A Review of the Dermatologic Clinical Applications of Topical Photodynamic Therapy

Topical photodynamic therapy is a widely approved therapy for actinic keratoses and low-risk nonmelanoma skin cancers with a rapidly growing range of emerging indications for other cutaneous diseases. This review summarizes the best-available evidence to provide a clinical update for dermatologists on the approved and emerging indications of photodynamic therapy. The body of evidence suggests that photodynamic therapy is superior or noninferior to other available treatment modalities for actinic keratoses, low-risk basal cell carcinomas, Bowen's disease, skin field cancerization, chemoprevention of keratinocyte carcinomas in organ transplant recipients, photoaging, acne vulgaris, and cutaneous infections including verrucae, onychomycosis, and cutaneous leishmaniasis. There is emerging evidence that photodynamic therapy plays a role in the management of actinic cheilitis, early-stage mycosis fungoides, extramammary Paget disease, lichen sclerosis, and folliculitis decalvans but there are no comparative studies with other active treatment modalities. Common barriers to topical photodynamic therapy include procedural pain, costs, and the time required for treatment delivery. There is significant heterogeneity in the photodynamic therapy protocols reported in the literature, including different photosensitizers, light sources, number of treatments, time between treatments, and use of procedural analgesia. Topical photodynamic therapy should be considered in the management of a spectrum of inflammatory, neoplastic, and infectious dermatoses. However, more comparative research is required to determine its role in the treatment algorithm for these dermatologic conditions and more methodological research is required to optimize photodynamic therapy protocols to improve the tolerability of the procedure for patients.

Systematic review of photodynamic therapy for the treatment of hidradenitis suppurativa

OBJECTIVE

To perform a systematic review of available literature regarding the use of 5-aminolevulinic acid (ALA) and ALA derivative photodynamic therapy (PDT) in the treatment of hidradenitis suppurativa (HS) and provide recommendations on its use.

METHODS

A systematic review was performed of all published studies up to September 1, 2019 from nine databases, including PubMed, that evaluated PDT in the treatment of HS. For each study, quality of evidence and risk of bias was evaluated. Recommendations from the body of evidence were created based on Strength of Recommendation and Taxonomy (SORT) criteria.

RESULTS

Eighteen studies met inclusion criteria. The majority of studies had a high risk of bias. Blue light PDT with 20% ALA and red light PDT with 16% methyl aminolevulinate (MAL) demonstrated some benefit based on a small number of poor-quality studies with a high risk of bias (Grade C, level III evidence). The most promising results were for 1%-5% ALA with intralesional diode, with good to complete response in 78%-94% of anatomic sites treated (Grade B, level II evidence).

LIMITATIONS

The majority of studies contained high levels of bias, with significant heterogeneity between studies. Conclusions are limited by small samples sizes, lack of randomized controlled trials, and differing protocols.

CONCLUSION

Further studies are needed to determine the clinical efficacy of 20% ALA with blue light and MAL with red light. Intralesional diode PDT shows the most promise and warrants further investigation in larger, randomized controlled trials.

A Skin Cancer Prophylaxis Study in Hairless Mice Using Methylene Blue, Riboflavin, and Methyl Aminolevulinate as Photosensitizing Agents in Photodynamic Therapy

The high incidence of sunlight-induced human skin cancers reveals a need for more effective photosensitizing agents. In this study, we compared the efficacy of prophylactic photodynamic therapy (PDT) when methylene blue (MB), riboflavin (RF), or methyl aminolevulinate (MAL) were used as photosensitizers. All mice in four groups of female C3.Cg/TifBomTac hairless immunocompetent mice (N = 100) were irradiated with three standard erythema doses of solar-simulated ultraviolet radiation (UVR) thrice weekly. Three groups received 2 × 2 prophylactic PDT treatments (days 45 + 52 and 90 + 97). The PDT treatments consisted of topical administration of 16% MAL, 20% MB, or 20% RF, and subsequent illumination that matched the photosensitizers’ absorption spectra. Control mice received no PDT. We recorded when the first, second, and third skin tumors developed. The pattern of tumor development after MB-PDT or RF-PDT was similar to that observed in irradiated control mice (p > 0.05). However, the median times until the first, second, and third skin tumors developed in mice given MAL-PDT were significantly delayed, compared with control mice (256, 265, and 272 vs. 215, 222, and 230 days, respectively; p < 0.001). Only MAL-PDT was an effective prophylactic treatment against UVR-induced skin tumors in hairless mice.

Methylene blue vs methyl aminolevulinate photodynamic therapy in the treatment of mild-to-moderate toenail onychomycosis: Short- and medium-term effects

Photodynamic therapy (PDT) has emerged as an interesting alternative option for onychomycosis treatment. The impact of a specific photosensitizer (PS) on the final result is an important factor to consider. We conducted a short- and medium-term controlled trial to compare the effectiveness of PDT in the treatment of mild-to-moderate onychomycosis when it is mediated by two different PSs. Twenty patients were randomized to receive nine sessions of PDT distributed over 16 weeks mediated either by methylene blue (MB/PDT group) or methyl aminolevulinate (MAL/PDT group). Onychomycosis severity index (OSI) and nail involvement were checked along the study. Complete cure, treatment success, and clinical improvement were tabulated at 16 and 40-week follow-ups. OSI scores decreased significantly along the study, from 12.1 ± 5.4 to 3.6 ± 3.2 (MB/PDT group) and from 14.8 ± 6.0 to 5.4 ± 4.4 (MAL/PDT group). At 16-week follow-up, only 20% of the patients in the MB/PDT group reached complete cure and none in the group of MAL/PDT. At 40-week follow-up, complete cure rates were 70% and 40% in the MB/PDT group and MAL/PDT group respectively. Both modalities showed good outcomes in treatment of moderate toenail onychomycosis. MB/PDT showed a faster action but with relapse rates slightly higher than MAL/PDT.

Methylene blue vs methyl aminolevulinate photodynamic therapy in combination with oral terbinafine in the treatment of severe dermatophytic toenail onychomycosis: Short- and long-term effects

BACKGROUND

Photodynamic therapy (PDT) kills target microorganisms via reactive oxygen species (ROS) production. PDT seems to be a good alternative treatment option for onychomycosis.

OBJECTIVE

To compare the efficacy of combined therapies based on oral terbinafine (TN) plus adjunctive PDT mediated by methylene blue (MB) (TN + MB/PDT) or methyl aminolevulinate (MAL) (TN + MAL/PDT) in the treatment of onychomycosis.

METHODS

Twenty patients affected by severe dermatophyte onychomycosis in the nails of the big toe (>60% disease involvement of target nail) received oral TN for 12 weeks and concomitantly were randomly allocated to receive nine sessions, separated by 2-week intervals, of urea (40%) plus a PDT protocol mediated by MB (TN + MB/PDT: group I) or mediated by MAL (TN + MAL/PDT: group II). Clinical and mycological efficacy was evaluated at 16-, 40- and 52-week follow-up.

RESULTS

Both protocols showed a significant decrease in Onychomycosis Severity Index (OSI) scores (P < .05), from 24.2 ± 4.6 to 0.7 ± 0.6 (group I)) and from 18.5 ± 10.1 to 2.1 ± 2.0 (group II). No side effects or complications were reported in any of the combinations used. Mycological cure rates were significantly higher during the last third of the evaluated period of time, reaching 100% and 90% in group I and group II, respectively, at the 52-week follow-up. In both modalities, complete cure was achieved in 70% of the patients at the 52-week follow-up.

CONCLUSIONS

TN + MB/PDT and TN + MAL/PDT show similar outcomes in the treatment of toenails with severe onychomycosis. PDT is an effective method to accelerate the TN-mediated healing process.

Epigallocatechin Gallate Enhances MAL-PDT Cytotoxic Effect on PDT-Resistant Skin Cancer Squamous Cells

Photodynamic therapy (PDT) has been used to treat certain types of non-melanoma skin cancer with promising results. However, some skin lesions have not fully responded to this treatment, suggesting a potential PDT-resistant phenotype. Therefore, novel therapeutic alternatives must be identified that improve PDT in resistant skin cancer. In this study, we analyzed the cell viability, intracellular protoporphyrin IX (PpIX) content and subcellular localization, proliferation profile, cell death, reactive oxygen species (ROS) detection and relative gene expression in PDT-resistant HSC-1 cells. PDT-resistant HSC-1 cells show a low quantity of protoporphyrin IX and low levels of ROS, and thus a low rate of death cell. Furthermore, the resistant phenotype showed a downregulation of HSPB1, SLC15A2, FECH, SOD2 and an upregulation of HMBS and BIRC5 genes. On the other hand, epigallocatechin gallate catechin enhanced the MAL-PDT effect, increasing levels of protoporphyrin IX and ROS, and killing 100% of resistant cells. The resistant MAL-PDT model of skin cancer squamous cells (HSC-1) is a reliable and useful tool to understand PDT cytotoxicity and cellular response. These resistant cells were successfully sensitized with epigallocatechin gallate catechin. The in vitro epigallocatechin gallate catechin effect as an enhancer of MAL-PDT in resistant cells is promising in the treatment of difficult skin cancer lesions.

Photodynamic Therapy Using a New Painless Light-Emitting Fabrics Device in the Treatment of Extramammary Paget Disease of the Vulva (the PAGETEX Study): Protocol for an Interventional Efficacy and Safety Trial

Background

Extramammary Paget disease of the vulva (EMPV) is a rare skin disorder commonly seen in postmenopausal Caucasian females that appears clinically as red, eczematous, pruriginous, and sometimes painful lesions. Although most cases are noninvasive, EMPV may be associated with an underlying or distant adenocarcinoma. EMPV has a chronic and relapsing course. The reference treatment is based on local surgical excision with negative margins. However, disease frequently extends far from the visible lesion, and surgical margins are frequently positive. Topical photodynamic therapy (PDT) is an established treatment modality for various dermatooncologic conditions. For example, red light irradiation with the Aktilite CL 128 and Metvixia (Galderma SA) as a photosensitizing molecule is a conventional protocol approved and widely used in Europe for PDT treatment of actinic keratosis, but this treatment is not yet widely used for EMPV because it has never clearly been demonstrated and is very painful.

Objective

The aim of the study is to investigate the efficacy and safety relating to the medical device PAGETEX as a new painless PDT device using Metvixia in the treatment of vulvar Paget disease. The primary end point is the disease control rate at 3 months in 30% of the patients included, defined as stability, partial response, or total response, considering the extent of the lesion. Secondary end points are the disease control rate at 6 months, patient quality of life, level of pain experienced by the patient at each PDT session, severity of erythema, presence of protoporphyrin IX in Paget cells after each PDT session, and overall satisfaction level of the patient.

Methods

The trial is an interventional, exploratory, simple group, nonrandomized, and single center (Lille University Hospital) study. Twenty-four patients will be included according to Simon’s optimal plan. Therapeutic procedure is based on a cycle of two PDT sessions with the PAGETEX medical device at 15-day intervals (Metvixia incubation during 30 minutes and 635 nm red light illumination with a low irradiance for 2 hours and 30 minutes for a total fluence of 12 J/cm²). At the assessment session, 3 months after inclusion, if the control of the disease is partial or null, the patient will complete another cycle of two PDT sessions. A final evaluation will be performed in all patients at 6 months. Analyses will be performed using SAS version 9.4 software (SAS Institute Inc). The characteristics of the patients at baseline will be described; qualitative variables will be described by numbers and percentages, and quantitative variables will be described either by the mean and standard deviation for Gaussian distribution or by the median and interquartile range (ie, 25th and 75th percentiles). The normality of the distributions will be tested by a Shapiro-Wilk test and checked graphically by histograms.

Results

First patient was included in September 2019 and clinical investigations are planned until August 2022. The final results of this study are expected to be available in January 2023.

Conclusions

This clinical trial aims to evaluate the efficacy and safety of a new PDT protocol for the treatment of EMPV. The PAGETEX device could become the treatment of choice if it is effective, painless, and easy to implement and use in hospitals.

Trial Registration

ClinicalTrials.gov NCT03713203; https://clinicaltrials.gov/ct2/show/NCT03713203

International Registered Report Identifier (IRRID)

PRR1-10.2196/15026

Long Term Effectiveness of Photodynamic Therapy for CIN Treatment

(1) Background: Cervical cancer is the third most commonly diagnosed cancer and the fourth leading cause of cancer death in women worldwide. The highest incidence rates are in Africa, followed by South-Central Asia and South America. According to the Brazilian National Institute of Cancer (INCA), 16,370 new cases of cervical cancer were estimated for each year of the biennium of 2018-2019. About 90% of cervical cancers originate from the malignant progression of cervical intraepithelial neoplasia (CIN) which is classified based on cytohistological characteristics (low- and high-grade lesions). The present study reports the long-term effectiveness of topical photodynamic therapy (PDT) for CIN grades 1 and 2/3 with up to two years of follow up. (2) Methods: A total of 56 patients with CIN 1, ten with CIN 2, and 14 patients for the placebo group were enrolled in this study. (3) Results: 75% (n = 42) of CIN 1 patients presented a complete response to PDT and only 23.2% (n = 13) of recurrence, progression, and/or lesions remaining two years after PDT. For CIN 2/3 patients, 90% were observed to be cured after one and two years of follow up. (4) Conclusions: PDT presented best results two years after a non-invasive, fast, and low-cost procedure and in comparison with the placebo group, preventing the progression of cervical intraepithelial neoplasia and preserving the cervix.

MAL-PDT inhibits oral precancerous cells and lesions via autophagic cell death

BACKGROUND

Oral cancer is a common cancer with a high mortality rate. While surgery is the most effective treatment for oral cancer, it frequently causes deformity and dysfunction in the orofacial region. In this study, methyl aminolevulinate photodynamic therapy (MAL-PDT) as a prevention tool against progression of precancerous lesion to oral cancer was explored.

METHODS

For in vitro studies, we evaluated the effects of MAL-PDT on viability of DOK oral precancerous cells by XTT, cell morphology by TEM, and intracellular signaling pathways by flow cytometry, Western blotting, and immunofluorescence. For in vivo study, DMBA was used to induce oral precancerous lesions in hamsters followed by MAL-PDT treatment. We measured tumor size and body weight weekly. After sacrifice, buccal pouch lesions were processed for H&E stain and immunohistochemistry analysis.

RESULTS

MAL-PDT induced autophagic cell death in DOK oral precancerous cells. The autophagy-related markers LC3II and p62/SQSTM1 and autophagosome formation in DOK cells were increased after MAL-PDT treatment. In vivo, Metvix^® -PDT treatment decreased tumor growth and enhanced LC3II expression in hamster buccal pouch tumors induced by DMBA.

CONCLUSIONS

Our in vitro and in vivo results suggest that MAL-PDT may provide an effective therapy for oral precancerous lesions through induction of autophagic cell death.

Is a single day patient friendly methyl aminolevulinate photodynamic therapy illumination scheme for superficial basal cell carcinoma feasible? A randomized multicenter pilot trial

BACKGROUND

Topical methyl aminolevulinate photodynamic therapy (MAL-PDT) is highly effective for the treatment of superficial basal cell carcinoma (sBCC). Current European treatment protocol requires two hospital visits, which is costly and unpractical. The aim of this study was to evaluate the efficacy of fractionated MAL-PDT, using two light fractions at 3 and 4 h compared to illumination at 3 and 5 h after MAL-application.

METHODS

Thirty patients were randomized into two groups. The first group received illumination at 3 and 4 h (20 + 55 J/cm²) after MAL-application (3/4 group). In the other group, two light fractions were performed at 3 and 5 h (20 + 55 J/cm²) after MAL-application (3/5 group). The lesion response was evaluated at 3 and 12 months posttreatment.

RESULTS

In the 3/5 group, 70.0% showed a complete response (CR) at 3 months compared to 63.6% in the other group. At 12 months, 100% showed a CR in the 3/5 group compared to 80.0% in the other group. However, most failures/recurrences were eventually due to the presence of a more aggressive BCC subtype, mostly caused by sampling error of the primary punch biopsy.

CONCLUSION

Single day protocol for MAL-PDT for sBCC is feasible and this study shows promising results.

Comparative study of the bactericidal effects of indocyanine green- and methyl aminolevulinate-based photodynamic therapy on Propionibacterium acnes as a new treatment for acne

Acne vulgaris is one of the most common dermatological problems, and its therapeutic options include topical and systemic retinoids and antibiotics. However, increase in problems associated with acne treatment, such as side-effects from conventional agents and bacterial resistance to antibiotics, has led to greater use of photodynamic therapy. The purpose of this study was to compare the bactericidal effects of indocyanine green- and methyl aminolevulinate-based photodynamic therapy on Propionibacterium acnes. P. acnes were cultured under anaerobic conditions; then they were divided into three groups (control, treated with indocyanine green and treated with methyl aminolevulinate) and illuminated with different lights (630-nm light-emitting diode, 805-nm diode laser and 830-nm light-emitting diode). The bactericidal effects were evaluated by comparing each group's colony-forming units. The cultured P. acnes were killed with an 805-nm diode laser and 830-nm light-emitting diode in the indocyanine green group. No bactericidal effects of methyl aminolevulinate-based photodynamic therapy were identified. The clinical efficacy of indocyanine green-based photodynamic therapy in 21 patients was retrospectively analyzed. The Korean Acne Grading System was used to evaluate treatment efficacy, which was significantly decreased after treatment. The difference in the efficacy of the 805-nm diode laser and 830-nm light-emitting diode was not statistically significant. Although the methyl aminolevulinate-based photodynamic therapy showed no bactericidal effect, the indocyanine green-based photodynamic therapy has bactericidal effect and clinical efficacy.

Daylight-Mediated Photodynamic Therapy With Methyl Aminolevulinate in Actinic Keratosis Treatment

BACKGROUND

Research has shown daylight-mediated photodynamic therapy (PDT) for the treatment of actinic keratosis (AK) to be effective, tolerable, and convenient, with excellent patient satisfaction and cosmesis. Although success has been demonstrated in areas with similar latitudes to Switzerland and Scandinavia, this treatment has not been studied in a Canadian population.

OBJECTIVES

The purpose of this study is to investigate the effectiveness, safety, and patient satisfaction of daylight-mediated methyl 5-aminolevulinate (MAL)-PDT to make recommendations for its use in Canadian practice.

METHODS

A retrospective chart review of patients who received treatment of daylight-mediated MAL-PDT for the indication of AK at the Institute of Cosmetic and Laser Surgery in Oakville, Ontario, between 2009 and 2016.

RESULTS

A total of 112 patients were included, consisting of 94 males and 18 females with a mean age of 63.79 years. A total of 177 sites were treated among all patients, mostly consisting of the face (n = 92) and scalp (n = 55). A total of 13.4% of patients experienced side effects, the most common being redness (n = 4) and scabbing (n = 4). Of the 42 patients who expressed their level of satisfaction, 83.3% reported being happy with the treatment, χ²(1) = 18.67, P ≤ .05; 6.3% of patients were noted to be completely clear, 86.6% had a good response, 0.9% had a mild response, and 0% had no response, χ²(1) = 101.04, P ≤ .05.

CONCLUSIONS

Daylight-mediated MAL-PDT is a suitable treatment option for AK lesions in a Canadian population due to the demonstrated efficacy, patient satisfaction, tolerability, and convenience.

Nonpigmented hair removal using photodynamic therapy in animal model

BACKGROUND AND OBJECTIVE

Lasers have been successfully used for decades to remove dark hair. However, laser removal of nonpigmented hair is challenging due to the lack of chromophores. The aim of this study was to use photodynamic therapy (PDT) to remove nonpigmented hair.

STUDY DESIGN/MATERIAL AND METHODS

We compared the efficacy of permanent hair reduction in white BALB/c and black C57BL/6 mice treated with PDT or an 800-nm diode laser. We collected skin biopsy specimens and investigated post-PDT histologic changes and molecular changes.

RESULTS

We observed keratin 15 staining in the bulge area and alkaline phosphatase staining in the dermal papilla following PDT. We observed a temporary, catagen-like transformation in nonpigmented hair follicles after PDT. We observed apoptotic cells in the hair matrix after PDT. Irradiation with an 800-nm diode laser did not achieve nonpigmented hair removal. Multiple PDT sessions achieved permanent reduction of nonpigmented hair. Interestingly, removal of black hair using PDT was less efficient.

CONCLUSION

Our results suggest that PDT can damage the nonpigmented hair matrix, but not stem cells or dermal papillae. Repeated PDT may impair the hair-regeneration capacity via a bystander effect on bulge stem cells or dermal papillae. In this study, we found it was possible to remove nonpigmented hair using PDT. Lasers Surg. Med. 48:748-762, 2016. © 2016 Wiley Periodicals, Inc.

Alternatives to Outdoor Daylight Illumination for Photodynamic Therapy--Use of Greenhouses and Artificial Light Sources

Daylight-mediated photodynamic therapy (daylight PDT) is a simple and pain free treatment of actinic keratoses. Weather conditions may not always allow daylight PDT outdoors. We compared the spectrum of five different lamp candidates for indoor "daylight PDT" and investigated their ability to photobleach protoporphyrin IX (PpIX). Furthermore, we measured the amount of PpIX activating daylight available in a glass greenhouse, which can be an alternative when it is uncomfortable for patients to be outdoors. The lamps investigated were: halogen lamps (overhead and slide projector), white light-emitting diode (LED) lamp, red LED panel and lamps used for conventional PDT. Four of the five light sources were able to photobleach PpIX completely. For halogen light and the red LED lamp, 5000 lux could photobleach PpIX whereas 12,000 lux were needed for the white LED lamp. Furthermore, the greenhouse was suitable for daylight PDT since the effect of solar light is lowered only by 25%. In conclusion, we found four of the five light sources and the greenhouse usable for indoor daylight PDT. The greenhouse is beneficial when the weather outside is rainy or windy. Only insignificant ultraviolet B radiation (UVB) radiation passes through the greenhouse glass, so sun protection is not needed.

Photodynamic therapy for basal cell carcinoma

Topical photodynamic therapy is an effective and safe noninvasive treatment for low-risk basal cell carcinoma, with the advantage of an excellent cosmetic outcome. Efficacy of photodynamic therapy in basal cell carcinoma is supported by substantial research and clinical trials. In this article, we review the procedure, indications and clinical evidences for the use of photodynamic therapy in the treatment of basal cell carcinoma.

Photodynamic therapy in the treatment of basal cell carcinoma

Photodynamic therapy (PDT) is a medical procedure based on the activation of the molecules of various exogenous or endogenous chemical substances called photosensitizers by a light source emitting radiation of an adequate wavelength, usually situated in the visible spectrum; photosensitizers are chemical compounds bearing the capacity to selectively concentrate in the neoplastic cells. The energy captured by the molecules of these substances pervaded in the tumor cells is subsequently discharged in the surrounding tissue, triggering certain photodynamic reactions that result in the destruction of the tumor. The procedure is applicable in numerous medical fields. Skin basal cell carcinoma (BCC), the most frequent type of cancer of the human species, is a cutaneous tumor that responds very well to this innovative treatment method. By reviewing numerous recent studies in the field, this article aims to present the role and the indications of photodynamic therapy in the management of basal cell carcinoma, as well as the most important results achieved so far by this therapy in the field of dermato-oncology.