Experimental studies to assess the potential of photodynamic therapy for the treatment of bronchial carcinomas

Integration of interventional bronchoscopy in the management of lung cancer

Tracheal or bronchial proximal stenoses occur as complications in 20-30% of lung cancers, resulting in a dramatic alteration in quality of life and poor prognosis. Bronchoscopic management of these obstructions is based on what are known as "thermal" techniques for intraluminal stenosis and/or placement of tracheal or bronchial prostheses for extrinsic compressions, leading to rapid symptom palliation in the vast majority of patients. This invasive treatment should only be used in cases of symptomatic obstructions and in the presence of viable bronchial tree and downstream parenchyma. This review aims to clarify 1) the available methods for assessing the characteristics of stenoses before treatment, 2) the various techniques available including their preferred indications, outcomes and complications, and 3) the integration of interventional bronchoscopy in the multidisciplinary management of proximal bronchial cancers and its synergistic effects with the other specific treatments (surgery, radiotherapy or chemotherapy).

Photodynamic therapy using methylene blue in lung adenocarcinoma xenograft and hamster cheek pouch induced squamous cell carcinoma

BACKGROUND

Photodynamic therapy (PDT) is used to treat early proximal bronchial cancer during a flexible bronchoscopy. The technique relies on the excitation of a photosensitizer by an appropriate wavelength, which is delivered into the bronchus in close contact with the tumor.

OBJECTIVE

To assess methylene blue (MB) as a PDT agent for the treatment of respiratory tract cancer in animal models.

METHODS

MB-induced PDT was performed on 7 subcutaneous NCI-H460 lung adenocarcinoma xenografts in nude mice and 9 induced squamous cell cancer in the hamster cheek pouch model. In mice, PDT was carried out on right-sided tumors after intratumoral injection of methylene blue 1% (w/v) and illumination at 630nm at 200J/cm (Diomed PDT 630), with the left tumor used as control (illumination alone or MB alone). The tumoral volume was assessed before and 15 days after PDT.

RESULTS

Fourteen xenografts were treated in mice, including seven treated with MB-PDT, producing a 52% mean tumor volume regression (1568mm(3)vs. 544mm(3)) compared to seven control cases in which tumor volume increased (p=0.007; Mann-Whitney test). Nine cheek pouch induced carcinomas were treated in the hamster group, with a mean volume decrease of 85.8% (from 44.8% to 100%) (initial mean volume=210mm(3)vs. post PDT mean volume=97mm(3)). Histology analysis showed 4/9 complete responses.

CONCLUSION

Intratumoral MB appears efficient as PDT agent for cancer treatment in animal models. Further studies are needed to assess the safety and efficacy of MB-associated PDT for the treatment of lung cancer in humans.

Photodynamic therapy in the management of endobronchial metastatic lesions from renal cell carcinoma

STUDY OBJECTIVES

Bronchoscopic procedures to ablate endobronchial lesions (EBL) from renal cell carcinoma (RCC) are frequently complicated by hemorrhage because of the vascular nature of the metastases. After ablation, recurrence of symptoms from the EBLs is common. Photodynamic therapy (PDT), because of its mode of action, may be a safer and a more effective alternative in the nonemergent management of EBL from RCC.

METHODS

Medical records of patients undergoing PDT at the authors' institutions between December 2005 and December 2008 were reviewed and patients undergoing treatment for EBLs from RCC were identified. Procedure-related complications, 30-day mortality, and efficacy of PDT measured by recurrence in symptoms and the need for additional interventions on the treated EBLs were reviewed.

RESULTS

Eleven patients underwent a total of 13 treatments with PDT. Hemoptysis, with or without symptomatic airway obstruction, was the most common presenting symptom. The most common location for the EBLs was the lobar or segmental bronchi. Six patients had undergone other interventions (rigid bronchoscopy, mechanical debridement, or argon plasma coagulation) before treatment with PDT, with recurrence in symptoms. No immediate complications were seen with PDT and none of the patients had recurrence of symptoms or required airway interventions during the 30-day follow-up. Four patients died at a median of 4 months (range: 3 to 6 mo) after PDT and all deaths were due to progression of cancer and none of the deaths were due to airway complications.

CONCLUSIONS

PDT is a safe and effective option for the management of hemoptysis or airway obstruction caused by EBLs from RCC.

The role of interventional pulmonary procedures in the management of post-obstructive pneumonia

Post-obstructive pneumonia is the result of airway obstruction, commonly due to lung cancer. The majority of patients with lung cancer are non-operable and incurable at initial presentation. The clinical course of these patients is steadily downhill with complicating events such as post-obstructive pneumonia, respiratory failure, pleural effusion, and severe debilitation. Non-invasive conventional options for post-obstructive pneumonia include broad-spectrum antibiotics, combined with attempts at relieving the obstruction using radiation therapy. There is scant literature on the natural course of post-obstructive pneumonia, disease resolution, and optimal treatment. With the recent surge in technologic advances in interventional pulmonology, multiple airway recanalizaton options are now available. In this paper, we describe the causes of post-obstructive pneumonia, and the role of interventional pulmonary procedures in -establishing an open airway.

Emerging technologies for the thorax: indications, management and complications

The field of interventional pulmonology has rapidly expanded to include the management and treatment of complex diseases of the chest. The management of central airway obstruction, pleural disease diagnosis, treatment and palliation, advanced bronchoscopic techniques to aid in the diagnosis of lung cancer and innovative therapies to treat asthma and COPD have all emerged over the past decade. As astute clinicians, we are all aware of the risks and benefits of using these therapies to treat our patients. In order to appropriately treat and manage these often complex medical situations, the physician should have an expert knowledge of all available modalities, the expertise to safely perform the procedure and the ability to minimize the risk of and manage the associated complications that may arise. In this chapter we review and update some of the bronchoscopic and pleural interventions offered by interventional pulmonologists as well as the associated complications and management.

Central Airway Obstruction

Central airway obstruction is a problem facing all medical and surgical subspecialists caring for patients with chest diseases. The incidence of this disorder appears to be rising because of the epidemic of lung cancer; however, benign causes of central airway obstruction are being seen more frequently as well. The morbidity is significant and if left untreated, death from suffocation is a frequent outcome. Management of these patients is difficult, but therapeutic and diagnostic tools are now available that are beneficial to most patients and almost all airway obstruction can be relieved expeditiously. This review examines current approaches in the workup and treatment of patients suffering from airway impairment. Although large, randomized, comparative studies are not available, data show significant improvement in patient outcomes and quality of life with treatment of central airway obstruction. Clearly, more studies assessing the relative utility of specific airway interventions and their impact on morbidity and mortality are needed. Currently, the most comprehensive approach can be offered at centers with expertise in the management of complex airway disorders and availability of all endoscopic and surgical options.

The advantages of aminolevulinic acid photodynamic therapy in dermatology

Photodynamic therapy (PDT) is being increasingly employed in the detection and treatment of malignant and non-malignant disease. This local technique uses a photosensitizing drug activated by light to generate cell death via the production of reactive oxygen species. This review describes the fundamental processes behind PDT, focussing on the use of 5-aminolevulinic acid (ALA). ALA itself is not a photosensitizing drug, but administration of exogenous ALA induces the build-up of the natural endogenous photosensitizer protoporphyrin IX (PpIX). This form of PDT has proved promising for the treatment of a number of dermatological indications. An overview of these current and potential applications of ALA-based PDT is presented, with emphasis on the advantages of the technique that make it especially suitable for skin conditions and the problem areas on which future research should be focussed.

Photodynamic therapy: a case series demonstrating its role in patients receiving mechanical ventilation

Photodynamic therapy (PDT) has long been used to treat cancers within the tracheobronchial tree. There have been many reports about the use of PDT for the treatment of carcinoma in situ and for obstructive endobronchial lesions. PDT has not been previously reported in patients receiving mechanical ventilation. PDT offers the advantages of a relatively short duration of treatment, a low side effect profile, and relatively low risk when compared to Nd-YAG laser in patients receiving mechanical ventilation. We report the first successful use of PDT to wean patients from mechanical ventilation.

Endobronchial photodynamic therapy: comparison of mTHPC and polyethylene glycol-derived mTHPC on human tumor xenografts and tumor-free bronchi of minipigs

BACKGROUND AND OBJECTIVE

Photodynamic therapy (PDT) with mTHPC and polyethylene glycol-derived mTHPC (pegylated mTHPC) was compared on nude mice bearing human squamous cell carcinoma and adenocarcinoma xenografts. The same treatment regimens were applied to the bronchi of tumor-free minipigs to assess injury to normal tissue.

STUDY DESIGN/MATERIALS AND METHODS

Laser light (652 nm, 20 J/cm2) was delivered as surface radiation to the xenografts 4 days after intraperitoneal administration of 0.1 mg/kg mTHPC or an equimolar dose of pegylated mTHPC, respectively. The extent of tumor necrosis was assessed by histomorphometry. Endobronchial PDT was performed on the bronchi of minipigs with the same drug and light doses at drug-light intervals ranging from 12-96 hr.

RESULTS

Both sensitizers produced larger necrosis of squamous cell carcinoma and adenocarcinoma xenografts than was observed in untreated controls (P < 0.005). Pegylated mTHPC led to larger tumor necrosis than mTHPC in squamous cell carcinoma (P < 0.001), but not in adenocarcinoma xenografts. mTHPC-PDT resulted in ulceration and necrosis of bronchial mucosa in minipigs at drug-light intervals ranging from 12-48 hr, which was not observed after use of pegylated mTHPC.

CONCLUSIONS

In this setting, pegylated mTHPC had advantages as a photosensitiser compared to mTHPC.

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

STUDY OBJECTIVE

To look at the effect of interstitial photodynamic therapy (PDT) in normal lung parenchyma to assess its potential for treating localized, peripheral lung tumors.

DESIGN

Studies were performed on normal Wistar rats using the photosensitizer meso-tetrahydroxyphenyl chlorine. Drug distribution was measured by fluorescence microscopy on tissue sections. Light was delivered to the lungs via a single fiber inserted percutaneously under x-ray control and the PDT effect studied in animals killed at times up to 6 months later.

RESULTS

Fluorescence studies showed that the drug was initially distributed throughout the lung, but was later predominantly in the vasculature, bronchi, and macrophages. PDT produced sharply defined zones of hemorrhagic necrosis up to 12 mm in diameter that healed with regeneration of bronchial epithelium and local fibrosis. Different histologic effects were seen between drug light intervals of 1 and 3 days. Treatment was well tolerated, there was a low incidence of pneumothorax, and as long as the fiber tip was within the lung parenchyma, there was no damage to adjacent tissues.

CONCLUSION

Interstitial PDT produces zones of necrosis in normal lung that heal safely by a percutaneous technique without affecting adjacent areas of untreated lung. If the lesion size can be increased by using multiple fibers, this could be a promising new technique for treating localized, peripheral lung cancers in patients who are unfit for surgery.

Clinical photodynamic therapy for superficial cancer in the oesophagus and the bronchi: 514 nm compared with 630 nm light irradiation after sensitization with Photofrin II

Photodynamic therapy (PDT) for cancer in the oesophagus and bronchi with red (630 nm) light may occasionally lead to wall perforation and fistula. Therefore, we investigated the clinical use of a less penetrating wavelength (514 nm) for the curative treatment of nine superficial carcinomas in the oesophagus and bronchi after photosensitization with Photofrin II. Tumours without infiltration beyond the submucosa in the oesophagus and beyond the lamina propria in the bronchi were considered as superficial cancers. The outcome and complications were compared with those of 13 superficial cancers treated with PDT and 630 nm light. In addition, we evaluated histologically the extent of the long-term tissue damage and scarring following treatment of six oesophageal cancers with either green or red light. At first endoscopic control, 7-10 days after PDT, tissue necrosis simply matched the illuminated area, without evidence of selective tumour damage. Six of nine tumours treated with 514 nm light had a complete response compared with nine of 13 after 630 nm irradiation. No perforation or fistula occurred in either treatment group. However, severe chest pain and fever with or without pleural effusion, consistent with occult perforation, were observed in three patients after 630 nm illumination in the oesophagus. Histologically, fibrous scarring in the three distinct sites treated with green light was limited to the superficial layers of the oesophagus. After red light treatment, transmural fibrosis with marked thinning of the oesophageal wall was evident in two of the three specimens available for inspection. These results indicate that PDT with 514 nm light has the potential to cure superficial cancer in the oesophagus and bronchi with essentially the same probability of success as red light. In the oesophagus, green light prevents deep tissue damage, thus reducing the risk of perforation.

Photodynamic therapy: an effective, but non-selective treatment for superficial cancers of the oral cavity

It has often been claimed that photodynamic therapy (PDT) produces selective destruction of small cancers without affecting the adjacent normal tissue. The objective of our work was to treat small cancers of the oral cavity with PDT and subsequently excise the treated areas for histological studies of tumour and adjacent normal tissue exposed to the same light dose. Eleven patients with histologically proven T1NO oral squamous-cell carcinomas were treated with PDT, using Photofrin as a sensitiser. The tumours plus a surrounding cuff of normal tissue were exposed to 50 J/cm2 non-thermal laser light at 630 nm delivered by surface illumination and the treated areas subsequently excised. Histological staining and image analysis were used to determine the nature and extent of injury. No macroscopic distinction was evident between tumour and normal tissue exposed to light. Histologically, replacement of superficial epithelium, tumour and connective tissue with a fibrinous necrotic slough was seen. There was also loss of endothelium from small vessels, with haemorrhage and thrombosis. Preservation of subepithelial collagen and elastin was demonstrated with EVG staining. No evidence of selective tumour necrosis was found. Although depth of injury was variable, full thickness mucosal necrosis occurred in all cases.

Photodynamic therapy in lung cancer. A review

Photodynamic therapy (PDT) in lung cancer was introduced in 1980 to treat tumours located in the major airways. After systemic injection of photosensitizers, tumour illumination is performed using a laser fibre to transmit light of a specific wavelength. PDT can be performed under local anaesthesia using the flexible fibreoptic bronchoscope. Skin photosensitivity is the most important treatment morbidity caused by the prolonged cutaneous retention of photosensitizer molecules. Ample data have shown that PDT is effective in obtaining tumour necrosis, but the skin photosensitivity issue limits its palliative potential. Moreover, competing bronchoscopic techniques, such as electrosurgery, Nd-YAG laser and brachytherapy, are available and seem to be equally palliative for the debulking of intraluminal obstructive lung tumours. The curative potential of PDT in patients with roentgenologically occult lung cancer is the most interesting aspect of this treatment modality. A significant number of patients with lung cancer have limited pulmonary function. A normal tissue sparing treatment such as PDT may provide an alternative, as patients may also have subsequent multiple lung cancer primaries. Since early lung cancer detection is now becoming feasible, PDT may be applied to treat roentgenologically occult tumours with curative intent. This may optimize treatment efficacy in the near future.

Photodynamic therapy on the normal rabbit larynx with phthalocyanine and 5-aminolaevulinic acid induced protoporphyrin IX photosensitisation

Photodynamic therapy (PDT) is a promising technique for the treatment of small tumours in organs where it is essential to minimise damage to immediately adjacent normal tissue as PDT damage to many tissues heals by regeneration rather than scarring. As preservation of function is one of the main aims of treating laryngeal tumours, this project studied the effects of PDT on the normal rabbit larynx with two photosensitisers, endogenous protoporphyrin IX (PPIX) induced by the administration of 5-aminolaevulinic acid (ALA) and disulphonated aluminium phthalocyanine (AIS2Pc). The main aims of the study were to examine the distribution of protoporphyrin IX and AIS2Pc by fluorescence microscopy in the different regions of the larnyx and to assess the nature and subsequent healing of PDT damage. Peak levels of PPIX were found 0.5-4 h after administration of ALA (depending on dose) with highest levels in the epithelium of the mucosa. With 100 mg kg-1, PDT necrosis was limited to the mucosa, whereas with 200 mg kg-1 necrosis extended to the muscle. With 1 mg kg-1 AIS2Pc, 1 h after administration, the drug was mainly in the submucosa and muscle, whereas after 24 h, it was predominantly in the mucosa. PDT at 1 h caused deep necrosis whereas at 24 h it was limited to the mucosa. All mucosal necrosis healed by regeneration whereas deeper effects left some fibrosis. No damage to cartilage was seen in any of the animals studied. The results of this study have shown that both photosensitisers are suitable for treating mucosal lesions of the larynx, but that for both it is important to optimise the drug dose and time interval between drug and light to avoid unacceptable changes in normal areas.

The effect of photodynamic therapy on the mechanical integrity of normal rabbit carotid arteries

Photodynamic therapy (PDT) for tumor ablation is effective in the treatment of superficial cancers. Adjunctive intraoperative PDT has been proposed for the "sterilization" of tumor beds after the resection of malignancies. Arteries in photosensitized animal models exposed to appropriate light receive characteristic injury. This study was conducted to determine whether photodynamic injury to the rabbit carotid artery results in thrombotic occlusion or weakening of the vessel wall. PDT of the carotid arteries of New Zealand white rabbits, using either disulphonated aluminum phthalocyanine or 5-aminolevulinic-acid-induced protoporphyrin IX as the photosensitizer, was performed with a light dose of 100 J/cm2. Histologic examination of the carotids treated with either agent demonstrated typical full-thickness loss of cellularity 3 days after PDT. All vessels remained patent, and no inflammatory infiltrate was evident. Elastin van Gieson staining showed preservation of inner and medial elastic laminae and medial and adventitial collagen. Additional rabbits were similarly treated with PDT to 1-cm segments of both common carotid arteries. The animals were sacrificed at 3, 7, and 21 days. The carotids were exposed, and both control and treated segments were subjected to intraluminal hydrostatic distention until the vessels burst. No reduction in the pressure required to burst the vessels was evident in the treated vessels as compared with the control vessels. The authors of the study concluded that despite full-thickness cell death, PDT-treated arteries are not at risk for thrombotic occlusion or hemorrhage.

Bronchoscopic treatment of lung tumors

Several bronchoscopic techniques for the treatment of patients with tracheobronchial pathology have become available during the last decade. Technical development and additional instruments have provided the bronchoscopist with several alternatives for bronchoscopic therapeutic interventions. The majority of patients with malignant tracheobronchial neoplasm have a dismal prognosis. Palliation is the main aim of the treatment. However, in patients with an early-stage tumor, bronchoscopic treatment may have a curative potential. Resectability, after tumor reduction by a bronchoscopic treatment, may be improved. This article discusses various bronchoscopic techniques, the advantages and disadvantages of each method and the possible benefit which can be derived from such a treatment.