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Photodynamic Therapy in Oncology: Mechanisms and Clinical Use
Abstract
In photodynamic therapy (PDT), a sensitizer, light, and oxygen are used to cause photochemically induced cell death. The mechanism of cytotoxicity involves generation of singlet oxygen and other free radicals when the light-excited sensitizer loses or accepts an electron. Although selective retention of sensitizer by malignant tissue is seen in vivo, the mechanisms for this sensitizer targeting remain unclear. The first-generation sensitizers are porphyrin based and vary in lipophilicity and hydrophilicity. Targeting of the vasculature seems to be a prominent feature of the cytotoxic effect of these sensitizers in vivo, with resulting necrosis. Treatment depth varies with the wavelength of light that activates the sensitizer used, and the second-generation sensitizers are activated at longer wavelengths, allowing for a 30% increase in treatment depths. The selectivity of targeting can be increased when the sensitizer is delivered with the use of liposomes or monoclonal antibodies specific for tumor antigens. Studies have demonstrated direct effects of PDT on immune effector cells, specifically those with lineage from macrophages or other monocytes. Clinically, this therapy has been chiefly used for palliation of endobronchial and esophageal obstruction, as well as for treatment of bladder carcinomas, skin malignancies, and brain tumors. The future of PDT rests in defining its use either as an intraoperative adjuvant to marginal surgical procedures or as a primary treatment for superficial malignancies. Phase III trials in esophageal cancer and lung cancer are in progress and will help in evaluation of whether Photofrin II, the most widely used sensitizer, can be added to the oncologic armamentarium, pending approval from the U.S. Food and Drug Administration.
... P hotodynamic therapy (PDT) treats diseases by dosing photosensitizers into a body and irradiating them with light to generate reactive oxygen species (ROS) [1][2][3] . It is noninvasive with few adverse effects and exhibits a high therapeutic effect on lesions that are difficult to treat by surgical techniques. ...
... Since singlet oxygens ( 1 O 2 ), which are generated from photosensitizers by the PDT process, are transformed to other types of ROS and are considered to damage several cytoplasmic organelles 2,14,17,20,22,23 , the amount of photosensitizer s introduced into the cells may influence the effect of PDT observed for cancer and normal cells 17,20 . In fact, PDT with talaporfin sodium uses the difference in its amount taken up in cancer and normal cells. ...
... One possible factor is the difference in the location of PLP accumulated in cells. The lifetime of 1 O 2 produced in cells by the PDT process is short; they readily oxidize surrounding substances or are transformed into other ROS 2,14,22,24 . Therefore, the organelles where PLPs accumulate are rapidly affected. ...
Polphylipoprotein (PLP) is a recently developed nanoparticle with high biocompatibility and tumor selectivity, and which has demonstrated unprecedentedly high performance photosensitizer in photodynamic therapy (PDT) and photodynamic diagnosis. On the basis of these discoveries, PLP is anticipated to have a very high potential for PDT. However, the mechanism by which PLP kills cancer cells effectively has not been sufficiently clarified. To comprehensively understand the PLP-induced PDT processes, we conduct multifaceted experiments using both normal cells and cancer cells originating from the same sources, namely, RGM1, a rat gastric epithelial cell line, and RGK1, a rat gastric mucosa-derived cancer-like mutant. We reveal that PLP enables highly effective cancer treatment through PDT by employing a unique mechanism that utilizes the process of autophagy. The dynamics of PLP-accumulated phagosomes immediately after light irradiation are found to be completely different between normal cells and cancer cells, and it becomes clear that this difference results in the manifestation of the characteristic effect of PDT when using PLP. Since PLP is originally developed as a drug delivery agent, this study also suggests the potential for intracellular drug delivery processes through PLP-induced autophagy.
... Photodynamic therapy (PDT) is a method in which a photosensitizer is administered in vivo and irradiated with light to generate reactive oxygen species (ROS), thereby causing the selective death of cancer cells. [1][2][3][4][5][6] Since PDT is a noninvasive cancer treatment method with few adverse effects, it has been attracting attention and is being increasingly used to increase the quality of life of patients post-treatment. Previous studies have shown that PDT has two main effects. ...
... Various photosensitizers have been developed, most of which are molecules with a porphyrin ring. 1,3,16,17 In PDT, this porphyrin ring is photoexcited to generate singlet oxygen, which is converted to other ROS such as OH radicals and H 2 O 2 . 1,3,16,17 In process (1) above, the main mechanism is the destruction of the cytoplasm and cell membrane by ROS. ...
... 1,3,16,17 In PDT, this porphyrin ring is photoexcited to generate singlet oxygen, which is converted to other ROS such as OH radicals and H 2 O 2 . 1,3,16,17 In process (1) above, the main mechanism is the destruction of the cytoplasm and cell membrane by ROS. 3,11 On the other hand, in process (2), cell destruction is considered to be caused by cell-cell interaction and cell contraction due to an increase in the numbers of intracellular actin laments (A-laments) around the tumor (cancer tissue). ...
We have combined atomic force microscopy with other techniques to reveal the mechanism of the actin filament and stress fibers formation processes that underlies the cell death process due to photodynamic therapy.
... In the past few decades, the 'activated' form of oxygen, singlet oxygen ( 1 O 2 ), has been intensely reviewed for its use as an oxidation reagent in several fields of science, ranging from pure synthetic organic chemistry to nanoscience, encompassing medical and pharmaceutical applications as well [1][2][3][4][5][6][7][8]. Generation of 1 O 2 from ground state triplet oxygen can occur in a large variety of manners. ...
... The PS should exhibit sufficient photostability (1) and a high absorption coefficient (2) in the spectral area of the excitation light. The triplet state should possess the appropriate energy (3) and lifetime (4) to allow for efficient energy transfer to the ground state molecular oxygen. Additionally, an appropriate quantum yield (Φ > 0.4) of the triplet state (5) is required, meaning that a sufficient population of molecules, initially excited to the singlet state, should cross over to the triplet state [8]. ...
... The PS should exhibit sufficient photostability (1) and a high absorption coefficient (2) in the spectral area of the excitation light. The triplet state should possess the appropriate energy (3) and lifetime (4) to allow for efficient energy transfer to the ground state molecular oxygen. Additionally, an appropriate quantum yield (Φ T > 0.4) of the triplet state (5) is required, meaning that a sufficient population of molecules, initially excited to the singlet state, should cross over to the triplet state [8]. ...
Singlet oxygen (1O2) is the excited state of ground, triplet state, molecular oxygen (O2). Photosensitized 1O2 has been extensively studied as one of the reactive oxygen species (ROS), responsible for damage of cellular components (protein, DNA, lipids). On the other hand, its generation has been exploited in organic synthesis, as well as in photodynamic therapy for the treatment of various forms of cancer. The aim of this review is to highlight the versatility of 1O2, discussing the main bioorganic applications reported over the past decades, which rely on its production. After a brief introduction on the photosensitized production of 1O2, we will describe the main aspects involving the biologically relevant damage that can accompany an uncontrolled, aspecific generation of this ROS. We then discuss in more detail a series of biological applications featuring 1O2 generation, including protein and DNA labelling, cross-linking and biosensing. Finally, we will highlight the methodologies available to tailor 1O2 generation, in order to accomplish the proposed bioorganic transformations while avoiding, at the same time, collateral damage related to an untamed production of this reactive species.
... Photodynamic therapy (PDT) is believed to be a safe option for treatment of cancer [1][2][3]. PDT, which is composed of light, oxygen and photosensitizers, can be specifically applied on the tumor tissue only and minimizing adverse physiological effect against normal cells or tissues because photosensitizers only activated and produced excess amount of reactive oxygen species (ROS) in the field of light irradiation eradicating abnormal cells [4,5]. However, PDT is suitable for epithelial or squamous cancer phenotypes such as cervical cancer, melanoma and oral cancers since the light penetration depth is normally limited to 15 mm of the physiological interface [6][7][8]. ...
... From these intrinsic properties, PDT is a suitable treatment option for cervical cancers because morphology of cervical cancer is mostly squamous cell carcinoma phenotype and then irradiated light is ease to penetrate to tumor tissues [9]. Furthermore, photosensitizers have little toxicity against normal cells or tissues in the absence of light irradiation and then side effects can be minimized while 2 chemotherapeutic agents have serious side effects such as bone marrow depression, neurotoxicity, hematological toxicity, neutropenia and nephrotoxicity [9,10]. Despite of these advantages of PDT regimen, PDT with traditional photosensitizers has limitations in clinical application because some of them such as 5-aminolevulinic acid (5-ALA) have low tumor specificity, rapid clearance from human body, and low penetration depth against tissues, and then distributed throughout the whole body [11,12]. ...
The aim of this study is to prepare redox-sensitive nanophotosensitizers for targeted delivery of chlorin e6 (Ce6) against cervical cancer. For this purpose, Ce6 was conjugated with β-cyclodextrin (bCD) via disulfide bond creating nanophotosensitizers that were fabricated for redox-sensitive delivery of Ce6 against cancer cells. bCD was treated with succinic anhydride to synthesize suc-cinylated bCD (bCDsu). After that, cystamine was attached to the carboxylic end of bCDsu (bCDsu-ss) and the amine end group of bCDsu-ss was conjugated with Ce6 (bCDsu-ss-Ce6). Chemical composition of bCDsu-ss-Ce6 was confirmed with 1H and 13C NMR spectra. bCDsu-ss-Ce6 nanophotosensitizers were fabricated by dialysis procedure. They formed small particles with an average particle size of 152.0±23.2 nm and they showed improved singlet oxygen (SO) generation in the aqueous solution under light irradiation and was significantly higher than that of Ce6 alone. Ce6 release rate from bCDsu-ss-Ce6 nanophotosensitizers was accelerated by addition of glutathione (GSH), indicating that bCDsu-ss-Ce6 nanophotosensitizers have re-dox-sensitive photosensitizer delivery capacity. bCDsu-ss-Ce6 nanophotosensitizers have low in-trinsic cytotoxicity against CCD986Sk human skin fibroblast cells as well as Ce6 alone. However, bCDsu-ss-Ce6 nanophotosensitizers showed improved Ce6 uptake ratio, higher reactive oxygen species (ROS) production and phototoxicity compared to those of Ce6 alone. GSH addition resulted in higher Ce6 uptake ratio, ROS generation and phototoxicity than those of Ce6 alone, indicating that bCDsu-ss-Ce6 nanophotosensitizers have redox-sensitive biological activity in vitro against HeLa human cervical cancer cells. At tumor xenograft model using HeLa cells, bCDsu-ss-Ce6 nanophotosensitizers efficiently accumulated in the tumor rather than normal organs, i.e. fluores-cence intensity in tumor tissues was significantly higher than those of other organs while Ce6 alone did not specifically target tumor tissue. These results indicated higher anticancer activity of bCDsu-ss-Ce6 nanophotosensitizers, by efficiently inhibiting growth of tumor in in vivo animal tumor xenograft study.
... Its principle is to deliver a fluorescent drug, a photosensitiser (PS), to a tissue and activate it with the light of appropriate wavelength. By photoexcitation of PS, energy is transferred to molecular oxygen, leading to the formation of reactive oxygen species (ROS) that are cytotoxic or antiangiogenic [1,2]. ...
... Evaluation of vascular damage of CAM 24h after irradiation in experimental groups based on the determined score(1)(2)(3)(4)(5). C1 -CAM with PBS; C2control for laser light; C3 -control for leptin; Lep + Hypgroup with simultaneously applied hypericin and leptin (3 h before irradiation); Hyp + Lep1leptin application 1h after irradiation; Hyp + Lep3 -leptin application 3h after irradiation; Hyppure hypericin + irradiation. ...
Background:
The chorioallantoic membrane (CAM) of the Japanese quail is an excellent model for studying photodynamic therapy (PDT) due to its rich vascularisation. PDT is used not only in oncological treatment but also in infectious diseases, or psoriasis, where it yields significant advantages. This treatment also has its limitations, such as burning, itching, erythema, redness, swelling, and delayed wound healing. The aim of this study was to analyse the potentially protective properties of the tissue hormone leptin during PDT.
Methods:
Japanese quail embryos incubated ex ovo were used in this experiment. On the 9th day of embryonic development, leptin (5 μg) and photosensitiser hypericin (79 μM) were topically applied, followed by irradiation. The effect of leptin co-administration was evaluated from CAM images and histological structure analysis, histological samples, and qPCR, where the expression of genes involved in angiogenesis, apoptosis, and oxidative stress was monitored.
Results:
We observed vascular damage in all experimental groups, the highest damage was found after the application of hypericin without leptin coadministration. Histological analysis confirmed the protective effect of leptin. qPCR analysis presented differences in FREK gene expression, but also in genes involved in oxidative stress like SOD, NRF-1, NRF-2, and GPX7. The application of leptin significantly reduced the expression of apoptosis regulatory proteins CASP3, cytochrome C, and APAF1.
Conclusions:
Our results in the CAM model suggest a possible protective effect of leptin to prevent PDT damage and aid in the subsequent regeneration of target tissues after antimicrobial PDT.
... Photodynamic therapy (PDT) treats diseases by injecting photosensitizers into the body and irradiating them with light to generate reactive oxygen species (ROS) [1][2][3][4]. It is noninvasive with few adverse effects and exhibits a high therapeutic effect on lesion areas that are difficult to treat with surgical techniques. ...
... Porphyrin has been mainly used as a photosensitizer. In PDT, porphyrin ring is photoexcited to generate singlet oxygen, which is converted into OH radicals and other ROS, such as H2O2, which destroy the cytoplasm [1,3,12,13]. The performance of the photosensitizer determines the therapeutic effect of PDT, for example, the degree of selective uptake into the affected area, permeability, and persistence. ...
We revealed the difference in the mechanism of photodynamic therapy (PDT) between two photosensitizers: porphylipoprotein (PLP), which has recently attracted attention for its potential to be highly effective in treating cancer, and talaporphyrin sodium (NPe6). (1) NPe6 accumulates in lysosomes, whereas PLP is incorporated into phagosomes formed by PLP injection. (2) PDT causes NPe6 to generate reactive oxygen species, thereby producing actin filaments and stress fibers. In the case of PLP, however, reactive oxygen species generated by PDT remain in the phagosomes until the phagosomal membrane is destroyed, which delays the initiation of RhoA activation and RhoA*/ROCK generation. (4) After the disruption of the phagosomal membrane, however, the outflow of various reactive oxygen species accelerates the production of actin filaments and stress fibers, and blebbing occurs earlier than in the case of NPe6. (5) PLP increases the elastic modulus of cells without RhoA activity in the early stage. This is because phagosomes are involved in polymerizing actin filaments and pseudopodia formation. Considering the high selectivity and uptake of PLP into cancer cells, a larger effect with PDT can be expected by skillfully combining the newly discovered characteristics, such as the appearance of a strong effect at an early stage.
... Without a detailed molecular analysis of these intracellular processes, it is difficult to ascertain exactly why this trend appeared in the present study. However, it is known that CP94 enters cells via simple diffusion, whilst ALA enters cells through different modalities, including GABA receptors, depending on the cell type, which may mean that CP94 enters the cells more readily than ALA or MAL [23,37,38]. The separate administration of these molecules may, therefore, have led to CP94 entering the glioma cells faster, and this may have reduced the amount of available intracellular iron to levels that altered cellular functions such as respiration to be compromised. ...
(1) Background: The protoporphyrin IX (PpIX)-mediated fluorescence-guided resection and interoperative photodynamic therapy (PDT) of remaining cells may be effective adjuvants to the resection of glioma. Both processes may be enhanced by increasing intracellular PpIX concentrations, which can be achieved through iron chelation. AP2-18 is a novel combinational drug, which ester-links a PpIX precursor (aminolaevulinic acid; ALA) to an iron-chelating agent (CP94). (2) Methods: Human glioma U-87 MG cells were cultured in 96-well plates for 24 h and incubated for 3 or 6 h with various test compound combinations: ALA (±) CP94, methyl aminolevulinate (MAL) (±) CP94 and AP2-18. PpIX fluorescence was measured at 0, 3 or 6 h with a Bio-tek Synergy HT plate reader, as well as immediately after irradiation with a 635 nm red light (Aktilite CL16 LED array), representing the PDT procedure. Cell viability post-irradiation was assessed using the neutral red assay. (3) Results: AP2-18 significantly increased PpIX fluorescence compared to all other test compounds. All treatment protocols effectively achieved PDT-induced cytotoxicity, with no significant difference between test compound combinations. (4) Conclusions: AP2-18 has potential to improve the efficacy of fluorescence-guided resection either with or without the subsequent intraoperative PDT of glioma. Future work should feature a more complex in vitro model of the glioma microenvironment.
... Photodynamic therapy (PDT) is believed to be a safe option for the treatment of cancer [1][2][3]. PDT, which is composed of light, oxygen, and photosensitizers, can be specifically applied to tumor tissue only, minimizing adverse physiological effects against normal cells or tissues. This is because photosensitizers are only activated and produce an excess amount of reactive oxygen species (ROS) in the field of light irradiation, eradicating abnormal cells [4,5]. ...
The aim of this study is to prepare redox-sensitive nanophotosensitizers for the targeted delivery of chlorin e6 (Ce6) against cervical cancer. For this purpose, Ce6 was conjugated with β-cyclodextrin (bCD) via a disulfide bond, creating nanophotosensitizers that were fabricated for the redox-sensitive delivery of Ce6 against cancer cells. bCD was treated with succinic anhydride to synthesize succinylated bCD (bCDsu). After that, cystamine was attached to the carboxylic end of bCDsu (bCDsu-ss), and the amine end group of bCDsu-ss was conjugated with Ce6 (bCDsu-ss-Ce6). The chemical composition of bCDsu-ss-Ce6 was confirmed with 1H and 13C NMR spectra. bCDsu-ss-Ce6 nanophotosensitizers were fabricated by a dialysis procedure. They formed small particles with an average particle size of 152.0 ± 23.2 nm. The Ce6 release rate from the bCDsu-ss-Ce6 nanophotosensitizers was accelerated by the addition of glutathione (GSH), indicating that the bCDsu-ss-Ce6 nanophotosensitizers have a redox-sensitive photosensitizer delivery capacity. The bCDsu-ss-Ce6 nanophotosensitizers have a low intrinsic cytotoxicity against CCD986Sk human skin fibroblast cells as well as Ce6 alone. However, the bCDsu-ss-Ce6 nanophotosensitizers showed an improved Ce6 uptake ratio, higher reactive oxygen species (ROS) production, and phototoxicity compared to those of Ce6 alone. GSH addition resulted in a higher Ce6 uptake ratio, ROS generation, and phototoxicity than Ce6 alone, indicating that the bCDsu-ss-Ce6 nanophotosensitizers have a redox-sensitive biological activity in vitro against HeLa human cervical cancer cells. In a tumor xenograft model using HeLa cells, the bCDsu-ss-Ce6 nanophotosensitizers efficiently accumulated in the tumor rather than in normal organs. In other words, the fluorescence intensity in tumor tissues was significantly higher than that of other organs, while Ce6 alone did not specifically target tumor tissue. These results indicated a higher anticancer activity of bCDsu-ss-Ce6 nanophotosensitizers, as demonstrated by their efficient inhibition of the growth of tumors in an in vivo animal tumor xenograft study.
... Both types of reactions can occur simultaneously, however, for tissue-based PS it is assumed that mechanism II is dominant and determines the effectiveness of therapy. The ROS generated is influenced by substrate and oxygen concentration, pH of the environment and dye quantum yield (Gomer and Razum, 1984;Henderson and Dougherty, 1992;Pass, 1993;Luksiene, 2003;Vrouenraets et al., 2003;Allison et al., 2006). Photodynamic therapy uses different wavelengths of visible light depending on the photosensitizer and its absorption range, as well as the desired depth of penetration of the light into the tissue. ...
Brain tumors, including glioblastoma multiforme, are currently a cause of suffering and death of tens of thousands of people worldwide. Despite advances in clinical treatment, the average patient survival time from the moment of diagnosis of glioblastoma multiforme and application of standard treatment methods such as surgical resection, radio- and chemotherapy, is less than 4 years. The continuing development of new therapeutic methods for targeting and treating brain tumors may extend life and provide greater comfort to patients. One such developing therapeutic method is photodynamic therapy. Photodynamic therapy is a progressive method of therapy used in dermatology, dentistry, ophthalmology, and has found use as an antimicrobial agent. It has also found wide application in photodiagnosis. Photodynamic therapy requires the presence of three necessary components: a clinically approved photosensitizer, oxygen and light. This paper is a review of selected literature from Pubmed and Scopus scientific databases in the field of photodynamic therapy in brain tumors with an emphasis on glioblastoma treatment.
... PPIX, the final intermediate for heme biosynthesis (46), was used for cancer diagnosis (47) and as a photosensitizer with which to treat cancer (48,49). It has been well-documented in the literature that PPIX exerts broad-spectrum antiviral activity by suppressing several enveloped viruses, including HIV-1, influenza A, vesicular stomatitis virus, severe acute respiratory syndrome coronavirus 2, Lassa virus, and Machupo virus (50)(51)(52). ...
CA and its assembled viral core play essential roles in distinct steps during HIV-1 replication, including reverse transcription, integration, nuclear entry, virus assembly, and maturation through CA–CA or CA–host factor interactions. These functions of CA are fundamental for HIV-1 pathogenesis, making it an appealing target for antiviral therapy.
... This type of reaction is caused by free radicals that generate oxidized products. The photosensitizer can create a much more reactive form of oxygen in the triplet state (type II reaction) [27][28][29][30], therefore it is assumed that the type II mechanism is overbearing and determines the effectiveness of the therapy [31]. Both mechanisms take place at the same time, and the ratio of their share is influenced, among other factors, by the concentration of the substrate and oxygen, the pH of the environment or the dye composition [32]. ...
The treatment of neoplastic disease of the brain is still a challenge for modern medicine. Therefore, advanced methodologies are needed that can rationally and successfully contribute to the early diagnosis of primary and metastatic tumors growing within the brain. Photodynamic therapy (PDT) seems to be a valuable method of treatment for precancerous and cancerous lesions including brain tumors. The main advantage of PDT is its high efficiency, minimal invasiveness and no serious side effects, compared with chemotherapy and radiotherapy. This review was conducted through a comprehensive search of articles, scientific information databases and the websites of organizations dealing with cancer treatment. Key points from clinical trials conducted by other researchers are also discussed. The common databases such as PubMed, Google Scholar, EBSCO, Scopus, and Elsevier were used. Articles in the English language of reliable credibility were mainly analyzed. The type of publications considered included clinical and preclinical studies, systematic reviews, and case reports. Based on these collected materials, we see that scientists have already demonstrated the potential of PDT application in the field of brain tumors. Therefore, in this review, the treatment of neoplasm of the Central Nervous System (CNS) and the most common tumor, glioblastoma multiforme (GBM), have been explored. In addition, an overview of the general principles of PDT, as well as the mechanism of action of the therapy as a therapeutic platform for brain tumors, is described. The research was carried out in June 2022.
... Первые работы, выполненные в середине 80-х годов ХХ века в Японии, показали ее высокую эффективность при лечении с HpD бронхогенной карциномы [52]. Современные мировые данные свидетельствуют, что бронхоскопическая ФДТ является наиболее эффективной для малых (< 1 см), поверхностных и ранних стадий немелкоклеточного рака легкого, а также в качестве паллиативной терапии при обструктивном раке трахеобронхиального дерева [64]. В некоторых странах ФДТ с фотофрином используется в качестве адъювантного интраоперационного метода лечения злокачественной плевральной мезотелиомы. ...
... The lifetime of the T 1 species (normally in the millisecond range) is sufficiently long for it to interact with the surrounding molecules. Then, the T 1 state of the excited photosensitizer can undergo two types of reaction [78][79][80][81]: ...
Cisplatin is one of the most widely used anticancer drugs in the treatment of various types of solid human cancers, as well as germ cell tumors, sarcomas, and lymphomas. Strong evidence from research has demonstrated higher efficacy of a combination of cisplatin and derivatives, together with hyperthermia and light, in overcoming drug resistance and improving tumoricidal efficacy. It is well known that the antioncogenic potential of CDDP is markedly enhanced by hyperthermia compared to drug treatment alone. However, more recently, accelerators of high energy particles, such as synchrotrons, have been used to produce powerful and monochromatizable radiation to induce an Auger electron cascade in cis-platinum molecules. This is the concept that makes photoactivation of cis-platinum theoretically possible. Both heat and light increase cisplatin anticancer activity via multiple mechanisms, generating DNA lesions by interacting with purine bases in DNA followed by activation of several signal transduction pathways which finally lead to apoptosis. For the past twenty-seven years, our group has developed infrared photo-thermal activation of cisplatin for cancer treatment from bench to bedside. The future development of photoactivatable prodrugs of platinum-based agents injected intratumorally will increase selectivity, lower toxicity and increase efficacy of this important class of antitumor drugs, particularly when treating tumors accessible to laser-based fiber-optic devices, as in head and neck cancer. In this article, the mechanistic rationale of combined intratumor injections of cisplatin and laser-induced thermal therapy (CDDP–LITT) and the clinical application of such minimally invasive treatment for cancer are reviewed.
... Under bronchoscopic guidance, a laser catheter positioned directly at the tumor and the light source with a wavelength of 630 nm is activated with a recommended light dose of 200 J/cm and exposure time of 500 s [25]. The proposed mechanism of PDT is multifactorial including the generation of singlet oxygen radicals which result in apoptosis and cell death, the development of small vessel thrombosis mediated by thromboxane A2 leading to ischemic necrosis, and the formation of a tumor-specific cytotoxic immunity that can provide long-term suppression of tumor growth [26][27][28][29]. ...
Purpose of Review
The number of patients diagnosed with early medically inoperable lung cancer is on the rise. With the recent advances in peripheral bronchoscopy, bronchoscopic ablation has become a desirable alternative to potentially diagnose, stage, and treat these patients in a single procedure. Our goal is to review the most promising techniques and the available data to support them.
Recent Findings
Pre-clinical studies have shown that techniques such as radiofrequency ablation, photodynamic therapy, microwave ablation, laser, and thermal vapor ablation can be safely delivered bronchoscopically into the periphery of the lungs providing ablated areas that appear large enough to encompass small lung tumors. Human data is very scant and mostly consistent of case reports, except for a study of radiofrequency ablation which demonstrated results similar to those of percutaneous ablation.
Summary
Though promising, bronchoscopic ablation of lung nodules is currently at a very early experimental stage and requires rigorous research prior to becoming a regularly used technique. At this time, bronchoscopists should venture into the field of therapeutics with extreme caution.
... Photodynamic therapy (PDT) has been extensively investigated in the last two decades because it is regarded as a safe candidate for the treatment of cancer patients [1][2][3][4][5]. PDT and its output are normally composed of a photosensitizer, light and oxygen species, and furthermore, photosensitizers are only activated in a specific wavelength of light and then produce reactive oxygen species (ROS) (i.e., PDT produces excessive ROS in the site of irradiation and then inhibits the viability of disease cells) [6]. ...
Folic acid-conjugated nanophotosensitizers composed of folic acid (FA), poly(ethylene glycol) (PEG) and chlorin e6 (Ce6) tetramer were synthesized using diselenide linkages for reactive oxygen species (ROS)- and folate receptor-specific delivery of photosensitizers. Ce6 was conjugated with 3-[3-(2-carboxyethoxy)-2,2-bis(2-carboxyethoxymethyl)propoxy]propanoic acid (tetra acid, or TA) to make Ce6 tetramer via selenocystamine linkages (TA-sese-Ce6 conjugates). In the carboxylic acid end group of the TA-sese-Ce6 conjugates, FA-PEG was attached again using selenocystamine linkages to make FA-PEG/TA-sese-Ce6 conjugates (abbreviated as FAPEGtaCe6 conjugates). Nanophotosensitizers were fabricated by a dialysis procedure. In the morphological observations, they showed spherical shapes with small diameters of less than 200 nm. Stability of the aqueous FAPEGtaCe6 nanophotosensitizer solution was maintained (i.e., their particle sizes were not significantly changed until 7 days later). When H2O2 was added to the nanophotosensitizer solution, the particle size distribution was changed from a monomodal pattern to a multimodal pattern. In addition, the fluorescence intensity and Ce6 release rate from the nanophotosensitizers were also increased by the addition of H2O2. These results indicated that the nanophotosensitizers had ROS-sensitive properties. In an in vitro cell culture study, an FAPEGtaCe6 nanophotosensitizer treatment against cancer cells increased the Ce6 uptake ratio, ROS generation and light-irradiated cytotoxicity (phototoxicity) compared with Ce6 alone against various cancer cells. When the folic acid was pretreated to block the folate receptors of the Y79 cells and KB cells (folate receptor-overexpressing cells), the intracellular Ce6 uptake, ROS generation and thereby phototoxicity were decreased, while the MCF-7 cells did not significantly respond to blocking of the folate receptors. These results indicated that they could be delivered by a folate receptor-mediated pathway. Furthermore, an in vivo pulmonary metastasis model using Y79 cells showed folate receptor-specific delivery of FAPEGtaCe6 nanophotosensitizers. When folic acid was pre-administered, the fluorescence intensity of the lungs was significantly decreased, indicating that the FAPEGtaCe6 nanophotosensitizers had folate receptor specificity in vitro and in vivo. We suggest that FAPEGtaCe6 nanophotosensitizers are promising candidates for a targeted photodynamic therapy (PDT) approach against cancer cells.
... Photodynamic therapy (PDT) is an approach to treating infections and cancer by exploiting the production of reactive oxygen species (ROS) by illumination of an administered photosensitizer (PS). Different types of PSs with different advantages and disadvantages have been developed, including organic PSs such as porphyrins and porphyrin derivatives [1], noble metal complexes containing for instance Ru(II) and Ir(III) [2,3], protein-based PSs such as KillerRed [4], as well as various nanomaterials. With regard to the latter, TiO2 nanoparticles have attracted particular attention because they present numerous advantages over other established PSs, such as low production cost and straightforward synthesis, chemical stability, biological inertness, and high light conversion efficiency [5,6]. ...
Coatings of modified TiO2 nanoparticles (TiO2-m) have been shown to effectively and selectively trap non-adherent cancer cells, with an enormous potential for applications in photodynamic therapy (PDT). Leukemia cells have a remarkable affinity for TiO2-m coatings, adhering to the surface by membrane structures and exhibiting morphologic characteristics of amoeboid locomotion. However, the details of the cell–substrate interaction induced by the TiO2-m coating remain elusive. With the aim to obtain a better understanding of this phenomenon, leukemia cell adhesion to such coatings was characterized by atomic force microscopy (AFM) for short contact times up to 60 min. The cell and membrane morphological parameters mean cell height, contact area, cell volume, and membrane roughness were determined at different contact times. These results reveal cell expansion and contraction phases occurring during the initial stage of adhesion. Subsequently, the leukemic cells reach what appears to be a new resting state, characterized by pinning of the cell membrane by TiO2-m nanoparticle aggregates protruding from the coating surface.
... The Food and Drug Administration (FDA) approved Photofrin for esophageal cancer in 1995. In addition, Photofrin was approved for the treatment of early nonsmall cell lung cancer in 1998 (Pass, 1993;Dougherty et al., 1998;Kato, 2004;Huang, 2005). ...
Photodynamic therapy (PDT) has been used as an anti-tumor treatment method for a long time and photosensitizers (PS) can be used in various types of tumors. Originally, light is an effective tool that has been used in the treatment of diseases for ages. The effects of combination of specific dyes with light illumination was demonstrated at the beginning of 20th century and novel PDT approaches have been developed ever since. Main strategies of current studies are to reduce off-target effects and improve pharmacokinetic properties. Given the high interest and vast literature about the topic, approval of PDT as the first drug/device combination by the FDA should come as no surprise. PDT consists of two stages of treatment, combining light energy with a PS in order to destruct tumor cells after activation by light. In general, PDT has fewer side effects and toxicity than chemotherapy and/or radiotherapy. In addition to the purpose of treatment, several types of PSs can be used for diagnostic purposes for tumors. Such approaches are called photodynamic diagnosis (PDD). In this Review, we provide a general overview of the clinical applications of PDT in cancer, including the diagnostic and therapeutic approaches. Assessment of PDT therapeutic efficacy in the clinic will be discussed, since identifying predictors to determine the response to treatment is crucial. In addition, examples of PDT in various types of tumors will be discussed. Furthermore, combination of PDT with other therapy modalities such as chemotherapy, radiotherapy, surgery and immunotherapy will be emphasized, since such approaches seem to be promising in terms of enhancing effectiveness against tumor. The combination of PDT with other treatments may yield better results than by single treatments. Moreover, the utilization of lower doses in a combination therapy setting may cause less side effects and better results than single therapy. A better understanding of the effectiveness of PDT in a combination setting in the clinic as well as the optimization of such complex multimodal treatments may expand the clinical applications of PDT.
... The PDT has been found to be effective against pre-cancerous lesions, non-myeloma skin cancers, skin infections, ache, and microbial infections ( Table 1). The first clinical approval of PDT was reported in year 1993 which includes the application of Hematoporphyrin-derived photosensitizers [83]. Photofrin is one of the early photosensitizer that was used clinically for treatment of carcinomas. ...
The application of photo-excited dyes for treatment is known as photodynamic therapy (PDT). PDT is known to target GTPase proteins in cells, which are the key proteins of diverse signalling cascades which ultimately modulate cell proliferation and death. Cytoskeletal proteins play critical roles in maintaining cell integrity and cell division. Whereas, it was also observed that in neuronal cells PDT modulated actin and tubulin resulting in increased neurite growth and filopodia. Recent studies supported the role of PDT in dissolving the extracellular amyloid beta aggregates and intracellular Tau aggregates, which indicated the potential role of PDT in neurodegeneration. The advancement in the field of PDT led to its clinical approval in treatment of cancers, brain tumour, and dermatological acne. Although several question need to be answered for application of PDT in neuronal cells, but the primary studies gave a hint that it can emerge as potential therapy in neural cells.
... Here, we review recent advances in PDTs to resolve the current problems. To avoid redundancy with general review articles on PDT, as reported previously [32][33][34][35][36] , we focus on innovative PDT strategies based on tailoring photosensitive ROS generation, which include the use of proteinaceous PS, self-illumination, or oxygen-independent methods. To expand the usefulness of PDT, we further discuss ROS generation and targeting models in advanced PDT and summarize recent research results. ...
Photodynamic therapy (PDT) has been considered a noninvasive and cost-effective modality for tumor treatment. However, the complexity of tumor microenvironments poses challenges to the implementation of traditional PDT. Here, we review recent advances in PDT to resolve the current problems. Major breakthroughs in PDTs are enabling significant progress in molecular medicine and are interconnected with innovative strategies based on smart bio/nanomaterials or therapeutic insights. We focus on newly developed PDT strategies designed by tailoring photosensitive reactive oxygen species generation, which include the use of proteinaceous photosensitizers, self-illumination, or oxygen-independent approaches. While these updated PDT platforms are expected to enable major advances in cancer treatment, addressing future challenges related to biosafety and target specificity is discussed throughout as a necessary goal to expand the usefulness of PDT. Advancements in photosensitive proteins, nanomaterials, and luminescence are improving the ability of photodynamic therapy (PDT) to attack cancerous tumors. In PDT photosensitive drugs are introduced into tumors, which are then exposed to light, producing reactive oxygen species that kill cells. Young-Pil Kim and coworkers at Hanyang University in Seoul, South Korea, reviewed the challenges of PDT, including drug side effects and how to deliver light into tumors. They highlight advances in protein-based photosensitive drugs, which avoid the side effects of their non-protein counterparts, and could even be generated within the body through genetic manipulation. Bioluminescent and chemiluminescent chemicals have been incorporated into nanomaterials such as quantum dots, carrying light deep into tumors. The use of hybrid oxygen-carrying proteins can provide oxygen for PDT, even inside oxygen-poor tumors that have depleted the local blood supply.
... Der Begriff der antimikrobiellen photodynamischen Therapie (aPDT) wurde bereits im (Pass, 1993;Wolf, 1999 (Kömerik und Wilson, 2002). Es wird vermutet, dass die basische Umgebung die Penetration von Toluidinblau in den Zellen erleichtert (Wakayama et al., 1980). ...
Ziel der vorliegenden Studie ist die Untersuchung der antimikrobiellen photodynamischen Therapie (aPDT) in Kombination mit Isopropylalkohol auf E. faecalis in künstlich infizierten Wurzelkanälen.
... However, limited by shallow penetration depth of the light, phototherapy is mainly subject to superficial applications and inefficient for metastatic cancers that had spread throughout the bodies and in deep tissues [35,36]. ICD is a cell death modality. ...
Phototherapy and immunogenic cell death (ICD) are powerful strategies to fight cancer. However, their therapeutic outcomes are diminished by immunosuppressive and hypoxia microenvironment. Herein, a photo-based, immunomodulating and hypoxia-alleviated nanosystem, [email protected], is proposed to achieve the synergism between phototherapy and immunotherapy. Catalase (CAT) and anti-GITR antibody (DTA-1) are loaded to photothermal agent and photosensitizer composed PDA-ICG nanoparticles. The [email protected] exhibits intrinsic local hyperthermia and enhanced ROS generation in tumor and abrogates tumor immune suppression. It results in reduction of intratumoral FOXP3⁺ regulatory T cells (4.3-fold) and increase of CD4⁺ effector T cells (1.5-fold) compare with the control, and promoting damage associated molecular patterns generation to reinvigorate ICD effect. The potent antitumor of [email protected] is proved in 4T1 bilateral tumor-bearing mice, with inhibition ratio of 95.1% for primary cancers and 68.7% for abscopal cancers. Our findings highlight great promise of the constructed versatility nanosystem to fix bottlenecks for cancer therapy.
... Importantly, this diagnostic performance is achieved without the need for contrast agents such as nanoparticle systems, with diagnostic readouts based solely on the underlying biochemistry of the tissues. Similarly, PDT is an optical therapeutic modality that combines light, oxygen, and a photosensitiser to provide spatially and temporally controlled tumour destruction [34,35]. Following local or systemic administration, photosensitiser activation by light of a specific wavelength produces a photochemical reaction that generates reactive oxygen species resulting in controlled tumour destruction directly and indirectly [36,37]. ...
Theranostics, the combination of diagnosis and therapy, has long held promise as a means to achieving personalised precision cancer treatments. However, despite its potential, theranostics has yet to realise significant clinical translation, largely due the complexity and overriding toxicity concerns of existing theranostic nanoparticle strategies.
Methods: Here, we present an alternative nanoparticle-free theranostic approach based on simultaneous Raman spectroscopy and photodynamic therapy (PDT) in an integrated clinical platform for cancer theranostics.
Results: We detail the compatibility of Raman spectroscopy and PDT for cancer theranostics, whereby Raman spectroscopic diagnosis can be performed on PDT photosensitiser-positive cells and tissues without inadvertent photosensitiser activation/photobleaching or impaired diagnostic capacity. We further demonstrate that our theranostic platform enables in vivo tumour diagnosis, treatment, and post-treatment molecular monitoring in real-time.
Conclusion: This system thus achieves effective theranostic performance, providing a promising new avenue towards the clinical realisation of theranostics.
... Moreover, immunotherapy can be synergistically combined with another anticancer therapy strategy, such as chemotherapy, PDT, or PTT and is ideal for long treatment periods together with other treatments. [47][48][49][50][51][52][53][54][55] In this study, we combined spherical, mesoporous UCNPs with semiconducting manganese nanoparticles as a nanoplatform with good photodynamic and photothermal effects. Fluorescence or absorption methods can be used for detecting glutathione (GSH) and H 2 O 2 . ...
Objective
Immunotherapy is an effective tumor treatment strategy. However, its long treatment cycle limits its wide application across all cancer types. In this study, we optimized upconversion nanoparticles and manganese composite particles with a porous structure as a nanoplatform for synergistic photodynamic therapy (PDT) and photothermal therapy (PTT), and subsequent longer-term immunotherapy.
Methods
The morphology, phase, and stability were first characterized to evaluate the biocompatibility of this material. The upconversion and near infrared II luminescence properties of the material and its stimuli-response effect were assessed from the absorbance and photoluminescence spectra. Phototherapy including PDT and PTT was demonstrated in vitro and in vivo, and immunotherapy was used to enhance the phototherapy. This study was approved by the Xi’an Jiaotong University, China (approval No. XJTULAC2020-585) on April 2, 2020.
Results
The nanoplatform showed good PDT and PTT effects with high upconversion luminescence, and exhibited a more sensitive glutathione response (detection limit: 55 μg/mL) using fluorescence recovery than that based on absorbance recovery, with the detection range extending up to 1.2 mg/mL. When the surface of the composite particles was modified with an anti-PD-L1 immune checkpoint inhibitor, it targeted A549 lung cancer cells. The resulting immune response enhanced the long-term anti-tumor effect of the therapy, especially in lung cancer patients with high PD-L1 expression.
Conclusion
The designed composite can be simultaneously used to detect the glutathione concentration based on luminescence recovery in the tumor cells and as a theranostic nanoplatform for synergistic immuno-phototherapy when combined with an antibody.
... The chlorophyll metabolite pheophorbide a was isolated from Vatica cinerea King (Dipterocarpaceae) and was shown to have promising anti-HIV activity . It was already known quite well to have promise against cancer in the context of photodynamic therapy, being a photosensitizer that exhibits photocytotoxicity against human tumor cells when applied in conjunction with the proper light (Pass, 1993;Cheng et al., 2001;Zhang et al., 2003). The potential for pheophorbide a and more broadly porphyrins and photosensitizers to have shared bioactivity against human cancer and HIV/AIDS in the context of selective nucleic acid and protein adduct formation and dysfunction and production of reactive oxygen species was discussed as an interesting commonality and starting point for more intensive research (Zhang et al., 2003). ...
Field botanical research and phytochemistry research were pursued to evaluate the anticancer drug discovery potential of medicinal plants from mainland Southeast Asia (Laos and Vietnam). Collection and documentation of 201 samples from 96 medicinal plant taxa proceeded from two different Lao tropical forest preserves (Xiengkhouang Medicinal Biodiversity Preserve and Bolikhamxay Medicinal Plant Preserve) managed by local communities. Subsequent cytotoxicity testing of the extracts of these samples in the HT-29 human colon adenocarcinoma cell line revealed that six of the samples had bioactivity significant enough to merit re-collection and further study. None of these plants were used in Laos for cancer treatment, and only three of six collections were from the plant part employed locally in ethnomedicine, demonstrating that liberal collection of plant parts from medicinal plants is an effective strategy in maximizing the hit rate for unanticipated bioactivity. Two plant parts from a Vietnamese collection of Streptocaulon juventas (Lour.) Merr. (AA06944/LF+TW and AA06945/ST; Apocynaceae) were extracted, partitioned, and fractionated towards the isolation of cytotoxic components. Separation procedures yielded a known cardiac glycoside, corchorusoside C, with submicromolar cytotoxicity, not previously reported in HT-29 cells and other human tumor cell lines tested, from the leaf and twig material (AA06944/LF+TW). This work allowed for further cytotoxicity and mechanistic studies of corchorusoside C and additional isolates that originated from the stem material (AA06945/ST). These research activities are discussed and analyzed both in terms of their own merit and potential and from the broader perspective of negotiating and abiding by international collection agreements for plant-based bioprospecting in Southeast Asia and worldwide, in anticancer drug discovery paradigms and beyond.
... Heme is an important cofactor for oxygen transfer and oxygen storage [25] and is a constituent of hemoproteins which play a variety of roles in cellular metabolism [26]. The light-activable photodynamic effect of protoporphyrin IX was used for cancer diagnosis [27] and approved by FDA for treatment of bronchial and esophageal cancers and early malignant lesions of the skin, bladder, breast, stomach, and oral cavity [28,29]. Verteporfin was approved for the treatment of age-related macular degeneration [30]. ...
The SARS-CoV-2 infection is spreading rapidly worldwide. Efficacious antiviral therapeutics against SARS-CoV-2 is urgently needed. Here, we discovered that protoporphyrin IX (PpIX) and verteporfin, two FDA-approved drugs, completely inhibited the cytopathic effect produced by SARS-CoV-2 infection at 1.25 µmol/Land 0.31 µmol/L respectively, and their EC50 values of reduction of viral RNA were at nanomolar concentrations. The selectivity indices of PpIX and verteporfin were 952.74 and 368.93, respectively, suggesting broad margin of safety. Importantly, PpIX and verteporfin prevented SARS-CoV-2 infection in mice adenovirally transduced with human ACE2. The compounds, sharing a porphyrin ring structure, were shown to bind viral receptor ACE2 and interfere with the interaction between ACE2 and the receptor-binding domain of viral S protein. Our study suggests that PpIX and verteporfin are potent antiviral agents against SARS-CoV-2 infection and sheds new light on developing novel chemoprophylaxis and chemotherapy against SARS-CoV-2.
Photodynamic therapy is an effective method for treating superficial forms of malignant neoplasms, characterized by a minimal risk of damage to normal tissues. In this study, we presented our experience of treating cancer of the oral mucosa using photodynamic therapy, and analyzed the immediate and long-term results of treatment. 38 patients with squamous cell carcinoma of oral cavity mucosa, with a depth of invasion no more than 7 mm, were included in the study. All patients underwent photodynamic therapy with chlorine e6 based photosensitizer. Photosensitizers were administered intravenously 3 hours before irradiation, at a dosage of 1 mg/kg of the patient’s weight. Photodynamic therapy was performed with the following parameters: P – 1.0 W, Ps – 0.31 W/cm2, E – 300 J/cm2. The area of one irradiation field ranged 1.0-2.0 cm2. Treatment effect was evaluated by RECIST 1.1. Overall survival, cancer-specific survival, and disease-free survival were calculated using Kaplan-Meier curves. Evaluation of adverse events was made by .TCAE 5.0 criteria. At 35 (92.1%) out of 38 cases, complete regression was observed after photodynamic therapy. Among them in 3 out of 35 patients relapse was diagnosed in 11.5 to 43.2 months. The total number of patients who didn’t respond to treatment was 6 (15.8%). Follow-up period was 4.2-87.3 months. (mean 42.9). 34 (89.5%) out of 38 patients are alive, 1 (2.6%) died from progression, and three died from other causes. The 5-year overall survival rate was 82.1%, cancer-specific survival rate was 97.0%, and disease-free survival rate was 81.1%. Among the factors significantly (p < 0.05) influencing relapse-free survival: depth of invasion < 5 mm (p – 0.013) and the presence of leukoplakia (p – 0.007). When assessing cancer-specific survival, factors worsening the prognosis were: age >70 years (p – 0.034) and the presence of leukoplakia (p – 0.007). Photodynamic therapy is an alternative treatment method of oral cancer superficial lesions, in case of proper assessment of primary lesion and in case of possibility of full irradiation of the tumor. Moreover, after using photodynamic therapy, the underlying connective-muscular structures are preserved, which promotes rapid healing with minimal scarring, the functions of the affected organ remain intact, and cosmetic defects do not form.
Enhanced X-PDT against TNBC by using PPIX&PFOB co-loaded liposomes.
Literature review reflects the current status and development status of intraoperative photodynamic therapy in neurooncology and discusses the results of the most important studies on photodynamic therapy (PDT). We searched the Pubmed, EMBASE, Cochrane Library and eLibrary databases for publications published between January 2000 and December 2022. Found 204 publications in foreign sources and 59 publications in domestic editions, dealing with the issues of photodynamic therapy in neurooncology. An analysis of the literature has shown that intraoperative PDT in neurooncology is an important tool that contributes to increasing the radicality of the operation and local control. The basic rationale for the effectiveness of PDT lies in the study of the pathways leading to the complete devitalization of a malignant tumor, the study of the mechanisms of the local and systemic immune response. In addition, subcellular targets in PDT are determined by the properties of photosensitizers (PS). Second generation PSs have already been introduced into clinical practice. The effectiveness of PDT using photoditazine, 5-aminolevulinic acid has been demonstrated. The mechanisms of action and targets of these PS have been established. In Russia, a number of studies have repeatedly shown and proved the clinical effectiveness of PDT in groups of neurooncological patients with glial tumors and secondary metastatic tumors, but so far, the method has not been included in the clinical guidelines for the provision of high-tech neurosurgical care. There is certainly a need for further development of PTD techniques in neurooncology, especially in patients at high risk of recurrence and aggressive CNS tumors.
Photodynamic therapy is a clinical technique employing the combination of light, oxygen and a sensitising compound to induce the photochemical destruction of unwanted tissue. Light therapy has been known for some time, but it was not until the earlier part of this century that the first clinical work was performed using sensitisers and light. More recently a sensitising compound of a complex mixture of porphyrins has been tested on various cancers, and been awarded regulatory approval for its use. In this paper the synthesis and properties of some novel and easily prepared water soluble ruthenium phthalocyanine complexes are reported. One of these complexes, JM 2929, has been extensively studied and has photosensitising properties which when used in combination with light and oxygen in vitro and in vivo during photodynamic therapy displays remarkable cytotoxic effects.
Literature review reflects the current status and development status of intraoperative photodynamic therapy in neurooncology and discusses the results of the most important studies on photodynamic therapy (PDT). We searched the Pubmed, EMBASE, Cochrane Library and eLibrary data-bases for publications published between January 2000 and December 2022. Found 204 publications in foreign sources and 59 publications in domestic editions, dealing with the issues of photodynamic therapy in neurooncology. An analysis of the literature has shown that intraoperative PDT in neurooncology is an important tool that contributes to increasing the radicality of the operation and local control. The basic rationale for the effectiveness of PDT lies in the study of the pathways leading to the complete devitalization of a malignant tumor, the study of the mechanisms of the local and systemic immune response. In addition, subcellular targets in PDT are determined by the properties of photosensitizers (PS). Second generation PSs have already been introduced into clinical practice. The effectiveness of PDT using photoditazine, 5-aminolevulinic acid has been demonstrated. The mechanisms of action and targets of these PS have been established. In Russia, a number of studies have repeatedly shown and proved the clinical effectiveness of PDT in groups of neurooncological patients with glial tumors and secondary metastatic tumors, but so far, the method has not been included in the clinical guidelines for the provision of high-tech neurosurgical care. There is certainly a need for further development of PTD techniques in neurooncology, especially in patients at high risk of recurrence and aggressive CNS tumors.
Metal-organic frameworks (MOFs) with periodically arranged porphyrinic linkers avoiding the self-quenching issue of porphyrins in photodynamic therapy (PDT) have been widely applied. However, the porphyrinic MOFs still face challenges of poor stability under physiological conditions and limited photodynamic efficiency by the hypoxia condition of tumors. Herein, we fabricate the MOF@MOF structure with a protective MOF shell to improve the stability and relieve the hypoxia condition of tumors for sensitized PDT. Under protection of the MOF shell, the MOF@MOF structure can keep intact for 96 hours under physiological conditions. Consequently, the tumoral accumulation efficiency is two folds of the MOF core. Furthermore, the MOF shell decomposes under acidic environment, and the loaded inhibitor of mitochondria pyruvate carrier (7-amino carboxycoumarins-2, 7ACC2) will be released. 7ACC2 inhibits the mitochondrial pyruvate influx and simultaneously blocks glucose and lactate from fueling the mitochondrial respiration, thereupon relieving the hypoxia condition of tumors. Under a 5-min laser irradiation, the 7ACC2 carrying MOF@MOF nanoplatforms induced doubled cellular apoptosis and reduced 70% of the tumor growth compared with the cargo-free MOF@MOF. In summary, the design of this stable and hypoxia self-relievable MOF@MOF nanoplatform will enlighten the future development of MOF-based nanomedicines and PDT. STATEMENT OF SIGNIFICANCE: : Porphyrinic metal-organic frameworks (MOFs) have been widely applied in photodynamic therapy (PDT) as a kind of superior nano-photosensitizers. However, they still face challenges in poor stability under physiological conditions and limited photodynamic efficiency due to the hypoxia condition of tumors. In order to solve these problems, (1) we developed a MOF@MOF strategy to improve the physiological stability; (2) an inhibitor of mitochondria pyruvate carrier, 7-amino carboxycoumarins-2 (7ACC2), was loaded to inhibit the mitochondrial pyruvate influx and simultaneously block glucose and lactate from fueling the mitochondrial respiration, thereupon relieving the hypoxia condition of tumors. The design of this stable and hypoxia self-relievable MOF@MOF nanoplatform will enlighten the future development of MOF-based nanomedicines and PDT.
Vaccination immunotherapy has revolutionized cancer treatment modalities. Although the immunomodulatory adjuvant generally employs for potentiating vaccine response, systemic administration may drive immune‐related side effects, even immune tolerance. Therefore, tunable immunoadjuvants are highly desirable to simultaneously stimulate the immune response and mitigate systemic toxicity. Self‐immolated nanoadjuvants are herein reported to potentiate vaccination immunotherapy of cancer. The nanoadjuvants are engineered by co‐assembling an intracellular acidity‐ionizable polymeric agonist of toll‐like receptor 7/8 resiquimod (R848) and polymeric photosensitizer pyropheophorbide a (PPa). The resultant nanoadjuvants specifically accumulate at the tumor site via passive targeting and are dissociated in the acidic endosome versicles to activate PPa via protonation of the polymer backbone. Upon 671 nm laser irradiation, PPa performed photodynamic therapy to induce immunogenic cell death of tumor cells and subsequently releases R848 in a customized manner, which synergistically activates dendritic cells (DCs), promotes antigen cross‐presentation, and eventually recruits cytotoxic T lymphocytes for tumor regression. Furthermore, the synergistic in situ vaccination immunotherapy with immune checkpoint blockade induce sustained immunological memory to suppress tumor recurrence in the rechallenged colorectal tumor model.
Efficacy of PDT with new chlorin e6 photosensitizer (BLC 1010) has been tested in 72 cancer patients. 44 patients (61 %) achieved a complete response and 39 % of the patients a partial response (28 patients, including 15 patients treated for palliation).
Rapid elimination of BLC 1010 from the organism solves the problem of skin phototoxicity encountered in PDT up to now. This property together with its high tumor to normal ratio makes it a promising photosensitizer for PDT. Further advantage is that portable diode lasers with proper wavelength are available.
Ductal carcinoma in situ (DCIS) of the breast is often managed by lumpectomy and radiation or mastectomy, despite its indolent features. Effective non-invasive treatment strategies could reduce the morbidity of DCIS treatment. We have exploited the high heat shock protein 90 (HSP90) activity in premalignant and malignant breast disease to non-invasively detect and selectively ablate tumors using photodynamic therapy (PDT). PDT with the HSP90-targeting photosensitizer, HS201, can not only ablate invasive breast cancers (BCs) while sparing non-tumor tissue, but also induce antitumor immunity. We hypothesized that HS201-PDT would both non-invasively ablate DCIS and prevent progression to invasive BC. We tested in vitro selective uptake and photosensitivity of HS201 in DCIS cell lines compared to the non-selective parental verteporfin, and assessed in vivo antitumor efficacy in mammary fat pad and intraductal implantation models. Selective uptake of HS201 enabled treatment of intraductal lesions while minimizing toxicity to non-tumor tissue. The in vivo activity of HS201-PDT was also tested in female MMTV-neu mice prior to the development of spontaneous invasive BC. Mice aged 5 months were administered HS201, and their mammary glands were exposed to laser light. HS201-PDT delayed the emergence of invasive BC, significantly prolonged disease-free survival (DFS) (p = 0.0328) and tended to improve overall survival compared to the no-treatment control (p = 0.0872). Systemic administration of anti-PD-L1 was combined with HS201-PDT and was tested in a more aggressive spontaneous tumor model, HER2delta16 transgenic mice. A single PDT dose combined with anti-PD-L1 improved DFS compared to the no-treatment control, which was significantly improved with repetitive HS201-PDT given with anti-PD-L1 (p = 0.0319). In conclusion, a non-invasive, skin- and tissue-sparing PDT strategy in combination with anti-PD-L1 antibodies effectively prevented malignant progression of DCIS to invasive BC. This non-invasive treatment strategy of DCIS may be safe and effective, while providing an option to reduce the morbidity of current conventional treatment for patients with DCIS. Clinical testing of HS201 is currently underway.
Organelle specificity is an important facet of more efficient and highly selective drugs with reduced side effects which have now been the great challenge to the scientists. In eradication of lethality of cancer, the appropriate anticancer therapeutics should render less toxicity towards the normal healthy cells. Therefore, in present scenario the application of photodynamic therapy (PDT) in healing cancer has brought about a renaissance in the field of anticancer research as PDT is very selective treatment procedure under irradiation of localized light at a particular portion of the body without creating any phototoxic damage to the normal cells. Metal complexes, especially ruthenium (II), iridium (III) and rhenium (I) complexes have been seen to be highly apt for PDT. Hence, a bucket of Ru (II), Ir (III) and Re (I) based various types of complexes have been showcased here mentioning their capability to target specific organelle along with the detailed discussion on pathway of photodynamic therapy.
Phototherapy is a noninvasive cancer treatment that relies on the interaction between light and photoactive agents. These photoactive agents are typically organic dyes, but their hydrophobic nature and self-aggregation tendency in biological media greatly restricts the development of highly effective phototherapeutic systems. In the past decade, functional dye-doped metal-organic framework (MOF)-based phototherapy has attracted enormous interest because organic dyes can be encapsulated and isolated within the MOF structure to show superior treatment efficacy. In addition to incorporating the reported phototherapeutic dyes into MOF as the ligand or the guest in the pores, the construction of an MOF-based phototherapy agent can also be extended to these dye units that are previously inactive for phototherapy. Thus, this review focuses on the emerging development of phototherapeutic MOFs that exhibited better performance than the involving dye units due to the controlled dye aggregation within the MOF. The related mechanisms and some emerging future directions of dye-doped MOF-based phototherapy are also discussed and summarized.
Boron dipyrromethene dyes are highly attractive for image-guided photodynamic therapy. Nevertheless, their clinical breakthrough as theranostic agents is still obstructed by several limitations. Here, we report a series of strongly absorbing, heavy-atom-free, distyryl-BODIPY donor–acceptor dyads operating within the phototherapeutic window. Whereas diphenylamine and carbazole donors lead to strong fluorescence, dimethylacridine, phenoxazine, and phenothiazine units afford a decent fluorescence combined with the efficient formation of singlet oxygen. Dedicated photophysical analysis and quantum-chemical calculations are performed to elucidate the excited state dynamics responsible for the pronounced differences within the BODIPY series. Femtosecond transient absorption spectra reveal the nature of the excited state processes and the involvement of charge-transfer states in triplet formation.
Photodynamic therapy (PDT) has been thriving in the theranostics of cancer in recent years. However, due to a series of problems such as high concentration of GSH and insufficient O2 partial pressure in the tumor micro-environment, it is difficult to achieve the desired therapeutic effects with single PDT. Mesoporous carbon (MC-COOH) has been widely used in photothermal therapy (PTT) due to its high photothermal conversion efficiency and drug loading. In addition, we have discovered that MC-COOH owned high-efficiency glutathione oxidase-like activity for intracellular lasting GSH consumption. Hence, a smart mesoporous carbon nanozyme (CCM) was designed as a dual-GSH depletion agent and O2 generator combined with PTT to overcome the dilemma of PDT. MnO2-doped carbon nanozyme (MC-Mn) was developed as the photothermal vehicles for the efficient loading of photosensitizer (Ce6). Subsequently, 4T1 membrane-coated nanozyme (Ce6/CCM) was constructed to achieve homologous targeting capability. The carbon nanozyme owned the sustained dual-GSH depletion function through MC-COOH and MnO2, which greatly destroyed the antioxidant system of the tumor. Meanwhile, MnO2 could produce affluent O2 in the presence of H2O2, thereby alleviating the hypoxic state of tumor tissues and further promoting the generation of ROS. In addition, the novel carbon nanozyme was designed as photoacoustic imaging (PAI) agent and magnetic resonance imaging (MRI) contrast for real-time imaging during tumor therapy. In summary, this work showed that the biomimetic carbon nanozyme could be used as dual-GSH depletion agent and O2 generator for dual-mode imaging-guided PTT-PDT.
Statement of Significance
- MC-COOH with highly efficient GSH-OXD activity was first discovered and applied in PDT.
- MnO2 acted as an O2 generator and GSH depletion agent to enhance PDT.
- The tumor-targeting ability of the nanozyme was improved by cell membrane camouflage.
- CCM nanozyme possesses both PAI and MRI dual-mode imaging modalities to guide PDT/PTT.
Photodynamic therapy (PDT) is one of the most prominent therapies in the cancer treatment. PDT is a treatment that makes use of a drug, called photosensitizer or photosensitizing agent, and a peculiar type of light. When photosensitizers are irradiated by a specific wavelength of light, they produce a kind of oxygen that kills nearby cells. Needs-based research has been carried out on in the field of luminescence depending upon the disease undergoing treatment. It has the main advantage that it has no long-term side effects. Rare-earth doped upconversion (UC) materials are suitable for a vast range of potential biological applications in PDT, biological imaging, drug delivery, and sensing. The conversion of a higher wavelength photon (near infra-red [NIR] or red light region) into a lower wavelength photon (ultraviolet [UV] or near UV) is used in UC PDT. Absorbance of NIR wavelengths allow light to penetrate into deeper tissues, hence PDT of deeper tissues can be effectively done. The phosphor efficiency has been increased by the beneficial effect by co-doping and decreasing the particle size of the UC PD phosphors (UC nanoparticles). In this chapter, the mechanism of PDT, the history and scientific development related to PDT in the cancer treatment are discussed.
In the present work, we have synthesized new molecular hybrids consisting of porphyrin ring system connected at the meso positions with phenyl groups and/or, through p-phenylene linkers, with 1,4-dihydropyridine or pyridine moieties. In general, the directed use of dihydropyridine aldehyde, under time-modified Adler–Longo procedures, gave the best overall yields of the following meso-substituted dihydropyridine-porphyrins of general formula A1B3, A2B2, or A4, where A stands for phenyl-dihydropyridine and B for phenyl substituents. The corresponding meso-substituted pyridine-porphyrin hybrids were obtained from oxidation of the dihydropyridineporphyrins with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. The UV-vis spectra bands of the A4 dihydropyridine-porphyrin were unexpectedly red-shifted, having a rhodoporphyrin Q-bands profile. It was also found that an increased production of 1O2 correlates with a higher number of dihydropyridine or pyridine moieties in the hybrid molecule. All porphyrin hybrids were considered adequate candidates to be employed in photodynamic therapy.
Nattokinase is a thrombolytic drug that is more advantageous than urokinase, streptokinase, and tissue plasminogen activator because of its low price, high efficiency, and nontoxic side effects. However, it is a protease that is sensitive to gastric acid and is degraded by strong acid and pepsin when it passes through the digestive tract. Moreover, if it is administered orally, the purpose of dissolving thrombus cannot be achieved, which limits the application of nattokinase in food and medicine. The emergence of microcapsule technology can be useful in overcoming these limitations. Special structural properties of lipids, polysaccharides, protein, and other biological macromolecules have been utilised for embedding nattokinase to form a special shell-core structure, which can increase the acid resistance and storage stability of nattokinase. This paper discusses the structural characteristics and physiological properties of nattokinase and reviews the current research progress of nattokinase microencapsulation. In addition, reasonable suggestions for the future research direction for the development of a suitable nattokinase delivery system are put forward.
In order to maximize the retention of the photodynamic therapy (PDT) efficacy, while avoiding the dilemma of hypoxia and high reducing substances in tumor tissue, fluoropolymers were synthesized in a simple and effective methods. Fluorous effect with good oxygen carrying capacity was endowed by the fluorine-containing section in fluoropolymers and the perfluorodecalin (PFD) together, the reaction site with GSH was provided by the disulfide bond, which enhanced PDT efficiency through the sequential “AND” logic gate design. Two kind of fluorine-containing nanocarriers (M-Ce6 and E-Ce6) were obtained by solvent evaporation or ultrasound emulsification with PFD, respectively. In vitro, both of them showed promising high ROS generation under photoirradiation. Benefiting by cavitation effects, E-Ce6 had a more significant statistical difference in celluar uptake. Furthermore, the cells incubating with E-Ce6 hardly were noticed that the hypoxia signal appeared under hypoxia, while reducing the intracellular GSH content by more than 15%. Through the sequential “AND” logic gate design, ROS production even under hypoxia and GSH conditions of E-Ce6 was also almost 1.5 times that of Ce6 under normoxia. Enhancing effect of E-Ce6 was 13.47 times and 6.85 times, while selectivity ratio reached 5.13 times and 4.81 times compared with Ce6 and M-Ce6. The two-pronged strategy showed a high potential for delivering the Ce6 to deep inside of cancer cells and killing it in the simulated tumor by PDT. These above results demonstrated the potential of E-Ce6, as oxygen self-sufficiency and GSH depletion nanocarriers for combined enhancement of photodynamic therapy.
Photodynamic therapy (PDT) has been widely studied in recent decades owing to its effectiveness in killing cancer cells. By utilizing a photosensitizer and irradiating it with light of a specific wavelength, the photosensitizer can be activated to generate reactive oxygen species (ROS) through energy transfer processes in the presence of molecular oxygen. The ROS are responsible for causing damage, inhibiting cancer cell growth and even killing the cancer cells. Understandably, just like other cancer treatments, PDT is an intriguing idea that requires consistent refining to improve on the constraints such as photostability, selectivity and tissue penetration. It is a powerful means of treatment as the oxidizing power of ROS and strong and non-discriminative and the PDT process is minimally invasive. However, it is crucial to ensure (1) the ROS is generated at the desired regions of interests to avoid undesired damage to healthy cells and (2) the photosensitizer is sufficiently stable in its journey to reach the regions of interest.
The choice of excitation light has varied over the years of PDT research, with researchers trying to balance the penetration strength with the absorption ability of the photosensitizer. The development of multiphoton excitation is welcoming as near-infrared excitation is able to evade the absorption of biological tissues—known as the biological window; nevertheless, it is not an easy task to structurally design photosensitizers that could be excited by multiphoton excitation. Latest research explores the possibility of using X-ray as the excitation source to activate photosensitizers for generating ROS. X-ray has high tissue penetration ability and a low dosage of X-ray can ensure minimal radiation risks while maintaining effective excitation in vivo. The penetration depth and duration of photosensitizer excitation determines the efficacy of PDT treatments.
On the other hand, PDT agents, just like other modalities, requires target-specificity to minimize side effects and increase the overall treatment efficacy, thereby reducing the dosage amount. The stability of the photosensitizers is also vital to ensure the photosensitizers remain able to carry out its function to generate ROS at the designated target regions. Researchers have devoted an extraordinary amount of effort in modifying the structure to improve stability and most recently, the idea of using molecular nanoplatforms such as nano-micelles has been able to hit “two birds with one stone.” The nanoplatform benefits from the enhanced permeability and retention effect for tumor cell localization and the micellar structure protects photosensitizers from potential destruction and decomposition by encapsulation.
Encouraging results from recent PDT research showed us that there is still much unexplored potential in the development of PDT photosensitizers and we expect PDT to remain one of the most effective clinical means for cancer treatment in the near future. This review covers the recent development of PDT agents from simple molecular level to nanoparticles. Discussion on different classical frameworks and clinically approved photosensitizers are included as well. The potential development of photosensitizers is discussed for the advancement of PDT in the near future.
Objectives
In this in vitro study, a bioluminescent marker was investigated for its potential to illuminate the assessment of dental caries and dental erosion, which are significant clinical and public health problems, through its binding of those ions, notably Ca²⁺, known to be released during the process of demineralization.
Materials and Methods
The light output from the selected bioluminescent marker was investigated in several experiments, including: (a)contact with a range of Ca²⁺ ion concentrations; (b) treatment of extracted teeth with solutions of differing pH, followed by application of the bioluminescence marker to assess Ca²⁺ ion release; and (c) application of the marker to freshly extracted teeth with natural and artificially created caries lesions on occlusal and smooth surfaces to image the Ca²⁺ ion distribution.
Results
The results of: experiment (a) showed that the light output from the marker increases with increasing Ca²⁺ concentration and of experiment (b) showed increases in light being observed as increasingly acidic solutions were applied. The results of experiment (c) showed the bioluminescence images of the extracted teeth produced “demineralization maps” of the imaged surfaces.
Conclusions
These results demonstrate the ability of a novel bioluminescence technology to image Ca²⁺ ions on tooth enamel surfaces which has potential in dental caries and dental erosion applications and provides the scientific basis for the ongoing development of that novel technology.
Near-infrared (NIR) aggregation-induced emission (AIE) of previous organic photosensitizers is usually weak because of the competition between twisted intramolecular charge transfer (TICT) effect and AIE. Herein, we report a rational molecular design strategy to boost NIR AIE of photosensitizers and still to keep strong ¹O2 production capacity via rotor effect. To this end, one new triphenylamine (TPA)-based AIE photosensitizer, TPAM-1, is designed to give strong ability to generate ¹O2 but weak NIR fluorescence in the aggregate state due to the strong TICT effect. Another new TPA-based AIE photosensitizer, TPAM-2, is designed by introducing three p-methoxyphenyl units as rotors into the structure of TPAM-1 to modulate the competition between AIE and TICT. TPAM-1 and TPAM-2 exhibit stronger ability to generate ¹O2 in the aggregate state than the commercial photosensitizer, Ce6. Furthermore, TPAM-2 gives much brighter NIR luminescence (25-times higher quantum yield) than TPAM-1 in the aggregate state due to the rotor effect. TPAM-2 with strong NIR AIE and ¹O2 production capability was encapsulated by DSPE-PEG2000 to give good biocompatibility. The DSPE-PEG2000-encapsulated TPAM-2 nanoparticles show good cell imaging performance and remarkable photosensitive activity for killing HeLa cells. This work provides a new way for designing ideal photosensitizers for AIE imaging-guided photodynamic therapy.
Eleven human bladder carcinomata of different degrees of differentiation were implanted in mice immunosuppressed by thymectomy, anti-thymocyte serum and x-rays. Seven carcinomata grew well and one poorly and 3 produced mainly fibrous nodules in the mice. Normal human bladder tissues were grown from 4 other patients. The administration of a haematoporphyrin derivative (HpD), followed 24 h later by exposure to white light, caused marked destruction of tumours but little or none of normal bladder tissues. HpD or light alone caused no damage to tumours or normal tissues. It is suggested that photodynamic therapy may be applicable in the treatment of superficial transitional cell carcinoma of the bladder.
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The photodynamic effects of sulphonated aluminium phthalocyanine (SALPC) have been compared on cultured AR4-2J cells of a pancreatic carcinoma cell line and on exocrine cells of the normal phenotype freshly isolated from the rat pancreas; a multi-channel perifusion system was used for this kinetic study in vitro. Whereas light alone or SALPC alone was without effect on either cell type, photon activation of cellularly-bound SALPC with light greater than 570 nm permeabilised the cells and caused an increase in amylase secretion from normal acinar cells but a dose-dependent inhibition (10(-7) to 10(-5) M) of amylase release from AR4-2J cells. In contrast, direct permeabilisation of the plasma membrane with digitonin, 10 micrograms ml-1, evoked a marked release of amylase from both types of cell. Elevation of [Ca2+]i by the ionophore A23187, 10(-6) M, elicited secretion of amylase from normal cells but had little effect on AR4-2J cells. Finally, it was established that the differential photodynamic effects of SALPC on amylase release were not attributable to any topographical differences in the microanatomical organisation of normal or tumour-derived cells; furthermore, the structural integrity of normal and AR4-2J cells was maintained after the photodynamic action of SALPC. It is concluded that the generation of singlet oxygen is responsible for permeabilisation of both types of cell and that photon-activated SALPC has functionally distinct effects on the constitutive secretion of amylase of tumour cells and the regulated secretory pathway of normal cells. These observations may be important in the development of drugs with a selective photodynamic action on pancreatic tumour cells.
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Figure 8
Four patients underwent intraoperative photodynamic therapy after surgery with meso-tetra-(hydroxyphenyl)-chlorin (mTHPC-PDT) for diffuse malignant mesothelioma. Preliminary procedures were performed in two patients in order to establish the efficacy of mTHPC-PDT and to optimise its tumoricidal effect. The tumoricidal effect was related to the mTHPC dose, light dose and the time interval between sensitation and activation. 0.3 mg kg-1 mTHPC activated after 48 h with 10 Joules cm-2 of non-thermal laser light at 650 nm resulted in a 10 mm deep tumour infarction, due to tumour vessel necrosis and thrombosis. The mTHPC tissue concentration was up to 14 times higher in the tumour than in normal tissues. Skin photosensitivity was mild, dose dependent and occurred 3 to 10 days after administration of mTHPC. According to the results obtained, intraoperative mTHPC-PDT was performed following pleuropneumonectomy in two, pleurectomy and lobectomy in one and pleurectomy in one patient. Ten Joules cm-2 were delivered to the diaphragm and the costophrenic sulcus and 5 Joules cm-2 to the remaining thoracic cavity. The postoperative course was marked by loss of appetite, fluid retention, hypoproteinemia and severe chest pain. One patient succumbed from aspiration pneumonia. The remaining patients developed no neural or vascular alterations and no bronchial stump insufficiency during follow-up. mTHPC-PDT following surgical tumour resection deserves further evaluation in good risk patients with diffuse malignant mesothelioma.
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Juvenile laryngotracheobronchial papillomatosis (JLTBP) is a recurrent, prolonged disease usually confined to the upper airway. Rarely, tracheobronchial tree or lung parenchymal involvement occurs. The various therapeutic interventions are often unsuccessful once extralaryngeal involvement becomes apparent. Photodynamic therapy (PDT) has been successful in eradicating JLTBP in a few case reports. We present a case of extensive JLTBP with parenchymal involvement treated with multiple courses of PDT. We demonstrated temporary regression of endobronchial papillomas, but no change in parenchymal lesions. Recurrent endobronchial disease was most likely related to reinfection from parenchymal lesions inaccessible to PDT.
The in vivo characteristics of four analogues of benzoporphyrin derivative (BPD) have been investigated. Biodistribution data obtained in DBA/2J mice with BPD-MA (monoacid ring A analogue) which had been tritiated or internally labelled with 14C showed that both labelled materials acted in an essentially identical manner during the period of study. Biodistribution and clearance studies showed that relative distribution in a variety of mouse tissues was similar for all BPD analogues. M1 tumour cells (rhabdomyosarcoma in DBA/2J mice) taken from tumours excised from animals treated 3 h earlier with BPD, and tested in vitro for photosensitivity provided evidence that significant levels of photosensitiser detected in tumour was both active and associated with tumour cells. The monoacid forms of BPD were found to be much more photodynamically active in this test than were the diacid analogues. The ability of the analogues to ablate tumours in mice by photodynamic therapy was also tested. Again, BPD-MA and BPD-MB proved to be measurably better than the diacid analogues. These findings are discussed in reference to structural and physical differences between the analogues.
A photosensitizer conjugate, chlorin e6 (Ce6) covalently bound to 1-micron-diameter polystyrene microspheres, has been investigated in the photodynamic destruction of MGH-U1 human bladder carcinoma cells in vitro. The microspheres were taken up avidly by the carcinoma cells; confocal laser scanning fluorescence microscopy showed them to be localized in the cytoplasm, apparently within lysosomes, visualized by labeling with acridine orange. In contrast, fluorescence of unconjugated Ce6 was present within most cellular membranes. Use of Ce6-microsphere conjugates led to a 20-fold-higher mean intracellular concentration, compared with unconjugated Ce6. Cells incubated in the presence of Ce6-microsphere conjugates (0.43 microM equivalent) and subsequently irradiated at 659 nm with a dye laser pumped by an argon-ion laser showed dose-dependent phototoxicity, leading to total inhibition of colony formation at a radiant exposure of 5J/cm2; in contrast, cells incubated with either unconjugated Ce6 (0.43 microM) or unconjugated microspheres before laser irradiation were unaffected. Cells pretreated with Ce6-microsphere conjugates and irradiated in the presence of 90% 2H2O showed significantly increased phototoxicity, an effect consistent with an important role for excited-state singlet oxygen in the mechanism of injury. In solution, however, photosensitized generation of singlet oxygen with Ce6-microsphere conjugates was 9 times less efficient than with unconjugated Ce6. The markedly greater phototoxicity of Ce6-microsphere conjugates compared to unconjugated Ce6 was therefore a consequence of the high intracellular Ce6 concentration attained by phagocytosis of the conjugates and their particular sites of intracellular localization. Thus, these conjugates are an efficient system for the delivery of photosensitizing drugs to carcinoma cells.
The origins of light as a therapy in medicine and surgery are traced from antiquity to the modern day. Phototherapy began in ancient Greece, Egypt and India but disappeared for many centuries, only being rediscovered by Western civilization at the beginning of the twentieth century through the Dane, Niels Finsen, and the Germans Oscar Raab and Herman von Tappeiner. The discovery of the tumour-localizing ability of haematoporphyrin, together with its phototoxic effect on tumour cells led to the development of photodynamic therapy, a promising tool in modern cancer treatment.
Photodynamic therapy was investigated as a potential new modality for the treatment of human malignant mesothelioma (HMM) utilizing the H-MESO-1 HMM cell line and the photosensitizing agent, Photofrin-II (PF-II). Up-take of PF-II by H-MESO-1 was documented by incubating H-MESO-1 cells with PF-II and measuring the fluorescence at 625 nm following excitation at 400 nm. Cytotoxicity of photodynamic therapy was determined by incubating H-MESO-1 cells (2 X 10(5)) in microtiter plates for 24 hr with concentrations of PF-II varying from 0 to 10 micrograms/ml. The wells were exposed to gold vapor laser light (628 nm) in doses ranging from 0 to 24,000 J/m2. Twenty-four hours following treatment, [3H]thymidine (1 microCi) was added to each well. Cells were harvested 24 hr later and counted for tritium incorporation. Five replicates were performed for each combination of light and drug. Peak absorption of PF-II by H-MESO-1 was reached within 8 hr. Maximal doses of light alone caused minimal cell killing. PF-II without light was cytotoxic only at the highest concentrations. However, the combination of PF-II at concentrations at or above 2.5 micrograms/ml and light produced a significant increase in cytotoxicity. These data demonstrate that photodynamic therapy can effectively kill human malignant mesothelioma cells in vitro.
Fluorescence imaging using hematoporphyrin derivative (HpD) or Photofrin II as a tumor marker has been used for localization of early bronchogenic carcinoma. Wider clinical application of HpD or Photofrin II as a cancer imaging agent has been hampered by the potentially serious and prolonged skin photosensitivity. Using a sensitive fluorescence bronchoscope system with a ratio fluorometer probe, carcinoma in situ was detected in four patients with low dose Photofrin II (0.25 mg/kg) with no apparent skin phototoxicity to 30 J/cm² visible light on skin photosensitivity test.
(Chest 1990; 97:333–37)
Lipoproteins are now recognized as major blood carriers of many hydrophobic porphyrins and related chromophores which are being investigated as possible photosensitizers in the photodynamic therapy of tumours. In vitro and in vivo studies have demonstrated the role of the low density lipoprotein (LDL) receptor pathway in the delivery of photosensitizers to tumour cells and its importance in porphyrin accumulation by tumours. Lysosomes, which are involved in the cellular processing of LDL, are important intracellular targets in the LDL—porphyrin-induced phototoxicity. The use of the LDL receptor pathway as a tool for enhancing the selectivity of photosensitizer delivery to tumour cells appears to be a promising field of research in the photodynamic therapy of tumours.
Photodynamic therapy utilizes the tumor localizing drug dihematoporphyrin ether and red laser light to produce both direct tumor cell destruction via damage to mitochondrial membranes, and also indirect cell kill via destruction of the tumor vasculature. As a first step towards examining the mechanistic relationship between metabolic and vascular effects of photodynamic therapy, murine RIF-1 tumors were treated with a subcurative treatment (500J/cm2). Tumor metabolic status was monitored using in vivo31P NMR before, during and after the treatment. The tumor blood flow immediately before and after treatment was measured by direct intratumor injection of D2O saline and observation of the tracer signal clearance from the tumor via 2H NMR. During the photodynamic therapy treatment, significant decreases were observed for the nucleoside triphosphate concentrations, tumor pH and tumor blood flow, while inorganic phosphate concentrations increased. Animals treated with laser light alone and those not given any treatment, demonstrated no significant changes in tumor metabolic status, tumor pH or tumor blood flow. Further studies are required to determine whether tumor blood flow or metabolic status is affected first.
— Zinc phthalocyanines sulfonated to different degrees are tested for their ability to sensitizeV–79 Chinese hamster cells andEMT–6 mouse mammary tumors to red light. In vitro, the lower sulfonated derivatives were the most active with the exception of the poorly water-soluble monosulfonated dye. An isomeric mixture of tetrasulfonated derivatives obtained via direct sulfonation was ten times more active than the homogeneous tetrasulfo derivative prepared via the condensation of sulfophthalic acid. In vivo, the latter dye was completely inactive, whereas the remainder of the sulfonated preparations exhibited a similar structure-activity pattern as observed with theV–79 cells in vitro. The disulfonated zinc phthalocyanine showed the best tumoricidal activity in the series and also appeared to be a more efficient photosensitizer of cell inactivation and tumor cure than the aluminum or gallium complexes as well as hematoporphyrin derivative preparations. No significant differences in skin phototoxicity were observed among the various dyes.
Tetraphenylporphinesulfonate (TPPS4) is a synthetic porphyrin that localizes in certain tumors to a higher absolute concentration and with more favorable tumor to other tissue ratios than any other porphyrin yet studied. Its utilization for photodynamic therapy and other applications has been inhibited by reported neurotoxicity. We injected TPPS4 over a broad dose range of 5-150 mg kg−1 and observed the effects on peripheral nerve in groups of animals sacrificed 35, 70 and 140 days later. No immediate deaths or phototoxic manifestations were seen. Light and electron microscopy, however, revealed cytoskeletal abnormalities and nerve fiber degeneration affecting both myelinated and unmyelinated fibers in all the time and dose groups. These findings have similarities to those of other experimental toxic neuropathies, and may also be related to the preponderance of autonomic manifestations in patients with porphyric neuropathy. The morphological changes consisted of tangles of fibrillar material in the myelinated fibers and loss of neurotubules in the unmyelinated fibers. Our studies indicate a direct interaction of TPPS4 with tubulin. This biological mechanism may be involved in the selective distribution of certain parenterally administered porphyrins.
Hematoporphyrin derivative (HPD) is retained by malignant tumors and emits fluorescence with peaks of 630 and 690 nm wavelength when HPD is exposed to light. It is therefore theoretically possible to make a diagnosis of malignant tumors by detecting the fluorescence of HPD. The authors developed a spectroscope system compatible with fiberoptic endoscopes to analyze the shape of the fluorescence light spectrum. We could clearly recognize the HPD-specific fluorescence in human cancer foci. This system can be applied to the measurement of the relative amount of HPD absorbed in superficial tumor tissue before the photodynamic therapy. This might suggest the extent of tumor. The clinical diagnostic applications of this system are described in this study.
Numerous photosensitizers with absorption peaks spanning the 600-800 nm "therapeutic window" have been and continue to be synthesized. Structural modifications of the dyes can then be made in order to improve tumor deliverability and retention. Chemical alterations can also enhance the yields of light generated reactive oxygen species. Utilization of lipoproteins, emulsions and antibody conjugates can enhance the selectivity of drug localization. Most cell types and subcellular structures are highly photosensitive and biochemical analysis indicates that cellular target sites associated with PDT correlate with photosensitizer location. In vivo data suggest that vascular and direct tumor cell damage as well as systemic and local immunological reactions are involved in PDT responsiveness. Additional mechanistic, synthetic and developmental studies are required in order to fully appreciate the potentials of PDT. However, continued enthusiasm and support for basic PDT research (as observed during the past 8 years) will depend to a large extent on the outcome of the current clinical trials.
The role of radiotherapy in the treatment of isolated local recurrence of breast cancer after mastectomy is controversial. In an attempt to define this role, the results of moderate-dose radiotherapy in 90 such patients were reviewed. The median follow-up time for these patients was 81 months. The actuarial probability of local control after treatment was 42% at 5 years and 35% at 10 years. Freedom from distant failure was 30% at 5 years and only 7% at 10 years. The rate of appearance of distant metastasis was fairly constant at approximately 20% of patients per year. Overall survival was 50% at 5 years and 26% at 10 years. Overall survival and relapse-free survival were both chiefly influenced by the disease-free interval (DFI). Patients who presented with a DPI of greater than or equal to 2 years had a 5-year actuarial overall survival rate of 58% compared to 33% for patients with a DFI of less than 2 years (P = 0.04). Subsequent local failures after radiotherapy were principally seen at the initial site of recurrence, but also at other sites in or at the edge of the radiation fields. These results strongly suggest that patients with apparently isolated local recurrence after mastectomy are incurable by further local treatment. Effective systemic therapy is required to improve the results in these patients. Radiotherapy is a useful palliative procedure in patients with long disease-free intervals. The role of radiotherapy in conjunction with systemic therapy is, as yet, undefined.
Abstract— Protoporphyrin-induced phototoxicity in rat peritoneal mast cells was manifested either by inhibition of 48/80-stimulated histamine secretion or by cell lysis. At a protoporphyrin concentration of 100ng/m/ (0.17 μM), histamine secretion was completely inhibited after 30min illumination. After initiation, the inhibited state progressed in the dark, and was irreversible, however, it did not develop into cell lysis. More severe phototoxic reactions in mast cells could not be produced by increasing the PP concentration or the incubation time; however, cell lysis was evoked by increasing the light intensity between 180–950W/m2, using a light source with emission maxima in the 350–470nm region. Dual phototoxic effects could also be demonstrated in erythrocytes by manipulating the illumination conditions. Increased resistance to osmotic lysis was seen under moderate conditions, and decreased resistance and cell lysis were seen under severe conditions. In the absence of protoporphyrin, the effect of light alone on mast cells was similar to protoporphyrin-phototoxicity, although the light intensities required were higher both for inhibition (60–130W/m2) and lysis (280–950W/m2). The data therefore indicate that certain cell functions can be specifically disrupted by phototoxic reactions that are not cytotoxic; however, phototoxic reactions that lead to severe membrane protein denaturation and cell lysis also occur. The manifestation of these dual effects depends on the intensity of illumination in the 350–470nm region.
Abstract The treatment of bladder carcinoma using dihematoporphyrin ether (DHE) and laser photodynamic therapy (PDT) is described herein. Patients selected for this study have cytology- and biopsy-proven transitional cell carcinoma, no histologic evidence of muscle invasion, and negative excretory urograms.
Sixteen patients have been treated, with follow-up from 6 to 36 months. Eleven have had a complete response, and 3 a partial response in that they required re-treatment for recurrence. Two of these patients have not recurred at this time. One of the patients who recurred had tumor extension into the prostatic urethra and has been successfully re-treated (disease-free at 6 months). There was one treatment failure and 1 patient lost to follow-up.
Photosensitivity for up to 4 weeks is a known side-effect, but unexpected morbidity included a transient but significant increase in urinary frequency, urgency, and occasionally hematuria which spontaneously resolved within 3-4 weeks. Careful placement of the fiberoptic tip in the centre of the bladder, bladder distension during treatment with saline rather than water, the instillation of the minimum volume required to “smooth out” the mucosa for complete bladder photoradiation, and delivered energy of 25 J cm’or less may have prevented the more severe complications (i.e. bladder shrinkage) reported by Dougherty and Nseyo (personal communication).
We also feel that there is some early evidence that a heightened immune response (similar to intravesical BCG) may potentially play some role in explaining the efficacy of PDT in long disease-free intervals, although this is just a histologic observation at present.
It appears the PDT offers another practical treatment modality for non-invasive transitional cell carcinoma in patients refractory to standard surgical and chemotherapeutic regimens, and has been addressed by numerous other investigators such as Benson (1985) and Hisazumi (1983). We are presently recommending to our patients in these categories to undergo a course of PDT prior to relinquishing to cystectomy.
Leukemia L1210 cells were incubated in vitro with the tumor-localizing product HPD (hem-atoporphyrin derivative) for 0.5. 4 and 18 h. Effects of subsequent irradiation on viability, membrane transport and integrity, DNA synthesis and intracellular ATP concentration were assessed. Intracellular porphyrin pools were analyzed by HPLC. A 30 min incubation led to concentration of a readily-exchangeable pool of monomeric HPD components at plasma membrane loci; irradiation resulted in photodamage to membrane transport and a loss in capacity for dye exclusion. In contrast, increasing the incubation time led to a corresponding increase in the size of a non-exchangeable intracellular pool of other HPD components. Subsequent irradiation led to depletion of intracellular ATP and loss of capacity for biosynthesis of DNA, but little plasma membrane damage.
Five patients with various gynecologic neoplasms were treated with photodynamic therapy using 630-nm light delivered from an argon dye laser system following the intravenous injection of hematoporphyrin derivative (HpD). A patient with multifocal squamous cell cancer of the vagina had no evidence of disease 15 months after her first photodynamic therapy treatment. Autopsy nine months after the first treatment of another patient with multifocal invasive cancer of the vagina and parametrium showed no evidence of tumor on the surface of the vagina. Eight months after treatment of an 8 × 12 cm area of Bowen's disease of the vulva and thigh, there was no evidence of disease. Vaginal bleeding from breast cancer metastatic to the endometrium was controlled by one treatment until the patient expired five months later from her disease. Adenocarcinoma metastatic to the vaginal cuff showed partial response when vaginectomy was performed five weeks after photodynamic therapy.
We are reporting our experience with intraoperative PDT in 32 patients with malignant supratentorial gliomas; in 19 cases the tumour was recurrent. There were 20 males and 12 females with an age range of 17‐73 (mean = 45) yr. The first 8 patients in this series received HpD (Photofrin I) and the next 24 received DHE (Photofrin II). A photo‐illuminating device, of the author's design, was coupled to an argon dye pump laser in order to deliver light at 630 nm to a tumour cavity created by radical tumour resection and/or tumour cyst drainage. The total light energy delivered ranged from 440 to 3888 J and the light energy density ranged from 8 to 68 J cm ⁻² .
There were two post‐operative deaths as the consequence of hematoma accumulation in an extensive tumour resection cavity. In two patients neurological function was worse post‐operatively and did not recover. Post‐operative cerebral edema was pronounced in eight cases and required emergency craniotomy in two patients (the histology from both showed hemorrhagic necrosis of residual tumour). We have fashioned continuous post‐operative ICP measurements in the last 15 patients treated with PDT and compared the values to those obtained from cases with malignant gliomas who did not have PDT; the mean ICP was significantly greater in the PDT group. Four patients developed wound infections; two of these required surgical treatment. Four patients, two of whom were hemiparetic, developed deep vein thrombosis and required anticoagulant therapy. There were no adverse systemic reactions to the administration of either photosensitizer and only 3 skin photosensitivity reactions.
Follow up has ranged from 1 to 26 months at the time of writing; 38% were still alive; in the interval between PDT and death, the deaths per observation year was 1.11 for the whole group and 1.00 when the two post‐operative deaths are excluded. In the interval between first diagnosis and death the rate was 0.45 deaths per observation year. Photodynamic therapy of malignant brain tumours using surface or cavitary photo‐illumination can be carried out with acceptable risk.
In eight patients we determined the penetration depth of light in brain tissue in vivo by reading the detected light flux from a fiber passed radially into the brain towards the centre of the irradiation volume. The optical fiber consisted of a single 400 μ.m, cleaved fiber fixed in a 17‐gauge biopsy needle coupled to a photometer. The light penetration depth ranged from 0.8 to 4.9. The mean PD values in the‘tumour’group and the‘brain’group was 2.9 ± 1.5 and 1.5 ± 0.43, respectively. We attribute this significant difference to the differences in the absorption and scattering properties of brain and tumour.
Photodynamic therapy (PDT) is an experimental form of cancer therapy which employs photoactivation of a sensitizing chemical by light of a given wavelength via the production of toxic oxygen species. PDT causes local destruction of cancer, and relies on a therapeutic index between normal and malignant tissue since the latter seems to selectively retain the sensitizer. PDT has both direct tumoricidal effects as well as indirect effects on tumor vasculature causing an early hemorrhagic necrosis of tissue. The treatment has been used for the treatment of endobronchial obstruction by primary and metastatic tumors. Most recently, trials are being performed to evaluate this therapy as a surgical adjunct in the treatment of pleural malignancies such as mesothelioma.
Abstract The techniques of photodynamic therapy (PDT) and the indications for its use in the treatment of intraocular tumors have evolved during the years in which it has been assessed in patients at our institution. It is now clear that transcorneal PDT delivered at a subthermal dose-rate to the surface of a pigmented lesion such as choroidal melanoma has little effect. In the absence of pigment, however, as in the case of retinoblastoma or amelanotic melanoma of the iris or choroid, the tumor kill attributed to PDT alone is significant. Data from animal tumor models in our institution and from patient studies elsewhere suggest that the addition of heat with the light delivery will predictably improve the outcome of the treatment of pigmented lesions. Ocular PDT delivered in conjunction with heat will be useful clinically as an adjunct to scleral plaque therapy by reducing the height of a lesion and concurrently the dose of radiation necessary at the base of the tumor for sterilization. Since the clinical tumoricidal effect of PDT is now known to be due at least in part to vascular damage, trans-scleral application of light to the base of melanomas and occlusion of its blood supply holds significant promise of efficacy with continued improvement of the light delivery system. Finally, a transpupillary approach to occlusion of the choroidal vascular supply to a melanoma by surrounding the tumor with photodynamic lesions may provide the best approach for ocular PDT as a primary therapy.
Photodynamic therapy is a new, experimental method of treating malignant tumors by utilizing the relatively selective retention of the photosen-sitizer (hematoporphyrin derivative or dihematoporphyrin ether) and its ability to elicit an efficient photodynamic reaction upon activation with penetrating viable light. Application of this therapy to tumors in the bronchus, bladder, skin, and several other sites has demonstrated both safety and efficacy, even in advanced cases. Eradication of early stage tumors in the bronchus and bladder has been demonstrated. Selective retention of the photosensitizers in tumors is apparently related to the relatively large size of the aggregates of these materials causing phagocytosis by reticuloendothelial cells as well as preventing rapid clearance from tumor interstitial fluid and subsequent uptake in lipophylic components of cells. Upon light activation, generally delivered from lasers via fiber optics, the sensitizers generate singlet oxygen, the apparent cytotoxic agent, causing both vascular damage and injury to tumor cells.
Tumour recurrences in the gynaecological field after conventional therapy are a big problem because there is little choice for other therapies without inflicting further damage. Photodynamic therapy (PDT) is indicated because it is selective and without side-effects in flat or small recurrences.
We treated 15 patients with vaginal and vault recurrences of cervix carcinoma, adenocarcinoma in the corpus uteri and rectum. The PDT was performed after 24–48 h with Hp, 5 mg/kg body weight, injection, and an argon-dye laser for 13 cases, tungsten and xenon lamps in 2 cases. All patients were previously treated with conventional therapy (i.e. surgery, radiotherapy, chemotherapy). Doses ranged from 60 to 500 J cm−2. The results were: 8 complete local responses, 6 partial responses, 1 no change. Four patients died because of distant metastases or progression. One partial response was treated with brachytherapy and is now disease free. All the other patients are still living. In all cases we have seen no side-effects from PDT. The patients were sheltered from the sunlight for 20–30 days after therapy.
Twenty-one patients with recurrent gynecologic malignancies were treated with photodynamic therapy using Photofrin II and argon dye laser. Seven of twenty-one patients with cutaneous lesions treated palliatively had a complete response and four of eleven patients with cervical and vaginal recurrences had an objective response to phototherapy. Two of the patients with complete response continued to be free of disease after 28 and 36 months of follow-up.
The biodistribution of a new and very potent photosensitizer, benzoporphyrin derivative—monoacid, ring A (BPD-MA), was determined in normal and P815 (mastocytoma) or M1 (rhabdomyosarcoma) tumor-bearing DBA/2J mice. A dose of 80 μg Of 3H-BPD-MA was determined at 3, 24, 48, 72, 96 and 168 h post injection. The following tissues were tested: blood, brain, heart, intestine, kidney, lung, liver, muscle, skin, stomach, spleen, thymus and tumor.The biodistribution of 3H-BPD-MA in normal and tumor-bearing mice was comparable overall. 3H-BPD-MA localized in tumors better than in other tissues except kidney, liver and spleen. The tumor to tissue ratios were in the range 1.5 – 3 at 24 h post injection and increased further during the next 72 h. The highest levels of 3H-BPD-MA were observed in all tissues at 3 h post injection and decreased rapidly during the first 24 h. After 24 h the clearance from tissues was rather slow.The preliminary clearance data obtained in a group of five normal mice indicated that the majority of the injected dose (60%) cleared from the body via the bile and feces, while only about 4% cleared via kidneys and urine. Studies in which 3H-BPD-MA was extracted from tumor, kidney and liver 3 and 24 h after injection showed that, at 3 h, all the photosensitizing activity in tumor was retained. At 24 h only 39% of the activity was retained and considerably less active material was present in liver and kidney.
Benzoporphyrin derivatives (BPDs) are photosensitizers, which fluoresce strongly at 690 nm, and may be candidates for various applications of photodynamic therapy (PDT). Fluorescence-activated cell sorting (FACS) analysis, subsequent to ultraviolet light excitation, revealed pronounced differences in red fluorescence between leukemic cell lines (HL60, K562 and L1210), leukemic clinical isolates, and normal human or murine bone marrow cells incubated with BPD. These observed differences in BPD-mediated fluorescence provide the rationale for sorting leukemic from normal cells via FACS or may constitute a novel method for extracorporeal purging of remission marrow by photodynamic therapy in autologous bone marrow transplantation.
The P388 murine leukemia and P388/ADR, a subline expressing the multi-drug resistance (MDR) phenotype, were examined with regard to the role of MDR as a determinant of responsiveness to photodynamic therapy in vitro. Mesoporphyrin was used as a model substrate. We found no differences in porphyrin accumulation nor transport alterations associated with exposure of P388/ADR cells to the verapamil analog DMDP. There was a significant correlation between photodamage to mitochondria vs loss of cell viability in both cell lines, and LD50 sensitizer levels were not significantly different in P388 vs P388/ADR. P388/ADR cells were partly resistant to porphyrin-catalyzed photodamage to amino acid transport, but this result was not associated with differences in sensitizer localization, as indicated by fluorescence studies. Moreover, photodamage to membrane transport was not associated with loss of viability. These studies suggest that cells which express the MDR phenotype are unlikely to be cross-resistant to photodynamic therapy.
Mice bearing a subcutaneously growing tumour (Colo 26) were injected intravenously with the photosensitiser chloroaluminum sulphonated phthalocyanine (5 mg/kg) 24 h prior to irradiating the tumour with laser light (675 nm; 50mW, 100 J/tumour). Energy status of the tumour, as assessed by the loss of high energy phosphates in the 31P-nuclear magnetic resonance spectra, was altered dramatically following treatment, such that the ATP fell to undetectable levels within 1 h of light irradiation. However, assessment of the clonogenic capacity of neoplastic cells isolated from dissociated tumours showed that these rapid changes in cellular metabolism were not reflected in similar rapid changes in cell viability. Reductions in clonogenic capacity, which fell to less than 0.1% of control values at 24h postirradiation, closely mirrored those resulting from the cessation of vascular perfusion. Evaluation of tumour blood flow, using the technique of hydrogen washout, showed that the treatment protocol evoked a gradual and selective reduction in flow within the tumour resulting in complete vascular stasis by approximately 5 h after treatment. The results indicate that while chloroaluminum sulphonated phthalocyanine-mediated photodynamic therapy caused early metabolic damage in neoplastic cells, loss of viability paralleled the induction of complete inhibition of vascular flow in the tumour.
A monoclonal antibody-dextran-Sn(IV) chlorin e6 immunoconjugate was prepared by a technique involving the site-specific covalent modification of the monoclonal antibody oligosaccharide moiety. Dextran carriers were synthesized with a single chain-terminal hydrazide group, which was used as the coupling point between the carrier and the monoclonal antibody carbohydrate. Selective in vitro photolysis of SK-MEL-2 human malignant melanoma cells was accomplished using several conjugates prepared from anti-melanoma 2.1 (chromophore:antibody molar ratios, 6.8 and 11.2). Phototoxicity, as measured by clonogenic assay, was dependent on the delivered dose of 634-nm light and was observed only for conjugates that bound SK-MEL-2 cells. As judged by competitive inhibition radioimmunoassay, conjugates prepared in this fashion showed excellent retention of antigen binding activity relative to the unmodified antibody.
CaD2 mammary carcinomas transplanted into the feet of mice were treated with tetrasulfonated phthalocyanine (AlPcS4) and laser light at 680 nm. A light dose of 135 J/cm2 was either given as continuous radiation (15 min) or fractionated with 15 s exposure, 15 s darkness, 15 s exposure and so on for 30 min. The CaD2 tumors were found to respond better to a fractionated exposure than to the same energy given in one exposure. The reason for this is assumed to be a relocalization of the dye upon illumination, seen as a rapid decrease in fluorescence. When the laser light was turned off, the fluorescence returned to almost the initial value.
Laser-induced fluorescence (LIF) of photosensitizers is used to detect cancer. The effect of argon laser light with an average irradiance of 31 mW cm-2 and Photofrin II (Dihematoporphyrin ether, DHE) at concentrations of 1.0 and 5.0 micrograms ml-1 on C1300 murine neuroblastoma cells (MNB, NB41A3) in vitro was investigated. Growth curves and cell viability (trypan blue dye exclusion) were determined at 1, 24, 96, and 144 hr post-irradiation. Light doses of 1.8 and 9.0 J cm-2 combined with 5.0 micrograms DHE ml-1 decreased both cell numbers and viability, immediately and up to 144 hr postirradiation. Argon laser light alone at a fluence of 9.0 J cm-2 caused reversible injury to the cells. This in vitro study shows that both low energy argon laser light and low dose DHE are cytocidal to C1300 MNB cells. LIF promises to aid in the detection and destruction of neuroblastoma. Surgeons should be aware that tissue irreversible damage is likely to occur when performing LIF detection of neuroblastoma. The doses of laser light and of Photofrin II found to be toxic to neuroblastoma cells in culture may provide guidelines for photodynamic therapy ablation of neuroblastoma clinically.
The tumoricidal response of subcutaneously growing SMT-F adenocarcinoma implanted into syngeneic DBA/2 mice to Photofrin II-sensitized photodynamic therapy (PDT) was statistically significantly enhanced by the addition of a single dose of intravenously administered recombinant human tumor necrosis factor-alpha (rHuTNF-alpha). The interaction appeared to be approximately additive, i.e. tumor response to PDT plus rHuTNF-alpha was about the same as that observed by doubling the PDT dose. Conversely, rHuTNF-alpha did not significantly potentiate the cutaneous phototoxicity in mouse feet due to PDT. These data suggest that combination therapy should be considered for improving tumor response while retaining treatment selectivity in human malignancies.
A degree of resistance to photodynamic therapy (PDT) has been induced in radiation-induced fibrosarcoma-1 (RIF-1) tumor cells by repeated photodynamic treatment with Photofrin (4 or 18 h incubation) in vitro to the 0.1-1% survival level, followed by regrowth from single surviving colonies. The resistance is shown as increased cell survival in the strain designated RIF-8A, compared to the wild-type RIF-1 cells, when exposed to increasing Photofrin concentration for 18 h incubation and fixed light exposure. No difference was found between RIF-1 and RIF-8A in the uptake of Photofrin per unit cell volume at 18 h incubation.
Resistance to PDT was also observed in Chinese hamster ovary-multi-drug resistant (CHO-MDR) cells compared to the wild-type CHO cells, possibly associated with decreased cellular concentration of Photofrin in the former. By contrast, the PDT-resistant RIF-8A cells did not show any cross-resistance to Adriamycin, nor was there any significant drug concentration difference between RIF-1 and RIF-8A. These findings suggest that different mechanisms are responsible for PDT-induced resistance and multi-drug resistance.
We have developed procedures in which the photosensitizer benzoporphyrin derivative monoacid ring A (BPD) can be covalently
linked to carrier molecules of modified polyvinyl alcohol (PVA) to produce water-soluble PVA-BPD conjugates with a molecular
mass in the range of 30 kd. These carriers can subsequently be covalently linked to monoclonal antibodies (MoAbs) using heterobifunctional
linking agents. We describe here such a conjugate in which the MoAb (5E8) has specificity for a glycoprotein detected on human
squamous cell carcinomas of the lung. We provide evidence that the conjugates produced were covalently linked and retained
both their photosensitizing and antigen-binding activities. We show further that the MoAb-PVA-BPD conjugate, in the presence
of 10% fetal calf serum, exhibited highly enhanced phototoxic killing of the target cell line (A549) over that exhibited by
free BPD or a control MoAb-PVA-BPD conjugate. These results demonstrate, therefore, both the selectivity and specificity of
this MoAb conjugate. [J Natl Cancer Inst 83:1218–1225, 1991]
Singlet oxygen (1O2) is thought to be the cytotoxic agent in photodynamic therapy (PDT) with current photosensitizers. Direct monitoring of 1O2 concentration in vivo would be a valuable tool in studying biological response. Attempts were made to measure 1O2 IR luminescence during PDT of cell suspensions and two murine tumour models using the photosensitizers Photofrin II and aluminium chlorosulphonated phthalocyanine. Instrumentation was virtually identical to that devised by Parker in the one positive report of in vivo luminescence detection in the literature. Despite the fact that our treatments caused cell killing and tissue necrosis, we were unable to observe 1O2 emission under any conditions. We attribute this negative result to a reduction in 1O2 lifetime in the cellular environment. Quantitative calibration of our system allowed us to estimate that the singlet oxygen lifetime in tissue is less than 0.5 microsecond. Some technical improvements are suggested which would improve detector performance and perhaps make such measurements feasible.
This preliminary study was undertaken to test for the presence of urinary cytokines whose detection would provide evidence in support of the theory that photodynamic therapy (PDT) produces an immunologic response in patients treated for bladder cancer. Gamma interferon, interleukin 1-beta, interleukin 2, and tumor necrosis factor-alpha were assayed for in the urine of 4 patients treated with photodynamic therapy for bladder cancer, in 7 control patients undergoing transurethral surgical procedures, and in 5 healthy control subjects. Quantifiable concentrations of all cytokines, except gamma interferon, were measured in urine samples from the PDT patients with the highest light energies, while no urinary cytokines were found in the PDT patient who received the lowest light energy nor in any of the control subjects. These findings suggest that a local immunologic response may occur following PDT for bladder cancer.
The photodynamic therapy (PDT) of tumors involves illumination of the tumorous area following the administration of a tumor-localizing photodynamic sensitizer. Hematoporphyrin derivative (HPD) and Photofrin II (a purified form of HPD), the main sensitizers used clinically for PDT to date, are complex mixtures of porphyrins; furthermore, these preparations absorb light very poorly in the red region of the spectrum (wavelengths greater than 600 nm) where light penetration into mammalian tissues is greatest. Thus there is considerable interest in identifying new sensitizers that localize more effectively in tumors, absorb more strongly at longer wavelengths and can be prepared in high purity. Much of this interest has been directed towards chlorins (reduced porphyrins), which typically absorb strongly in the red. This review summarizes research that has been carried out on selected types of chlorins, some of which may have important applications as sensitizers for PDT.
5-Aminolaevulinic acid (ALA) is a precursor of protoporphyrin IX (Pp IX) in the biosynthetic pathway for haem. Certain types of cells have a large capacity to synthesize Pp IX when exposed to an adequate concentration of exogenous ALA. Since the conversion of Pp IX into haem is relatively slow, such cells tend to accumulate photosensitizing concentrations of Pp IX. Pp IX photosensitization can be induced in cells of the epidermis and its appendages, but not in the dermis. Moreover, since ALA in aqueous solution passes readily through abnormal keratin, but not through normal keratin, the topical application of ALA in aqueous solution to actinic keratoses or superficial basal cell or squamous cell carcinomas induces Pp IX photosensitization that is restricted primarily to the abnormal epithelium. Subsequent exposure to photoactivating light selectively destroys such lesions. In our ongoing clinical trial of ALA-induced Pp IX photodynamic therapy, the response rate for basal cell carcinomas following a single treatment has been 90% complete response and 7.5% partial response for the first 80 lesions treated. The cosmetic results have been excellent, and patient acceptance has been very good.
Several studies have examined the synergism of hyperthermia or chemotherapy agents in combination with photodynamic therapy (PDT) to enhance tumor eradication. In our unique approach to treatment, multiple photosensitizers and wavelengths were used: two photosensitizers, Photofrin II and meso-tetra-(4-sulfonatophenyl)-porphine (TPPS4), irradiated at the appropriate therapeutic wavelength for each photosensitizer. EMT-6 mammary tumors were induced in the flanks of BALB/c mice. The mice were assigned to a control group (50 mice) or treatment group (150 mice). All treatment animals and some control animals received photosensitizing drug (5 mg/kg of TPPS4, 5 mg/kg of Photofrin II, or 2.5 mg/kg of both TPPS4 and Photofrin II). All treatment animals and some control animals also received light treatment (630 nm for TPPS4 and/or 658 nm for Photofrin II). The results show that the approach using both drugs and the corresponding therapeutic wavelengths enhanced the effectiveness of PDT. This approach achieved a cure rate of up to 100%, which was, depending on the light intensity used, as much as 40% greater than the rate achieved by the approach using one drug and one wavelength. The results also show that lesser amounts of drug and/or light may be required if both drugs and wavelengths are used, thus lowering the chances of side effects common to PDT. Furthermore, the results indicate that the increased tumor kill is due to a synergistic effect of the two photosensitizers that was tested on the tumor microvasculature in the first few hours after PDT.
Endoscopic photodynamic therapy (PDT) with haematoporphyrin derivative was used in the primary treatment of 69 patients with inoperable gastrointestinal neoplasms. Patients were divided into three groups: 31 with oesophageal squamous cell carcinoma, 17 with adenocarcinoma of the stomach or lower third of the oesophagus and 21 with rectosigmoid adenocarcinoma. After infusion of 2.5-5.0 mg haematoporphyrin derivative per kilogram of body weight, lesions were irradiated using an argon dye laser (632 nm). During a follow-up period averaging 20 months (27.9 months for 35 surviving patients), complete local tumour destruction and negative histology were observed in 32 out of 69 cases. Flow-cytometric analysis of DNA content before and after PDT suggests that a clonal selection occurs in some cases of treatment failure. The results of this open pilot study suggest the potential efficacy of PDT as a curative treatment for selected cases of inoperable gastrointestinal cancers.
Among the sequence of events which occur during photodynamic therapy (PDT) are depletion of oxygen and disruption of tumor blood flow. In order to more clearly understand these phenomena we have utilized transcutaneous oxygen electrodes to monitor tissue oxygen disappearance. These results provide, for the first time, non-invasive real-time information regarding the influence of light dose on tissue oxygenation during irradiation. Measurements were conducted on transplanted VX-2 skin carcinomas grown in the ears of New Zealand white rabbits. Rabbits were treated with Photofrin II and tumors were irradiated with up to 200 kJ/m2 (500 W/m2) of 630-nm light. Substantial reductions in tumor oxygen tension were observed upon administration of as little as 20 kJ/m2. For a series of brief irradiations, oxygen tension was modulated by the appearance of laser light. Tissue oxygen reversibility appeared to be dependent upon PDT dose. Long-term, irreversible tissue hypoxia was recorded in tumors for large (200 kJ/m2) fluences. These results suggest that transcutaneous oxygen tension may be useful as a general indicator of the effectiveness of PDT and as an in situ predictor of the energy required to elicit tumor damage.