Practical approach to the use of daylight photodynamic therapy with topical methyl aminolevulinate for actinic keratosis: a European consensus

The impact of occlusive vs non-occlusive application of methyl aminolevulinate on the efficacy and tolerability of daylight photodynamic therapy for actinic keratosis

BACKGROUND

Conventional photodynamic therapy (c-PDT) is an effective treatment for actinic keratoses (AKs) and nonmelanoma skin cancer which exploits the photosensitizing properties of methyl aminolaevulinate (MAL). Daylight photodynamic therapy (DL-PDT) is an alternative to c-PDT which does not require the application of MAL in occlusion and that is better tolerated by patients. The impact of occlusion on the efficacy of DL-PD has not been investigated by previous studies.

OBJECTIVE

To compare the efficacy and tolerability of occlusive and non-occlusive DL-PDT.

METHODS

We conducted a prospective intraindividual left/right comparison study. AKs of the face or scalp were marked in two symmetrical treatment areas. The two target areas were randomly assigned to DL-PDT with occlusive and non-occlusive application of MAL. The efficacy and cosmetic outcome were determined by a "blinded" investigator.

RESULTS

Lesions in occluded areas showed a better response in the clearance rate of the lesions (65.5% vs 35.0 %, p < 0.001 %), and cosmetic outcome (P < 0.001). There was no difference in phototoxicity or pain between occluded and non-occluded areas.

CONCLUSION

The occlusive application of MAL improves the efficacy of DL-PDT in clearing AKs and does not increase the incidence of side effects.

Ablative Fractional Laser Enhances Artificial or Natural Daylight Photodynamic Therapy of Actinic Field Cancerization: A Randomized and Investigator-initiated Half-side Comparative Study

Artificial daylight photodynamic therapy is a near-painless treatment for actinic keratoses, which can be performed indoors using a controlled light dose. Daylight photodynamic therapy is approved only for treatment of grade I-II actinic keratoses. The aim of this study was to evaluate whether fractional laser pre-treatment improves the outcomes of daylight photodynamic therapy for actinic keratoses of all grades. In addition, the study compared the outcomes of artificial and natural daylight photodynamic therapy. This randomized single-blinded split-side comparative study included 60 patients with  ≥ 2 actinic keratoses of the head. Fractional laser pre-treatment was assigned randomly for actinic keratoses on 1 side of the head and, subsequently, the entire treatment area was treated with artificial or natural daylight photodynamic therapy. Fractional laser-mediated daylight photodynamic therapy achieved significantly higher complete clearance (50.0% vs 30.3%, p = 0.04), partial clearance (78.6% vs 50.0%, p < 0.01) and lesion-specific clearance (86.2% vs 70.2%, p < 0.01) than daylight photodynamic therapy alone at the 6-month follow-up. No significant differences were found in the outcomes of artificial vs natural daylight photodynamic therapy or grade I lesions vs grade II-III lesions. Thus, fractional laser pre-treatment appears to significantly increase the efficacy of artificial and natural daylight photodynamic therapy, and to be suitable for treatment of actinic keratoses of all grades.

Equivalent efficacy of indoor daylight and lamp-based 5-aminolevulinic acid photodynamic therapy for treatment of actinic keratosis

Background

Photodynamic therapy (PDT) is widely used as a treatment for actinic keratoses (AK), with new sunlight-based regimens proposed as alternatives to lamp-based treatments. Prescribing indoor daylight activation could help address the seasonal temperature, clinical supervision, and access variability associated with outdoor treatments.

Objective

To compare the AK lesion clearance efficacy of indoor daylight PDT treatment (30 min of 5-aminolevulinic acid (ALA) pre-incubation, followed by 2 h of indoor sunlight) versus a lamp-based PDT treatment (30 min of ALA preincubation, followed by 10 min of red light).

Methods

A prospective clinical trial was conducted with 41 patients. Topical 10% ALA was applied to the entire treatment site (face, forehead, scalp). Patients were assigned to either the lamp-based or indoor daylight treatment. Actinic keratosis lesion counts were determined by clinical examination and recorded for pre-treatment, 1-month, and 6-month follow-up visits.

Results

There was no statistical difference in the efficacy of AK lesion clearance between the red-lamp (1-month clearance = 57 ± 17%, 6-month clearance = 57 ± 20%) and indoor daylight treatment (1-month clearance = 61 ± 19%, 6-month clearance = 67 ± 20%). A 95% confidence interval of the difference of the means was measured between -4.4% and 13.4% for 1-month, and -2.2% and +23.6% for 6-month timepoints when comparing the indoor daylight to the red-lamp treatment, with a priori interval of equivalence of ±20%.

Limitations

Ensuring an equivalent dose between the indoor and lamp treatment cohorts limited randomisation since it required performing indoor daylight treatments only during sunny days.

Conclusion

Indoor-daylight PDT provided equivalent AK treatment efficacy to a lamp-based regimen while overcoming temperature limitations and UV-block sunscreen issues associated with outdoor sunlight treatments in the winter.

Clinical trial registration

Clinicaltrials.gov listing: NCT03805737.

Effective fluence and dose at skin depth of daylight and lamp sources for PpIX-based photodynamic therapy

SIGNIFICANCE

Skin-based photodynamic therapy (PDT) is used for the clinical treatment of actinic keratosis (AKs) and other skin lesions with continued expansion into the standard of care. Due to the spectral dependency of photosensitizer activation and skin optical fluence, there is a need for more accurate methods to estimate the delivered dose at depth from different PDT light sources and treatment regimens.

AIM

Develop radiometric methods for calculating photosensitizer-effective fluence and dose at depth and determine differences between red-lamp, blue-lamp, and daylight-based PDT treatments.

METHODS

Radiometric measurements of FDA-approved PDT lamp sources, outdoor daylight, and indoor daylight were performed for clinically relevant AK treatments. The protoporphyrin IX (PpIX) equivalent irradiance, fluence, and dose for each light source were calculated from the PpIX absorption spectrum and a 7-layer skin fluence model. The effective fluence and dose at depth was estimated by combining the spectral attenuation predicted at each wavelength and depth with the source fluence at each wavelength.

RESULTS

The red-lamp source had the highest illuminance (112,000 lumen/m²), but lowest PpIX-effective irradiance (9.6 W/m²), and highest effective fluence at depth (10.8 W/m² at 500 µm). In contrast, the blue light source had the lowest illuminance (2300 lumen/m²), but highest PpIX effective irradiance (37.0 W/m²), and ultimately the lowest effective fluence at depth (0.18 W/cm² at 500 µm). The daylight source had values of (outdoor | indoor) illuminance of (49,200 | 37,800 lumen/m²), effective irradiance of (19.2 | 10.7 W/m²), and effective fluence of (1.50 | 1.08 W/m² at 500 µm). The effective fluence and dose at depth facilitated the comparison of treatment regimens, for example, calculating an equivalent dose for a 2 hr indoor daylight treatment and a 10 min red-light treatment for the 300-1000 μm depth range.

CONCLUSIONS

The consideration of PpIX-effective fluence at varying depths is necessary to provide adequate comparisons of the delivered dose from PDT light sources. Methods for calculating radiometric fluence and delivered dose at depth were introduced, with open source MATLAB code, to help overcome the limitations of commonly used photometric and irradiance-based reporting.

Randomized Clinical Trial of Conventional versus Indoor Daylight Photodynamic Therapy for Treatment of Actinic Cheilitis

Introduction

Actinic cheilitis (AC) is the biologic precursor of invasive squamous cell carcinoma (SCC) of the vermilion, and different treatment options have been investigated, but their efficacy is hampered by local inflammation, pain and slow recovery. Daylight photodynamic therapy (dl-PDT) has been demonstrated to represent a valuable treatment option for AC, but its feasibility is limited by weather conditions and latitude.

Methods

Our study proposed to compare the efficacy and tolerability of conventional photodynamic therapy (c-PDT) and indoor daylight photodynamic therapy (idl-PDT) with a white LED lamp for the treatment of AC. Sixteen patients were enrolled in the study: 8 (50%) treated with c-PDT and 8 (50%) treated with idl-PDT. All patients completed the study protocol.

Results

Both idl-PDT and c-PDT were demonstrated to be highly effective in terms of reduction of the cumulative lesional area and severity of the clinical score. Neither treatment was inferior to the other. The inflammatory reaction and the pain scores were milder with idl-PDT, whereas the cosmetic outcome was not different.

Conclusion

The present findings confirm that idl-PDT can represent a valid therapeutic strategy for AC patients as well, despite the procedural difficulties and the risk of poor tolerability related to the body site.

Ablative Fractional Laser-assisted Low-irradiance Photodynamic Therapy for Treatment of Actinic Keratoses in Organ Transplant Recipients: A Prospective, Randomized, Intraindividual Controlled Trial

Pain and inferior efficacy are major limiting factors of conventional photodynamic therapy for the field treatment of actinic keratoses in immunosuppressed organ transplant recipients. This prospective randomized controlled study evaluates the efficacy and tolerability of ablative fractional laser system pretreatment combined with low-irradiance photodynamic therapy (18.5 mW/cm2) compared with conventional photodynamic therapy (61.67 mW/cm2) in the treatment of actinic keratoses on the face and scalp in organ transplant recipients, using a red light-emitting diode lamp at a total light dose of 37 J/cm2. Low-irradiance photodynamic therapy combined with Er:YAG pretreatment achieved a significantly superior lesion response rate (mean ± standard deviation 77.3 ± 23.6%) compared with conventional photodynamic therapy (61.8 ± 21.4%; p = 0.025) in intra-individual fields at 3 months without negatively impacting pain (p = 0.777) or cosmetic outcome (p = 0.157).

An open-label prospective study to assess short incubation time white LED light photodynamic therapy in the treatment of superficial basal cell carcinoma

Artificial white LED light photodynamic therapy (awl-PDT) is an effective, pain-free treatment for actinic keratosis. The efficacy of awl-PDT in the treatment of superficial basal cell carcinoma (sBCC) has not been assessed. Patients with histologically confirmed sBCC underwent two treatments of awl-PDT 1 week apart. Lesions were incubated with methyl 5-aminolaevulinic acid for 30 min and then illuminated using the Maquet Power LED 500 theatre light (405-800nm, 140 000 lux) to deliver an equivalent red light dose of 75 J/cm² at a rate of 55 mW/cm² . Pain was measured using a visual analogue scale during treatment. Clinical response was assessed at day 28. Follow-up continued 3 months for 1 year. Cosmetic outcome was assessed at 3 months and 1 year. Twenty-eight patients with 36 lesions and a mean age of 63.64 (SD 2.62) were recruited. The median lesion size was 15 mm (IQR 8.75). The response rate at day 28 was 100%. Recurrence rates were 3/36 (8.3%) at 3 months, 6/36 (16.7%) at 6 months, 10/36 (27.8%) at 9 months and 11/36 (30.6%) at 1 year. Median pain scores were 0/100 (IQR 0) and 0/100 (IQR 5) during treatments one and two, respectively. Cosmetic outcome was excellent or good in the majority of cases. Although initially effective for sBCC at 28 days, 30.6% of lesions recurred 1 year after awl-PDT. Pain scores were negligible, and the cosmetic outcome was favourable. Further head-to-head studies with optimised protocols are required to determine if awl-PDT has a role in the treatment of sBCC.

A split-face clinical trial of conventional red-light photodynamic therapy versus daylight photodynamic therapy for acne vulgaris

BACKGROUND

Photodynamic therapy (PDT) is considered an effective treatment for acne vulgaris. A significant drawback is pain during illumination. Daylight PDT (DL-PDT) is more tolerable.

OBJECTIVE

To assess and compare the efficacy and tolerability of DL-PDT and C-PDT for acne vulgaris through a prospective split-face trial.

METHODS AND MATERIALS

Fifteen patients underwent 4 treatment sessions at 3-week intervals. First, 5-aminolevulinic acid (ALA) was applied to the entire face, after which the face was divided into 2 symmetrical areas: The right side was exposed to sunlight, and the left half was illuminated with red light. Photographs were obtained and evaluated by two dermatologists blinded to the study protocol. The patients reported side effects and downtime.

RESULTS

There was a statistically significant decrease in the number and percent change of inflammatory and non-inflammatory lesions on both sides. Adverse effects were markedly decreased on the DL-PDT side compared to the C-PDT side (p < .01). The average downtime duration was longer for the C-PDT side (p < .001).

CONCLUSION

DL-PDT was at least as effective as C-PDT with fewer adverse effects and a shorter downtime duration.

A randomized split-face clinical trial of conventional vs indoor-daylight photodynamic therapy for the treatment of multiple actinic keratosis of the face and scalp and photoaging

BACKGROUND

Recently, indoor daylight photodynamic therapy (idl-PDT) has been developed; however, its efficacy and tolerability remain to be assessed.

OBJECTIVE

This is a not-inferiority study to compare treatment outcomes of cPDT with a red LED lamp and idlPDT with a polychromatic white LED lamp in adult patients affected by symmetrical AKs of face and/or scalp.

METHODS

In this comparative, intra-patient, split-face, randomized clinical trial forty-three adult patients were enrolled. Two contralateral and symmetrical target areas of the face and/or scalp harboring at least 5 AKs were selected and randomized 1:1 to treatment with cPDT and idlPDT. The AKs number and cumulative area were assessed at baseline (T0). Efficacy and cosmetic outcome were assessed 3 months after treatment (T1).

RESULTS

Total AKs number and area reduced significantly with both idlPDT (p < .0001) and cPDT (p < .0001) in comparison to baseline. cPDT was more painful (p < .0001) and induced a more severe inflammation (p < .0001). Twenty-nine patients (70.7%) gave their overall preference to idlPDT (p < .001).

CONCLUSION

idlPDT may represent an alternative treatment protocol to cPDT for in-office treatment of AKs patients with better tolerability and a not inferior efficacy.

Pretreatment with ablative fractional carbon dioxide laser improves treatment efficacy in a synergistic PDT protocol for actinic keratoses on the head

BACKGROUND

A recently proposed synergistic photodynamic therapy protocol (s-PDT) combining advantages of both conventional- and daylight-PDT proved to be an effective and almost painless treatment for patients with actinic keratoses (AKs). This study investigated the safety and efficacy of an additional ablative fractional CO2-laser (AFXL) pretreatment.

METHODS

28 patients with AKs on the head received s-PDT using 5-aminolevulinic acid. AFXL pretreatment was conducted using the following parameters: pulse energy 8 mJ, spot density 50 spots/cm², power 30 W, beam size 4-18 mm. Outcome was assessed by AK area and severity index (AKASI) and lesion count (LC) before and 3 months after treatment. Safety was monitored by blood pressure and pulse measurements. Intensity of pain was determined by use of a visual analog scale (VAS).

RESULTS

Most patients (96.4 %) showed a significant AKASI reduction (P < 0.0001) 3 months after PDT (median AKASI 1.6 [0-2.4]) compared to baseline (5.3 [4-7.75]). Median reduction rate was 75.5 % (61.3 %-100 %). Eleven patients (39.3 %) achieved AKASI 100, three (10.7 %) AKASI 75 and ten (35.7 %) AKASI 50. Blood pressure and pulse did not change significantly throughout treatment. Median VAS for pain during irradiation was 0 (0-0), 0 (0-2) and 0 (0-2) at the beginning, in the meantime and at the end, respectively. Compared to data without AFXL pretreatment, this study showed significantly higher AKASI and LC reduction rates (75.5 % vs. 63.7 % [P = 0.023] and 91.3 % vs. 80.4 % [P = 0.043]).

CONCLUSIONS

S-PDT with AFXL pretreatment represents a safe and almost painless treatment for patients with AKs on the head and improves treatment efficacy.

The application of physical pretreatment in photodynamic therapy for skin diseases

Photodynamic therapy (PDT) is widely used in skin diseases; the response rate of PDT treatment varies widely. The limited penetration in the tissue of photosensitizers influenced the penetration depth of PDT, which obviously impacts the therapeutic effect. The studies have improved the efficacy of PDT through various pretreatment applications; especially, the physical pretreatment had achieved significant outcomes. We will review the physical pretreatment to optimize the efficacy of PDT in skin diseases by searching the literature on this topic. The types of physical pretreatment commonly used in the clinical practice are discussed: curettage, superficial shaving, laser, surgical resection, plum-blossom needles, and microneedles. Compared with PDT alone, the physical pretreatment before PDT application was generally improved the efficacy and reduced the recurrence, especially in actinic keratoses (AK), Bowen disease (BD), basal cell carcinoma (BCC), and viral warts. The application of the physical pretreatments before PDT may improve the efficacy of PDT in various skin diseases. However, each kind of physical pretreatment has the benefit and shortcoming, and the applicable situation is different.

Daylight Photodynamic Therapy: An Update

Daylight photodynamic therapy (dPDT) uses sunlight as a light source to treat superficial skin cancer. Using sunlight as a therapeutic device has been present for centuries, forming the basis of photodynamic therapy in the 20th century. Compared to conventional PDT, dPDT can be a less painful, more convenient and an effective alternative. The first clinical uses of dPDT on skin cancers began in Copenhagen in 2008. Currently, aminolevulinic acid-mediated dPDT has been approved to treat actinic keratosis patients in Europe. In this review article, we introduce the history and mechanism of dPDT and focus on the pros and cons of dPDT in treating superficial skin cancers. The future applications of dPDT on other skin diseases are expected to expand as conventional PDT evolves.

Theoretical and Experimental Analysis of Protoporphyrin IX Photodegradation Using Multi-Wavelength Light Sources

Photodynamic procedures have been used in many applications, ranging from cancer treatment to microorganism inactivation. Photodynamic reactions start with the activation of a photosensitizing molecule with light, leading to the production of cytotoxic molecules that promote cell death. However, establishing the correct light and photosensitizer dosimetry for a broadband light source remains challenging. In this study, we proposed a theoretical mathematical model for the photodegradation of protoporphyrin IX (PpIX), when irradiated by multi-wavelength light sources. The theoretical model predicts the experimental photobleaching (temporal change in PpIX concentration) of PpIX for different light sources. We showed that photobleaching occurs independently of the light source wavelengths but instead depends only on the number of absorbed photons. The model presented here can be used as an important mathematical approach to better understand current photodynamic therapy protocols and help achieve optimization of the doses delivered.

European Dermatology Forum guidelines on topical photodynamic therapy 2019 Part 1: treatment delivery and established indications - actinic keratoses, Bowen's disease and basal cell carcinomas

Topical photodynamic therapy (PDT) is a widely approved therapy for actinic keratoses, Bowen's disease (squamous cell carcinoma in situ), superficial and certain thin basal cell carcinomas. Recurrence rates when standard treatment protocols are used are typically equivalent to existing therapies, although inferior to surgery for nodular basal cell carcinoma. PDT can be used both as lesional and field therapies and has the potential to delay/reduce the development of new lesions. A protocol using daylight to treat actinic keratoses is widely practised, with conventional PDT using a red light after typically a 3-h period of occlusion employed for other superficial skin cancer indications as well as for actinic keratoses when daylight therapy is not feasible. PDT is a well-tolerated therapy although discomfort associated with conventional protocol may require pain-reduction measures. PDT using daylight is associated with no or minimal pain and preferred by patient. There is an emerging literature on enhancing conventional PDT protocols or combined PDT with another treatment to increase response rates. This guideline, published over two parts, considers all current approved and emerging indications for the use of topical PDT in dermatology, prepared by the PDT subgroup of the European Dermatology Forum guidelines committee. It presents consensual expert recommendations reflecting current published evidence.

Light Sources and Dosimetry Techniques for Photodynamic Therapy

Effective treatment delivery in photodynamic therapy (PDT) requires coordination of the light source, the photosensitizer, and the delivery device appropriate to the target tissue. Lasers, light-emitting diodes (LEDs), and lamps are the main types of light sources utilized for PDT applications. The choice of light source depends on the target location, photosensitizer used, and light dose to be delivered. Geometry of minimally accessible areas also plays a role in deciding light applicator type. Typically, optical fiber-based devices are used to deliver the treatment light close to the target. The optical properties of tissue also affect the distribution of the treatment light. Treatment light undergoes scattering and absorption in tissue. Most tissue will scatter light, but highly pigmented areas will absorb light, especially at short wavelengths. This review will summarize the basic physics of light sources, and describe methods for determining the dose delivered to the patient.

Daylight photodynamic therapy with methyl aminolevulinate cream is as effective as conventional photodynamic therapy with blue light in the treatment of actinic keratosis: a controlled randomized intra-individual study

BACKGROUND

We know the efficacy of daylight phototherapy dynamic (DL-PDT) in the treatment of actinic keratosis (AK). But the almost studies have compared daylight with red light using methyl aminolevulinate cream and not with blue light. PDT with blue light is another conventional PDT that is effective in the treatment of AKs.

OBJECTIVES

The aim of this study is to assess the efficacy and the safety of DL-PDT vs. PDT in blue light in the treatment of AKs.

METHODS

This randomized, controlled, intra-individual efficacy and safety study enrolled 26 subjects. AKs on the face/scalp were treated once, with DL-PDT on one side and c-PDT on the contralateral side. Primary endpoints for DL-PDT at week 12 were efficacy with clearance of AKs and safety with assessment of pain. Lesions with complete response 12 weeks after one treatment session were followed until week 24.

RESULTS

More than 1000 AK were studied. At week 12, the raw number of disappeared AK lesions at 3-month follow-up was 19.6 (±6.0) for DL-PDT and 20.0 (±6.9) for c-PDT with P = 0.8460 (90.5% vs. 94.2% of AK disappearance, respectively). The response was maintained at 6 months (90.0% and 94.6% of AK reduction, respectively). DL-PDT was nearly painless than c-PDT with light blue: 1.2 vs. 5.1, respectively (P < 0.0001).

CONCLUSIONS

Daylight-PDT seems as effective as c-PDT with light blue and DL-PDT is less painful. The response of DL-PDT was sustainable until 6 months.

Weather-informed Light-tissue Model-Based Dose Planning for Indoor Daylight Photodynamic Therapy

Daylight activation for photodynamic therapy (PDT) of skin lesions is now widely adopted in many countries as a less painful and equally effective treatment mechanism, as compared to red or blue light activation. However, seasonal daylight availability and transient weather conditions complicate light dose estimations. A method is presented for dose planning without placing a large burden on clinical staff, by limiting spectral measurements to a one-time site assessment, and then using automatically acquired weather reports to track transient conditions. The site assessment tools are used to identify appropriate treatment locations for the annual and daily variations in sunlight exposure for clinical center planning. The spectral information collected from the site assessment can then be integrated with real-time daily electronic weather data. It was shown that a directly measured light exposure has strong correlation (R² : 0.87) with both satellite cloud coverage data and UV index, suggesting that the automated weather indexes can be surrogates for daylight PDT optical dose. These updated inputs can be used in a dose-planning treatment model to estimate photodynamic dose at depth in tissue. A simple standardized method for estimating light dose during daylight-PDT could help improve intersite reproducibility while minimizing treatment times.

Methadone enhances the effectiveness of 5-aminolevulinic acid-based photodynamic therapy for squamous cell carcinoma and glioblastoma in vitro

Although having shown promising clinical outcomes, the effectiveness of 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT) for squamous cell carcinoma (SCC) and glioblastoma remains to be improved. The analgesic drug methadone is able to sensitize various tumors to chemotherapy. In this in vitro study, the influence of methadone to the effectiveness of ALA-PDT for SCC (FADU) and glioblastoma (A172) was investigated on the protoporphyrin IX (PpIX) fluorescence, survival rates, apoptosis, and cell cycle phase, each with or without the presence of methadone. The production of PpIX was increased by methadone in FADU cells while it was decreased in A172 cells. The survival rates of both cell lines treated by ALA-PDT were significantly reduced by the combination with methadone (P < .05). Methadone also significantly increased the percentage of apoptotic cells and improved the effect of ALA-PDT on the cell cycle phase arrest in the G0/G1 phase (P < .05). This study demonstrates the potential of methadone to influence the cytotoxic effect of ALA-PDT for both SCC and glioblastoma cell lines.

Measuring Daylight: A Review of Dosimetry in Daylight Photodynamic Therapy

Successful daylight photodynamic therapy (DPDT) relies on the interaction of light, photosensitisers and oxygen. Therefore, the 'dose' of light that a patient receives during treatment is a clinically relevant quantity, with a minimum dose for effective treatment recommended in the literature. However, there are many different light measurement methods used in the published literature, which may lead to confusion surrounding reliable and traceable dose measurement in DPDT, and what the most appropriate method of light measurement in DPDT might be. Furthermore, for the majority of practitioners who do not carry out any formal dosimetry and for the patients receiving DPDT, building confidence in the evidence supporting this important treatment option is of key importance. This review seeks to clarify the methodology of DPDT and discusses the literature relating to DPDT dosimetry.

Photodynamic therapy for skin cancer: How to enhance drug penetration?

Photodynamic therapy (PDT) induced by protoporphyrin IX (PpIX) has been widely used in dermatological practices such as treatment of skin cancers. Clearance rate depends on different factors such as light irradiation, skin oxygenation and drug penetration. The poor penetration of 5-aminolevulinic acid (5-ALA) with topical application is limited and restrains the production of PpIX which could restrict PDT outcomes. This review will focus on techniques already used to enhance drug penetration in human skin, and will present their results, advantages, and drawbacks. Chemical and physical pretreatments will be discussed. Chemical pre-treatments comprise of drug formulation modification, use of agents that modify the heme cycle, enhance PpIX formation, and the combination of differentiation-promoting agent prior to PDT. On the other hand, physical pretreatments affect the skin barrier by creating holes in the skin or by removing stratum corneum. To promote drug penetration, iontophoresis and temperature modulation are interesting alternative methods. Cellular mechanisms enrolled during chemical or physical pretreatments have been investigated in order to understand how 5-ALA penetrates the skin, why it is preferentially metabolized in PpIX in tumour cells, and how it could be accumulated in deeper skin layers. The objective of this review is to compare clinical trials that use innovative technology to conventional PDT treatment. Most of these pretreatments present good or even better clinical outcomes than usual PDT.

Efficacy of the combination of superficial shaving with photodynamic therapy for recalcitrant periungual warts

BACKGROUND

Periungual warts are a viral infectious disease that occurs in a particular location. It is difficult to eliminate completely, and recurrence is common. Photodynamic therapy (PDT) as an option that has been widely recommended to treat viral warts. However, there are always a few patients with poor efficacy after PDT treatment. We have considered that the reason is the limitation of PDT penetrating deep into tissue. Thus, we combined superficial shaving with PDT to treat recalcitrant periungual warts.

METHODS

Twenty-three patients had a total of 61 periungual wart lesions. All patients had recalcitrant periungual warts that had failed to respond to various treatments that had poor curative effects. After local injection of anesthesia, the lesions were shaved in situ, and PDT was performed immediately. A total of three sessions of PDT were applied for each patient after only one superficial shaving. The overall clinical response rate, recurrence rates, cosmetic outcomes, adverse events, patient satisfaction and quality of life were assessed. The potential risk factors have also been recorded.

RESULTS

We achieved a 96% success rate (defined as more than 50% on clearance) in our 23 patients using combination superficial shaving with PDT after treatment for 3 months. At the 12-month follow-up, 21 patients (91%) had excellent cosmetic outcomes. All patients had satisfactory therapeutic effects and significant improvement in the quality of life. Pain during the illumination process was the main adverse event, but all patients were able to tolerate it. We also found that frequent or continuous hand activity, such as playing Mah-jong, may be a potential risk factor for periungual warts.

CONCLUSION

Our results offer promise for combining superficial shaving with PDT as an effective and safe therapy for patients with periungual warts, especially for those periungual warts that are recurrent, have multiple lesions, and thickness corneum stratum of lesions. For nails that are not suitable for routine surgery, combined superficial shaving with PDT is recommended.

Prise en charge thérapeutique des kératoses actiniques

Dermatologists have many therapeutic options for the management of actinic keratoses (AK), in order to treat individual lesions or wider areas. Field cancerization is an area of sun-damaged skin, where visible and subclinical lesions co-exist, and is prone to the development of further AK lesions and sun-related skin cancers (SC). Treatments available are instrumental or medical. Resistance to treatment or atypical symptoms must lead to a biopsy for histological exam. Cryotherapy is the most frequently used method to destroy small or isolated AK, whereas photodynamic therapy (PDT), 5-fluoro-uracil (5-FU), imiquimod, ingenol mebutate and diclofenac are required for large, multiple lesions, and for the treatment of field cancerization. Side-effects of these therapies are essentially local, including pain, irritation, erythema, edema and scars. There is no randomized comparative study reviewing all these treatments, therefore physicians must also consider clinical characteristics, patient's compliance, side-effects and cost when treating AK. Medicoeconomic data of these treatments have been analyzed in several countries, and annual costs are estimated between 250 € and 2 000 €, with an uncertain cost-effective relation. Finally, beyond treatment of AK lesions, patients with AK are at high risk of developing SC, and must therefore have regular full-body examination, in order to be detected and treated precociously. © 2019 Elsevier Masson SAS. All rights reserved. Cet article fait partie du numéro supplément Kératoses actiniques : comprendre et traiter réalisé avec le soutien institutionnel de Galderma International.

Split-face study comparing conventional MAL photodynamic therapy in multiple actinic keratosis with complete time vs. half-time red light LED conventional illumination

BACKGROUND

Conventional photodynamic therapy (PDT) with methylaminolevulinic acid (MAL) and daylight PDT have demonstrated similar efficacy in the treatment of actinic keratosis (AK). The reason for the use of daylight is to reduce pain during illumination but daylight has the limitation of the weather conditions. The difference in the doses of red light applied between these two methods suggests that an intermediate dose with red light conventional illumination could be effective in PDT of AK.

OBJECTIVE

To compare the efficiency of conventional MAL-PDT with half-time conventional red light illumination in patients with multiple AK.

MATERIAL AND METHODS

Adult patients with more than five symmetrically distributed AK were selected. After randomization, one area was treated with conventional PDT (Aktilite^® , 630 nm, 37 J/cm² , 8 min), while the contralateral was illuminated half time (Aktilite^® , 630 nm, 37 J/cm² , 4 min). Patients evaluated pain in each different side. Patients were evaluated at baseline, 3 and 6 months after PDT treatment by a blinded dermatologist. A questionnaire to be done at home 24 h after completing treatment was deliver to the patients to evaluate any side-effects.

RESULTS

A total of 774 lesions were treated, 385 with conventional PDT and 389 with half-time PDT (P > 0.05). Conventional PDT was 85% of complete response of AK (327/385) at 3 months, and half-time PDT was 82% (319/389). At 6 months, conventional PDT was 70% (268/385) of complete response and half-time PDT was 65% (252/389). Pain during illumination was significantly lower in the VAS with the half-time protocol with a mean of 5.59 (SD 1.48) vs. 6.41 (SD 1.66) in conventional PDT. No difference in adverse effects was found between protocols.

CONCLUSION

Conventional PDT with half-time illumination in multiple actinic keratosis is as effective as complete time illumination and decreased pain significantly.

What is the most relevent factor causing pain during ALA-PDT? A multi-center, open clinical pain score research trial of actinic keratosis, acne and condylomata acuminata

BACKGROUND

To date, it has been reported that the intrinsic factors(lesions location, lesions area, disease tynpes) and extrinsic factors(fluence rate) contribute to the pain during 5-aminolevulinic acid photodynamic therapy (ALA-PDT). But there are few studies on pain during ALA-PDT and lack of sufficient clinical evidence related to the pain intensity.

OBJECTIVE

To investigate pain intensity and its relative factors during ALA-PDT and to provide clinical implication.

METHODS

The pain numeric rating scale (PNRS) score was used to evaluate the patients' pain intensity at different times during ALA-PDT irradiation from 0 to 10 min during treatment. Gender, age, lesions location, lesions area, ALA concentration and fluence rate were recored.

RESULTS

The trial enrolled 274 patients in total, including 118 acne patients (in face), 30 actinic keratosis(AK)patients(in face), 126 Condylomatata acuminate patients(in genitalia). The average pain score in PDT was highest in the patients with actinic keratosis(7.3 ± 0.7), and that of condylomata acuminata was the lowest (4.5 ± 1.1) (p < 0.05). The highest pain score in patients with AK, acne and condylomata acuminata was 8, 6 and 6 respectively which occurred at 4 min, 4 min and 6 min respectively. The pain score of males was higher compared with females in all of the three diseases (p < 0.05). The pain score of facial diseases (5.6 ± 1.2) was higher than that of the genitalia (4.5 ± 1.1) (p < 0.05). The lesions area was positively correlated with the pain score (p < 0.05). In facial diseases, the pain score of patients with high fluence rate (7.3 ± 0.7) was higher than patients with low fluence rate (5.1 ± 0.9) (p < 0.05).

CONCLUSIONS

Intrinsic and extrinsic factors both correlate with pain during PDT. Intrinsic factors are difficult to change, so extrinsic factors are the key point to control. We can reduce the fluence rate and extend the treatment time, relieving pain intensity while still ensuring equivalent efficacy.

Modeling PpIX effective light fluence at depths into the skin for PDT dose comparison

BACKGROUND

Daylight-activated PDT has seen increased support in recent years as a treatment method for actinic keratosis and other non-melanoma skin cancers. The inherent variability observed in broad-spectrum light used in this methodology makes it difficult to plan and monitor light dose, or compare to lamp light doses.

METHODS

The present study expands on the commonly used PpIX-weighted effective surface irradiance metric by introducing a Monte Carlo method for estimating effective fluence rates into depths of the skin. The fluence rates are compared between multiple broadband and narrowband sources that have been reported in previous studies, and an effective total fluence for various treatment times is reported. A dynamic estimate of PpIX concentration produced during pro-drug incubation and treatment is used with the fluence estimates to calculate a photodynamic dose.

RESULTS

Even when there is up to a 5x reduction between the effective surface irradiance of the broadband light sources, the effective fluence below 250 μm depth is predicted to be relatively equivalent. An effective threshold fluence value (0. 70Jeff/cm2) is introduced based on a meta-analysis of previously published ALA-PpIX induced cell death. This was combined with a threshold PpIX concentration (50 nM) to define a threshold photodynamic dose of 0.035 u M Jeff/cm2.

CONCLUSIONS

The threshold was used to generate lookup tables to prescribe minimal treatment times to achieve depth-dependent cytotoxic effect based on incubation times and irradiance values for each light source.

Efficacy of different photoprotection strategies in preventing actinic keratosis new lesions after photodynamic therapy. The ATHENA study: a two-center, randomized, prospective, assessor-blinded pragmatic trial

Background: Treatment of actinic keratosis (AK) and field cancerization with photodynamic therapy (PDT) is an effective therapeutic approach with a significant reduction in the number of AK lesions (-75% or more) associated with a significant cosmetic improvement of the photodamaged skin. Recently, also, the daylight PDT (DL-PDT) has proven to be as effective as the conventional PDT (C-PDT), but with a better tolerability. After C-PDT and DL-PDT it is advised to use photoprotection strategies to improve the clinical evolution and prevent the appearance of new AK lesions that usually appear 3-6 months after the last phototherapy session. However, there are no robust clinical data regarding the type of photoprotection to be used (SPF level, duration of treatment, etc.) after successful PDT.Study aim: The present study (ATHENA trial) evaluated the efficacy and tolerability of a topical product based on 0.8% piroxicam and 50+ solar filters (ACTX), applied twice a day as sequential therapy after C-PDT or DL-PDT on the evolution of AK lesions number compared to the use of very high photoprotection products commonly used in this clinical setting (SPF50+ or SPF100+ associated with photolyase) (Standard Sunscreens: SS group). Subjects and methods: This was a multicenter, randomized, two-arm, prospective controlled, assessor-masked outcome evaluation, parallel group (1:1), pragmatic study of 6 months duration in patients with multiple AK lesions suitable for photodynamic therapy. The objectives of the study were the evaluation of the evolution of the number of AK lesions during the period of treatment/application of the study products, and the Investigator global clinical assessment score (IGA score; 4: marked improvement, 3: good, 2: moderate; 1 no improvement; 0: worsening) 2, 3, and 6 months after the last PDT session. A total of 68 subjects (50 men, 18 women; mean age 70 years), 34 assigned to treatment with ACTX and 34 to treatment with SS (17 treated with a SPF50+ and 17 with a photolyase-containing SPF100+ products), were enrolled in the study.Results: The number of AK lesions present before C-PDT/DL-PDT was 11.8 ± 5.8 in the ACTX group and 12.4 ± 6.9 in the SS group. In both groups, there was a progressive reduction of AK lesions observed at baseline (-86% and -87% after 2 months and -88% and -83% at month 3 in ACTX and in the SS group, respectively). At month 6, AK mean lesion number was 1.8 ± 1.6 in the ACTX and 3.2 ± 2.3 in the SS group; this difference was statistically significant (p = 0.03). The IGA score at the end of the study was 3.2 in the ACTX and 2.7 in the SS group (p = 0.05). The percentage of subjects with an IGA score of 4/3 (very good or good) was 81% in the ACTX and 55% in the SS group (p = 0.06).Conclusion: In subjects with AK treated with C-PDT or DL-PDT, a "medicalized" photoprotection treatment is associated with a favorable clinical outcome with progressive reduction of lesions. In contrast to a very high photoprotection (SPF50+ or SPF100+/photolyase), the use of piroxicam 0.8%/SPF 50+ is associated with a significantly greater improvement in clinical evolution of AK lesions.

Daylight Photodynamic Therapy for Actinic Keratoses

Topical photodynamic therapy (PDT) using daylight is effective in the treatment of actinic keratoses (AKs), offering the potential for treatment of large fields such as full face and balding scalp, but with minimal therapy-associated pain. Comparison with conventional PDT indicates similar efficacy for thin and moderate-thickness AKs, but with significantly less discomfort/pain, driving a patient preference for daylight-mediated PDT (DL-PDT) compared with conventional PDT using high-intensity office/hospital-based light sources. Treatment protocol involves the application of a photosensitizing agent without occlusion and subsequent exposure to ambient daylight within 30 min, with patients exposed to daylight for 1.5-2.0 h. Pivotal randomized controlled trials in Europe and Australia have confirmed the efficacy of methyl aminolevulinic acid (MAL) DL-PDT in comparison with conventional MAL-PDT for mild and moderate-thickness lesions on the face and scalp. Initial clearance rates of 70-89% are reported. DL-PDT using a nanoemulsion aminolevulinic acid (ALA) has recently been shown to be at least as effective as MAL DL-PDT in treating mild and moderate-thickness AKs. DL-PDT may offer a better-tolerated method for treating patients with extensive AK disease. There is emerging literature on the potential for field PDT to reduce the number of new AKs developing, potentially preventing/slowing skin cancer development. Conventional PDT remains established as a therapy for Bowen's disease (squamous cell carcinoma in situ), superficial and certain thin basal cell carcinomas (BCCs), and AKs. The evidence for the use of DL-PDT beyond AK is limited, although has been reported in actinic cheilitis, superficial BCC, and acne and cutaneous leishmaniasis. There is emerging interest in combination therapy for AK, using one or more field therapies such as DL-PDT as an option to complement with localized treatment for residual lesions. We review current recommendations and consider the appropriate place for DL-PDT in our treatment armamentarium.

Preclinical Evaluation of White Led-Activated Non-porphyrinic Photosensitizer OR141 in 3D Tumor Spheroids and Mouse Skin Lesions

Photodynamic therapy (PDT) is used to treat malignancies and precancerous lesions. Near-infrared light delivered by lasers was thought for a while to be the most appropriate option to activate photosensitizers, mostly porphyrins, in the depth of the diseased tissues. More recently, however, several advantages including low cost and reduced adverse effects led to consider light emitting diodes (LED) and even daylight as an alternative to use PDT to treat accessible lesions. In this study we examined the capacity of OR141, a recently identified non-porphyrin photosensitizer (PS), to exert significant cytotoxic effects in various models of skin lesions and tumors upon white light activation. Using different cancer cell lines, we first identified LED lamp as a particularly suited source of light to maximize anti-proliferative effects of OR141. We then documented that OR141 diffusion and light penetration into tumor spheroids both reached thresholds compatible with the induction of cell death deep inside these 3D culture models. We further identified Arlasove as a clinically suitable solvent for OR141 that we documented by using Franz cells to support significant absorption of the PS through human skin. Finally, using topical but also systemic administration, we validated growth inhibitory effects of LED-activated OR141 in mouse skin tumor xenograft and precancerous lesions models. Altogether these results open clinical perspectives for the use of OR141 as an attractive PS to treat superficial skin malignant and non-malignant lesions using affordable LED lamp for photoactivation.

A novel light source with tuneable uniformity of light distribution for artificial daylight photodynamic therapy

OBJECTIVES

Implementation of daylight photodynamic therapy (dPDT) is somewhat limited by variable weather conditions. Light sources have been employed to provide artificial dPDT indoors, with low irradiances and comparable treatment times to dPDT. Uniform light distribution across the target area is desirable in effective treatment planning, particularly for large areas. A novel light source is developed with tuneable direction of light emission in order to meet this challenge.

METHODS

Wavelength composition of the novel light source is controlled such that the protoporphyrin-IX (PpIX) weighted spectra of both the light source and daylight match. The uniformity of the light distribution is characterised on a flat surface, a model head and a model leg. For context, a typical conventional PDT light source is also characterised. Additionally, the wavelength uniformity across the treatment site is characterised.

RESULTS

The PpIX-weighted spectrum of the novel light source matches the PpIX-weighted daylight spectrum, with irradiance values within the bounds for effective dPDT. By tuning the direction of light emission, improvements are seen in the uniformity across large anatomical surfaces. Wavelength uniformity is discussed.

CONCLUSIONS

We have developed a light source that addresses the challenges in uniform, multiwavelength light distribution for large area artificial dPDT across curved anatomical surfaces.

Comparison of Blue and White Lamp Light with Sunlight for Daylight-Mediated, 5-ALA Photodynamic Therapy, in vivo

Daylight-mediated photodynamic therapy (d-PDT) as a treatment for actinic keratosis (AK) is an increasingly common technique due to a significant reduction in pain, leading to better patient tolerability. While past studies have looked at different light sources and delivery methods, this study strives to provide equivalent PpIX-weighted light doses with the hypothesis that artificial light sources could be equally as effective as natural sunlight if their PpIX-weighted fluences were equalized. Normal mouse skin was used as the model to compare blue LED light, metal halide white light and natural sunlight, with minimal incubation time between topical ALA application and the onset of light delivery. A total PpIX-weighted fluence of 20 J_eff cm^-2 was delivered over 2 h, and the efficacy of response was quantified using three acute bioassays for PDT damage: PpIX photobleaching, Stat3 crosslinking and quantitative histopathology. These bioassays indicated blue light was slightly inferior to both sunlight and white light, but that the latter two were not significantly different. The results suggest that metal halide white light could be a reasonable alternative to daylight PDT, which should allow a more controlled treatment that is independent of weather and yet should have similar response rates with limited pain during treatment.

Long-term efficacy data for daylight-PDT

INTRODUCTION

Conventional photodynamic therapy (c-PDT) is an established successful treatment for non-melanoma skin cancers (NMSC). Daylight PDT (DL-PDT) was introduced to overcome the main inconveniencies associated with c-PDT such as pain during illumination and long clinic visits. DL-PDT was shown to have similar short-term efficacy to c-PDT for the treatment of mild/moderate actinic keratosis (AKs) but it is associated with better tolerability. Since AKs tend to regress and reoccur over time, data on long-term efficacy of DL-PDT become crucial.

EVIDENCE ACQUISITION

We performed a systematic review search up to February 2018 of available studies on DL-PDT long-term efficacy using the MEDLINE database and made a manual search of selected references.

EVIDENCE SYNTHESIS

Most current studies on DL-PDT have limited follow-up periods of 3 to 6 months. Only 2 randomized, intra-individual studies provided efficacy data on AK treatment at 12 month-follow-up and supported the long-term efficacy of this novel treatment modality showing a low recurrence rate, varying from 8.7% to 13%. Current evidences for other NMSCs are limited and efficacy seems to be not as good as for AK.

CONCLUSIONS

DL-PDT is a very promising treatment for mild to moderate AKs of the face and scalp. Efficacy outcomes of DL-PDT are similar to those of c-PDT in the short-term. Additional studies are required to increase our knowledge on DL-PDT long-term efficacy, as limited data are currently available.

The background and philosophy behind daylight photodynamic therapy

Conventional photodynamic therapy (PDT) is associated with side effects, primarily related to the waiting time between pretreatment with application of photosensitizer and illumination. Pain during illumination is a major issue for the patients and options for effective pain relief are limited. Post-treatment inflammation can often be severe and cause inconvenient down-time for the patients and their employers. To avoid the problems of pain and patients crowding in the clinic we eliminated red light treatment of high PpIX concentration and introduced illumination in daylight which may be performed at home. We also investigated if protoporphyrin IX (PpIX) could be activated continuously during its formation which might reduce pain and inflammation. Continuous activation of PpIX during its formation turned out to minimize pain as single PpIX molecules are activated continuously without accumulation of PpIX in the skin. PpIX molecules are formed in the mitochondria and the photodynamic effect only takes place in the mitochondria when continuously activated. This results primarily in apoptosis with little inflammation. Continuous activation of PpIX can be obtained by performing photodynamic therapy in daylight, as well as with daylight-emitting light sources of appropriate wavelengths. Use of daylight prevents the patients from crowding in the clinic. Daylight-PDT completely fulfils the purpose of minimizing pain and inflammation, as well as limiting the strain on the clinic treating the patients.

Quantifying the radiant exposure and effective dose in patients treated for actinic keratoses with topical photodynamic therapy using daylight and LED white light

Daylight photodynamic therapy (dl-PDT) is as effective as conventional PDT (c-PDT) for treating actinic keratoses but has the advantage of reducing patient discomfort significantly. Topical dl-PDT and white light-PDT (wl-PDT) differ from c-PDT by way of light sources and methodology. We measured the variables associated with light dose delivery to skin surface and influence of geometry using a radiometer, a spectral radiometer and an illuminance meter. The associated errors of the measurement methods were assessed. The spectral and spatial distribution of the radiant energy from the LED white light source was evaluated in order to define the maximum treatment area, setup and treatment protocol for wl-PDT. We compared the data with two red LED light sources we use for c-PDT. The calculated effective light dose is the product of the normalised absorption spectrum of the photosensitizer, protoporphyrin IX (PpIX), the irradiance spectrum and the treatment time. The effective light dose from daylight ranged from 3  ±  0.4 to 44  ±  6 J cm^-2due to varying weather conditions. The effective light dose for wl-PDT was reproducible for treatments but it varied across the treatment area between 4  ±  0.1 J cm^-2 at the edge and 9  ±  0.1 J cm^-2 centrally. The effective light dose for the red waveband (615-645 nm) was 0.42  ±  0.05 J cm^-2 on a clear day, 0.05  ±  0.01 J cm^-2 on an overcast day and 0.9  ±  0.01 J cm^-2 using the white light. This compares with 0.95  ±  0.01 and 0.84  ±  0.01 J cm^-2 for c-PDT devices. Estimated errors associated with indirect determination of daylight effective light dose were very significant, particularly for effective light doses less than 5 J cm^-2 (up to 83% for irradiance calculations). The primary source of error is in establishment of the relationship between irradiance or illuminance and effective dose. Use of the O'Mahoney model is recommended using a calibrated logging illuminance meter with the detector in the plane of the treatment area.