Preliminary Study of New Gallium-68 Radiolabeled Peptide Targeting NRP-1 to Detect Brain Metastases by Positron Emission Tomography.

Due 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.

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.

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

Recent researches in photodynamic therapy have focused on novel techniques to enhance tumour targeting of anticancer drugs and photosensitizers. Coupling a photosensitizer with folic acid could allow more effective targeting of folate receptors which are over-expressed on the surface of many tumour cells. In this study, different folic acid-OEG-conjugated photosensitizers were synthesized, characterized and their photophysical properties were evaluated. The introduction of an OEG does not significantly improve the hydrophilicity of the FA-porphyrin. All the FA-targeted photosensitizers present good to very good photophysical properties. The best one appears to be Ce6. Molar extinction coefficient, fluorescence and singlet oxygen quantum yields were determined and were compared to the corresponding photosensitizer alone.

Ultrasmall Nanoplatforms as Calcium-Responsive Contrast Agents for Magnetic Resonance Imaging.

The preparation of ultrasmall and rigid platforms (USRPs) that are covalently coupled to macrocycle-based, calcium-responsive/smart contrast agents (SCAs), and the initial in vitro and in vivo validation of the resulting nanosized probes (SCA-USRPs) by means of magnetic resonance imaging (MRI) is reported. The synthetic procedure is robust, allowing preparation of the SCA-USRPs on a multigram scale. The resulting platforms display the desired MRI activity­i.e., longitudinal relaxivity increases almost twice at 7 T magnetic field strength upon saturation with Ca(2+). Cell viability is probed with the MTT assay using HEK-293 cells, which show good tolerance for lower contrast agent concentrations over longer periods of time. On intravenous administration of SCA-USRPs in living mice, MRI studies indicate their rapid accumulation in the renal pelvis and parenchyma. Importantly, the MRI signal increases in both kidney compartments when CaCl2 is also administrated. Laser-induced breakdown spectroscopy experiments confirm accumulation of SCA-USRPs in the renal cortex. To the best of our knowledge, these are the first studies which demonstrate calcium-sensitive MRI signal changes in vivo. Continuing contrast agent and MRI protocol optimizations should lead to wider application of these responsive probes and development of superior functional methods for monitoring calcium-dependent physiological and pathological processes in a dynamic manner.

Targeted Photodynamic Therapy using a Vectorized Photosensitizer coupled to Folic Acid Analog induces Ovarian Tumor Cell Death and inhibits IL-6-mediated Inflammation.

Ovarian cancer (OC) is one of the most lethal cancers among women. Frequent recurrence in the peritoneum due to the presence of microscopic tumor residues justifies the development of new therapies. Indeed, our main objective is to develop a targeted photodynamic therapy (PDT) treatment of peritoneal carcinomatosis from OC to improve the life expectancy of cancer patients. Herein, we propose a targeted-PDT using a vectorized photosensitizer (PS) coupled with a newly folic acid analog (FAA), named PSFAA, in order to target folate receptor alpha (FRα) overexpressed on peritoneal metastasis. This PSFAA was the result of the coupling of pyropheophorbide-a (Pyro-a), as the PS, to a newly synthesized FAA via a polyethylene glycol (PEG) spacer. The selectivity and the PDT efficacy of PSFAA was evaluated on two human OC cell lines overexpressing FRα compared to fibrosarcoma cells underexpressing FRα. Final PSFAA, including the synthesis of a newly FAA and its conjugation to Pyro-a, was obtained after 10 synthesis steps, with an overall yield of 19%. Photophysical properties of PSFAA in EtOH were performed and showed similarity with those of free Pyro-a, such as the fluorescence and singlet oxygen quantum yields (Φf = 0.39 and ΦΔ = 0.53 for free Pyro-a, and Φf = 0.26 and ΦΔ = 0.41 for PSFAA). Any toxicity of PSFAA was noticed. After light illumination, a dose-dependent effect on PS concentration and light dose was shown. Furthermore, a PDT efficacy of PSFAA on OC cell secretome was detected inducing a decrease of a pro-inflammatory cytokine secretion (IL-6). This new PSFAA has shown promising biological properties highlighting the selectivity of the therapy opening new perspectives in the treatment of a cancer in a therapeutic impasse.

Correlation between daily life aluminium exposure and breast cancer risk: A systematic review.

BACKGROUND: Epidemiological data indicate that the role of environmental factors on breast cancer (BC) incidence remains undetermined. Our daily life exposure to aluminium (Al) is suspected to influence BC development. This review proposes a state of the art on the association between Al and BC risk combined with a critical point of view on the subject. METHODS: We searched the PubMed database using terms related to Al and BC up to November 18, 2022. Reports were eligible if they were cohort or case-control studies or meta-analyses. FINDINGS: Six studies focused on the relationship between deodorant and antiperspirant use and BC incidence and didn't produce consistent results. Among 13 studies relating Al content in mammary tissues and BC risk, results are not unanimous to validate higher Al content in tumor tissues compared to healthy ones. We detail parameters that could explain this conclusion: the absence of statistical adjustments on BC risk factors in studies, the confusion between deodorant and antiperspirant terms, the non-assessment of global Al exposure, and the focus on Al in mammary tissues whereas a profile of several metals seems more appropriate. The clinical studies are retrospective. They were carried out on small cohorts and without a long follow-up. On the other hand, studies on cell lines have shown the carcinogenic potential of aluminum. Moreover, studies considered BC as a unique group whereas BC is a heterogeneous disease with multiple tumor subtypes determining the tumor aggressiveness. CONCLUSION: In light of the precautionary principle and based on the data obtained, it is better to avoid antiperspirants that contain Al. Deodorants without aluminum are not implicated in breast cancer, either clinically or fundamentally.

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

Triphenylamines (TPAs) were previously shown to trigger cell death under prolonged one- or two-photon illumination. Their initial subcellular localization, before prolonged illumination, is exclusively cytoplasmic and they translocate to the nucleus upon photoactivation. However, depending on their structure, they display significant differences in terms of precise initial localization and subsequent photoinduced cell death mechanism. Here, we investigated the structural features of TPAs that influence cell death by studying a series of molecules differing by the number and chemical nature of vinyl branches. All compounds triggered cell death upon one-photon excitation, however to different extents, the nature of the electron acceptor group being determinant for the overall cell death efficiency. Photobleaching susceptibility was also an important parameter for discriminating efficient/inefficient compounds in two-photon experiments. Furthermore, the number of branches, but not their chemical nature, was crucial for determining the cellular uptake mechanism of TPAs and their intracellular fate. The uptake of all TPAs is an active endocytic process but two- and three-branch compounds are taken up via distinct endocytosis pathways, clathrin-dependent or -independent (predominantly caveolae-dependent), respectively. Two-branch TPAs preferentially target mitochondria and photoinduce both apoptosis and a proper necrotic process, whereas three-branch TPAs preferentially target late endosomes and photoinduce apoptosis only.

Fighting Hypoxia to Improve PDT.

Photodynamic 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.

Titania and silica nanoparticles coupled to Chlorin e6 for anti-cancer photodynamic therapy.

In this study, light-sensitive photosensitizers (Chlorin e6, Ce6) were linked to TiO2 and SiO2 nanoparticles (NPs) in order to develop new kinds of NP-based drug delivery systems for cancer treatment by PDT. TiO2 or SiO2 NPs were modified either by the growth of a polysiloxane layer constituted of two silane reagents ((3-aminopropyl)triethoxysilane (APTES) and tetraethyl orthosilicate (TEOS)) around the core (PEGylated NPs: TiO2@4Si-Ce6-PEG, SiO2@4Si-Ce6-PEG) or simply modified by APTES alone (APTES-modified NPs: TiO2-APTES-Ce6, SiO2-APTES-Ce6). Ce6 was covalently attached onto the modified TiO2 and SiO2 NPs via an amide bond. The absorption profile of the hybridized NPs was extended to the visible region of the light. The physicochemical properties of these NPs were explored by TEM, HR-TEM, XRD, FTIR and zeta potential. The photophysical characteristics including the light absorption, the fluorescence properties and the production reactive oxygen species (1O2 and HO) were also addressed. In vitro experiments on glioblastoma U87 cells were performed to evaluate the photodynamic efficiency of the new hybridized NPs. The cells were exposed to different concentrations of NPs and illuminated (λexc = 652 nm, fluence rate 10 J/cm2). In contrast to the PEGylated NPs, the APTES-modified nanosystems were found to be more efficient for PDT. An interesting photodynamic effect was observed in the case of TiO2-APTES-Ce6 NPs. After illumination, the viability of U87 was decreased by 89% when they were exposed to 200 µg/mL of TiO2-APTES-Ce6 NPs, which corresponds to 0.22 µM of Ce6. The same effect can be obtained with free photosensitizer but using a higher concentration of 10 µM of Ce6.

Proton MR Spectroscopy and Diffusion MR Imaging Monitoring to Predict Tumor Response to Interstitial Photodynamic Therapy for Glioblastoma.

Despite 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.

Chemical and in vitro characterizations of a promising bimodal AGuIX probe able to target apoptotic cells for applications in MRI and optical imaging.

Different studies on AGuIX nanoparticles have been achieved in the biomedical domain, showing that they allow us to combine multimodal and theranostic properties in oncology. The targeting of apoptotic cells presents a wide range of biomedical applications, including the monitoring of antitumoral therapy and the diagnosis of diseases related to this process, such as atherosclerosis, ischemia, chronic inflammation or autoimmune disorders. AGuIX nanoparticles functionalized with a peptide that recognizes apoptotic cells and with organic fluorophores were characterized by several physicochemical and biological methods such as HPLC, relaxometry and photon correlation spectroscopy, which attested to their potential as bimodal tracers detected by optical imaging and MRI. An increase of relaxivity and stability of AGuIX nanoparticles is also observed after their vectorization. The biological efficiency of this novel bimodal probe to target apoptotic cells was evaluated by fluorescence microscopy, relaxometry, MRI and flow cytometry on a lymphoblastic human T-cell line. In vitro cell apoptosis was chemically induced by incubation with camptothecin. Our in vitro experiments showed a significant specificity of vectorized AGuIX nanoparticles for camptothecin-treated cells that suggests their potential efficiency as probes to target apoptosis. Copyright © 2016 John Wiley & Sons, Ltd.

Indocyanine green: photosensitizer or chromophore? Still a debate.

Indocyanine green (ICG) is a water-soluble anionic tricarbocyanine dye developed during the Second World War that was first approved for clinical use in humans in 1956. The main features of ICG that make it suitable for bioimaging applications are its near infrared absorption and its fluorescence. Although ICG is mainly used for its fluorescence emission properties, it has also been hypothesized that it can serve as a photosensitizer for photodynamic therapy applications, eliciting cytotoxic effects both in vitro and in vivo when used in combination with light at wavelengths in the region of 800-830 nm. Moreover, ICG can be used for hyperthermia of enhanced-photocoagulation of blood vessels treatment. In this paper we have gathered all the available data concerning the use of ICG for different treatments.

[FRα: a target for prophylactic photodynamic therapy of ovarian peritoneal metastasis?]. / FRα : une cible pour la thérapie photodynamique prophylactique des métastases péritonéales ovariennes ?

Partly 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.

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

Among 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 652nm with a range of light fluence from 1.0 to 10J/cm(2). 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.