[Photodynamic therapy of early squamous epithelial carcinomas and severe squamous epithelial dysplasias of the esophagus with 5-aminolevulinic acid]

INTRODUCTION

Photodynamic therapy (PDT) is a new local, endoscopically controlled therapeutic concept based on the selective sensitization of malignant and precancerous lesions prior to light-induced tissue destruction. 5-aminolaevulinic acid (5-ALA) appears to be a promising alternative photosensitizer with a high mucosa specificity without phototoxic side effects on the skin. We report on our experience with this new form of PDT in 24 patients.

PATIENTS AND METHODS

Five females and 19 males (aged 50 to 79 years) with histologically proven high-grade dysplasia (n = 9) and early cancer (normal EUS or uTlNOMO, n = 15) of the esophagus were included in this study. Four to six hours after oral ingestion of 5-ALA (dosage of 60 mg/kg b.w.) laser light irradiation was conducted with a dye laser system (XP 800 KTP/YAG, Laserscope, San José, USA) at a wavelength of 635 nm. With a light dose of 150 J/cm2.

RESULTS

The length of the segment with severe dysplasia or mucosal cancer varied between 0.5 and 9 cm (mean length: 3.6 cm). High-grade dysplasia was eradicated in all patients (9/9). In addition, 16 mucosal carcinomas in 15 patients were successfully treated in 8/16 cases with an average of 1.8 treatment sessions and a mean follow-up of 14.5 months (range: 3-31 months). A method-related mortality and morbidity was not observed.

CONCLUSIONS

Severe dysplasia and superficial (< or = 2 mm) mucosal cancer of the esophagus can be completely ablated by 5-ALA-PDT. Patients with early carcinoma thicker than 2 mm are not suitable for 5-ALA-PDT. PDT with 5-ALA has few side effects and might offer an alternative to esophagectomy or radio-chemotherapy.

Biomodulative effects induced by 805 nm laser light irradiation of normal and tumor cells

The influence of light emitted from a diode laser centred at lambda = 805 nm was investigated on murine skeletal myotubes (C2), normal urothelial cells (HCV29), human squamous carcinoma cells of the gingival mucosa (ZMK) and urothelial carcinoma cells (J82) in a computer-controlled irradiation chamber. Cells were treated with varying fluences between 0 and 20 J cm-2. The response was tested by analysis of the mitotic index using single cell counting after Orcein staining and proliferation index based on BrdU incorporation during DNA synthesis. While the mitotic index of C2, HCV29 and J82 cells increased at a fluence of 4 J cm-2, irradiation with fluences of 20 J cm-2 resulted in a slight decrease. ZMK tumor cells showed a decrease of the mitotic index with both fluences. No significant differences could be determined when using irradiances between 10 mW cm-2 and 150 mW cm-2. The BrdU test after irradiation showed no significant effects compared to the controls in each cell line.

Pharmacokinetics of 5-aminolevulinic acid-induced protoporphyrin IX in skin and blood

The fluorescence and photosensitivity of endogenously synthesized protoporphyrin IX (PPIX) is increasingly used for the diagnosis and treatment of malignant and certain non-malignant diseases. A selective accumulation of PPIX can be induced by application of 5-aminolevulinic acid (5-ALA), which is a precursor of PPIX in the cellular biosynthetic pathway of heme. The purpose of this study was to monitor the in vivo accumulation of PPIX in different locations of the skin after oral ingestion and to determine the pharmacokinetics of 5-ALA and PPIX in human blood plasma for various routes of application. At the same time we wanted to achieve an optimal treatment scheme but also study possible side-effects of 5-ALA administration. After oral application of 5-ALA in a concentration of 40 mg kg-1 body weight, the fluorescence intensities of PPIX in the skin showed maxima between 6.5 and 9.8 h depending on the location and decreased to values lower than 5% related to the maximum after a mean time of about 40 h. The measured absolute intensities of PPIX fluorescence varied strongly between different patients and different locations on one patient. In the plasma of blood samples, PPIX could be detected via its fluorescence for all studied routes of application with the exception of the ointment, where PPIX levels were below the detection limit of 1 microgram l-1. The highest mean concentration of 742 micrograms l-1 PPIX in the plasma was measured 6.7 h after oral application. For inhalation of 5-ALA, a mean maximum concentration of 12 micrograms l-1 could be detected 4.1 h after application, for intravesical instillation, the mean maximum concentration was found to be 1 microgram l-1 2.9 h after application. The kinetics of 5-ALA in the plasma peaked much earlier with a maximum concentration of 32 mg l-1 about 30 min. after oral administration. The 5-ALA levels did not exceed normal reference values after topical application. The results of our experiments suggest that for a systemic application of 5-ALA side-effects in sensitive patients cannot be excluded.

Endovascular catheter-delivered photodynamic therapy in an experimental response to injury model

BACKGROUND

The effectiveness of local endovascular photodynamic therapy (PDT) in preventing tissue hyperplasia was evaluated in a vascular injury model.

METHODS

Standardized unidirectional arterial injury with a directional atherectomy catheter was performed in porcine arteries (n = 180). Animals (n = 72) were randomly allocated to unidirectional injury only (Group 1), injury followed by drug delivery of photosensitizer with a porous balloon (Group 2), or by local exposure to monochromatic light (Group 3). In Group 4, injury was followed by local drug delivery of photosensitizer and subsequent exposure to light (PDT). Up to 21 days after treatment, all experimental vessels were excised, fixed and processed for histology, immunohistochemistry and transmission electron microscopy.

RESULTS

After vascular injury an inflammatory and myoproliferative response was observed in Groups 1, 2 and 3 (mean tissue hyperplasia/media ratio 1.0 +/- 0.5 at 21 days; area tissue hyperplasia: 1.57 +/- 0.9 mm2). Proliferation in injured vascular segments (Group 1-3) reached a maximum at 7 days, with 6%. Only in Group 4, after injury followed by photodynamic therapy, was there no significant vascular response (mean tissue hyperplasia/media ratio 0.3 +/- 0.2: area tissue hyperplasia: 0.1 +/- 0.05 mm2 p < 0.001, proliferating cells 0.3%).

CONCLUSION

Vascular response after unidirectional injury was suppressed only by endovascular photodynamic therapy.

In vivo fluorescence kinetics of porphyrins following intravesical instillation of 5-aminolaevulinic acid in normal and tumour-bearing rat bladders

The fluorescence kinetics of protoporphyrin IX (PPIX) following intravesical instillation of 5-aminolaevulinic acid (5-ALA) have been studied in vivo in a rat bladder tumour model. 5-ALA dissolved in NaHCO3 was intravesically instilled for 60 min in tumour-bearing and normal bladders of Wistar rats. The fluorescence was excited with the violet lines of a Kr(+)-laser and recorded in vivo by means of a fibre coupled optical multichannel analyser. The fluorescence emission bands of PPIX at lambda = 636 nm and lambda = 708 nm were detected in normal and tumorous urothelium after only 30 min. The maximum fluorescence intensity was obtained in tumorous and normal urothelium 3-4 h after instillation. The ratio of the fluorescence intensity in tumorous to normal urothelium decreased continuously from four to about two during the time range of 6 h. PPIX fluorescence following 5-ALA instillation could also be observed in kidney and liver. Fluorescence from further porphyrin species with emission bands at lambda = 617 nm and lambda = 682 nm was detected in the bladder, indicating an efflux of hydrophilic porphyrins from the hepatic pathway.

Wavelength dependent photodynamic effects on chemically induced rat bladder tumors following intravesical instillation of 5-aminolevulinic acid

PURPOSE

The aim of the study was to determine photodynamic effects in chemically induced rat bladder tumors after intravesical instillations of 5-aminolevulinic acid (5-ALA) and PDT-dependence on laser wavelength and light dose.

MATERIAL AND METHODS

Following intravesical instillation of a 5-ALA solution (40 mg 5-ALA in isotonic saline and sodium-bicarbonate) rat bladder tumors have been treated with integral irradiation using laser light at wavelengths of lambda = 630 nm and lambda = 635 nm in a light dose range of 15 to 100 J/cm2.

RESULTS

A significantly higher amount of necrosis including damage of normal urothelium was obtained in rat bladder tumors using laser light at lambda = 635 nm.

CONCLUSIONS

For 5-ALA assisted photodynamic treatment of superficial bladder cancer in patients the irradiation wavelength of lambda = 635 nm is recommended.

Local photodynamic therapy reduces tissue hyperplasia in an experimental restenosis model

Local photodynamic therapy may have potential in preventing myointimal hyperplasia after angioplasty. In this study, the effect of photodynamic therapy was evaluated in an experimental model of restenosis. Standardized unidirectional arterial injury with a directional atherectomy catheter was performed in porcine arteries. Animals were randomly allocated to four groups: group 1, unidirectional injury only; group 2, injury followed by local delivery of photosensitizer; group 3, injury followed by local exposure to monochromatic light; and group 4, where injury was followed by local drug delivery of photosensitizer and subsequent exposure to light (photodynamic therapy). Seven, 14 or 21 days after treatment, all experimental vessels were excised, fixed and processed for histology. An inflammatory and myoproliferative response was observed after injury in vessels from groups 1, 2 and 3. In group 4, after injury followed by photodynamic therapy, the myoproliferative response was significantly reduced. Thus, in this study, tissue hyperplasia after unidirectional injury was effectively suppressed by photodynamic therapy.

Pharmacokinetics of 5-aminolevulinic-acid-induced porphyrins in tumour-bearing mice

Photodynamic therapy and photodynamic diagnosis help to support efficient treatment of superficial and early-stage cancer. During the last few years, 5-aminolevulinic acid (5-ALA), a precursor of haemoglobin in the haem biosynthetic pathway, was used to stimulate endogenous porphyrin production. In the following the time dependence of 5-ALA-induced porphyrin concentration will be investigated on several tissues in an in-vivo tumour model. 5-ALA was administered intravenously at a concentration of 50 mg-1 body weight. According to a certain time schedule the animals were sacrificed and 12 different organs as well as the tumour were removed. During excitation with the violet light of a Kr+ laser, porphyrin fluorescence spectra in the range 550-750 nm could be detected on the tissue samples. The intensity of the emission spectra at lambda = 635 +/- 2 nm was taken as a measure of the porphyrin concentration. All tissues showed porphyrin fluorescence. Brightest fluorescence was found on the tumour. A maximum contrast of the fluorescence intensity between the tumour and the non-malignant organs of up to 30 was observed at 4-6 h post-injection. The kinetics of the porphyrin concentration depend on the organ. Simple mathematical models will be derived and discussed.

[Computer-controlled laser irradiation unit for studies of light-induced processes in cell cultures]

For the photodynamic treatment of tumours, synergistic effects of photosensitizing substances and light (today usually laser light) are used. With the aim of optimizing photosensitizing drugs and therapy, the effects of light and drug dose were studied in cell experiments. To automate and standardize such in vitro experiments, a laser irradiation chamber was developed. Cells cultured from tumour cell lines are placed on micro-titre plates or in petri dishes, together with the photosensitizer, and subsequently irradiated in the irradiation chamber with a well-defined dose of laser light of a wavelength corresponding to the absorbance of the photosensitizing agent. The plates or dishes are irradiated from below. In this way, light dose errors due to refraction from the meniscus of the cell suspension as occurs with irradiation from above, are avoided. During irradiation, speckle effects on the underside of the plates or petri dishes lead to variation in irradiation. A vibrator keeps the light transmission fibre and thus speckle pattern in motion, guaranteeing a homogeneous irradiation of the cells.

[Photodynamic therapy of a gastric stump carcinoma with curative intent. The first case report of a clinical application in Germany]

Photodynamic treatment (PDT) of malignant tumours rests on the intravenous administration of a photosensitizer, which is predominantly in tumour tissue, and subsequent activation of this substance with light of a specific wavelength. The method was used in a 76-year-old man who had undergone a 2/3 gastric resection for ulcer in 1948 and was now found to have a carcinoma of the stump at the anastomosis. He refused surgical resection, but accepted PDT. 48 hours after intravenous administration of the photosensitizer dihematoporphyrin ether-ester (2 mg/kg) the 1.5 x 1.0 cm tumour was irradiated with an argon ion laser pumped colour laser system at a wavelength of 630 nm and energy density of 150 J/cm3. The irradiation was performed under endoscopic control via a specially developed applicator which had first been introduced through the biopsy channel of the endoscope. Four weeks after the first treatment biopsies from a 5 mm ulceration in the area of the tumour revealed malignant cell groups, so that a second treatment was undertaken. Two, three and six months later the ulcer was shown to have healed and biopsies were free of tumour. But nine months later tumour cells were again demonstrated and a third PDT was performed. Although biopsies were again free of tumour at the next control, it can not yet be assumed that the tumour has been cured.

Photodegradation of protoporphyrin-dimethylester in solution and in organized environments

The degradation of sensitizers used in photodynamic therapy (PDT) involves photooxidation either by molecular oxygen or by oxygen intermediates which leads to hydroxyaldehyde and formyl products or to ring opening. Our investigations focused on the spectroscopic changes which protoporphyrin-dimethylester (PP) exhibits upon irradiation. As the microenvironment strongly influences the effects, we used an aprotic organic solvent, L-alpha-phosphatidylcholine dioleoyl (DOPC) liposomes and isogenic fibrosarcoma cells (SSKII) as carriers for PP. Hydroxyaldehyde product isomers develop a new absorption band centred around 670 nm and a new emission band at 676 nm. These characteristics can be used to discriminate them from formyl products and intact PP. In organic solvents, the formation of the hydroxyaldehyde products dominates. In DOPC liposomes and cells, the hydroxyaldehyde yield drops and photooxidation results in attack of the macrocycle. Time-resolved fluorescence spectroscopy of monomeric PP in an organic solvent gives a monoexponential decay time tau of 10.1 +/- 1.3 ns. Upon irradiation a second component with a decay time of 4.9 +/- 0.6 ns, resulting from the hydroxyaldehyde product, was detected. In liposomes and cells the monomeric decay time was significantly longer (15 ns) due to the altered microenvironment. Additionally, we observed in liposomes and in cells a small contribution of a short component (1 ns) which is attributed to an aggregated sensitizer species. In irradiated cells the aggregated fraction doubles, indicating a change in the microenvironment caused by the photodynamic action of the sensitizer.

Gas chromatographic-electron-impact mass fragmentometric determination of lysergic acid diethylamide in urine

A sensitive method for the detection and quantitation of lysergic acid diethylamide (LSD) in urine was developed. After initial solvent extraction, the compound was further purified by liquid-liquid extraction or by solid-phase extraction. The trimethylsilyl derivative of LSD was detected by gas chromatography-mass spectrometry (GC-MS) operated in the electron-impact mode with selected-ion monitoring. The presence of LSD was confirmed by comparing retention times and relative abundances of ions of unknowns with that of a standard. The recovery of this procedure was greater than 89%. The intra-run and inter-run coefficients of variation were less than 5% and less than 7%, respectively. This procedure allows detection of LSD concentrations as low as 29 pg/ml. Quantitation of LSD was linear over the concentration range 50-2000 pg/ml.

[Photodynamic therapy of bronchial cancer]

Photodynamic therapy (PDT) with porphyrin derivatives (haematoporphyrin and dihaematoporphyrin äther/ester) and laser light of the wavelength 640 nm, is a new procedure for the treatment of carcinomas. This form of therapy is selective, can be applied through the bronchoscope, and is aimed at accomplishing curative elimination of central tumours of the lung. To date, we have successfully applied PDT in four selected patients. Our first patient was treated in April, 1987. The irradiation modalities and the clinical course are described.

Bronchoscopic photodynamic therapy of bronchial carcinoma

Photodynamic therapy with photosensitizers is a new method of treating malignant tumors. In the area of bronchoscopy it is employed for the selective therapy of early carcinomas at central localizations. We report on our first attempts at treatment with hematoporphyrin derivative in an inoperable patient. The modalities of irradiation and the recurrence-free progress of, to date, 2.5 years, are described.