Application of Photofrin II as a specific radiosensitising agent in patients with bladder cancer--a report of two cases

Recent Progress and Trends in X-ray-Induced Photodynamic Therapy with Low Radiation Doses

The prominence of photodynamic therapy (PDT) in treating superficial skin cancer inspires innovative solutions for its congenitally deficient shadow penetration of the visible-light excitation. X-ray-induced photodynamic therapy (X-PDT) has been proven to be a successful technique in reforming the conventional PDT for deep-seated tumors by creatively utilizing penetrating X-rays as external excitation sources and has witnessed rapid developments over the past several years. Beyond the proof-of-concept demonstration, recent advances in X-PDT have exhibited a trend of minimizing X-ray radiation doses to quite low values. As such, scintillating materials used to bridge X-rays and photosensitizers play a significant role, as do diverse well-designed irradiation modes and smart strategies for improving the tumor microenvironment. Here in this review, we provide a comprehensive summary of recent achievements in X-PDT and highlight trending efforts using low doses of X-ray radiation. We first describe the concept of X-PDT and its relationships with radiodynamic therapy and radiotherapy and then dissect the mechanism of X-ray absorption and conversion by scintillating materials, reactive oxygen species evaluation for X-PDT, and radiation side effects and clinical concerns on X-ray radiation. Finally, we discuss a detailed overview of recent progress regarding low-dose X-PDT and present perspectives on possible clinical translation. It is expected that the pursuit of low-dose X-PDT will facilitate significant breakthroughs, both fundamentally and clinically, for effective deep-seated cancer treatment in the near future.

Antitumor efficiency of contact radiotherapy in combination with a chlorin-based photosensitizer in experiment

Authors have studied the antitumor efficacy of contact radiation therapy (CRT) in combination with a chlorin-based photosensitizer (PS) in an experiment on laboratory animals with transplanted tumors. The experimental study was performed in 50 white outbred rats weighing 250±50 g. Subcutaneously transplanted Pliss lymphosarcoma (PLS) and alveolar liver cancer RS1 (RS1) were used as tumor models. Chlorinbased PS photolon (RUE «Belmedpreparaty», Republic Belarus) was injected intravenously at a dose of 2.5 mg/kg. The radiation sessions were carried out 2.5–4 hours (depending on the tumor model) after the administration of the PS using the device «microSelectron HDR V3 Digital» («Nucletron», Netherlands) with a 192-Ir radiation source in single focal doses 5 and 10 Gy. All laboratory animals (for PLS and RS1) were subdivided into 5 groups of 5 animals each: intact control, CRT 5 Gy, CRT 10 Gy, PS + CRT 5 Gy, PS + CRT 10 Gy. For the PLS tumor model – on the 14th day from the beginning of the experiment Vav. in groups were 26.31±5.81; 22.45±6.97; 18.99±4.86; 10.75±5.18 and 28.06±2.85 cm3, respectively (p˂0.05). The coefficients of tumor growth inhibition in the experimental groups were 14.67%, 27.82%, 59.14% and 6.65%, respectively. The frequency of complete tumor regressions 60 days after the start of the experiment was 0%, 20%, 20%, 60%, and 20%, respectively. On RS1 tumor model – on the 14th day from the beginning of the experiment Vav. in groups were 4.48±1.03; 0.80±0.21; 0.29±0.09; 0.19±0.07 and 0.32±0.08 cm3, respectively (p=0.009). The coefficients of tumor growth inhibition in the experimental groups were 82.14%, 93.53%, 95.76% and 92.86%, respectively. The frequency of complete tumor regressions 60 days after the start of the experiment was 0%, 0%, 20%, 0%, and 0%, respectively. Systemic administration of chlorin-based PS before the CRT session increases the antitumor efficacy of radiation therapy in animals with transplantable tumors of different histological structure and growth patterns. The data obtained indicate that further studies of the radiosensitizing properties of PS are promising.

Photophysical Properties of Protoporphyrin IX, Pyropheophorbide-a and Photofrin® in Different Conditions

Photodynamic therapy (PDT) is an innovative treatment of malignant or diseased tissues. The effectiveness of PDT depends on light dosimetry, oxygen availability, and properties of the photosensitizer (PS). Depending on the medium, photophysical properties of the PS can change leading to increase or decrease in fluorescence emission and formation of reactive oxygen species (ROS) especially singlet oxygen (¹O₂). In this study, the influence of solvent polarity, viscosity, concentration, temperature, and pH medium on the photophysical properties of protoporphyrin IX, pyropheophorbide-a, and Photofrin^® were investigated by UV-visible absorption, fluorescence emission, singlet oxygen emission, and time-resolved fluorescence spectroscopies.

5-Aminolevulinic acid radiodynamic therapy for treatment of high-grade gliomas: A systematic review

INTRODUCTION

Radiodynamic therapy (RDT) involves administration of a radiosensitizing agent and its subsequent activation by ionizing radiation for destruction of neoplastic cells.

MATERIALS AND METHODS

A comprehensive evaluation of the literature was performed to review the history of RDT using porphyrins for solid tumors, the cellular mechanisms of action, immunomodulatory effects, and both preclinical and clinical studies for use in high-grade gliomas (HGGs). This manuscript was prepared in accordance with the PRISMA guidelines.

RESULTS

A total of 271 articles were considered for initial review. After removal of duplicates, articles not unrelated to specific topic, and exclusion of commentary articles, a total of 11 articles were subject to full analysis that included in vivo, in vitro, and human studies. Porphyrins such as 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PpIX) selectively accumulate in neoplastic cells and are currently used for fluorescent-guided surgical resection and photodynamic therapy (PDT) of HGG and other brain tumors. 5-ALA is also shown to act as a radiosensitizer by increasing oxidative stress in neoplastic cell mitochondria and enhancing the host immune response. Postoperative radiation therapy is currently the standard of care for treatment of HGG.

CONCLUSION

RDT remains a promising adjuvant therapy for HGGs and requires further investigation. Clinical trials of 5-ALA RDT for HGG are needed to evaluate the optimum timing, dosing and effectiveness.

Using X-rays in photodynamic therapy: an overview

Photodynamic therapy is a therapeutic option to treat cancer and other diseases.

Effect of Photofrin II as a radio-sensitizing agent in two different oesophageal carcinoma cell lines

Background and Purpose: In spite of major advances in cancer treatment, the prognosis of patients with oesophageal carcinoma remains poor. Squamous cell carcinoma and adenocarcinoma account for 95% of all oesophageal tumors, although other histological subtypes are occasionally seen. We aimed to evaluate whether Photofrin II can enhance the effect of ionizing radiation on oesophageal cancer in an in vitro tumor model. Material and Methods: A human oesophageal squamous cancer cell line (OE-21) and a human oesophageal adenocarcinoma cell line (OE-33) were evaluated with and without incubation with Photofrin II. Cells were irradiated using doses ranging from 0 to 8 Gy. The response rate of the cells to irradiation was evaluated by a tetrazolium-based colorimetric assay, similar to the MTT test, with the aim to determine the efficiency of Photofrin II as a radiation sensitizer in comparison to irradiation alone. Results: The OE-21 cell line demonstrated a significantly reduced cellular survival rate, when irradiated in the presence of Photofrin, as compared to a control group irradiated in the absence of Photofrin II. For the OE-33 cell line, no significant differences were found between the group treated with Photofrin II and the control group. Conclusion: Our results demonstrate in an in vitro model that Photofrin II may act as a radio-sensitizer in squamous cell oesophageal cancer, but not in oesophageal adenocarcinoma.

Mechanisms in photodynamic therapy: Part three-Photosensitizer pharmacokinetics, biodistribution, tumor localization and modes of tumor destruction

Photodynamic therapy (PDT) has been known for over a hundred years, but is only now becoming widely used. Originally developed as cancer therapy, some of its most successful applications are for non-malignant disease. The majority of mechanistic research into PDT, however, is still directed towards anti-cancer applications. In the final part of series of three reviews, we will cover the possible reasons for the well-known tumor localizing properties of photosensitizers (PS). When PS are injected into the bloodstream they bind to various serum proteins and this can affect their phamacokinetics and biodistribution. Different PS can have very different pharmacokinetics and this can directly affect the illumination parameters. Intravenously injected PS undergo a transition from being bound to serum proteins, then bound to endothelial cells, then bound to the adventitia of the vessels, then bound either to the extracellular matrix or to the cells within the tumor, and finally to being cleared from the tumor by lymphatics or blood vessels, and excreted either by the kidneys or the liver. The effect of PDT on the tumor largely depends at which stage of this continuous process light is delivered. The anti-tumor effects of PDT are divided into three main mechanisms. Powerful anti-vascular effects can lead to thrombosis and hemorrhage in tumor blood vessels that subsequently lead to tumor death via deprivation of oxygen and nutrients. Direct tumor cell death by apoptosis or necrosis can occur if the PS has been allowed to be taken up by tumor cells. Finally the acute inflammation and release of cytokines and stress response proteins induced in the tumor by PDT can lead to an influx of leukocytes that can both contribute to tumor destruction as well as to stimulate the immune system to recognize and destroy tumor cells even at distant locations.

Radiosensitization of tumours by porphyrins

Our previous data indicate, that hematoporphyrin dimethyl ether (HPde) can totally inhibit the growth of aggressive Ehrlich ascite tumour, when combined with low doses (2Gy) of ionizing radiation. Taking into account these findings, it appears of particular interest to evaluate the dependence of radiosensitizing efficiency of porphyrins on tumour aggressiveness. For this purpose two experimental tumour models (aggressive murine Ehrlich ascite carcinoma, (EAT), and not-aggressive hepatoma MH-22A) were used. Moreover, radiosensitizing properties of three porphyrin-type compounds of different chemical heterogeneity were evaluated (hematoporphyrin dimethyl ether (HPde), photofrin II (PII) and hematoporphyrin derivative (HPD)). Data obtained indicate, that HPde is the most effective one in this context (HPde>PII>HPD). It is important to note, that only the aggressive EAT tumours were radiosensitized by these dyes. No signs of radiosensitization (inhibition of tumour growth, injury of tumour tissue, evaluated by histological analysis) were observed in not-aggressive MH-22A hepatoma. Moreover, it was shown, that ligands of peripheral benzodiazepine receptors (PBR) might diminish the cell growth in aggressive EAT, but not in not-aggressive MH-22A hepatoma. The mechanism of radiosensitization by porphyrins, proposed in our previous studies, was strongly confirmed by these data. Actually, dicarboxylic porphyrins, being ligands of PBR, which are highly expressed in just aggressive tumours, can inhibit tumour cell proliferation and act in concert with ionizing radiation. Thus, combination of porphyrin and ionising radiation reflects the action of two antiproliferative factors, what eventually increases the response of aggressive tumours to the low doses of ionising radiation.

Experimental survey of non-clonogenic viability assays for adherent cells in vitro

Results of rapid cell viability assays were experimentally compared in order to reveal the most suitable test for in vitro investigations of the combination of photodynamic therapy (PDT) with chemotherapeutic drugs. meso-Tetra(3-hydroxyphenyl)-chlorin (m-THPC) accumulating in cell membranes and meso-tetra(4-sulfonatophenyl)-porphin (TPPS4) accumulating in lysosomes were used as photosensitisers. Doxorubicin that localises, mainly, to nucleus and vincristine that binds to microtubules were used as cytostatic drugs. Two adherent rodent cell lines, baby hamster kidney (BHK-21) and murine hepatoma (MH-22A), were used to examine the contribution of a cell. We tested cytotoxicity assays of the main groups of fast (non-clonogenic) methods of cell viability measuring. Plasma membrane integrity was estimated by trypan blue exclusion and LDH leakage, metabolic activity was tested by [3H]-thymidine incorporation and MTT assay, loss of monolayer adherence was measured by staining with crystal violet and CyQUANT. The most sensitive test in each case was the assay related to the site of the direct damage, and measurement of the loss of monolayer adherence proved to be as sensitive assay as the damage-specific one. All the assays applied, except for the LDH release, revealed a higher effect of combination of m-THPC-mediated phototreatment and doxorubicin compared to either of the single treatments.

Development of an HPLC method for monitoring of Photofrin II therapy

OBJECTIVES

To develop and to validate a method to quantify plasma porphyrins after application of Photofrin II, a drug preparation that is used for photodynamic therapy (PDT) and as a radiosensitizer.

DESIGN AND METHODS

After solid phase extraction of postdose plasma samples, reversed phase high performance-liquid chromatography with fluorescence detection was performed. Plasma porphyrin concentrations were monitored in five patients that were treated with Photofrin II.

RESULTS

The method proved linear over a wide concentration range, precise, and applicable in a routine clinical laboratory setting.

CONCLUSIONS

The method described here will enable large-scale clinical pharmacokinetic studies on Photofrin II; investigations can now address possible correlations between individual concentrations of drug-derived plasma porphyrins and systemic photosensitivity--representing the main side effect of Photofrin II--with the perspective of individualized light protection regimens after Photofrin II administration.

Photofrin as a radiosensitizer in an in vitro cell survival assay

Chemical modifiers (radiosensitizers) are used in order to increase the efficacy of radiotherapy. The use of Photodynamic Therapy for tumor treatment, especially with Photofrin II, is also known. At present, no chemical modifier has been found to act as a selective radiosensitizer. Experiments using several series of cell lines were performed; human bladder cancer cell line (RT4), colon adenocarcinoma cells (HT-29), and the glioblastoma cells (U-373 MG) were investigated, with and without incubation with Photofrin II, before irradiation. The irradiation was performed using doses ranging from 0 to 8Gy. Colony forming tests were applied to determine the efficiency of Photofrin II as a radiation sensitizer in comparison to irradiation alone. Two of the cell lines tested, cultures of the RT4 and U-373 MG, treated with Photofrin II prior to radiation, showed cell survival lower than cultures untreated with Photofrin II but irradiated under identical conditions. For the HT-29 cells, the results did not differ between the two groups (with and without Photofrin). The results of this study showed that Photofrin II can act, under certain conditions as a tumor radiosensitizer.