Photodynamic therapy of the ciliary body with tin ethyl etiopurpurin and tin octaethyl benzochlorin in pigmented rabbits

BACKGROUND AND OBJECTIVES: The authors used a pigmented rabbit model to investigate two photosensitizers, tin ethyl etiopurpurin (SnET2) and tin octaethyl benzochlorin (BNZ 203), to determine their potential for creating ciliary body injuries during photodynamic therapy (PDT). MATERIALS AND METHODS: The biodistribution of SnET2 (n = 10) and BNZ 203 (n = 9) was studied by fluorescence microscopy using a low light detection system, based on charged-coupled device photography, with digital image processing at 1 and 24 hours after injection. PDT with SnET2 (n = 8; 664 +/- 7-nm light; 75 mW/cm2; 50 or 100 J/cm2; 1-mm spot size) and BNZ 203 (n = 6; 689 nm; 75 mW/cm2; 50 or 100 J/cm2; 1-mm spot size) was performed at 24 hours post-injection. The control subjects for SnET2 (n = 5) and BNZ 203 (n = 3) were given a maximal light dose (100 J/cm2). RESULTS: Both photosensitizers demonstrated an intravascular distribution at 1 hour that shifted to a ciliary body distribution at 24 hours (SnET2 much greater than BNZ 203). In addition, the SnET2 demonstrated suborgan localization to the nonpigmented ciliary body epithelium. Both photosensitizing agents were able to produce selective injury to the rabbit ciliary body (SnET2 much greater than BNZ 203), with evidence of a small component of thermal damage (SnET2 greater than BNZ 203). CONCLUSIONS: PDT with SnET2 or BNZ 203 can produce selective injury to the pigmented rabbit ciliary body. The nonpigmented ciliary body epithelium exhibits selective retention of SnET2. This finding warrants further investigation.     

Photodynamic therapy with local photosensitizer delivery inhibits experimental intimal hyperplasia

BACKGROUND: Photodynamic therapy (PDT), the light activation of photosensitizer dyes for the production of free radicals, effectively inhibits experimental intimal hyperplasia with systemic administration of the photosensitizer. The local application of the photosensitizer directly into a vascular lesion to avoid systemic side effects and tightly control dose administration has theoretical appeal. The aim of this study was to quantify serum and arterial tissue uptake after site-specific photosensitizer delivery and, following PDT, determine its effectiveness at inhibiting intimal hyperplasia. STUDY DESIGN/MATERIALS AND METHODS: The rat common carotid artery was balloon-injured, pressurized at 400 mm Hg for 2 minutes with the photosensitizer dye benzoporphyrin-derivative (BPD), and irradiated with 690 nm laser light at a fluence of 100 J/cm2. Control animals were pressurized with saline only, or received no additional treatment than balloon-injury. RESULTS: Pressurization with BPD resulted in complete penetration of the intima and media and was associated with relatively high tissue, but almost no detectable serum BPD concentrations. No skin photosensitization or other systemic side effects were observed with photosensitizer administration. After 9 days, PDT-treated arteries displayed a significantly lower number of smooth muscle cells in the arterial wall than balloon-injured (P < 0.001) or saline-pressurized arteries (P < 0.0002), and no intimal hyperplasia. At 21 days, IH after PDT was significantly reduced as compared with balloon-injured (P < 0.0004), or saline-pressurized arteries (P < 0.003) with no arterial dilatation. CONCLUSIONS: Site-specific delivery of liposomal BPD followed by PDT represents a safe method to treat arteries, and may be effectively used in vivo to inhibit the development of intimal hyperplasia.     

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.     

Effects of organophosphorus, carbamate, pyrethroid and organochlorine pesticides, and a heavy metal on survival and cholinesterase activity of Chironomus riparius Meigen

BACKGROUND & AIMS: The first therapeutic experiences with the conventional photosensitizer dihematoporphyrinester in the treatment of Barrett's esophagus show the curative potential of photodynamic therapy (PDT). The aim of this study was to test 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX, a photosensitizer with a high mucosa specificity without phototoxic side effects on the skin, as a new form of PDT. METHODS: Thirty-two patients (mean age, 68.5 years) with histologically proven high-grade dysplasia (n = 10) and mucosal cancer (n = 22) in Barrett's esophagus were treated. Four to 6 hours after oral ingestion of 5-ALA (dose, 60 mg/kg body wt), irradiation was conducted with a dye laser system (635 nm) with a light dose of 150 J/cm2. The patients received 20-80 mg omeprazole daily after PDT. RESULTS: High-grade dysplasia was eradicated in all patients (10 of 10), and mucosal cancer was eliminated in 17 of 22 patients (77%) at a mean follow-up of 9.9 months (range, 1-30 months). All tumors < or = 2 mm in thickness were completely ablated (17 of 17). The method-related mortality and morbidity was 0%. CONCLUSIONS: Severe dysplasia and thin (< or = 2 mm) mucosal cancer of Barrett's esophagus can be completely ablated. PDT might offer a minimally invasive treatment modality as an alternative to esophagectomy.     

Rapid tapering of cyclosporine for cytogenetic relapse shortly after bone marrow transplantation in a patient with chronic myeloid leukemia

A new therapy for the treatment of oral leukoplakia by 5-aminolevulinic acid (ALA) and photodynamic therapy (PDT) is presented. ALA, a precursor in the biosynthesis of haeme, induces the production of the endogenous photosensitizer protoporphyrin IX which can be used for PDT. Twelve patients, who had been suffering from leukoplakia of the oral mucosa for several years, were treated by ALA-mediated PDT. ALA was used as a topical photosensitizer and 20% ALA cream was applied to the leukoplakia lesion of the oral mucosa for two hours and then light activated at 630 nm, 100 mW/cm2 and 100 J/cm2. Five patients showed complete response to the treatment, four patients showed a partial response and in three patients treatment was unsuccessful. One patient with partial response was retreated, after which the lesion disappeared.     

Role of CT in patients with prostatic disease: usefulness of depiction of prostatic zonal anatomy

The purpose of this study was to evaluate the role of CT in patients with and without prostatic disease. CT and MR findings were reviewed in 25 patients without known prostatic disease, 11 patients with benign prostatic hyperplasia and 11 patients with prostatic cancer. Differential attenuation allowed for distinction of the peripheral zone and inner gland of the prostate by CT in 72% of normal patients. The distinction rate of prostatic zonal anatomy by CT decreased to 30% in the diseased group. When zonal anatomy of the prostate is not visualized on pelvic enhanced CT, the presence of prostatic disease might be considered.     

Feasibility of photodynamic therapy using endogenous photosensitization for colon cancer

A novel approach to photodynamic therapy (PDT) involves endogenous photosensitization by the oral administration of delta-aminolevulinic acid (ALA), a naturally occurring substance that is the precursor of protoporphyrin IX (PpIX). A 60-year-old man with adenocarcinoma of the sigmoid colon received ALA, 60 mg/kg by mouth. Six hours later, when the plasma level of PpIX had peaked, the tumor was exposed locally to red light at 633 nm to activate PpIX. Endoscopy and biopsy findings subsequent to this treatment showed unequivocal visible changes and necrosis. Six months later, the patient again underwent successful treatment without adverse effects. This report suggests a role for PDT using endogenous photosensitization in certain circumstances involving adenocarcinoma of the large intestine.     

Cholestasis assessment by activity of antioxidant enzymes and composition of plasma lipoproteins in patients with liver diseases]

23 patients with benign prostatic hyperplasia (BPH) aged 60-82 years underwent transurethral resection (TUR) of the prostate in different periods after thermal treatment which had appeared uneffective or brought complications. In the performance of the endoscopic techniques we found macroscopic changes of the prostatic parts of the urethra and bladder cervix characteristic for certain thermal impact (energy, power, site of exposure). Intraoperative bleeding of prostatic tissue was also different depending primarily on the time which had passed after the thermal treatment. Minimal bleeding occurred at least 3 months after the thermotherapy. Thus, thermal treatment of the prostate can be used in combined treatment of BPH for reducing intra- and postoperative hemorrhage due to subsequent TUR. Among the methods of thermal therapy, transurethral microwave thermotherapy is preferable as minimally invasive and deeply penetrating into the depth of the prostatic gland with maximal effect. TUR of the prostate should be performed not earlier than 3 months after thermotherapy which is indicated only for patients at high risk of intraoperative hemorrhage because of unaffected circulation. Therefore, it is desirable to include transrectal dopplerography of the prostate to urological examination of BPH patients.     

Pharmacological characterization of nociceptin receptor: an in vitro study

Pancreatic cancer is difficult to treat, even for tumours localized to the pancreas. Photodynamic therapy (PDT) is a non-thermal technique for producing localized tissue necrosis with light after prior administration of a photosensitizing drug and it could have a role in the local treatment of these cancers. We studied PDT in a transplanted cancer in the hamster pancreas using the photosensitizer mTHPC (meta-tetrahydroxyphenylchlorin). Fluorescence microscopy showed maximum levels of mTHPC in normal pancreas 2-4 days after sensitization and in tumour at 4-5 days. For PDT, animals were given 0.1 or 0.3 mg kg(-1) mTHPC and the tumour was treated at laparotomy 2 or 4 days later with red light (50 J at 650 nm, continuous or fractionated) delivered via a single fibre touching the tumour surface. The maximum zone of tumour necrosis (seen 3 days after PDT) was 8.7 mm in diameter with continuous irradiation, increasing to 12.4 mm with light fractionation (four equal fractions with 3 min between fractions). The main complication was sealed duodenal perforation, seen in 3 of 16 animals, probably due to inadequate shielding of the duodenum from the light. The duodenal problems seen in hamsters are unlikely to cause trouble in the much thicker human duodenum. PDT tumour necrosis in this animal model has now been shown with a range of photosensitizers, but mTHPC is attractive as it is likely to produce the largest volumes of necrosis around each treatment point with short light exposure times. This technique could have a role in the treatment of localized cancers of the pancreas in patients unsuitable for surgery and can now be considered for preliminary clinical trials.     

Photodynamic therapy using SnET2 for basal cell nevus syndrome: a case report

A 26-year-old man with basal cell nevus syndrome presented to the Rocky Mountain Cancer Center (Denver, Colorado) for treatment of several basal cell carcinomas with photodynamic therapy using tin ethyl etiopurpurin (SnET2). The patient was of northern European descent, had type I skin (always burns, never tans), and had a 10-year history of multifocal basal cell carcinomas. The patient had a family history of Gorlin's syndrome (basal cell nevus syndrome); the syndrome had been diagnosed in this patient in 1985. The patient was enrolled in a Phase I/II clinical trial. He was given 1.2 mg/kg (94 mg total) of SnET2 via intravenous infusion; he returned to the clinic the following day for red light application. Thirteen lesions, in 12 treatment fields, were illuminated with light totaling 200 J/cm2 at a fluence of 150 mW/cm2. At the 3-month follow-up examination, all tumors were graded as having a complete response by modified AIDS Clinical Trial Guidelines oncologic standards. No evidence of recurrence has been noted during the 6-month follow-up period.     

Photodynamic therapy using mono-L-aspartyl chlorin e6 (Npe6) for the treatment of cutaneous disease: a Phase I clinical study

The activity of a new photosensitizer, mono-L-aspartyl chlorin e6 (Npe6), was assessed in an ascending dose Phase I study for patients with superficial tumor. Eleven patients, with a total of 14 tumor sites, were treated with photodynamic therapy (PDT) using Npe6. Lesions included recurrent adenocarcinoma of the breast, basal cell carcinoma, and squamous cell carcinoma. The phototherapy protocol consisted of a single i.v. injection of 0.5-3.5 mg/kg Npe6, followed 4 h later by 25-100 j/cm2 at 664 nm of light. PDT using Npe6 caused no significant toxicity with the exception of temporary generalized skin photosensitivity. In all cases, light treatment caused immediate tissue blanching, followed by a marked necrosis of the tumor mass. Regression of tumor occurred over 24-48 h after the light treatment and was followed by the formation of a heavy eschar over the tumor site. Tumor regression was short-lived at Npe6 doses of 1.65 mg/kg and below. In two of three patients, tumor regression was either incomplete or tumors recurred within the 12-week observation period. Increasing the Npe6 dose to 2.5 or 3.5 mg/kg combined with 100 J/cm2 of light energy resulted in better control of tumor regrowth with 66% (6/9) of sites remaining tumor-free through 12 weeks observation. This increased tumor response came at the expense of the tissue selectivity observed at Npe6 doses of 1.65 mg/kg and below. There was no apparent selectivity for destruction of tumor compared with normal skin at Npe6 doses of 2.5 mg/kg and above. These data demonstrate that Npe6 is both an effective and safe photosensitizer for use in PDT and provide the impetus for continued study in Phase II clinical trials.     

Positive pressure ventilation with the laryngeal mask airway in non-paralysed patients: comparison of sevoflurane and propofol maintenance techniques

Photofrin photodynamic therapy (PDT) has recently received FDA approval for the palliative treatment of totally and partially obstructing esophageal malignancies. However, there is a need for new PDT photosensitizers because Photofrin has a number of undesirable features. The purpose of this study was to evaluate the efficacy of four amine-bearing silicon phthalocyanines--Pc4, Pc10, Pc12 and Pc18--as potential PDT photosensitizers. Equimolar concentrations of these Pc were found to be highly effective at causing the regression of RIF-1 tumors transplanted to C3H/HeN mice. The amount of Pc4 necessary to cause an equivalent amount of tumor regression in this model system was substantially less than the amount of Photofrin. The cutaneous phototoxicity of the silicon Pc photosensitizer was assessed by the utilization of the murine ear-swelling model. When C3H mice were exposed to 167 J/cm2 of polychromatic visible light from a UVB-filtered solar simulator, which emitted UV radiation and visible light above 320 nm, the Pc produced little, if any, cutaneous photosensitivity. These results indicate that Pc4, Pc10, Pc12 and Pc18 are at least as effective as Photofrin in PDT protocols, while at the same time addressing many of the drawbacks of Photofrin.     

Effective mechanisms of ATX-S10, a new photosensitizer, on HeLa tumors in nude mice

Photodynamic therapy (PDT) is a treatment modality that utilizes a photosensitizing drug activated by laser generated light. PDT is effective for oncologic applications. Many cancer patients have undergone a hematoporphyrin derivative (HpD)-mediated PDT. The HpD showed a side effect causing prolonged cutaneous photosensitivity. But ATX-S10, a new photosensitizer, provides rapid plasma and tissue clearance, comparable photoactivation efficiency, and superior light absorption of visible red. In this study, the tumor rejection mechanisms of PDT using ATX-S10 on HeLa tumors in nude mice were investigated with morphological and fluorometric methods. The mice were intracutaneously inoculated with HeLa cells, 5 x 10(5) or 1 x 10(7) cells. When tumors grew to about 10-12 mm in diameter, mice were intraperitoneally administered ATX-S10, 30 mg/kg, and 2 hours later the ATX-S10 in tumors was indirectly measured by a fluorometric machine, PMA-10 (Hamamatsu Photonics K. K.) and the tumors were irradiated by Optical Parametric Oscillator (Hamamatsu Photonics K. K.) tuned to a wave length at 670 nm, 5 mJ/pulse, 100 J/tumor. Before and after the irradiation, the effective mechanisms of PDT with ATX-S10 were studied by histological and ultrastructural approaches. The results showed occlusive thrombi in the microvasculature of the tumors and tumor cell death. These occlusive thrombi were observed within one hour after PDT at both light and electron microscopy levels, and were more remarkable as time passed after PDT. Therefore, the morphological studies of PDT with ATX-S10 suggested that the rejection mechanisms occurred mainly as a result of the destructive changes of the microvasculature in the tumors first, and secondly or simultaneously, tumor cells were destroyed through necrosis, and finally the tumors were rejected.     

Photophysical properties of tin ethyl etiopurpurin I (SnET2) and tin octaethylbenzochlorin (SnOEBC) in solution and bound to albumin

The photophysical characteristics of two second-generation PDT photosensitizers, tin ethyl etiopurpurin I (SnET2) and tin octaethylbenzochlorin (SnOEBC), have been measured in homogeneous solution and when bound to bovine serum albumin (BSA). The ground state and triplet state absorption spectra have been characterized, as have triplet lifetimes and quantum yields for intersystem crossing, singlet oxygen formation and photobleaching. In total, these parameters provide a complete set of data that can be used to quantitatively compare the photosensitizing efficiencies of these molecules. The photo-bleaching quantum yield of SnET2 is increased dramatically when it is bound to BSA, thus limiting the production of singlet oxygen at incident fluences above 1 J/cm2. In contrast, the quantum yield of photobleaching of SnOEBC is at least an order of magnitude lower than that of SnET2 under these conditions and does not significantly limit the photosensitization process for typical in vivo or in vitro fluences. This difference is expected to play a significant role in determining the relative photo-sensitizing ability of these compounds in vivo.     

Lack of mda-6/WAF1/CIP1-mediated inhibition of cyclin-dependent kinases in interferon-alpha resistant murine B16 melanoma cells

Photodynamic therapy (PDT) is a treatment modality for malignancies that, uses the accumulation of a photosensitizer in tumor tissue and a subsequent laser light irradiation to selectively destroy tumor cells. Usually PDT is carried out with a hematoporphyrin derivative (HPD) as photosensitizer. Fluorescence characteristics of the HPD Photosan-3 were determined at different concentrations with time-resolved fluorescence spectroscopy. Photosan-3 showed a concentration dependent fluorescence with one fluorescence decay time below a concentration of 10 micrograms/ml, two or three decay times at 50 and 100 micrograms/ml Photosan-3 respectively. These findings confirm results of former studies on other HPD that aggregates and dimers are probably more responsible for the photodynamic effect than monomers.     

Ultrasonically determined patterns of enlargement in benign prostatic hyperplasia

A series of 430 men aged 40 to 79 years underwent transrectal ultrasonography (TRUS) as part of a community survey of benign prostatic hyperplasia (BPH). We describe a reproducible method of prostate volume estimation and discuss the implications of prostate dimension changes in BPH. The mean prostate and adenoma volumes for the group were 32 ml (SD 14) and 15 ml (SD 11) respectively. The antero-posterior dimension of the prostate (APD) had the strongest correlation with gland volume compared with the transverse dimension (TD) and length (L). The mean ratio of adenoma volume to prostate volume was 0.45 (SD 0.13) and this increased with increasing gland volume. There was a modest correlation between the ratio and prostate volume. BPH is characterised by a proportionally greater increase in the APD compared with L and TD and by an increasing adenoma/prostate ratio. TRUS is useful in assessing the type and extent of adenoma and prostate enlargement in BPH.     

Comparative bioavailability of two immediate release tablets of cisapride in healthy volunteers

Irradiation of B16 pigmented melanoma subcutaneously transplanted in C57 mice with a single 650 mJ pulse (10 ns) of 1064 nm light from a Q-switched Nd: YAG laser caused instantaneous bleaching of the pigmented tissue. Visual and histological examination of the resulting gray-colored tumor revealed the breakdown of melanosomes with no detectable alteration of the normal and tumor-overlying skin. Histological examination of the irradiated tumor showed some degree of vascular damage; the depth of the photodamage was not affected by the successive delivery of three consecutive light pulses. The bleached tumor grew at a modestly slower rate but the high-peak-power (HPP) laser treatment did not affect the tumor concentration of a photodynamic sensitizer Si(i.v.)-naphthalocyanine (isoBO-SiNc) intravenously injected 24 h before Nd:YAG irradiation. Treatment of the B16 pigmented melanoma by photodynamic therapy (PDT: 1 mg/kg isoBO-SiNc, 300 mW/cm2, 520 J/cm2) from a 774 nm diode laser immediately after the 1064 nm irradiation resulted in a 16 day delay of tumor regrowth, which was markedly longer than the delay (ca 6 days) obtained after PDT under identical conditions without the preirradiation. Thus, pretreatment of pigmented tumors with HPP 1064 nm light appears to enhance their susceptibility to conventional PDT. The tumor response was further enhanced by repeating the combined HPP/PDT treatment at an interval of 10 days (regrowth delay: 27 days), as well as by applying hyperthermia immediately after HPP/PDT (regrowth delay: ca 34 days).     

Reduction of tumour oxygenation during and after photodynamic therapy in vivo: effects of fluence rate

It has been proposed that the generation of O2 during photodynamic therapy (PDT) may lead to photochemical depletion of ambient tumour oxygen, thus causing acute hypoxia and limiting treatment effectiveness. We have studied the effects of fluence rate on pO2, in the murine RIF tumour during and after PDT using 5 mg kg(-1) Photofrin and fluence rates of 30, 75 or 150 mW cm(-2). Median pO2 before PDT ranged from 2.9 to 5.2 mmHg in three treatment groups. Within the first minute of illumination, median tumour pO2 decreased with all fluence rates to values between 0.7 and 1.1 mmHg. These effects were rapidly and completely reversible if illumination was interrupted. During prolonged illumination (20-50 J cm(-2)) pO2 recovered at the 30 mW cm(-2) fluence rate to a median value of 7.4 mmHg, but remained low at the 150 mW cm(-2) fluence rate (median pO2 1.7 mmHg). Fluence rate effects were not found after PDT, and at both 30 and 150 mW cm(-2) median tumour pO2 fell from control levels to 1.0-1.8 mmHg within 1-3 h after treatment conclusion. PDT with 100 J cm(-2) at 30 mW cm(-2) caused significantly (P = 0.0004) longer median tumour regrowth times than PDT at 150 mW cm(-2), indicating that lower fluence rate can improve PDT response. Vascular perfusion studies uncovered significant fluence rate-dependent differences in the responses of the normal and tumour vasculature. These data establish a direct relationship between tumour pO2, the fluence rate applied during PDT and treatment outcome. The findings are of immediate clinical relevance.     

Mathematical description of photobleaching in vivo describing the influence of tissue optics on measured fluorescence signals

The observed decrease in the fluorescence signal during photodynamic therapy (PDT) may contain dosimetric information as this photobleaching provides direct information on the photodynamic processes occurring in the tissue. A correct interpretation of the photobleaching signal, however, is crucial for its use in dosimetry. In this study the influence of scattering and absorption phenomena in tissue on the emitted fluorescence signal are described mathematically. Analytical solutions of the resulting expression show a difference from the single-decaying-exponential function generally used for describing photobleaching signals. The solutions are a function of the fluence rate at the inner side of tissue boundary psi(0*), the photobleaching dose constant beta, the incident irradiation power I0 and time. The accuracy of the results was investigated by comparison of the analytic solutions with numerical calculations using fluence rate profiles and escape functions obtained by Monte Carlo (MC) simulations. Good resemblance is observed when the value for psi(0*) calculated by the MC simulations is used in the analytical solutions. Experimental results in this study indicate the photobleaching dose constant of ALA-induced PpIX to be 33 +/- 3 J cm-2. Determination of beta for different types of photosensitizer and the development of an accurate method to determine psi(0*) can make monitoring of photobleaching during PDT valuable for dosimetry.