Proton MR spectroscopy and diffusion MR imaging monitoring to predict tumor response to interstitial photodynamic therapy for glioblastoma

International audienceDespite recent progress in conventional therapeutic approaches, the vast majority of glioblastoma recur locally, indicating that a more aggressive local therapy is required. Interstitial photodynamic therapy (iPDT) appears as a very promising and complementary approach to conventional therapies. However, an optimal fractionation scheme for iPDT remains the indispensable requirement. To achieve that major goal, we suggested following iPDT tumor response by a non-invasive imaging monitoring. Nude rats bearing intracranial glioblastoma U87MG xenografts were treated by iPDT, just after intravenous injection of AGuIX® nanoparticles, encapsulating PDT and imaging agents. Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS) allowed us an original longitudinal follow-up of post-treatment effects to discriminate early predictive markers. We successfully used conventional MRI, T2 star (T2*), Diffusion Weighted Imaging (DWI) and MRS to extract relevant profiles on tissue cytoarchitectural alterations, local vascular disruption and metabolic information on brain tumor biology, achieving earlier assessment of tumor response. From one day post-iPDT, DWI and MRS allowed us to identify promising markers such as the Apparent Diffusion Coefficient (ADC) values, lipids, choline and myoInositol levels that led us to distinguish iPDT responders from non-responders. All these responses give us warning signs well before the tumor escapes and that the growth would be appreciated

Folic acid conjugates with photosensitizers for cancer targeting in photodynamic therapy: Synthesis and photophysical properties

International audienc

FRα : une cible pour la thérapie photodynamique prophylactique des métastases péritonéales ovariennes ?

International audiencePartly due to delays in its diagnosis, ovarian cancer's prognosis remains dire after primary therapy. Treatment consists in complete cytoreductive surgery and platinum-based chemotherapy. Recurrence rates are disappointingly high, as 60% of women with advanced epithelial ovarian cancer considered in remission will develop recurrent disease within five years. Special attention to undetected peritoneal metastasis and residual tumorous cells during surgery is necessary as they are the main predictors of recurrences. Targeted therapies aim to bring chemotherapy, radiotherapy and selective tumor photosensitizer (PS) agents to the targeted cell and its tumoral microenvironment. Folate receptor α (FRα) shows promising prospects in targeting ovarian cancerous cells. Indeed, with good specificity and frequent overexpression in ovarian cancer, FRα is a recurrent topic in recent publications. The aim of this review is to present FRα and the reasons that make it an ideal targeting ligand for ovarian carcinoma therapy. Prophylactic photodynamic therapy (PPDT) using new generation FRα-coupled agents combined with complete cytoreductive surgery could allow for a significant decrease in recurrence rates. Preclinical trials are being run in order to allow for human clinical applications

Folate-based radiotracers for nuclear imaging and radionuclide therapy

International audienceFolate receptor α (FRα) is overexpressed on numerous tumorous cell types such as ovarian or endometrial cancer cells. Moreover, FRα is absent from most healthy tissues as it is normally expressed only on the surface of proximal tubules cells of kidneys and choroid plexus. Thus, folate-based radiopharmaceuticals have emerged this last two decades as FRα is a target of choice to diagnose and treat numerous cancers. Nuclear imaging is a performing diagnostic technology using highly sensitive detectors and specific radiopharmaceuticals used to detect tumors at an earlier stage. Herein, an overview of the development of folate-based radiopharmaceuticals to detect FRα-positive tumors by nuclear imaging using positron emission tomography (PET) and single photon emission computed tomography (SPECT) is exposed. Strategies developed to improve precursor synthesis, bioavailability, clearance, and affinity to FRα will be detailed. Advances made to decrease kidney uptake open the gate to targeted radionuclide therapy (TRT) using folate-based radiopharmaceuticals to treat FRα-positive tumors. Thus, radiofolates used in TRT and more precisely in a theranostic approach will be depicted in this revie

Use of Cyclodextrins in Anticancer Photodynamic Therapy Treatment

Photodynamic therapy (PDT) is mainly used to destroy cancerous cells; it combines the action of three components: a photoactivatable molecule or photosensitizer (PS), the light of an appropriate wavelength, and naturally occurring molecular oxygen. After light excitation of the PS, the excited PS then reacts with molecular oxygen to produce reactive oxygen species (ROS), leading to cellular damage. One of the drawbacks of PSs is their lack of solubility in water and body tissue fluids, thereby causing low bioavailability, drug-delivery efficiency, therapeutic efficacy, and ROS production. To improve the water-solubility and/or drug delivery of PSs, using cyclodextrins (CDs) is an interesting strategy. This review describes the in vitro or/and in vivo use of natural and derived CDs to improve antitumoral PDT efficiency in aqueous media. To achieve these goals, three types of binding modes of PSs with CDs are developed: non-covalent CD–PS inclusion complexes, covalent CD–PS conjugates, and CD–PS nanoassemblies. This review is divided into three parts: (1) non-covalent CD-PS inclusion complexes, covalent CD–PS conjugates, and CD–PS nanoassemblies, (2) incorporating CD–PS systems into hybrid nanoparticles (NPs) using up-converting or other types of NPs, and (3) CDs with fullerenes as PSs

Fighting hypoxia to improve PDT

Article de 115 pagesInternational audiencePhotodynamic therapy (PDT) has drawn great interest in recent years mainly due to its low side effects and few drug resistances. Nevertheless, one of the issues of PDT is the need for oxygen to induce a photodynamic effect. Tumours often have low oxygen concentrations, related to the abnormal structure of the microvessels leading to an ineffective blood distribution. Moreover, PDT consumes O2. In order to improve the oxygenation of tumour or decrease hypoxia, different strategies are developed and are described in this review: (1) The use of O2 vehicle; (2) the modification of the tumour microenvironment (TME); (3) combining other therapies with PDT; (4) hypoxia-independent PDT; (5) hypoxia-dependent PDT and (6) fractional PDT

Preparation and characterization of mTHPC-loaded solid lipid nanoparticles for photodynamic therapy

International audienceAmong various attempts to enhance the therapeutic efficacy of PhotoDynamic Therapy (PDT), the specific delivery of PhotoSensitizer (PS) in the tumor tissue is expected to improve its clinical applications. The aim of this study was to engineer Lipid Nanoparticles (LNP) with different sizes and various PS contents, using simple solvent-free and easily scale up manufacturing processes. Meso-(tetrahydroxyphenyl) chlorin (mTHPC) is one of the most potent photoactive compounds for clinical use. We demonstrated that mTHPC was efficiently incorporated into the lipid core of LNP, leading to a large range of stable and reproducible mTHPC-loaded LNP with narrow size distribution. Photophysical and physico-chemical properties of mTHPC-loaded LNP were assessed as well as absorption spectra and singlet oxygen emission, colloidal stability, particle size and zeta potential. The photocytotoxicity of selected mTHPC-loaded solid LNP was demonstrated on MCF-7 cells under irradiation at 652 nm with a range of light fluence from 1.0 to 10 J/cm². All physico-chemical, photophysical and biological results allow us to conclude that solid LNP appear as a very promising nano-mTHPC delivery system for PDT

Preliminary study of new gallium-68 radiolabeled peptide targeting NRP-1 to detect brain metastases by positron emission tomography

International audienceDue to their very poor prognosis and a fatal outcome, secondary brain tumors are one of the biggest challenges in oncology today. From the point of view of the early diagnosis of these brain micro- and macro-tumors, the sensitivity and specificity of the diagnostic tools constitute an obstacle. Molecular imaging, such as Positron Emission Tomography (PET), is a promising technique but remains limited in the search for cerebral localizations, given the commercially available radiotracers. Indeed, the [18F]FDG PET remains constrained by the physiological fixation of the cerebral cortex, which hinders the visualization of cerebral metastases. Tumor angiogenesis is recognized as a crucial phenomenon in the progression of malignant tumors and is correlated with overexpression of the neuropilin-1 (NRP-1) receptor. Here, we describe the synthesis and the photophysical properties of the new gallium-68 radiolabeled peptide to target NRP-1. The KDKPPR peptide was coupled with gallium-68 anchored into a bifunctional NODAGA chelating agent, as well as Cy5 for fluorescence detection. The Cy5 absorbance spectra did not change, whereas the molar extinction coefficient (ε) decreased drastically. An enhancement of the fluorescence quantum yield (φF) could be observed due to the better water solubility of Cy5. [68Ga]Ga-NODAGA-K(Cy5)DKPPR was radiosynthesized efficiently, presented hydrophilic properties (log D = −1.86), and had high in vitro stability (>120 min). The molecular affinity and the cytotoxicity of this new chelated radiotracer were evaluated in vitro on endothelial cells (HUVEC) and MDA-MB-231 cancer cells (hormone-independent and triple-negative line) and in vivo on a brain model of metastasis in a nude rat using the MDA-MB-231 cell line. No in vitro toxicity has been observed. The in vivo preliminary experiments showed promising results, with a high contrast between the healthy brain and metastatic foci for [68Ga]Ga-NODAGA-K(Cy5)DKPPR

Interplay between Cellular Uptake, Intracellular Localization and the Cell Death Mechanism in Triphenylamine-Mediated Photoinduced Cell Death

International audienc