Nicolas Joudiou

Injectable nanomedicine hydrogel for local chemotherapy of glioblastoma after surgical resection

&NA; Glioblastoma (GBM) treatment includes, when possible, surgical resection of the tumor followed by radiotherapy and oral chemotherapy with temozolomide, however recurrences quickly develop around the resection cavity borders leading to patient death. We hypothesize that the local delivery of Lauroyl‐gemcitabine lipid nanocapsule based hydrogel (GemC12‐LNC) in the tumor resection cavity of GBM is a promising strategy as it would allow to bypass the blood brain barrier, thus reaching high local concentrations of the drug. The cytotoxicity and internalization pathways of GemC12‐LNC were studied on different GBM cell lines (U251, T98‐G, 9L‐LacZ, U‐87 MG). The GemC12‐LNC hydrogel was well tolerated when injected in mouse brain. In an orthotopic xenograft model, after intratumoral administration, GemC12‐LNC significantly increased mice survival compared to the controls. Moreover, its ability to delay tumor recurrences was demonstrated after perisurgical administration in the GBM resection cavity. In conclusion, we demonstrate that GemC12‐LNC hydrogel could be considered as a promising tool for the post‐resection management of GBM, prior to the standard of care chemo‐radiation. Graphical abstract Figure. No caption available.

Mapping of global R1 and R2* values versus lipids R1 values as potential markers of hypoxia in human glial tumors: A feasibility study

Availability of an innocuous and repeatable technique for monitoring tumor oxygenation throughout therapeutic course should be a key factor for adaptative therapeutic strategies. We previously qualified lipids R1 as a marker of oxygen level on experimental tumor models. The objectives of the present study were to assess the applicability of measuring lipids R1 in primary central nervous system malignancies in a clinical setting as well as to compare lipids R1 with global (water+lipids) R1 and R2* which are also sensitive to the oxygen environment. 25 patients with brain neuroepithelial tumors were examined on a clinical 3T MR system. Values obtained within regions of interest contouring contrast-enhanced tumor (C+), unenhanced tumor (C-), peritumoral edema, and normal appearing white matter (NAWM) were compared to those obtained for the normal brain parenchyma of 17 healthy volunteers. Global R1 and lipids R1 values were significantly lower in tumors than in NAWM of patients or healthy brain of normal volunteers. In contrast, R2* values were not significantly different in tumors compared to NAWM or healthy brains. None of them showed significant difference between C+ and C- tumors. Global R1 values within NAWM were significantly different from that of both tumor and peritumoral edema, but lacked sensitivity to differentiate between tumor and peritumoral edema. In turn, lipids R1 measurements enabled discrimination between tumor areas and peritumoral edema. In conclusion, global R1 and lipids R1 deserve further attention as potential markers of tumor hypoxia in primary brain tumors.

Novel model of orthotopic U-87 MG glioblastoma resection in athymic nude mice.

In vitro and in vivo models of experimental glioma are useful tools to gain a better understanding of glioblastoma (GBM) and to investigate novel treatment strategies. However, the majority of preclinical models focus on treating solid intracranial tumours, despite surgical resection being the mainstay in the standard care of patients with GBM today. The lack of resection and recurrence models therefore has undermined efforts in finding a treatment for this disease. Here we present a novel orthotopic tumour resection and recurrence model that has potential for the investigation of local delivery strategies in the treatment of GBM. The model presented is simple to achieve through the use of a biopsy punch, is reproducible, does not require specific or expensive equipment, and results in a resection cavity suitable for local drug delivery systems, such as the implantation or injection of hydrogels. We show that tumour resection is well tolerated, does not induce deleterious neurological deficits, and significantly prolongs survival of mice bearing U-87 MG GBM tumours. In addition, the resulting cavity could accommodate adequate amounts of hydrogels for local delivery of chemotherapeutic agents to eliminate residual tumour cells that can induce tumour recurrence.

Multi-modality imaging to assess metabolic response to dichloroacetate treatment in tumor models

Reverting glycolytic metabolism is an attractive strategy for cancer therapy as upregulated glycolysis is a hallmark in various cancers. Dichloroacetate (DCA), long used to treat lactic acidosis in various pathologies, has emerged as a promising anti-cancer drug. By inhibiting the pyruvate dehydrogenase kinase, DCA reactivates the mitochondrial function and decreases the glycolytic flux in tumor cells resulting in cell cycle arrest and apoptosis. We recently documented that DCA was able to induce a metabolic switch preferentially in glycolytic cancer cells, leading to a more oxidative phenotype and decreasing proliferation, while oxidative cells remained less sensitive to DCA treatment. To evaluate the relevance of this observation in vivo, the aim of the present study was to characterize the effect of DCA in glycolytic MDA-MB-231 tumors and in oxidative SiHa tumors using advanced pharmacodynamic metabolic biomarkers. Oxygen consumption, studied by 17O magnetic resonance spectroscopy, glucose uptake, evaluated by 18F-FDG PET and pyruvate transformation into lactate, measured using hyperpolarized 13C-magnetic resonance spectroscopy, were monitored before and 24 hours after DCA treatment in tumor bearing mice. In both tumor models, no clear metabolic shift was observed. Surprisingly, all these imaging parameters concur to the conclusion that both glycolytic tumors and oxidative tumors presented a similar response to DCA. These results highlight a major discordance in metabolic cancer cell bioenergetics between in vitro and in vivo setups, indicating critical role of the local microenvironment in tumor metabolic behaviors.

17 O MRS assesses the effect of mild hypothermia on oxygen consumption rate in tumors.

Although oxygen consumption is a key factor in metabolic phenotyping, its assessment in tumors remains critical, as current technologies generally display poor specificity. The objectives of this study were to explore the feasibility of direct 17O nuclear magnetic resonance (NMR) spectroscopy to assess oxygen metabolism in tumors and its modulations. To investigate the impact of hypometabolism induction in the murine fibrosarcoma FSAII tumor model, we monitored the oxygen consumption of normothermic (37°C) and hypothermic (32°C) tumor‐bearing mice. Hypothermic animals showed an increase in tumor pO2 (measured by electron paramagnetic resonance oximetry) contrary to normothermic animals. This was related to a decrease in oxygen consumption rate (assessed using 17O magnetic resonance spectroscopy (MRS) after the inhalation of 17O2‐enriched gas). This study highlights the ability of direct 17O MRS to measure oxygen metabolism in tumors and modulations of tumor oxygen consumption rate.

Oxygen Mapping within Healthy and Acutely Infarcted Brain Tissue in Humans Using the NMR Relaxation of Lipids: A Proof-Of-Concept Translational Study.

The clinical applicability of brain oxygenation mapping using the MOBILE (Mapping of Oxygen By Imaging Lipids relaxation Enhancement) magnetic resonance (MR) technique was assessed in the clinical setting of normal brain and of acute cerebral ischemia as a founding proof-of-concept translational study. Changes in the oxygenation level within healthy brain tissue can be detected by analyzing the spin-lattice proton relaxation (‘Global T 1 ’ combining water and lipid protons) because of the paramagnetic properties of molecular oxygen. It was hypothesized that selective measurement of the relaxation of the lipid protons (‘Lipids T 1 ’) would result in enhanced sensitivity of pO2 mapping because of higher solubility of oxygen in lipids than in water, and this was demonstrated in pre-clinical models using the MOBILE technique. In the present study, 12 healthy volunteers and eight patients with acute (48–72 hours) brain infarction were examined with the same clinical 3T MR system. Both Lipids R1 (R1 = 1/T1) and Global R1 were significantly different in the infarcted area and the contralateral unaffected brain tissue, with a higher statistical significance for Lipids R1 (median difference: 0.408 s-1; p<0.0001) than for Global R1 (median difference: 0.154 s-1; p = 0.027). Both Lipids R1 and Global R1 values in the unaffected contralateral brain tissue of stroke patients were not significantly different from the R1 values calculated in the brain tissue of healthy volunteers. The main limitations of the present prototypic version of the MOBILE sequence are the long acquisition time (4 min), hampering robustness of data in uncooperative patients, and a 2 mm slice thickness precluding accurate measurements in small infarcts because of partial volume averaging effects.

Combined endogenous MR biomarkers to predict basal tumor oxygenation and response to hyperoxic challenge

Hypoxia is a common feature of solid tumors, which translates into increased angiogenesis, malignant phenotype cell selection, change in gene expression and greater resistance to radiotherapy and chemotherapy. Therefore, there is a need for markers of hypoxia to stratify patients, in order to personalize treatment to improve therapeutic outcome. However, no modality has yet been validated for the screening of hypoxia in routine clinical practice. Magnetic resonance imaging (MRI) R1 and R2* relaxation parameters are sensitive to tissue oxygenation: R1 is sensitive to dissolved oxygen and R2* is sensitive to intravascular deoxyhemoglobin content. Two rat tumor models with distinct levels of hypoxia, 9L–glioma and rhabdomyosarcoma, were imaged for R1 and R2* under air and carbogen (95% O2 and 5% CO2) breathing conditions. It was observed that the basal tumor oxygenation level had an impact on the amplitude of response to carbogen in the vascular compartment (R2*), but not in the tissue compartment (R1). In addition, the change in tissue oxygenation estimated by ΔR1 correlated with the change in vascular oxygenation estimated by ΔR2*, which is consistent with an increase in oxygen supply generating an elevated tumor pO2. At the intra‐tumoral level, we identified four types of voxel to which a hypoxic feature was attributed (mild hypoxia, severe hypoxia, normoxia and vascular steal), depending on the carbogen‐induced change in R1 and R2* values for each voxel. The results showed that 9L–gliomas present more normoxic fractions, whereas rhabdomyosarcomas present more hypoxic fractions, which is in accordance with a previous study using 18F–fluoroazomycin arabinoside (18F–FAZA) and electron paramagnetic resonance (EPR) oximetry. The response of the combined endogenous MRI contrasts to carbogen challenge could be a useful tool to predict different tumor hypoxic fractions.

Imaging markers of response to combined BRAF and MEK inhibition in BRAF mutated vemurafenib-sensitive and resistant melanomas

A majority of patients with a V600x melanoma respond quickly to BRAF/MEK inhibition (BRAFi/MEKi) and have an obvious clinical benefit. Nearly all the patients after this initial phase will develop resistance. Therefore, non-invasive early markers of response/non-response are needed in order to identify those patients who, due to intrinsic or acquired resistance, do not respond to treatment and would be eligible for alternative treatments. The aim of this study was to investigate the value of magnetic resonance spectroscopy (1H-MRS) of choline and diffusion-weighted magnetic resonance imaging (DW-MRI) as early markers of response to BRAF inhibition (BRAFi) with vemurafenib alone or in combination with MEK inhibition (MEKi) with trametinib, in BRAFi-sensitive and BRAFi-resistant melanoma xenografts. Tumor response was significantly improved by the combination of BRAFi and MEKi, compared to BRAFi alone, only in sensitive xenografts; thus indicating that vemurafenib-resistant A375R xenografts were cross-resistant to the inhibition of MEK, as confirmed by immunohistochemistry analysis for phosphorylated ERK. In vivo 1H-MRS showed that in sensitive melanoma xenografts, a significant blockage of ERK phosphorylation, but not a decrease in cell proliferation, was required to affect total choline (tCho) levels, thus suggesting that tCho could serve as a pharmacodynamic (PD) marker for agents targeting the MAPK cascade. In addition, early effects of the combination therapy on tumor cellularity could be detected via DW-MRI. In particular, skewness and kurtosis of the apparent diffusion coefficient (ADC) distribution may be useful to detect changes in the diffusional heterogeneity that might not affect the global ADC value.

Post-resection treatment of glioblastoma with an injectable nanomedicine-loaded photopolymerizable hydrogel induces long-term survival

ABSTRACT Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor. Despite available therapeutic options, the prognosis for patients with GBM remains very poor. We hypothesized that the intra‐operative injection of a photopolymerizable hydrogel into the tumor resection cavity could sustain the release of the anti‐cancer drug paclitaxel (PTX) encapsulated in poly (lactic‐co‐glycolic acid) (PLGA) nanoparticles and prevent GBM recurrence. The tumor was resected 13days after implantation and a pre‐gel solution composed of polyethylene glycol dimethacrylate (PEG‐DMA) polymer, a photoinitiator and PTX‐loaded PLGA nanoparticles (PTX PLGA‐NPs) was injected into the tumor resection cavity. A solid gel filling the whole cavity was formed immediately by photopolymerization using a 400nm light. PTX in vitro release study showed a burst release (11%) in the first 8h and a sustained release of 29% over a week. In vitro, U87 MG cells were sensitive to PTX PLGA‐NPs with IC50 level of approximately 0.010&mgr;g/mL. The hydrogel was well‐tolerated when implanted in the brain of healthy mice for 2 and 4months. Administration of PTX PLGA‐NPs‐loaded hydrogel into the resection cavity of GBM orthotopic model lead to more than 50% long‐term survival mice (150days) compared to the control groups (mean survival time 52days). This significant delay of recurrence is very promising for the post‐resection treatment of GBM.

Magnetic targeting of paclitaxel-loaded poly(lactic- co -glycolic acid)-based nanoparticles for the treatment of glioblastoma

Introduction Glioblastoma (GBM) therapy is highly challenging, as the tumors are very aggressive due to infiltration into the surrounding normal brain tissue. Even a combination of the available therapeutic regimens may not debulk the tumor completely. GBM tumors are also known for recurrence, resulting in survival rates averaging <18 months. In addition, systemic chemotherapy for GBM has been challenged for its minimal desired therapeutic effects and unwanted side effects. Purpose We hypothesized that paclitaxel (PTX) and superparamagnetic iron oxide (SPIO)-loaded PEGylated poly(lactic-co-glycolic acid) (PLGA)-based nanoparticles (NPs; PTX/SPIO-NPs) can serve as an effective nanocarrier system for magnetic targeting purposes, and we aimed to demonstrate the therapeutic efficacy of this system in an orthotopic murine GBM model. Materials and methods PTX/SPIO-NPs were prepared by emulsion–diffusion–evaporation method and characterized for physicochemical properties. In vitro cellular uptake of PTX/SPIO-NPs was evaluated by fluorescence microscopy and Prussian blue staining. Orthotopic U87MG tumor model was used to evaluate blood–brain barrier disruption using T1 contrast agent, ex vivo biodistribution, in vivo toxicity and in vivo antitumor efficacy of PTX/SPIO-NPs. Results PTX/SPIO-NPs were in the size of 250 nm with negative zeta potential. Qualitative cellular uptake studies showed that the internalization of NPs was concentration dependent. Through magnetic resonance imaging, we observed that the blood–brain barrier was disrupted in the GBM area. An ex vivo biodistribution study showed enhanced accumulation of NPs in the brain of GBM-bearing mice with magnetic targeting. Short-term in vivo safety evaluation showed that the NPs did not induce any systemic toxicity compared with Taxol® (PTX). When tested for in vivo efficacy, the magnetic targeting treatment significantly prolonged the median survival time compared with the passive targeting and control treatments. Conclusion Overall, PTX/SPIO-NPs with magnetic targeting could be considered as an effective anticancer targeting strategy for GBM chemotherapy.