Gadolinium based nanoparticles for radiosensitization of head and neck squamous cell carcinoma

International audiencePurpose: Head and neck squamous cell carcinoma (HNSCC) is an aggressive and recurrent malignancy that displays intrinsic resistance to radio- and chemotherapy. The aim of this study is to radiosensitize these tumors using gadolinium based nanoparticles (GBN) made of a polysiloxane matrix and surrounded by gadolinium chelates. The nanoparticles in the tumors should enhance the efficacy of radiotherapy (thanks to the high Z of gadolinium) through the generation of electron Auger cascade and secondary electrons

Effect of the nanoparticle synthesis method on dendronized iron oxides as MRI contrast agents

Équipe 401 : Nanomatériaux pour la vie et développement durableInternational audienceAqueous suspensions of dendronized iron oxide nanoparticles (NPs) have been obtained after functionalization, with two types of dendrons, of NPs synthesized either by coprecipitation (leading to naked NPs in water) or by thermal decomposition (NPs in situ coated by oleic acid in an organic solvent). Different grafting strategies have been optimized depending on the NPs synthetic method. The size distribution, the colloidal stability in isoosmolar media, the surface complex nature as well as the preliminary biokinetic studies performed with optical imaging, and the contrast enhancement properties evaluated through in vitro and in vivo MRI experiments, have been compared as a function of the nature of both dendrons and NPs. All functionalized NPs displayed good colloidal stability in water, however the ones bearing a peripheral carboxylic acid function gave the best results in isoosmolar media. Whereas the grafting rates were similar, the nature of the surface complex depended on the NPs synthetic method. The in vitro contrast enhancement properties were better than commercial products, with a better performance of the NPs synthesized by coprecipitation. On the other hand, the NPs synthesized by thermal decomposition were more efficient in vivo. Furthermore, they both displayed good biodistribution with renal and hepatobiliary elimination pathways and no consistent RES uptake

Assessment of simplified methods for quantification of [ 18 F]-DPA-714 using 3D whole-brain TSPO immunohistochemistry in a non-human primate

International audienceThe 18 kDa translocator protein (TSPO) is the main molecular target to image neuroinflammation by positron emission tomography (PET). However, TSPO-PET quantification is complex and none of the kinetic modelling approaches has been validated using a voxel-by-voxel comparison of TSPO-PET data with the actual TSPO levels of expression. Here, we present a single case study of binary classification of in vivo PET data to evaluate the statistical performance of different TSPO-PET quantification methods. To that end, we induced a localized and adjustable increase of TSPO levels in a non-human primate brain through a viral-vector strategy. We then performed a voxel-wise comparison of the different TSPO-PET quantification approaches providing parametric [ 18 F]-DPA-714 PET images, with co-registered in vitro three-dimensional TSPO immunohistochemistry (3D-IHC) data. A data matrix was extracted from each brain hemisphere, containing the TSPO-IHC and TSPO-PET data for each voxel position. Each voxel was then classified as false or true, positive or negative after comparison of the TSPO-PET measure to the reference 3D-IHC method. Finally, receiver operating characteristic curves (ROC) were calculated for each TSPO-PET quantification method. Our results show that standard uptake value ratios using cerebellum as a reference region (SUV CBL ) has the most optimal ROC score amongst all non-invasive approaches

Targeting Bcl-2/Bcl-XL induces antitumor activity in uveal melanoma patient-derived xenografts.

Uveal melanoma (UM) is associated with a high risk of metastases and lack of efficient therapies. Reduced capacity for apoptosis induction by chemotherapies is one obstacle to efficient treatments. Human UM is characterized by high expression of the anti-apoptotic protein Bcl-2. Consequently, regulators of apoptosis such as Bcl-2 family inhibitors may constitute an attractive approach to UM therapeutics. In this aim, we have investigated the efficacy of the Bcl-2/Bcl-XL inhibitor S44563 on 4 UM Patient-Derived Xenografts (PDXs) and derived-cell lines.Four well characterized UM PDXs were used for in vivo experiments. S44563 was administered alone or combined with fotemustine either concomitantly or after the alkylating agent. Bcl-2, Bcl-XL, and Mcl-1 expressions after S44563 administration were evaluated by immunohistochemistry (IHC).S44563 administered alone by at 50 and 100 mg/kg i.p. induced a significant tumour growth inhibition in only one xenograft model with a clear dose effect. However, when S44563 was concomitantly administered with fotemustine, we observed a synergistic activity in 3 out of the 4 tested models. In addition, S44563 administered after fotemustine induced a tumour growth delay in 2 out of 3 tested xenografts. Finally, IHC analyses showed that Bcl-2, Bcl-XL, and Mcl-1 expression were not modified after S44563 administration.The novel anti-apoptotic experimental compound S44563, despite a relative low efficacy when administered alone, increased the efficacy of fotemustine in either concomitant or sequential combinations or indeed subsequent to fotemustine. These data support further exploration of potential therapeutic effect of Bcl-2/Bcl-xl inhibition in human UM

TGI and complete remission induced by a combination of S44563 and fotemustine.

<p>Complete remissions are indicated in brackets.</p><p>p<0.005.</p

Inhibition of the interaction between Bcl-2 or Bcl-X_L and fluorescent Puma BH3 peptide measured by the decrease of fluorescence polarisation as a function of S44563-2 concentration.

<p>Three independent experiments are presented. FP data are presented in millipolarization units (mP). For each experiment, measures are assessed in triplicate.</p

<i>In vivo</i> responses of UM PDXs to S44563 administered alone or in combination with fotemustine.

<p>A. MP41 xenograft was treated either by S44563 at 50/kg (▪) or 100 mg/kg (□) 5 days a week for 5 weeks. <b>B.</b> Overall survival of mice bearing MP41 tumors treated by S44563 (O), fotemustine (▪), and concomitant fotemustine+S44563 (⧫). <b>C.</b> MP77 xenograft was treated by S44563 at 100 mg/kg (□), fotemustine 15 mg/kg (Δ), or both (▴). <b>D.</b> MM66 xenograft was treated by S44563 at 50 mg/kg (□), fotemustine 30 mg/kg (Δ), or both (▴). Mice in the control group (•) received 0,3 ml of the drug-formulating vehicle with the same schedule as the treated animals. Tumor growth was evaluated by plotting the mean of the RTV (relative tumor volume) ± SD per group. Between 8 to 12 mice per group were included in <i>in vivo</i> experiments.</p

<i>In vitro</i> apoptosis induction by S44563.

<p>A and B. Apoptosis induction by S44563. The MP41, MM26, and MM66 cell lines were incubated with 17 µM and 34 µM S44563 for 24 hours, after which the samples were labeled with DAPI/annexin V-FITC (A) or JC1 (B). The proportion of annexin V-positive cells and low Δψ_m cells was indicated in C and E, respectively. A two-way ANOVA with Bonferroni post-test was then performed (<b>*</b> p<0.05). <b>C.</b> Cell cycle analyses after S44563 exposure (17 or 34 µM for 24 h) in the 3 UM cell lines. Cell cycle analysis was determined by labeling the DNA with propidium iodide. Each of the three lines was treated by 17 µM or 34 µM of S44563. The proportion of cells (%) in different cell cycle phases was compared with the control (untreated). Two-way ANOVA with Bonferroni post-test was then performed (<b>*</b> means a p<0.05). <b>D.</b> Cell cycle analyses of the xMP41 UM cell line. I and J. Measurement of autophagy on the 3 UM cell lines after S44563 exposure (2 or 4 µM for 24 h). After S44563 treatment, the amount of active and inactive protein LC3 was determined and reported to ß-actine. The quantity of total LC3 protein was calculated to study the activation of LC3. Results were presented as percentage and total amount of active cleaved LC3, relative to β-actin. A two-way ANOVA with Bonferroni post-test was then performed (<b>*</b> means a p<0.05).</p

Immunohistochemical analyses under S44563 administration.

<p>Immunohistochemical analyses of the MM66 UM xenograft after S44563, fotemustine, or S44563+fotemustine.</p

Overall and median survival after combination of S44563 and fotemustine.

<p><b>Abbreviations:</b> F-30/S-50, fotemustine followed by S44563 adminstration since day 43; OS (day), overall survival observed at the indicated day; Median S, median survival in days since start of treatment.</p><p>F-30 versus F-30+S-50 or F-30/S-100: p = 0.04.</p><p>F-30/S-100 versus F-30+S-50/S-100: p = 0.038.</p