with molecular combing.

Results

In SN38 resistant HCT116 clones we identified three new TOP1 mutations, which are located in the core subdomain III (p.R621H and p.L617I) and in the linker domain (p.E710G) and are packed together at the interface between these two domains. The presence of these TOP1 mutations in SN38 resistant HCT116 cells did not modify TOP1 expression or intrinsic activity. Conversely, following challenge with SN38, we observed a decrease of TOP1-DNA cleavage complexes and a reduction in double-stranded break formation). In addition, we showed that SN38 resistant HCT116 cells present a strong decrease in the SN38-dependent asymmetry of replication forks that is characteristic of SN38 sensitive HCT116 cells.

Conclusions

These results indicate that the TOP1 mutations are involved in the development of SN38 resistance. We hypothesize that p.L617, p.R621 and p.E710 TOP1 residues are important for the functionality of the linker and that mutation of one of these residues is sufficient to alter or modulate its flexibility. Consequently, linker fluctuations could have an impact on SN38 binding by reducing the enzyme affinity for the drug.