Development of new platforms to improve the treatment of glioblastoma by photodynamic therapy

Le traitement des tumeurs malignes du cerveau, dont le glioblastome multiforme est la forme la plus agressive, est un défi majeur de la cancérologie. La thérapie photodynamique (PDT) apparaît comme une technique prometteuse dans ce contexte. La PDT permet une destruction des cellules cancéreuses par l’action de trois éléments à savoir un photosensibilisateur (PS), la lumière et l’oxygène. Après photoexcitation sous lumière visible, le PS engendre, en présence d’oxygène, la formation d’espèces réactives de l’oxygène dont d’oxygène singulet (1O2), toxiques, qui vont détruire les tissus avoisinants. Malheureusement, la PDT souffre de deux inconvénients majeurs qui sont le manque de sélectivité de nombreux PSs actuellement utilisés cliniquement ainsi que le besoin d’oxygène pour être efficace. Pour pallier le manque de sélectivité, le ciblage des néovaisseaux tumoraux est une approche prometteuse. L’affinité du peptide KDKPPR pour le récepteur NRP–1 surexprimé sur les cellules endothéliales a déjà été prouvée par notre équipe. Concernant le manque d’oxygène, nous nous sommes intéressés aux alcoxyamines capables de générer des radicaux alkyles toxiques par activation lumineuse, même en milieu hypoxique. Ces alcoxyamines photoactivables sont décrites dans la littérature mais jamais utilisées dans le traitement de tumeurs. Dans le cadre de cette thèse, nous avons développé une plateforme trimodale combinant un PS et un alcoxyamine photoactivable pour une PDT en milieu normoxique et hypoxique, respectivement, et un peptide pour cibler NRP–1. La synthèse de cette plateforme a été réalisée avec succès. L’étude de cette plateforme a montré un maintien de la capacité à former de l’1O2 et de l’affinité pour NRP–1. Grâce à la technique de spectroscopie RPE, les radicaux engendrés par l’illumination de l’alcoxyamine ont pu être détectés. Bien que prometteuse, cette plateforme n’est pas applicable en PDT en raison d’une photoactivation de l’alcoxyamine à une longueur d'onde UV inadaptée. La seconde partie de cette thèse a donc été consacrée à l’optimisation de cette plateforme. Nous nous sommes focalisés sur trois pistes : 1) le design d’une nouvelle alcoxyamine absorbant à de plus hautes longueurs d’onde 2) l’amélioration de la solubilité de la plateforme en greffant une cyclodextrine et 3) le développement d’un nouveau peptide ciblant NRP–1 et pouvant être internalisé dans les cellules.The treatment of malignant brain tumors, of which glioblastoma multiform is the most aggressive form, is a major challenge in oncology. Photodynamic therapy (PDT) appears to be a promising technique in this context. PDT destroys cancer cells by the action of three elements: a photosensitizer (PS), light and oxygen. After photoexcitation under visible light, PS generates, in the presence of oxygen, the formation of reactive oxygen species including singlet oxygen (1O2), toxic, which will destroy surrounding tissues. Unfortunately, PDT suffers from two major drawbacks which are the lack of selectivity of many PSs currently used clinically as well as the need for oxygen to be effective. To overcome the lack of selectivity, targeting tumor neovessels is a promising approach. The affinity of KDKPPR peptide for the overexpressed NRP–1 receptor on endothelial cells has already been demonstrated by our team. Regarding the lack of oxygen, we were interested in alkoxyamines able of generating toxic alkyl radicals by light activation, even in hypoxic environment. These photoactivatable alkoxyamines are described in the literature but never used in tumor treatment. In this thesis, we developed a trimodal platform combining a PS and a photoactivatable alkoxyamine for PDT in normoxic and hypoxic medium, respectively, and a peptide to target NRP–1. The synthesis of this platform was successfully performed. The platform study confirmed the conservation of the ability to form 1O2 and the NRP–1 affinity. The detection of the photogenerated radicals from alkoxyamine is detected by EPR spectroscopy. Although promising, this platform is not applicable in PDT due to the use of an unsuitable UV wavelength for photoactivation of alkoxyamine. The second part of this thesis was devoted to the platform optimization. We focused on three avenues: 1) Design of a new alkoxyamine absorbing at higher wavelengths, 2) Improvement of the platform solubility by grafting a cyclodextrin and 3) Development of a new NRP–1–targeted peptide which can be internalized in cells

Développement de nouvelles plateformes pour l’amélioration du traitement du glioblastome par thérapie photodynamique

The treatment of malignant brain tumors, of which glioblastoma multiform is the most aggressive form, is a major challenge in oncology. Photodynamic therapy (PDT) appears to be a promising technique in this context. PDT destroys cancer cells by the action of three elements: a photosensitizer (PS), light and oxygen. After photoexcitation under visible light, PS generates, in the presence of oxygen, the formation of reactive oxygen species including singlet oxygen (1O2), toxic, which will destroy surrounding tissues. Unfortunately, PDT suffers from two major drawbacks which are the lack of selectivity of many PSs currently used clinically as well as the need for oxygen to be effective. To overcome the lack of selectivity, targeting tumor neovessels is a promising approach. The affinity of KDKPPR peptide for the overexpressed NRP–1 receptor on endothelial cells has already been demonstrated by our team. Regarding the lack of oxygen, we were interested in alkoxyamines able of generating toxic alkyl radicals by light activation, even in hypoxic environment. These photoactivatable alkoxyamines are described in the literature but never used in tumor treatment. In this thesis, we developed a trimodal platform combining a PS and a photoactivatable alkoxyamine for PDT in normoxic and hypoxic medium, respectively, and a peptide to target NRP–1. The synthesis of this platform was successfully performed. The platform study confirmed the conservation of the ability to form 1O2 and the NRP–1 affinity. The detection of the photogenerated radicals from alkoxyamine is detected by EPR spectroscopy. Although promising, this platform is not applicable in PDT due to the use of an unsuitable UV wavelength for photoactivation of alkoxyamine. The second part of this thesis was devoted to the platform optimization. We focused on three avenues: 1) Design of a new alkoxyamine absorbing at higher wavelengths, 2) Improvement of the platform solubility by grafting a cyclodextrin and 3) Development of a new NRP–1–targeted peptide which can be internalized in cells.Le traitement des tumeurs malignes du cerveau, dont le glioblastome multiforme est la forme la plus agressive, est un défi majeur de la cancérologie. La thérapie photodynamique (PDT) apparaît comme une technique prometteuse dans ce contexte. La PDT permet une destruction des cellules cancéreuses par l’action de trois éléments à savoir un photosensibilisateur (PS), la lumière et l’oxygène. Après photoexcitation sous lumière visible, le PS engendre, en présence d’oxygène, la formation d’espèces réactives de l’oxygène dont d’oxygène singulet (1O2), toxiques, qui vont détruire les tissus avoisinants. Malheureusement, la PDT souffre de deux inconvénients majeurs qui sont le manque de sélectivité de nombreux PSs actuellement utilisés cliniquement ainsi que le besoin d’oxygène pour être efficace. Pour pallier le manque de sélectivité, le ciblage des néovaisseaux tumoraux est une approche prometteuse. L’affinité du peptide KDKPPR pour le récepteur NRP–1 surexprimé sur les cellules endothéliales a déjà été prouvée par notre équipe. Concernant le manque d’oxygène, nous nous sommes intéressés aux alcoxyamines capables de générer des radicaux alkyles toxiques par activation lumineuse, même en milieu hypoxique. Ces alcoxyamines photoactivables sont décrites dans la littérature mais jamais utilisées dans le traitement de tumeurs. Dans le cadre de cette thèse, nous avons développé une plateforme trimodale combinant un PS et un alcoxyamine photoactivable pour une PDT en milieu normoxique et hypoxique, respectivement, et un peptide pour cibler NRP–1. La synthèse de cette plateforme a été réalisée avec succès. L’étude de cette plateforme a montré un maintien de la capacité à former de l’1O2 et de l’affinité pour NRP–1. Grâce à la technique de spectroscopie RPE, les radicaux engendrés par l’illumination de l’alcoxyamine ont pu être détectés. Bien que prometteuse, cette plateforme n’est pas applicable en PDT en raison d’une photoactivation de l’alcoxyamine à une longueur d'onde UV inadaptée. La seconde partie de cette thèse a donc été consacrée à l’optimisation de cette plateforme. Nous nous sommes focalisés sur trois pistes : 1) le design d’une nouvelle alcoxyamine absorbant à de plus hautes longueurs d’onde 2) l’amélioration de la solubilité de la plateforme en greffant une cyclodextrine et 3) le développement d’un nouveau peptide ciblant NRP–1 et pouvant être internalisé dans les cellules

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

New targeted gold nanorods for the treatment of glioblastoma by photodynamic therapy

International audienceThis study describes the employment of gold nanorods (AuNRs), known for their good reputation in hyperthermia-based cancer therapy, in a hybrid combination of photosensitizers (PS) and peptides (PP). We report here, the design and the synthesis of this nanosystem and its application as a vehicle for the selective drug delivery and the efficient photodynamic therapy (PDT). AuNRs were functionalized by polyethylene glycol, phototoxic pyropheophorbide-a (Pyro) PS, and a “KDKPPR” peptide moiety to target neuropilin-1 receptor (NRP-1). The physicochemical characteristics of AuNRs, the synthesized peptide and the intermediate PP-PS conjugates were investigated. The photophysical properties of the hybrid AuNRs revealed that upon conjugation, the AuNRs acquired the characteristic properties of Pyro concerning the extension of the absorption profile and the capability to fluoresce (Φf = 0.3) and emit singlet oxygen (ΦΔ = 0.4) when excited at 412 nm. Even after being conjugated onto the surface of the AuNRs, the molecular affinity of “KDKPPR” for NRP-1 was preserved. Under irradiation at 652 nm, in vitro assays were conducted on glioblastoma U87 cells incubated with different PS concentrations of free Pyro, intermediate PP-PS conjugate and hybrid AuNRs. The AuNRs showed no cytotoxicity in the absence of light even at high PS concentrations. However, they efficiently decreased the cell viability by 67% under light exposure. This nanosystem possesses good efficiency in PDT and an expected potential effect in a combined photodynamic/photothermal therapy guided by NIR fluorescence imaging of the tumors due to the presence of both the hyperthermic agent, AuNRs, and the fluorescent active phototoxic PS

Using X-rays in photodynamic therapy: an overview

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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

Design of a targeting and oxygen-independent platform to improve photodynamic therapy: A proof of concept

International audiencePhotodynamic therapy (PDT) is a promising technique to treat different kinds of disease especially cancer. PDT requires three elements: molecular oxygen, a photoactivatable molecule called the photosensitizer (PS), and appropriate light. Under illumination, the PSs generate, in the presence of oxygen, the formation of reactive oxygen species including singlet oxygen, toxic, which then destroys the surrounding tissues. Even if PDT is used with success to treat actinic keratosis or prostate cancer for example, PDT suffers from two major drawbacks: the lack of selectivity of most of the PSs currently used clinically as well as the need for oxygen to be effective. To remedy the lack of selectivity, targeting the tumor neovessels is a promising approach to destroy the vascularization and cause asphyxia of the tumor. KDKPPR peptide affinity for the neuropilin-1 (NRP-1) receptor overexpressed on endothelial cells has already been proven. To compensate for the lack of oxygen, we focused on photoactivatable alkoxyamines (Alks), molecules capable of generating toxic radicals by light activation. In this article, we describe the synthesis of a multifunctional platform combining three units: a PS for an oxygen-dependent PDT, a peptide to target tumor neovessels, and an Alk for an oxygen-independent activity. The synthesis of the compound was successfully carried out, and the study of its photophysical properties showed that the PS retained its capacity to form singlet oxygen and the affinity tests confirmed the affinity of the compound for NRP-1. Thanks to the electron paramagnetic resonance spectroscopy, a technique of choice for radical investigation, the radicals generated by the illumination of the Alk could be detected. The proof of concept was thus successfully established

Low incidence of SARS-CoV-2, risk factors of mortality and the course of illness in the French national cohort of dialysis patients

International audienceThe aim of this study was to estimate the incidence of COVID-19 disease in the French national population of dialysis patients, their course of illness and to identify the risk factors associated with mortality. Our study included all patients on dialysis recorded in the French REIN Registry in April 2020. Clinical characteristics at last follow-up and the evolution of COVID-19 illness severity over time were recorded for diagnosed cases (either suspicious clinical symptoms, characteristic signs on the chest scan or a positive reverse transcription polymerase chain reaction) for SARS-CoV-2. A total of 1,621 infected patients were reported on the REIN registry from March 16th, 2020 to May 4th, 2020. Of these, 344 died. The prevalence of COVID-19 patients varied from less than 1% to 10% between regions. The probability of being a case was higher in males, patients with diabetes, those in need of assistance for transfer or treated at a self-care unit. Dialysis at home was associated with a lower probability of being infected as was being a smoker, a former smoker, having an active malignancy, or peripheral vascular disease. Mortality in diagnosed cases (21%) was associated with the same causes as in the general population. Higher age, hypoalbuminemia and the presence of an ischemic heart disease were statistically independently associated with a higher risk of death. Being treated at a selfcare unit was associated with a lower risk. Thus, our study showed a relatively low frequency of COVID-19 among dialysis patients contrary to what might have been assumed