Guidelines for topical photodynamic therapy: report of a workshop of the British Photodermatology Group

Terapêutica fotodinâmica com ácido delta-aminolevulínico e luz de diodos em ceratoses actínicas

FUNDAMENTOS: A terapêutica fotodinâmica é técnica de tratamento em que se aplica uma substância fotossensibilizante nos tecidos ativada por uma fonte de luz de comprimento de onda específico, gerando destruição celular seletiva. Estudam-se novas fontes de luz que possam ser usadas no tratamento de ceratoses actínicas. OBJETIVOS: Avaliar a efetividade da terapêutica fotodinâmica com ácido delta-aminolevulínico utilizando como fonte de luz um aparelho emissor de luz de diodos no tratamento de ceratoses actínicas de face e membros superiores. MÉTODOS: Dezoito pacientes com ceratoses actínicas na face ou membros superiores realizaram uma aplicação de creme de ácido delta-aminolevulínico a 20% e foram submetidos à exposição de luz de diodos, comprimento de onda de 630 nm. RESULTADOS: Foram tratadas 328 ceratoses actínicas, obtendo-se cura clínica completa em 210 (64,0%) após 24 semanas. Lesões do dorso das mãos apresentaram cura clínica completa em 49,2%; nas demais áreas esse valor foi de 81,4%. Não houve registro de efeitos adversos graves, e obteve-se bom grau de satisfação dos pacientes com os resultados. CONCLUSÃO: A terapêutica fotodinâmica com fonte de emissão de luz de diodos mostrou-se eficaz e bem tolerada para tratamento de ceratoses actínicas, com resultados semelhantes aos encontrados na literatura utilizando outras fontes luminosas.

Photodynamic activity of aloe-emodin induces resensitization of lung cancer cells to anoikis

Aloe-emodin was found to be a photosensitizer and possess anti-tumor activity. However, the detailed mechanism underlying the biological effects of aloe-emodin remains unknown. In this study, we explored the mechanisms of photocytotoxicity induced by aloe-emodin in lung cancer H460 cells. According to the results of the photoactivated aloe-emodin-induced disruption of cytoskeleton, we verify that aloe-emodin with irradiation induces anoikis of H460 cells. Photosensitized aloe-emodin-induced anoikis is associated with the protein expression of α-actinin and mitogen-activated protein (MAP) kinase members. In this study, a rapid opening of the mitochondrial permeability transition pore and the change in apoptosis-related protein expression were involved in photoactivated aloe-emodin-induced cell death. We also demonstrated that anoikis induced by aloe-emodin with irradiation is mediated through the intrinsic and extrinsic death pathways in a caspase-dependent manner in H460 cells.

Primary and metastatic malignant tumors of the scalp: an update

In recent years there have been a number of interesting advances in several topics relating to the diagnosis and treatment of cutaneous lesions with particular applicability to primary and metastatic malignancies of the scalp. In this article we provide a general update of advances in this field, and cover the more salient points relating to a variety of malignant tumors that have been reported to appear on the scalp as primary or metastatic lesions. A search and review of the literature on PubMed was made to identify and discuss relevant points relating to diagnosis and treatment of primary and metastatic tumors of the scalp. We describe the anatomy of the scalp, epidemiology of scalp tumors, theories of field cancerization and field therapy, photodynamic therapy, excisional surgical techniques and reconstruction, lymphoscintigraphy, chemoprevention, as well as details relating to atypical fibroxanthoma, Brooke-Spiegler syndrome, nevus sebaceus, cutaneous lymphoma, and metastatic disease. There is a very broad differential diagnosis for scalp nodules, which includes many different benign and malignant diseases, and treatment should be tailored accordingly. Given the potential for poor prognosis with some of the more aggressive malignancies that can be found in this anatomic area, the importance of a thorough physical examination cannot be emphasized enough, and early detection is critical to provide patients with the best chance for a favorable outcome.

Terapia fotodinâmica: revisão da literatura e documentação iconográfica

A terapia fotodinâmica é uma reação química ativada por luz usada para destruição seletiva de um tecido e requer um agente fotossensibilizante no tecido-alvo, uma fonte de luz e oxigênio. Estão disponíveis, no momento, o ácido 5-aminolevulínico para tratamento de ceratoses actínicas e o metilaminolevulinato, aprovado para tratamento de ceratoses actínicas, carcinoma basocelular e doença de Bowen. As fontes de luz utilizadas para a terapia fotodinâmica devem emitir comprimentos de onda no espectro de absorção do fotossensibilizante escolhido. As lâmpadas LED (light emitting diode) são as indicadas para terapia fotodinâmica tópica no tratamento do câncer de pele não melanoma. A terapia fotodinâmica deve ser considerada, em particular, para pacientes que apresentam lesões superficiais, múltiplas, disseminadas e para pacientes imunossuprimidos. Mais recentemente, a terapia fotodinâmica tem sido indicada no tratamento do fotoenvelhecimento, acne, hidrosadenite, esclerodermia, psoríase, verrugas, leishmaniose, entre outras. Por este trabalho será possível ter acesso a uma extensa revisão da literatura sobre terapia fotodinâmica, seus mecanismos, indicações e resultados, seguida de comentários e críticas pertinentes ao assunto.

An economic evaluation of topical treatments for actinic keratosis

Actinic keratoses (AK) commonly occur as lesions, in sun-exposed areas. Various treatment modalities exist for their removal. We assessed the cost-effectiveness in 2007 of topical treatments (5-fluorouracil, imiquimod) and photodynamic therapy with methyl aminolevulinate (MAL-PDT) for AK under the perspective of the UK National Health Service (NHS) in England and Wales over two lines of treatment. We used a decision tree analytical approach. Efficacy data were taken from published trial literature for two investigator-assessed outcomes: 'complete clinical response' and 'excellent cosmetic outcome'. MAL-PDT at first line followed by various second-line treatments provided the greatest probability of complete clinical response (91.7%), but MAL-PDT at first line followed by further MAL-PDT as the second-line treatment provided the greatest probability of excellent cosmetic outcome (73.6%). The cost of MAL-PDT was 437 pounds sterling after two lines of treatment if MAL-PDT was that second-line treatment or 418 pounds sterling if various treatments were offered at second line. The probabilistic analysis produced consistent results. Based on this model, the costs and effectiveness of MAL-PDT in the UK NHS compare well with other treatments for AK.

Enrichment of hepatocytes in a HepaRG culture using spatially selective photodynamic treatment

The human hepatoma HepaRG cell line is an in vitro cell model that is becoming an important tool in drug metabolism, hepatotoxicity, genotoxicity, and enzyme induction studies. The cells are highly proliferative during their undifferentiated state but once committed, they differentiate into two distinctly different cell types, namely, hepatocyte-like and biliary epithelial-like cells. The presence of the latter in the cell culture is considered to be a drawback of the cell model. Since the proliferating undifferentiated HepaRG cells have a bipotent character, the only way to improve the content ratio of hepatic versus biliary cells of differentiated HepaRG cells is to eradicate biliary cells in situ, in a way that free surface space does not become available and thus no transdifferentiation can occur. Spatially selective photodynamic therapy has proven to be effective for that purpose. First, all the cells were administered aminolevulinic acid (delta-ALA) to stimulate the synthesis of protoporphyrin IX (PpIX), a naturally occurring photosensitizer. Then, the biliary cells were automatically identified and outlined by bright-field image processing. Last, UV light patterns were projected onto the epithelial cells alone by a spatial light modulation device connected to an optical microscope; therefore, only these cells were destroyed by photodynamic therapy.

Cost effectiveness of imiquimod 5% cream compared with methyl aminolevulinate-based photodynamic therapy in the treatment of non-hyperkeratotic, non-hypertrophic actinic (solar) keratoses: a decision tree model

BACKGROUND

Actinic keratosis (AK) is caused by chronic exposure to UV radiation (sunlight). First-line treatments are cryosurgery, topical 5-fluorouracil (5-FU) and topical diclofenac. Where these are contraindicated or less appropriate, alternatives are imiquimod and photodynamic therapy (PDT).

OBJECTIVE

To compare the cost effectiveness of imiquimod and methyl aminolevulinate-based PDT (MAL-PDT) from the perspective of the UK NHS.

METHODS

A decision tree model was populated with data from a literature review and used to estimate costs and QALYs gained and incremental cost effectiveness over 1 year. The model simulated patients who were in secondary care, who had four to nine AK lesions, and for whom cryosurgery, 5-FU and diclofenac were contraindicated or considered less appropriate.

RESULTS

Over 1 year, imiquimod cost £174 less than MAL-PDT (year 2006 values) but resulted in 0.005 fewer QALYs gained. The incremental cost-effectiveness ratio (ICER) of MAL-PDT over imiquimod was £34,576. In the probabilistic sensitivity analysis, there was a 75% probability that imiquimod was cost effective compared with MAL-PDT at a threshold of £20,000 per QALY gained, falling to 73% at £30,000.

CONCLUSIONS

Imiquimod may be the more cost-effective treatment at conventional cost-effectiveness thresholds. A direct head-to-head study of MAL-PDT versus imiquimod is required to reduce uncertainty.

An overview of topical photodynamic therapy in dermatology

This article is a review of the use of topical photodynamic therapy in dermatology and its current role in 2009 and future developments. The content of this article was presented at the EPPM in Wroclaw, September 2009.

Methyl aminolevulinate (Metvix®) photodynamic therapy - practical pearls

Topical photodynamic therapy (PDT) is an effective treatment for certain non-melanoma skin cancers (NMSCs), including superficial and nodular basal cell carcinomas (sBCC and nBCC), actinic keratosis (AK) and Bowen's disease. Methyl aminolevulinate (MAL, Metvix) is licensed in Europe for use in PDT for sBCC, nBCC and thin or non-hyperkeratotic and non-pigmented AK on the face and scalp, where other therapies are unsuitable. Optimal PDT response can be achieved through appropriate patient selection and lesion preparation. Evidence of efficacy is reviewed from guidelines and clinical experience. Red light from an LED source offers a relatively efficient method of activating the photodynamic reaction. The most common side effect of PDT is pain, burning or stinging discomfort at the site of treatment, although most patients do not request pain relief. The incidental observation of surface fluorescence three hours after photosensitizer application can be utilized for tumour detection as well as delineation. Topical PDT using Metvix MAL offers a practical non-invasive therapy option with the potential for high efficacy and good cosmesis.

Photodynamic therapy with 5-aminolevulinic acid and diamino acid derivatives of protoporphyrin IX reduces papillomas in mice without eliminating transformation into squamous cell carcinoma of the skin

Photodynamic therapy (PDT) is used to treat malignant and nonmalignant diseases. It is also used for cosmetological skin treatment. PDT is generally considered to have a low risk of carcinogenicity. However, instances of nonmalignant human tumors turning malignant have been linked to PDT. In this study, we used 5-aminolevulinic (ALA) acid and 3 water soluble photosensitizers-PP(Arg)(2), PP(Ser)(2)Arg(2), PP(Ala)(2)Arg(2), all diamino acid derivatives of protoporphyrin IX-to treat benign papillomas in FVB/N mice induced by 7,12-dimethylbenz(a)anthracene (DMBA)-12-O-tetradecanoyl-phorbol-13-acetate (TPA). Of these drugs, ALA and PP(Arg)(2) were found the most efficient. PDT reduced the number of papillomas, but with increasing effectiveness of the drugs, the risk of malignant transformation of the papillomas into squamous cell carcinomas increased. The underlying mechanisms are not clear and further investigations are needed.

Designing photosensitizers for photodynamic therapy: strategies, challenges and promising developments

Photodynamic therapy (PDT) and photodynamic antimicrobial chemotherapy (PACT) are techniques that combine the effects of visible light irradiation with subsequent biochemical events that arise from the presence of a photosensitizing drug (possessing no dark toxicity) to cause destruction of selected cells. Despite its still widespread clinical use, Photofrin® has several drawbacks that limit its general clinical use. Consequently, there has been extensive research into the design of improved alternative photosensitizers aimed at overcoming these drawbacks. While there are many review articles on the subject of PDT and PACT, these have focused on the photosensitizers that have been used clinically, with little emphasis placed on how the chemical aspects of the molecule can affect their efficacy as PDT agents. Indeed, many of the PDT/PACT agents used clinically may not even be the most appropriate within a given class. As such, this review aims to provide a better understanding of the factors that have been investigated, while aiming at improving the efficacy of a molecule intended to be used as a photosensitizer. Recent publications, spanning the last 5 years, concerning the design, synthesis and clinical usage of photosensitizers for application in PDT and PACT are reviewed, including 5-aminolevulinic acid, porphyrins, chlorins, bacteriochlorins, texaphyrins, phthalocyanines and porphycenes. It has been shown that there are many important considerations when designing a potential PDT/PACT agent, including the influence of added groups on the lipophilicity of the molecule, the positioning and nature of these added groups within the molecule, the presence of a central metal ion and the number of charges that the molecule possesses. The extensive ongoing research within the field has led to the identification of a number of potential lead molecules for application in PDT/PACT. The development of the second-generation photosensitizers, possessing shorter periods of photosensitization, longer activation wavelengths and greater selectivity for diseased tissue provides hope for attaining the ideal photosensitizer that may help PDT and PACT move from laboratory investigation to clinical practice.

Low-dose methotrexate enhances aminolevulinate-based photodynamic therapy in skin carcinoma cells in vitro and in vivo

PURPOSE

To improve treatment efficacy and tumor cell selectivity of delta-aminolevulinic acid (ALA)-based photodynamic therapy (PDT) via pretreatment of cells and tumors with methotrexate to enhance intracellular photosensitizer levels.

EXPERIMENTAL DESIGN

Skin carcinoma cells, in vitro and in vivo, served as the model system. Cultured human SCC13 and HEK1 cells, normal keratinocytes, and in vivo skin tumor models were preconditioned with methotrexate for 72 h and then incubated with ALA for 4 h. Changes in protoporphyrin IX (PpIX) levels and cell survival after light exposure were assessed.

RESULTS

Methotrexate preconditioning of monolayer cultures preferentially increased intracellular PpIX levels 2- to 4-fold in carcinoma cells versus normal keratinocytes. Photodynamic killing was synergistically enhanced by the combined therapy compared with PDT alone. Methotrexate enhancement of PpIX levels was achieved over a broad methotrexate concentration range (0.0003-1.0 mg/L; 0.6 nmol/L-2 mmol/L). PpIX enhancement correlated with changes in protein expression of key porphyrin pathway enzymes, approximately 4-fold increase in coproporphyrinogen oxidase and stable or slightly decreased expression of ferrochelatase. Differentiation markers (E-cadherin, involucrin, and filaggrin) were also selectively induced by methotrexate in carcinoma cells. In vivo relevance was established by showing that methotrexate preconditioning enhances PpIX accumulation in three models: (a) organotypic cultures of immortalized keratinocytes, (b) chemically induced skin tumors in mice; and (c) human A431 squamous cell tumors implanted subcutaneously in mice.

CONCLUSION

Combination therapy using short-term exposure to low-dose methotrexate followed by ALA-PDT should be further investigated as a new combination modality to enhance efficacy and selectivity of PDT for epithelial carcinomas.

Clinical and immunohistochemical assessment of vulval intraepithelial neoplasia following photodynamic therapy using a novel bioadhesive patch-type system loaded with 5-aminolevulinic acid

BACKGROUND

The work in this study appraised photodynamic treatment (PDT) as a treatment method for vulval intraepithelial neoplasia (VIN) using a novel bioadhesive patch to deliver aminolevulinic acid. An analysis of changes in expression of apoptotic and cell cycle proteins (p53, p21, Mdm2, Blc-2, Bax, Ki-67) in response to PDT was evaluated.

METHODS

PDT was performed using non-laser light, either as a one or two-cycle treatment, with clinical and pathological assessment following after 6 weeks. Twenty-three patients with 25 VIN lesions underwent 49 cycles of PDT. Patches were designed to conform to uneven vulval skin and contained 38 mg cm(-2) aminolevulinic acid. Assessment was carried out at 6 weeks post-treatment. Patient-based treatment assessment, along with clinical and pathological changes, were monitored. Immunohistochemical staining was used to elucidate a possible biomolecular basis for induced cellular changes.

RESULTS

Most patients (52%) reported a symptomatic response, with normal pathology restored in 38% of lesions. The patch was easy to apply and remove, causing minimal discomfort. Fluorescence inspection confirmed protoporphyrin accumulation. Pain during implementation of PDT was problematic, necessitating some form of local analgesia. Changes in expression of cell cycle and apoptotic-related proteins suggested involvement of apoptotic pathways. Down regulation of p21 and inverse changes in Bcl-2 and Bax were key findings.

CONCLUSION

Treatment of VIN lesions using a novel bioadhesive patch induced changes in cell cycle and apoptotic proteins in response to PDT with possible utilisation of apoptotic pathways. The efficacy of PDT in treating VIN could be improved by a better understanding of these apoptotic mechanisms, the influence of factors, such as HPV status, and of the need for effective pain management.

Three-dimensional fluence rate measurement and data acquisition system for minimally invasive light therapies

Light based therapies such as photodynamic therapy are in need of advanced tools for light fluence rate dosimetry and monitoring within the context of therapy planning and light delivery to ensure maximum treatment efficacy. The use of a single, multisensor fiber-based fluorescent probe capable of performing spatially resolved fluence rate measurements along an axis was demonstrated. This work extends the previous technique and describes a fluence rate quantification system able to employ up to 12 multisensor probes to simultaneously measure fluence rate distribution throughout a 3D treatment volume. The system optoelectronics provides for sensor calibration, data acquisition, and weighted least-squares processing to extract localized fluence rate information in real-time. Core components include an integrating cylinder for source sensor calibration, a 2D back thin CCD detector for sensor signal detection from multiple probes, high-speed data acquisition card, and custom software for real-time extraction of fluence rate information from all sensors.

In vitro and in vivo evaluation of photodynamic techniques for the experimental treatment of human hepatoblastoma and neuroblastoma: preliminary results

PURPOSE

The purpose of this study was to test the susceptibility of human hepatoblastoma and neuroblastoma cells to photodynamic diagnostics (PDD) and photodynamic therapy (PDT) using 5-aminolevulinic acid (5-ALA) as a photosensitizer.

METHODS

Cell cultures of human hepatoblastoma (HuH6) and neuroblastoma (MHH-NB-11) were incubated with 5-ALA at increasing concentrations to measure the cellular kinetics of photosensitization. After optimizing incubation parameters, the cell cultures were then irradiated with increasing light doses and cell viability was measured by CTB assay. Human fibroblastic cells served as controls. So far, only the hepatoblastoma cell line has been tested in vivo. After injection of HUH6 cells in immunoincompetent rats, the efficacy of PDT was assessed. Photosensitization was achieved by intraperitoneal injection of 5-ALA. The pharmacokinetics of different tissues was studied. In a second study, a PDT of implanted hepatoblastoma, liver and peritoneum was performed. The irradiated areas were excised 48 h after treatment and studied by microscopy.

RESULTS

Cell culture experiments demonstrated a selective fluorescence for both tumor lines compared to controls. The photosensitized tumor cells demonstrated marked reductions in cell viability at significantly lower irradiation doses than the fibroblasts under PDT. The specificity of fluorescence was confirmed in vivo for hepatoblastoma, and all the sensitized and irradiated tumors showed marked phototoxic necrosis.

CONCLUSION

Human hepatoblastoma and neuroblastoma demonstrate marked and specific fluorescence after the application of 5-ALA, making PDD possible. Cell death occurred in both cell lines after PDT in vitro. Additionally, hepatoblastoma was susceptible to PDT in an animal model. Further studies will be necessary to determine the role of PDT and PDD in a clinical setting.

Guidelines for the management of basal cell carcinoma

This article represents a planned regular updating of the previous British Association of Dermatologists guidelines for the management of basal cell carcinoma. These guidelines present evidence-based guidance for treatment, with identification of the strength of evidence available at the time of preparation of the guidelines, and a brief overview of epidemiological aspects, diagnosis and investigation.

Guidelines for topical photodynamic therapy: update

Multicentre randomized controlled studies now demonstrate high efficacy of topical photodynamic therapy (PDT) for actinic keratoses, Bowen's disease (BD) and superficial basal cell carcinoma (BCC), and efficacy in thin nodular BCC, while confirming the superiority of cosmetic outcome over standard therapies. Long-term follow-up studies are also now available, indicating that PDT has recurrence rates equivalent to other standard therapies in BD and superficial BCC, but with lower sustained efficacy than surgery in nodular BCC. In contrast, current evidence does not support the use of topical PDT for squamous cell carcinoma. PDT can reduce the number of new lesions developing in patients at high risk of skin cancer and may have a role as a preventive therapy. Case reports and small series attest to the potential of PDT in a wide range of inflammatory/infective dermatoses, although recent studies indicate insufficient evidence to support its use in psoriasis. There is an accumulating evidence base for the use of PDT in acne, while detailed study of an optimized protocol is still required. In addition to high-quality treatment site cosmesis, several studies observe improvements in aspects of photoageing. Management of treatment-related pain/discomfort is a challenge in a minority of patients, and the modality is otherwise well tolerated. Long-term studies provide reassurance over the safety of repeated use of PDT.

Risk of nonmelanoma skin cancer with azathioprine use

While often life-saving for many complex diseases, iatrogenic immunosuppression has been associated with life-threatening infections and malignancies. Among these malignancies is skin cancer. Skin cancer is the most common form of cancer in the United States; the nonmelanoma skin cancers have an annual incidence of greater than 1,000,000 people in the US. It is well documented that the risk of nonmelanoma skin cancer (NMSC) is increased in those who are immunosuppressed. While many articles have been published on skin cancer risk in organ transplant recipients, little has been written regarding the incidence of nonmelanoma skin cancer in inflammatory bowel disease. A review of the literature of patients who are immunosuppressed for autoimmune disorders, and specifically, inflammatory bowel diseases, is discussed, as well as clinical presentations and treatment options.

Photodynamic therapy with 5-aminolaevulinic acid, dimethylsulfoxide and curettage in basal cell carcinoma: a 6-year clinical and histological follow-up

BACKGROUND

Long-term follow-up data are needed to evaluate treatment effect after photodynamic therapy (PDT).

OBJECTIVE

To investigate long-term clinical, histological and cosmetic follow-up results in basal cell carcinoma (BCC) after PDT, including treatment response related to patients and lesion characteristics.

MATERIALS AND METHODS

A longitudinal study of 44 patients with 60 histologically verified BCC tumours, treated with one or two sessions of dimethylsulfoxide (DMSO)-supported 5-aminolaevulinic acid--PDT following curettage, was performed. Lesions in complete remission after 3 months were followed with clinical inspection, histological investigation and evaluation of cosmetic outcome at regular intervals; long-term efficacy assessed as verified recurrence within 72 months after PDT.

RESULTS

Complete remission at 3 months was achieved in 55 lesions from 39 patients. Two patients with one lesion each died. At 72 months, 43 of 53 lesions remained disease-free (81%); 68% remained after one treatment session, and 91% remained after two treatment sessions. Recurrence of tumour occurred at 6, 12, 24 and 36 months in 2, 4, 2 and 2 lesions, respectively; clinical investigation identified 97% of them. Male sex and H-mid-face zone were significantly associated with recurrence. The cosmetic outcome at 72 months was rated as good or excellent by patients and investigators in more than 90% of evaluated cases.

CONCLUSION

DMSO-PDT following curettage is an effective treatment for BCC, with favourable long-term clinical, histopathological and cosmetic results. Clinical examination of treated lesions appears to be sufficient for long term follow up.

Irradiance-dependent photobleaching and pain in delta-aminolevulinic acid-photodynamic therapy of superficial basal cell carcinomas

PURPOSE

In superficial basal cell carcinomas treated with photodynamic therapy with topical delta-aminolevulinic acid, we examined effects of light irradiance on photodynamic efficiency and pain. The rate of singlet-oxygen production depends on the product of irradiance and photosensitizer and oxygen concentrations. High irradiance and/or photosensitizer levels cause inefficient treatment from oxygen depletion in preclinical models.

EXPERIMENTAL DESIGN

Self-sensitized photobleaching of protoporphyrin IX (PpIX) fluorescence was used as a surrogate metric for photodynamic dose. We developed instrumentation measuring fluorescence and reflectance from lesions and margins during treatment at 633 nm with various irradiances. When PpIX was 90% bleached, irradiance was increased to 150 mW/cm(2) until 200 J/cm(2) were delivered. Pain was monitored.

RESULTS

In 33 superficial basal cell carcinomas in 26 patients, photobleaching efficiency decreased with increasing irradiance above 20 mW/cm(2), consistent with oxygen depletion. Fluences bleaching PpIX fluorescence 80% (D80) were 5.7 +/- 1.6, 4.5 +/- 0.3, 7.5 +/- 0.8, 7.4 +/- 0.3, 12.4 +/- 0.3, and 28.7 +/- 7.1 J/cm(2), respectively, at 10, 20, 40, 50, 60 and 150 mW/cm(2). At 20-150 mW/cm(2), D80 doses required 2.5-3.5 min; times for the total 200 J/cm(2) were 22.2-25.3 min. No significant pain occurred up to 50 mW/cm(2); pain was not significant when irradiance then increased. Clinical responses were comparable to continuous 150 mW/cm(2) treatment.

CONCLUSIONS

Photodynamic therapy with topical delta-aminolevulinic acid using approximately 40 mW/cm(2) at 633 nm is photodynamically efficient with minimum pain. Once PpIX is largely photobleached, higher irradiances allow efficient, rapid delivery of additional light. Optimal fluence at a single low irradiance is yet to be determined.

Bioavailability of aminolaevulinic acid and methylaminolaevulinate in basal cell carcinomas: a perfusion study using microdialysis in vivo

BACKGROUND

Photodynamic therapy is becoming a popular treatment for superficial nonmelanoma precancerous and cancerous lesions, showing excellent cosmetic results. Nevertheless, the reported cure rates vary and the transdermal penetration of drugs has been discussed as a limiting factor, particularly for treatment of nodular basal cell carcinoma (BCC).

OBJECTIVES

To investigate the transdermal penetration of aminolaevulinic acid (ALA) and methylaminolaevulinate (MAL) in BCC in vivo using a microdialysis technique. The different prodrugs were compared and the effect of curettage was studied.

METHODS

Twenty patients with 27 histologically verified BCCs (13 superficial, 14 nodular) were included. All lesions were located at the front of the body (head and face excluded). The first 10 patients included were treated with MAL (13 BCCs), and the following 10 patients with ALA (14 BCCs). A light curettage was performed on every second lesion (curettage, n = 13; noncurettage, n = 14). Microdialysis catheters were inserted into the tumours at tissue depths varying from 0.4 to 1.9 mm. Dialysates were collected at 15-30-min intervals for 4 h and the interstitial concentrations of MAL and ALA were determined using high-performance liquid chromatography.

RESULTS

No significant difference in interstitial drug concentration was observed between lesions treated with ALA or MAL during the 4-h measurement period. However, for the lesions with deeper catheter locations, i.e. at or below 1 mm (n = 11), drug concentrations above the detection limit were obtained in only six lesions. All but one BCC with superficial catheter location, i.e. < 1 mm (n = 16), exhibited detectable drug concentration (P = 0.026). The interstitial peak concentrations were reached within 90 min in 23 of the 27 BCCs, but were not found to be correlated with the depth of the catheters. No difference was found when comparing superficial and nodular BCCs, and the effect of curettage was found to be negligible.

CONCLUSIONS

The results imply that there is no significant difference in transdermal penetration of ALA and MAL in tumour tissue. Detectable levels of drug were not obtained in almost 50% of the lesions where catheters were situated 1-1.9 mm in the lesion. Curettage was not found to affect the interstitial concentration, indicating that penetration of drug indeed might be a problem when treating BCCs thicker than 1 mm.

A terapia fotodinâmica com ácido 5-aminolevulínico como modalidade de tratamento para neoplasias cutâneas não-melanoma

FUNDAMENTOS: A terapia fotodinâmica baseia-se na associação de fonte de luz e fotossensibilizador para destruir seletivamente as células. OBJETIVO: Avaliar os efeitos imediatos e tardios, a resposta clínica e os resultados estéticos da terapia fotodinâmica com ácido 5-aminolevulínico em neoplasias cutâneas não-melanoma. MÉTODOS: Trinta e quatro lesões, sendo 19 disceratoses de Bowen e 15 carcinomas basocelulares, foram submetidas à aplicação tópica e oclusiva do ácido 5-aminolevulínico a 20%, por seis horas, e posteriormente a sessão única de laser de diodo (630nm). RESULTADOS: Foram registrados: sensação de queimação durante as sessões; eritema, edema e erosões, nas primeiras 72 horas; cicatrização em média de quatro semanas; resultados estéticos variáveis de excelentes a bons. Aos três meses, a resposta clínica foi de 91,2%, sendo reduzida, aos 18 meses, para 73,3%, de modo similar tanto para disceratose de Bowen (72,2%) quanto para carcinoma basocelular (75%). Foi evidenciada relação de tendência linear entre a redução da freqüência da resposta clínica e o aumento da dimensão das neoplasias cutâneas não-melanoma (p<0,001). CONCLUSÃO: A terapia fotodinâmica com ácido 5-aminolevulínico tópico mostrou destacadas vantagens: minimamente invasiva no tratamento de lesões múltiplas em sessão única ou em sítios de pobre cicatrização com superioridade dos resultados estéticos. O tipo/subtipo(clínico e histopatológico), a dimensão e o adequado seguimento devem ser considerados para a sua indicação no tratamento de neoplasias cutâneas não-melanoma.

Clinical investigation of the novel iron-chelating agent, CP94, to enhance topical photodynamic therapy of nodular basal cell carcinoma

BACKGROUND

Photodynamic therapy (PDT) involves the activation of a photosensitizer by visible light to produce activated oxygen species within target cells, resulting in their destruction. Evidence-based guidelines support the efficacy of PDT using topical 5-aminolaevulinic acid (ALA-PDT) in actinic keratoses, Bowen disease and basal cell carcinoma (BCC). Efficacy for nodular BCC appears inferior to that for superficial BCC unless prior debulking or repeat treatments are performed. Objectives The aim of this study was to assess the safety and efficacy of adding a novel iron-chelating agent, CP94 (1,2-diethyl-3-hydroxypyridin-4-one hydrochloride), to topical ALA, to temporarily increase the accumulation of the photosensitizer in the tumour.

METHODS

A mixed topical formulation of ALA + increasing concentrations of CP94 was used to carry out PDT on previously biopsied nodular BCC with no prior lesion preparation using standard light delivery. The area was assessed clinically and surgically excised 6 weeks later for histological examination.

RESULTS

Enhanced PDT using 40% CP94 resulted in significantly greater clearance rates in nodular BCC than with ALA-PDT alone, in our protocol of single-treatment PDT with no lesion preparation.

CONCLUSIONS

The results of this study demonstrate the safe and effective use of an enhanced ALA-PDT protocol for nodular BCC using CP94, with no adverse reactions to this modification. This is the first time this formulation has been used in patients. This formulation is now the focus of further study.