Photosensitization of the endometrium with topical 5-aminolevulinic acid

Applications of Photodynamic Therapy in Endometrial Diseases

Photodynamic therapy (PDT) is a medical procedure useful for several benign conditions (such as wound healing and infections) and cancer. PDT is minimally invasive, presents few side effects, good scaring, and is able to minimal tissue destruction maintaining organ anatomy and function. Endoscopic access to the uterus puts PDT in the spotlight for endometrial disease treatment. This work systematically reviews the current evidence of PDT’s potential and usefulness in endometrial diseases. Thus, this narrative review focused on PDT applications for endometrial disease, including reports regarding in vitro, ex vivo, animal, and clinical studies. Cell lines and primary samples were used as in vitro models of cancer, adenomyosis and endometrioses, while most animal studies focused the PDT outcomes on endometrial ablation. A few clinical attempts are known using PDT for endometrial ablation and cancer lesions. This review emphasises PDT as a promising field of research. This therapeutic approach has the potential to become an effective conservative treatment method for endometrial benign and malignant lesions. Further investigations with improved photosensitisers are highly expected.

Effects of photodynamic therapy using 5-aminolevulinic acid on cultured human adenomyosis-derived cells

OBJECTIVE

To evaluate the potential of photodynamic therapy with aminolevulinic acid (ALA) on human adenomyosis-derived cells compared with endometrial stromal cells.

DESIGN

In vitro study.

SETTING

Department of Obstetrics and Gynecology, Tohoku University Hospital.

PATIENT(S)

Women with adenomyosis attending the University hospital.

INTERVENTION(S)

Photodynamic treatment.

MAIN OUTCOME MEASURE(S)

Cell survival rates.

RESULT(S)

Treatment with both ALA and irradiation caused significantly decreased survival of cells derived from human adenomyosis compared with ALA or irradiation alone. The combination of irradiation and ALA led to 79.3%, 68.0%, and 59.5% cell survival at 1.6, 4, and 8 J/cm2, respectively, whereas ALA and irradiation alone caused 92.8% and 97% survival, respectively.

CONCLUSION(S)

Photodynamic therapy using ALA caused extensive death of cells derived from human adenomyosis. Photodynamic treatment using ALA may be a new treatment for patients with adenomyosis uteri in the future.

Improved preoperative tumor staging by 5-aminolevulinic acid induced fluorescence laparoscopy

BACKGROUND

We report our data in 35 patients who underwent preoperative conventional and fluorescence-based staging laparoscopy. We use the data to address the questions of whether fluorescence examination increases the yield of metastatic lesions and alters treatment intervention.

METHODS

Fluorescence laparoscopy was successfully performed in 30 patients with GI malignancies. After sensitization with 5-aminolevulinic acid, conventional white-light mode and fluorescence-light laparoscopies were sequentially performed. A suspected malignancy was biopsied.

OBSERVATIONS

In 5 patients, examinations were incomplete because of adhesions. In 9 of 10 patients, hepatic or peritoneal metastases were detected by white-light examination. In 4 of these 9, blue-light examination yielded more metastatic lesions. In one patient with no lesions by white- or blue-light examination, surgery revealed hepatic metastasis in a location not accessible to laparoscopic examination. In 18 patients, surgery confirmed the absence of metastatic lesions.

CONCLUSIONS

A fluorescence, blue-light examination yielded more lesions than the conventional white-light examination but did not alter treatment intervention and did not enhance yield when metastatic lesion is in an inaccessible location. Continued research should focus on whether treatment intervention will be altered by the fluorescence examination.

Influence of the menstrual cycle on aminolevulinic acid induced protoporphyrin IX fluorescence in the endometrium: In vivo study

BACKGROUND AND OBJECTIVES

In vitro studies indicated that compared to postmenopausal women, premenopausal women had increased aminolevulinic acid induced protoporphyrin IX (ALA-induced PpIX) fluorescence expression in the endometrium. The aim of this study was to evaluate menstrual cycle dependency of ALA-induced PpIX fluorescence in the endometrium in vivo.

STUDY DESIGN/PATIENTS AND METHODS

Thirteen patients were included for in vivo spectrofluorometric measurements of ALA-induced PpIX in the endometrium and 51 patients for fluorescence hysteroscopy. Two milliliter of a 2% 5-ALA-solution at pH = 4.0 (ASAT AG/Zug, Switzerland) was topically administrated just before spectrofluorometry and 4 hours before hysteroscopy. Spectrofluorometry: Optical fiber based. Fluorescence hysteroscopy: STORZ-D-Light system (Storz, Tuttlingen, Germany). Histological classification of curettage and bioptic endometrial tissue stained with hematoxylin and eosin (H&E).

RESULTS

Hysteroscopic and in vivo spectrofluorometric measurements showed an increase of ALA-induced PpIX fluorescence in the secretory and hyperplastic endometrium compared to proliferative and atrophic endometrium.

CONCLUSIONS

The accuracy of fluorescence hysteroscopy and the success of the photodynamic endometrial ablation using ALA-induced PpIX may depend on the hormonal influence of the menstrual cycle. The mechanisms responsible for the increased ALA-induced PpIX fluorescence in the secretory versus proliferative phase of the menstrual cycle deserve further studies.

Detection of high-grade dysplasia in Barrett's esophagus by spectroscopy measurement of 5-aminolevulinic acid-induced protoporphyrin IX fluorescence

BACKGROUND

Preliminary studies with qualitative detection methods suggest that 5-aminolevulinic acid-induced protoporphyrin IX fluorescence might improve the detection of dysplastic Barrett's epithelium. This study used quantitative methods to determine whether aminolevulinic acid-induced protoporphyrin IX fluorescence can differentiate between Barrett's mucosa with and without dysplasia.

METHODS

Patients were given 10 mg/kg of aminolevulinic acid orally 3 hours before endoscopy. Quantitative fluorescence spectra were acquired by using a nitrogen-pumped dye laser (l 400 nm) spectrograph system. The protoporphyrin IX fluorescence intensity at 635 nm was compared with the histopathologic diagnosis for mucosal biopsy specimens taken immediately after the fluorescence measurements.

RESULTS

Ninety-seven spectra were obtained from 20 patients. The mean (+/- standard error) standardized protoporphyrin IX fluorescence intensity was significantly greater (p < 0.05) for high-grade dysplastic Barrett's epithelium (0.29 +/- 0.07, n = 13) than for nondysplastic Barrett's epithelium (0.11 +/- 0.02, n = 43). By using protoporphyrin IX fluorescence alone, high-grade dysplasia was distinguished from nondysplastic tissue types with 77% sensitivity and 71% specificity. Decreased autofluorescence was particularly found in nodular high-grade dysplasia. By using the fluorescence intensity ratio of 635 nm/480 nm, nodular high-grade dysplasia could be differentiated from nondysplastic tissue with 100% sensitivity and 100% specificity.

CONCLUSION

Protoporphyrin IX fluorescence may be useful for identifying areas of high-grade dysplasia in Barrett's esophagus and for targeting of biopsies.

Effectiveness of photodynamic ablation for destruction of endometrial explants in a rat endometriosis model

OBJECTIVE

To evaluate the potential of photodynamic therapy with aminolevulinic acid (ALA-PDT) for ablation of endometrial explants in a rat endometriosis model and to compare the effect of ALA-PDT, electrosurgery, and surgical resection on normal peritoneum.

DESIGN

Prospective controlled experimental trial.

SETTING

University medical center.

ANIMAL(S)

Mature Sprague-Dawley female rats.

INTERVENTION(S)

Induction of endometriosis and subsequent treatment with ALA-PDT; electrosurgery, and simple resection, and ALA-PDT of normal peritoneum.

MAIN OUTCOME MEASURE(S)

Histopathological assessment.

RESULT(S)

Systemic ALA followed by exposure to photoactivating light for 10 or 15 minutes resulted in ablation of all explants harvested 3-4 days after treatment. Permanent destruction was confirmed by absence of regrowth by week 3. Exposure of normal peritoneum to ALA-PDT resulted in initial necrosis, with complete recovery by day 16. Adhesions were present on day 16 in 50% of cases after electrosurgery and in 100% of cases after resection. No adhesions were present in ALA-PDT-treated animals.

CONCLUSION(S)

Systemic ALA followed by exposure to photoactivating light at relatively low power densities for periods as brief as 10 minutes resulted in ablation of endometriotic explants. Exposure of normal peritoneum to ALA-PDT resulted in complete resurfacing. Both electrosurgery and surgical resection resulted in a greater incidence of surface adhesions.

Photodynamic diagnosis of breast tumours after oral application of aminolevulinic acid

Photodynamic diagnosis is of increasing interest for diagnosis in oncology. It is based on a more intense incorporation of a fluorescent dye in tumours compared to normal tissue. As a feasibility study we investigated the effectiveness of oral application of 5-aminolevulinic acid for photodynamic diagnosis of human primary mammary tumours. The study included 16 patients with palpable breast tumours. Aminolevulinic acid was administered at a concentration of 40 mg kg(-1)bodyweight 150-420 min prior to tumourectomy. Intraoperatively blue light (405 nm) was applied to the operation site. Sections of the excised tumour and some lymph nodes were prepared and analysed with a fluorescent microscope. All primary mammary tumour tissues showed significantly higher fluorescence intensity than surrounding normal mammary tissue. Fluorescence of the mammary tumours could also be discriminated macroscopically and intraoperatively. Fluorescence intensity in nonmetastatic lymph node tissue was higher in 2 out of 3 patients than in primary tumour tissue. By photodynamic diagnosis using aminolevulinic acid we were able to reliably distinguish primary mammary tumours from normal mammary tissue microscopically and macroscopically in all our patients. We suggest that photodynamic diagnosis with aminolevulinic acid for breast tumours should be further investigated and developed for intraoperative use and may well be a simple tool for better intraoperative diagnosis and recognition of tumour margins. We hypothesize that lymph node metastasis of breast tumours will not be detectable by this method.

Assessment of 5-aminolevulinic acid-induced porphyrin fluorescence in patients with peritoneal endometriosis

OBJECTIVE

The purpose of this study was to examine the diagnostic potential for patients with endometriosis of porphyrin fluorescence after oral administration of 5-aminolevulinic acid.

STUDY DESIGN

Fifteen women referred for laparoscopy because of suspected endometriosis received 1 or 10 mg/kg 5-aminolevulinic acid orally. After 1.5 to 6 hours endoscopic fluorescence spectral analysis and video inspection were performed.

RESULTS

With 10 mg/kg 5-aminolevulinic acid and application intervals of >3 hours we observed a significantly higher porphyrin fluorescence in active peritoneal endometriosis than in adjacent normal peritoneum. Pigmented and nodular endometriosis showed weak to negative fluorescence. A strong fluorescence of the fimbrial mucosa was seen. A 1-mg/kg dose of 5-aminolevulinic acid was insufficient for fluorescence diagnosis. No side effects were recorded.

CONCLUSION

Porphyrin fluorescence after oral administration of 5-aminolevulinic acid may be beneficial in diagnosis of peritoneal endometriosis. The strong fluorescence of fimbrial mucosa may limit the applicability of this technique in young women, however, because phototoxic damage cannot be excluded at present.

Photosensitising drugs - their potential in oncology

Despite decades of targeted research, cancer remains a leading cause of death. Around one third of the population of Western Europe and North America will develop cancer in their lifetime and, virtually without exception, all of us will be affected by the disease, either directly as patients or by repercussions in family and friends. In certain specific cancers, advances in surgery, chemotherapy and radiotherapy have led to major achievements, but in many types of cancer there has been little or no improvement in long-term survival. In yet other cases, whilst there may be good initial responses to drug therapy, drug resistance develops and additional agents are required to induce further remission in these patients. There is therefore a clear need for new anticancer agents and novel therapies. It is in this context that photosensitising drugs may play a significant part.

Kidney-preserving tumour resection in renal cell carcinoma with photodynamic detection by 5-aminolaevulinic acid: preclinical and preliminary clinical results

OBJECTIVE

To identify the outer border of a renal cell carcinoma (RCC) during a kidney-preserving tumour resection by photodynamically detecting RCC after the exogenous administration of 5-aminolaevulinic acid (ALA) in an animal model and in humans.

PATIENTS, MATERIALS AND METHODS

Human RCC was xenotransplanted subcutaneously and orthotopically into the kidneys of nude mice. ALA was then administered orally or intravenously (100-400 mg/kg body weight). The tumours were removed and examined macroscopically and microscopically for fluorescence, and the concentrations of protoporphyrin IX (PPIX) evaluated in the subcutaneous tumours. In a pilot study, nine patients with RCC of <4 cm diameter underwent partial nephrectomy; 20 mg ALA/kg body weight was given orally 4 h before surgery. During the operation, the macroscopic fluorescence of the tumours was evaluated and any side-effects recorded.

RESULTS

In the mouse model, the RCC fluoresced in all tumours, both macro- and microscopically, reaching a maximum 1.5 h after intravenous and 4 h after oral administration. The tissue concentrations of PPIX in the subcutaneous tumours were also maximal 4 h after oral administration. In the patients undergoing surgery, the RCC also fluoresced clearly and was sufficiently intense to identify the outer margins of the tumours for kidney-preserving tumour resection. There were no side-effects of the ALA with the dosages and methods of administration used.

CONCLUSION

The photodynamic detection of RCC with ALA facilitates the identification of tumour margins in man and in the mouse model, producing no undesirable side-effects. It may be helpful in determining the boundaries of the resected tissue when carrying out conservative kidney-preserving surgery.

Effect of continuous and multiple doses of 5-aminolevulinic acid on protoporphyrin IX concentrations in the rat uterus

The objective of the present study was to determine if the concentration of protoporphyrin IX (PpIX) in the rat endometrium could be increased by administering 5-aminolevulinic acid (ALA) in multiple doses or by continuous infusion. The effect of pH, temperature and time in solution on the stability of ALA were also investigated. Estrogen-filled silastic capsules were implanted subcutaneously into ovary intact female rats (200-225 g) (n = 66). On the third day of hormonal priming, ALA (10 mg or 25 mg) dissolved in saline and adjusted to a pH of 5-5.5 was administered intrauterine either as a single bolus or as two injections 3 hours apart (n = 10). A fifth group of rats was infused with 25 mg ALA over a 12 hour period using an osmotic minipump (n = 6). In a second experiment, ALA (25 mg) was injected immediately after being dissolved in saline (pH 2) (n = 16) or after incubation at 37 degrees C for 12 hour (pH 2) (n = 7). PpIX was then extracted from the endometrium and myometrium using a 1:1 methanol/perchloric acid solution and quantified spectrofluorometrically. A dose-response relationship was observed between 10 and 25 mg of ALA and endometrial PpIX concentrations. However, no differences in endometrial PpIX concentrations were detected between rats administered ALA either as a single bolus or as two doses. Continuous infusion of 25 mg of ALA resulted in statistically lower endometrial PpIX concentrations compared to 25 mg ALA injected either as a single bolus or as two injections. Neither pH, temperature, nor time in solution affected ALA-induced PpIX accumulation. We conclude that the simplest way of achieving the highest PpIX concentration in the rat endometrium in vivo is to administer a bolus injection of 25 mg of ALA.

Photodynamic therapy (PDT) and photodiagnosis (PD) using endogenous photosensitization induced by 5-aminolevulinic acid (ALA): mechanisms and clinical results

5-Aminolevulinic acid (ALA), when added to many tissues, results in the accumulation of sufficient quantities of the endogenous photosensitizer protoporphyrin IX (PpIX) via the heme biosynthetic pathway, to produce a photodynamic effect when exposed to activating light. Therefore, ALA is the only photodynamic therapy (PDT) agent in current clinical development that is a biochemical precursor of a photosensitizer. Topical ALA application, followed by exposure to activating light (ALA PDT), has been reported effective for the treatment of a variety of dermatologic diseases including cutaneous superficial and nodular basal cell carcinoma, Bowen's disease, and actinic (solar) keratoses. Local internal application of ALA has also been used for selective endometrial ablation in animal model systems and in human clinical studies has shown selective formation of PpIX within the endometrium. PpIX induced by ALA application has also been used as a fluorescence detection marker for photodiagnosis (PD) of cancer and dysplastic conditions of the urinary bladder and other organs. Systemic, oral administration of ALA has been used for ALA PDT of superficial head and neck cancer, various gastrointestinal cancers, and the condition known as Barrett's esophagus. The current state of knowledge of the mechanisms of endogenous topical and systemic photosensitization using ALA, the results of published clinical trials, and possible methods of increasing the efficacy of endogenous photosensitization for ALA PDT are reviewed in this paper.

The accumulation of protoporphyrin IX in plaque psoriasis after topical application of 5-aminolevulinic acid indicates a potential for superficial photodynamic therapy

The success reported for the treatment of superficial skin carcinomas by photodynamic therapy with topical application of the photosensitizer precursor 5-aminolevulinic acid has therapeutic implications for the treatment of other skin disorders. This paper describes the accumulation of the photosensitizing agent protoporphyrin IX in areas of plaque psoriasis by monitoring of the fluorescence emission induced by low-intensity laser excitation at 488 nm. We present results from 15 patients with a total of 42 plaques and show that the characteristic fluorescence emission of protoporphyrin IX increases in intensity within the 6-h period following application of 5-ami-nolevulinic acid, suggesting that there is a potential for superficial photodynamic therapy. The rate of increase and maximum intensity of fluorescence emission was not directly related to the applied quantity of the precursor. The variability of the fluorescence intensity was as great between plaques at different sites on the same patient as between different patients. Also, the effect of plaque occlusion following application appeared insignificant. Although there was only limited enhancement of emission from areas of skin surrounding the plaque, a significant buildup of sensitizer was detected after several days in some areas of psoriasis that received no application.

Photodynamic therapy (PDT) and photodiagnosis (PD) using endogenous photosensitization induced by 5-aminolevulinic acid (ALA): current clinical and development status

Exogenous provision of 5-aminolevulinic acid (ALA) to many tissues results in the accumulation of sufficient quantities of the endogenous photosensitizer protoporphyrin IX (PpIX) via the heme biosynthetic pathway, to produce a photodynamic effect when exposed to activating light. Therefore, ALA may be considered the only current photodynamic therapy (PDT) agent in clinical development that is a biochemical precursor of a photosensitizer. Topical ALA application, followed by exposure to activating light (ALA PDT), has been reported effective for the treatment of a variety of dermatologic diseases including cutaneous superficial and nodular basal cell carcinoma, Bowen's disease, actinic (solar) keratoses, and T cell lymphoma. Local internal application of ALA has also been used for selective endometrial ablation in animal model systems and, in human clinical studies, it has shown selective formation of PpIX within the endometrium. PpIX induced by ALA application has also been used as a fluorescence detection marker for photodiagnosis (PD) of cancer and dysplastic conditions of the urinary bladder and other organs. Systemic, oral administration of ALA has been used for ALA PDT of superficial head and neck cancer, various gastrointestinal cancers, and the condition known as Barrett's esophagus. This paper reviews the current clinical and development status of ALA PDT and PD.