Fine-needle interstitial photodynamic therapy of the lung parenchyma: photosensitizer distribution and morphologic effects of treatment

Photo-induced antitumor effect of 3,6-bis(1-methyl-4-vinylpyridinium) carbazole diiodide

We have applied a fluorescent molecule 3,6-bis(1-methyl-4-vinylpyridinium) carbazole diiodide (BMVC) for tumor targeting and treatment. In this study, we investigated the photo-induced antitumor effect of BMVC. In vitro cell line studies showed that BMVC significantly killed TC-1 tumor cells at light dose greater than 40 J/cm(2). The fluorescence of BMVC in the tumor peaked at 3 hours and then gradually decreased to reach the control level after 24 hours. In vivo tumor treatment studies showed BMVC plus light irradiation (iPDT) significantly inhibited the tumor growth. At day 24 after tumor implantation, tumor volume was measured to be 225 ± 79 mm(3), 2542 ± 181 mm(3), 1533 ± 766 mm(3), and 1317 ± 108 mm(3) in the iPDT, control, light-only, and BMVC-only groups, respectively. Immunohistochemistry studies showed the microvascular density was significantly lower in the iPDT group. Taken together, our results demonstrated that BMVC may be a potent tumor-specific photosensitizer (PS) for PDT.

Photodynamic therapy of disseminated non-small cell lung carcinoma in a murine model

BACKGROUND AND OBJECTIVE

Photodynamic therapy (PDT) of thoracic malignancies involving the pleural surfaces is an active area of clinical investigation. The present report aims to characterize a model for PDT of disseminated non-small cell lung carcinoma (NSCLC) grown orthotopically in nude mice, and to evaluate the effect of PDT on tumor and normal tissues.

STUDY DESIGN

H460 human NSCLC cells were injected percutaneously into the thoracic cavity of nude mice. HPPH-PDT (1 mg/kg, 24 hours) was performed via the interstitial delivery (150 mW/cm) of 661 nm light to the thoracic cavity at fluences of 25-200 J/cm.

RESULTS

H460 tumors exhibited exponential growth within the thoracic cavity consisting of diffuse, gross nodular disease within 9 days after intrathoracic injection. Tumor volume, measured by magnetic resonance imaging (MRI), was highly correlated with the aggregate tumor mass extracted from the corresponding animal. Intrathoracic PDT at fluences of ≥50 J/cm produced significant decreases in tumor burden as compared to untreated controls, however, mortality increased with rising fluence. Accordingly, 50 J/cm was selected for MRI studies to measure intra-animal PDT effects. Tumor distribution favored the ventral (vs. dorsal), caudal (vs. cranial), and right (vs. left) sides of the thoracic cavity by MRI; PDT did not change this spatial pattern despite an overall effect on tumor burden. Histopathology revealed edema and fibrin deposition within the pulmonary interstitium and alveoli of the PDT-treated thoracic cavity, as well as occasional evidence of vascular disruption. Prominent neutrophil infiltration with a concomitant decline in the lymphocyte compartment was also noted in the lung parenchyma within 24 hours after PDT.

CONCLUSION

HPPH-PDT of an orthotopic model of disseminated NSCLC is both feasible and effective using intracavitary light delivery. We establish this animal model, together with the treatment and monitoring approaches, as novel and valuable methods for the pre-clinical investigation of intrathoracic PDT of disseminated pleural malignancies.

Improved in vivo delivery of m-THPC via pegylated liposomes for use in photodynamic therapy

Pegylated liposomal nanocarriers have been developed with the aim of achieving improved uptake of the clinical PDT photosensitiser, m-THPC, into target tissues through increased circulation time and bioavailability. This study investigates the biodistribution and PDT efficacy of m-THPC in its standard formulation (Foscan®) compared to m-THPC incorporated in liposomes with different degrees of pegylation (FosPEG 2% and FosPEG 8%), following i.v. administration to normal and tumour bearing rats. The plasma pharmacokinetics were described using a three compartmental analysis and gave elimination half lives of 90 h, 99 h and 138 h for Foscan®, FosPEG 2% and 8% respectively. The accumulation of m-THPC in tumour and normal tissues, including skin, showed that maximal tumour to skin ratios were observed at ≤ 24 h with FosPEG 2% and 8%, whilst skin photosensitivity studies showed Foscan® induces more damage compared to the liposomes at drug-light intervals of 96 and 168 h. PDT treatment at 24h post-administration (0.05 mg kg⁻¹) showed higher tumour necrosis using pegylated liposomal formulations in comparison to Foscan®, which is attributed to the higher tumour uptake and blood plasma concentrations. Clinically, this improved selectivity has the potential to reduce not only normal tissue damage, but the drug dose required and cutaneous photosensitivity.

Temoporfin (Foscan®, 5,10,15,20-tetra(m-hydroxyphenyl)chlorin)--a second-generation photosensitizer

This review traces the development and study of the second-generation photosensitizer 5,10,15,20-tetra(m-hydroxyphenyl)chlorin through to its acceptance and clinical use in modern photodynamic (cancer) therapy. The literature has been covered up to early 2011.

Photodynamic therapy for treatment of solid tumors--potential and technical challenges

Photodynamic therapy (PDT) involves the administration of photosensitizer followed by local illumination with visible light of specific wavelength(s). In the presence of oxygen molecules, the light illumination of photosensitizer can lead to a series of photochemical reactions and consequently the generation of cytotoxic species. The quantity and location of PDT-induced cytotoxic species determine the nature and consequence of PDT. Much progress has been seen in both basic research and clinical application in recent years. Although the majority of approved PDT clinical protocols have primarily been used for the treatment of superficial lesions of both malignant and non-malignant diseases, interstitial PDT for the ablation of deep-seated solid tumors are now being investigated worldwide. The complexity of the geometry and non-homogeneity of solid tumor pose a great challenge on the implementation of minimally invasive interstitial PDT and the estimation of PDT dosimetry. This review will discuss the recent progress and technical challenges of various forms of interstitial PDT for the treatment of parenchymal and/or stromal tissues of solid tumors.

The study of the characteristic of photocytotoxicity under high peak power pulsed irradiation with ATX-S10Na(II) in vitro

We studied hydrophilic photosensitizer ATX-S10Na(II) mediated photocytotoxicity against macrophage-like cell under pulsed irradiation. We found that photocytotoxicity suppression under high intensity irradiation was directly induced by a decrease in the Type-II photoreaction. We showed that this decrease was not attributable to absorption saturation with the high intensity irradiation. We found the cell lethality change from 70% to 13% with the pulse peak power density ranging from 0.29 MW/cm(2) to 1.36 MW/cm(2), at the light dose of 20 J/cm(2) and the pulse repetition rate at 40 Hz. To investigate the Type-II reaction, we measured the photobleaching, oxygen consumption and singlet oxygen luminescence of the photosensitizer solution. The transient absorption from the photosensitizer during the irradiation was measured with the pump-and-probe technique. We believe that the photocytotoxicity suppression induced by the high intensity irradiation might be useful for the treatment of depth-controlled photodynamic therapy without the wall damage of a hollow organ.

Microwave coagulation therapy in canine peripheral lung tissue

BACKGROUND

New modalities for local treatments that destroy tumor effectively but which are less invasive and less damaging to normal lung tissue must be developed for patients who are unable to undergo even video-assisted thoracic surgery (VATS) due to poor cardiopulmonary function, severe adhesion, or advanced age, etc. We evaluated the use of microwave coagulation therapy (MCT), which has been used successfully for coagulation of hepatic tumors, in normal canine lung tissue to evaluate its efficacy and safety.

MATERIALS AND METHODS

Measurements of thermal response and coagulation area and histological examinations after microwave coagulation were performed in normal canine lung tissue.

RESULTS

The temperature in normal canine lung tissue increased to 90-100 degrees C at 5 mm from the electrode after 60 s and 70-80 degrees C at 10 mm after 90 s at 40 or 60 W. The coagulation area was approximately 20 mm in diameter at 40 W and 60 W. Histological analysis demonstrated thickening of collagen fiber shortly after coagulation, stromal edema and granulation tissue after 3 months, and, finally, scar tissue was seen after 6 months.

CONCLUSIONS

Microwave coagulation therapy (MCT) is a useful modality for minimally invasive therapy in peripheral lung tumors.

Photodynamic therapy for peripheral lung cancer

Photodynamic therapy (PDT) has now achieved the status of a standard treatment modality for centrally located early-stage lung cancer. In the last decade, CT screening for lung cancer has attracted much attention for its ability to detect early peripheral lung cancer. Extremely recently, treatment using PDT has been introduced for the first time in patients with peripheral lung cancer, who did not meet the previous criteria for surgery. The procedure was carried out with local anesthesia with xylocain infiltrated into the chest wall, 48 h after Photofrin administration. Needles (19 gauge) containing an internal catheter were inserted percutaneously under CT guidance. The needles were then extracted and a diffuser fiber with a 2 cm long tip for light delivery was positioned in the tumor through the catheter. Of the nine patients enrolled in this trial, seven achieved partial remission (PR). No serious complications, except for two cases of pneumothorax, were noted. As an increasing number of patients consider quality of life after therapy, the indications for PDT are expected to expand. We conclude that PDT is a promising new technique for curative treatment of localized, peripheral lung cancer less than 1cm in size in patients who are unfit for surgery or radiotherapy.

Intracellular photobleaching of 5,10,15,20-tetrakis(m-hydroxyphenyl) chlorin (Foscan) exhibits a complex dependence on oxygen level and fluence rate

The understanding of photosensitizer photobleaching is important not only for mechanistic studies, but also for the development of monitoring techniques for clinical dosimetry in photodynamic therapy. In this study, we investigated the intracellular photobleaching of 5,10,15,20-tetrakis(m-hydroxyphenyl)chlorin (mTHPC, Foscan) in the murine macrophage cell line J774A.1, using quantitative fluorescence imaging microscopy, microspectrofluorometry and microspectrophotometry. Using 652 nm laser irradiation, it was found that mTHPC exhibits oxygen- and fluence rate-dependent intracellular photobleaching. The kinetics showed an inverse dose-rate behavior, i.e. a reduction of fluence rate resulted in more photobleaching at comparable fluences. The effect of deoxygenation was found to be more complex, with decreased bleaching at low fluence rates and increased bleaching at higher fluence rates. The intracellular formation of reactive oxygen species was measured using 2',7'-dichlorodihydrofluorescein diacetate. The results are analyzed in terms of competitive Type-I and Type-II mechanisms.

Bronchoscopic photodynamic diagnosis and therapy for lung cancer

Photodynamic diagnosis and therapy have exciting potential in lung cancer management. Fluorescence bronchoscopy enhances the detection of preinvasive lesions and early invasive carcinomas involving the central airways, whereas photodynamic therapy (PDT) provides an effective method for treating these lesions with preservation of lung tissue. However, the natural history of preinvasive lesions is poorly understood and so the value of treatment remains unclear. Although treatment for early invasive carcinomas'is not open to question, the possibility of undetected nodal disease means that PDT is unlikely to replace surgical resection in patients who are fit for thoracotomy. PDT also provides an effective method of palliating patients with advanced obstructing endobronchial tumors. Although it is considered superior to simple tumor debulking, its usefulness is limited by transient but potentially severe skin photosensitivity. There is therefore a need to develop new photosensitizing drugs with less severe side effects.