Photodynamic therapy for Bowen’s Disease (squamous cell carcinoma in situ) current review and update

Treatment of nonmelanoma skin cancer with pro-differentiation agents and photodynamic therapy: Preclinical and clinical studies (Review)

Photodynamic therapy (PDT) is a nonscarring cancer treatment in which a pro-drug (5-aminolevulinic acid, ALA) is applied, converted into a photosensitizer (protoporphyrin IX, PpIX) which is then activated by visible light. ALA-PDT is now popular for treating nonmelanoma skin cancer (NMSC), but can be ineffective for larger skin tumors, mainly due to inadequate production of PpIX. Work over the past two decades has shown that differentiation-promoting agents, including methotrexate (MTX), 5-fluorouracil (5FU) and vitamin D (Vit D) can be combined with ALA-PDT as neoadjuvants to promote tumor-specific accumulation of PpIX, enhance tumor-selective cell death, and improve therapeutic outcome. In this review, we provide a historical perspective of how the combinations of differentiation-promoting agents with PDT (cPDT) evolved, including Initial discoveries, biochemical and molecular mechanisms, and clinical translation for the treatment of NMSCs. For added context, we also compare the differentiation-promoting neoadjuvants with some other clinical PDT combinations such as surgery, laser ablation, iron-chelating agents (CP94), and immunomodulators that do not induce differentiation. Although this review focuses mainly on the application of cPDT for NMSCs, the concepts and findings described here may be more broadly applicable towards improving the therapeutic outcomes of PDT treatment for other types of cancers.

Long-term follow up of ALA 10% gel and red-light photodynamic therapy for the treatment of squamous cell carcinoma in situ

Photodynamic Therapy (PDT) with 10% aminolevulinic acid (ALA) gel and narrow-band red light has been previously shown to be safe and effective for the treatment of squamous cell carcinoma in situ (SCCis) on the trunk and extremities. However, there is a paucity of data in the literature evaluating long-term disease recurrence after PDT. Hence, we performed a follow-up study in which nine of the original twelve patients from our pilot study returned 29-40 months after their last PDT treatment. All patients were clinically clear of disease and only one of seven patients biopsied had residual disease, indicating a long-term clearance rate of 88%. Cosmetic outcomes and patient satisfaction were favorable. Our data supports that red-light PDT with 10% ALA gel can achieve long-term clinical and histopathologic disease clearance and is a viable alternative to surgery for select SCCis.

Vitamin D and Vitamin D3 Supplementation during Photodynamic Therapy: A Review

Photodynamic therapy is an unconventional yet increasingly common method of treating dermatological diseases and cancer that is implemented more often in adults than in children. Current clinical uses include treatment of actinic keratosis, superficial basal cell carcinomas, and acne. Despite its high efficiency, photodynamic therapy support supplements have recently been reported in the literature, including calcitriol (1,25-dihydroxycholecalciferol), the active form of vitamin D, and vitamin D3 cholecalciferol. In clinical trials, photodynamic therapy enhanced with vitamin D or D3 supplementation has been reported for treatment of squamous cell skin cancers, actinic keratosis, and psoriasis. Experimental research on the effect of photodynamic therapy with vitamin D or D3 has also been carried out in breast cancer cell lines and in animal models. The aim of this review is to evaluate the usefulness and effectiveness of vitamin D and D3 as supports for photodynamic therapy. For this purpose, the Pubmed and Scopus literature databases were searched. The search keyword was: “vitamin D in photodynamic therapy”. In the analyzed articles (1979–2022), the authors found experimental evidence of a positive effect of vitamin D and D3 when used in conjunction with photodynamic therapy. An average of 6–30% (in one case, up to 10 times) increased response to photodynamic therapy was reported in combination with vitamin D and D3 as compared to photodynamic therapy alone. Implementing vitamin D and D3 as a supplement to photodynamic therapy is promising and may lead to further clinical trials and new clinical methodologies.

Identification and pharmacological modification of resistance mechanisms to protoporphyrin-mediated photodynamic therapy in human cutaneous squamous cell carcinoma cell lines

BACKGROUND

Photodynamic therapy (PDT) is clinically approved to treat neoplastic skin diseases such as precursors of cutaneous squamous cell carcinoma (cSCC). In PDT, 5-aminolevulinic acid (5-ALA) drives the selective formation of the endogenous photosensitizer protoporphyrin IX (PpIX). Although 5-ALA PDT is clinically highly effective, resistance might occur due to decreased accumulation of PpIX in certain tumors. Such resistance may be caused by any fundamental step of PpIX accumulation: 5-ALA uptake, PpIX synthesis and PpIX efflux.

METHODS

We investigated PpIX accumulation and photodynamically induced cell death in PDT refractory SCC-13, PDT susceptible A431, and normal human epidermal keratinocytes (NHEK). Expression of genes associated with cellular PpIX kinetics was investigated on mRNA and protein level. PpIX accumulation and cell death upon illumination were pharmacologically manipulated using drugs targeting 5-ALA uptake, PpIX synthesis or efflux.

RESULTS

The experiments indicate that taurine transporter (SLC6A6) is the major pathway for 5-ALA uptake in cSCC cells, while being less important in NHEK. Downregulation of PpIX synthesis enzymes in SCC-13 was counteracted by methotrexate (MTX) treatment, which restored PpIX formation and cell death. PpIX efflux inhibitors targeting ABC transporters led to significantly increased PpIX accumulation in SCC-13, thereby fully overcoming resistance.

CONCLUSIONS

The results indicate a conserved threshold for PpIX accumulation with respect to PDT-resistance. Cells showed increased viability after PDT at PpIX concentrations below 1.5 nM. Selective uptake of 5-ALA via taurine transporter SLC6A6 in cutaneous tumor cells is novel but unrelated to resistance. MTX can partially abrogate resistance by PpIX synthesis enzyme induction, while efflux mechanisms via ABC transporters seem the main driving force and promising drug targets.

Folic acid conjugated PAMAM-modified mesoporous silica-coated superparamagnetic iron oxide nanoparticles for potential cancer therapy

In this study, novel folate-receptor-targeted polyamidoamine (PAMAM) dendrimer functional mesoporous silica-coated magnetic nanoparticles were prepared for drug delivery agents for photodynamic therapy applications. The surface of the magnetic nanoparticles was coated with mesoporous silica (M-MSN). The M-MSN nanoparticles were functionalized with siloxane-cored PAMAM dendrons (generation 1 to 3). The surface of the M-MSN-PAMAM nanocarriers was targeted with folic acid. Indocyanine green (ICG) a near-infrared dye was loaded in the M-MSN-PAMAM nanocarriers and the photodynamic therapy efficiency of the drug-loaded nanocarriers was evaluated on MCF-7 cells. MCF-7 cells were subjected to tissue culture E-Plate that was used to generate dynamic real-time data by measuring electrical impedance across interdigitated microelectrodes on the bottom of the plate. Light source (LEDs) was designed as a system that fit 96 well-plate and cells were irradiated at 785 nm for 20 min. Also, these results were confirmed by WST-1 assay in dark and light conditions for MCF-7 cells. The results showed that in vitro application of ICG loaded M-MSN-PAMAM-FA causes apoptosis in the MCF-7 cell line.

Acitretin Enhances the Cytotoxic Effect of 5-aminolevulinic Acid Photodynamic Therapy on Squamous Cell Carcinoma Cells

The efficacy of 5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) on invasive cutaneous squamous cell carcinoma (cSCC) remains to be improved due to the limited penetration of this treatment. Previous study showed that acitretin and ALA-PDT had synergistic effect on cSCC, but whether acitretin can enhance the cytotoxic effect of ALA-PDT on cSCC is unclear.

OBJECTIVE

To investigate whether acitretin can enhance the cytotoxic effect of ALA-PDT on SCL-1 cells, as well as the possible mechanism involved.

METHODS

Inverted microscopy, trypan blue exclusion assay, and flow cytometry were used to studied the morphology, viability and apoptosis of SCL-1 cells treated with acitretin, ALA-PDT and acitretin followed by ALA-PDT treatment, respectively. Confocal microscopy was applied to detect the ROS formation of SCL-1 cells treated with acitretin of four different concentrations. The ROS formation of SCL-I cells treated with acitretin of four different concentrations followed by ALA-PDT treatment was detected using confocal microscopy and flow cytometry.

RESULTS

SCL-1 cells exhibited a significant morphological alteration when treated with acitretin followed by ALA-PDT. The combination of acitretin and ALA-PDT induced a higher cell death rate and apoptosis than that with acitretin or ALA-PDT treatment alone. ROS could be induced when incubated with acitretin at a concentration of 6.4 × 10^-4mg /mL or above. However, a higher level of ROS formation was observed when SCL-1 cells were treated with acitretin followed by ALA-PDT than that with ALA-PDT or acitretin alone.

CONCLUSION

Acitretin can enhance the cytotoxic effect of ALA-PDT on SCL-1 cells, possibly via the ROS pathway.

Curettage and electrodessication combined with photodynamic therapy in the treatment of large squamous cell carcinomas in unfit and frail patients

A Caucasian female patient in her 90s was referred to the department of plastic and reconstructive surgery for surgical removal of a large invasive squamous cell carcinoma on the anterior chest wall. A skin biopsy prior to the referral indicated that the tumour was moderately differentiated. The patient suffered from severe congestive heart failure with a mechanical valve prosthesis and atrial fibrillation, and was therefore treated with anticoagulants. Hence, a surgical procedure would be hazardous. Therefore, other treatment options were considered. The principal aim was to reduce the amount of tumour tissue to an appropriate size suitable for later excision with primary wound closure. After interdisciplinary discussions, curettage and electrodessication combined with photodynamic therapy was judged the best alternative treatment in this case. At the 1.5 years follow-up after the intervention there was no indication for further surgery. The patient was at that stage content with the treatment and its outcome.

Analysis on the Effectiveness and Characteristics of Treatment Modalities for Bowen’s Disease: An Observational Study

Treatment options for Bowen’s disease (BD) include surgical excision, cryotherapy, curettage with cautery, topical 5-fluorouracil or imiquimod, and photodynamic therapy. However, it is not clear which treatment is the most effective due to lack of studies. We reviewed the electronic medical records of 158 patients who were diagnosed with BD and treated at Seoul St. Mary’s Hospital from January 2011 to December 2020. Treatment modalities were surgical excision, cryotherapy, photodynamic therapy, and imiquimod. A total of 121 patients was enrolled in this study. The average treatment period was longest for cryotherapy, followed by imiquimod, PDT, and excision (119.53, 87.75, 68.50, and 1 day, respectively). The therapeutic efficacy was highest in the surgical excision group (100%) and lowest in the PDT group (62.5%). The recurrence rate was highest in the imiquimod group (33.33%). Surprisingly, only in patients treated with cryotherapy, satellite lesions developed in 9.09% of them during follow-up. Surgical excision exhibited the highest clearance rate and the lowest recurrence rate, and its treatment period was the shortest, confirming that it remains the gold standard. In contrast, since cryotherapy demonstrated a relatively high recurrence rate including development of satellite lesions, careful monitoring is required when performing cryotherapy for treatment of BD.

Implications of photodynamic cancer therapy: an overview of PDT mechanisms basically and practically

BACKGROUND

Tumor eradication is one of the most important challengeable categories in oncological studies. In this account, besides the molecular genetics methods including cell therapy, gene therapy, immunotherapy, and general cancer therapy procedures like surgery, radiotherapy, and chemotherapy, photodynamic adjuvant therapy is of great importance. Photodynamic therapy (PDT) as a relatively noninvasive therapeutic method utilizes the irradiation of an appropriate wavelength which is absorbed by a photosensitizing agent in the presence of oxygen. In this procedure, a series of events lead to the direct death of malignant cells such as damage to the microvasculature and also the induction of a local inflammatory function. PDT has participated with other treatment modalities especially in the early stage of malignant tumors and has resulted in decreasing morbidity besides improving survival rate and quality of life. High spatial resolution of PDT has attracted considerable attention in the field of image-guided photodynamic therapy combined with chemotherapy of multidrug resistance cancers. Although PDT outcomes vary across the different tumor types, minimal natural tissue toxicity, minor systemic effects, significant reduction in long-term disease, lack of innate or acquired resistance mechanisms, and excellent cosmetic effects, as well as limb function, make it a valuable treatment option for combination therapies.

SHORT CONCLUSION

In this review article, we tried to discuss the potential of PDT in the treatment of some dermatologic and solid tumors, particularly all its important mechanisms.

TGFβ1 Secreted by Cancer-Associated Fibroblasts as an Inductor of Resistance to Photodynamic Therapy in Squamous Cell Carcinoma Cells

Simple Summary

Photodynamic therapy (PDT) is used for the treatment of in situ cutaneous squamous cell carcinoma (cSCC), the second most common form of skin cancer, as well as for its precancerous form, actinic keratosis. However, relapses after the treatment can occur. Transforming growth factor β1 (TGFβ1) produced by cancer-associated fibroblasts (CAFs) in the tumor microenvironment has been pointed as a key player in the development of cSCC resistance to other therapies, such as chemotherapy. Here, we demonstrate that TGFβ1 produced by CAFs isolated from patients with cSCC can drive resistance to PDT in SCC cells. This finding opens up novel possibilities for strategy optimization in the field of cSCC resistance to PDT and highlights CAF-derived TGFβ1 as a potential target to improve the efficacy of PDT.

Abstract

As an important component of tumor microenvironment, cancer-associated fibroblasts (CAFs) have lately gained prominence owing to their crucial role in the resistance to therapies. Photodynamic therapy (PDT) stands out as a successful therapeutic strategy to treat cutaneous squamous cell carcinoma. In this study, we demonstrate that the transforming growth factor β1 (TGFβ1) cytokine secreted by CAFs isolated from patients with SCC can drive resistance to PDT in epithelial SCC cells. To this end, CAFs obtained from patients with in situ cSCC were firstly characterized based on the expression levels of paramount markers as well as the levels of TGFβ1 secreted to the extracellular environment. On a step forward, two established human cSCC cell lines (A431 and SCC13) were pre-treated with conditioned medium obtained from the selected CAF cultures. The CAF-derived conditioned medium effectively induced resistance to PDT in A431 cells through a reduction in the cell proliferation rate. This resistance effect was recapitulated by treating with recombinant TGFβ1 and abolished by using the SB525334 TGFβ1 receptor inhibitor, providing robust evidence of the role of TGFβ1 secreted by CAFs in the development of resistance to PDT in this cell line. Conversely, higher levels of recombinant TGFβ1 were needed to reduce cell proliferation in SCC13 cells, and no induction of resistance to PDT was observed in this cell line in response to CAF-derived conditioned medium. Interestingly, we probed that the comparatively higher intrinsic resistance to PDT of SCC13 cells was mediated by the elevated levels of TGFβ1 secreted by this cell line. Our results point at this feature as a promising biomarker to predict both the suitability of PDT and the chances to optimize the treatment by targeting CAF-derived TGFβ1 in the road to a more personalized treatment of particular cSCC tumors.

Efficacy of Photodynamic Therapy for the Treatment of Bowen's Disease: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Photodynamic therapy is an established treatment option for Bowen's disease. Our meta-analysis was aimed at evaluating the efficacy and recurrence of photodynamic therapy or other topical treatments (5-fluorouracil, cryotherapy) and of photodynamic therapy alone or in combination with other therapies (ablative fractional CO2 laser or plum-blossom needle) for the treatment of Bowen's disease.

METHODS

Trials that met our inclusion criteria were identified from PubMed, EMBASE, Web of Science, and Cochrane Library databases, and meta-analyses were conducted with RevMan V.5.4. The risk of bias was estimated with the Cochrane Collaboration's risk of bias tools. Complete response rate, recurrence, pain/visual analogue scale score, cosmetic outcome, and adverse events were considered as outcomes.

RESULTS

Of the 2,439 records initially retrieved, 8 randomized controlled trials were included in this meta-analysis. According to our analyses, photodynamic therapy exhibited a significantly higher complete response rate (RR = 1.36, 95% CI [1.01, 1.84], I2 = 86%, p = 0.04), less recurrence (RR = 0.53, 95% CI [0.30, 0.95], I2 = 0%, p = 0.03), and better cosmetic outcome (RR = 1.34, 95% CI [1.15, 1.56], I2 = 0%, p = 0.0002) compared with other treatments. Moreover, there was a significant difference between the complete response rate of photodynamic therapy combined with ablative fractional CO2 laser and that of photodynamic therapy (RR = 1.85, 95% CI [1.38, 2.49], I2 = 0%, p < 0.0001). Photodynamic therapy combined with ablative fractional CO2 laser or plum-blossom needle also showed significantly less recurrence (RR = 0.21, 95% CI [0.09, 0.51], I2 = 0%, p = 0.0005) and a lower visual analogue scale score (RR = 0.51, 95% CI [0.06, 0.96], I2 = 0%, p = 0.03) than photodynamic therapy alone. However, there was no significant difference in the complete response rate between photodynamic therapy combined with ablative continuous CO2 laser and photodynamic therapy combined with ablative fractional CO2 laser (RR = 1.00, 95% CI [0.54, 1.86], I2 not applicable, p = 1.00).

CONCLUSIONS

This meta-analysis shows that photodynamic therapy can be used in the treatment of Bowen's disease with better efficacy, less recurrence, and better cosmetic outcomes than cryotherapy and 5-FU. Some methods, including ablative fractional CO2 laser, can be applied in combination with photodynamic therapy to improve efficacy. However, which laser-assisted photodynamic therapy scheme has the most advantages in the treatment of Bowen's disease warrants further exploration.

Photodynamic therapy utilizing 10% ALA nano-emulsion gel and red-light for the treatment of squamous cell carcinoma in-situ on the trunk and extremities: Pilot study and literature update

BACKGROUND

Data evaluating the effectiveness of photodynamic therapy (PDT) with aminolevulinic acid (ALA) 10% nanoemulsion gel and red-light LED lamp for the treatment of squamous cell carcinoma in situ (SCCis) on the trunk and extremities is limited. Our study sought to investigate the safety and efficacy of utilizing ALA 10% gel with red-light lamp for the treatment of SCCis on the trunk and extremities.

METHODS

A single center prospective study of 12 patients with biopsy proven SCCis underwent one or two cycles of red-light PDT with ALA 10 % gel and 3 hours incubation period. Each cycle consisted of two treatments approximately 10 days apart. All participants had a biopsy for histologic evaluation 4 weeks following the last treatment.

RESULTS

All patients achieved clinical and histologic clearance following either one or two cycles at the 4-week post treatment follow up period. The majority of lesions were located on the extremities (n=10) with the remainder located on the trunk (n=2). The mean diameter of the lesions was 1.83 cm. Mild pain was noted in patients, with no interruption of treatment.

CONCLUSIONS

Our study indicates that ALA 10% gel with a red-light lamp is a safe and effective treatment option for SCCis on the trunk and extremities.

Ulceration occurring after ALA-PDT combined with plum-blossom needle percussion for the treatment of pretibial Bowen's disease: A case report

We used 5-aminolevulinic acid-photodynamic therapy (ALA-PDT) combined with plum-blossom needle (PBN) on a 3.5 cm × 3.0 cm pretibial region to treat an elderly woman suffering from Bowen's disease (BD). Before the application of ALA, the PBN was inserted 3-4 times vertically starting at 5 cm above the lesion. Then, 20 % 5-ALA cream was applied with an incubation time of 3.5 h. A semiconductor laser at a wavelength of 635 nm was used to illuminate the lesion at 100 J/cm² using 60 mW/cm². A total of three sessions of ALA-PDT were performed at 2-3-week intervals, thus removing the lesion of BD. However, a 1.5 cm × 1.0 cm ulceration occurred 2 weeks after the third session when the PBN was used. Therefore, PBN percussion or other methods for promoting ALA penetration should be carefully applied to avoid ulceration, especially on the sites with less subcutaneous tissue.

Optimizing the spray parameters of a cryospray process

Smaller spray zone of single-hole nozzle (SHN) constrains cryospray as a treatment method suitable for lesions having diameter larger than 15 mm on the skin surface. The present study is an attempt to resolve this issue, through the improvement in conventional technique of spraying liquid nitrogen on cancerous lesion. A multi-hole nozzle (MHN) with 5 holes is fabricated to demarcate the variation in outcome when cryogen is sprayed through customised MHN instead of conventional SHN. Special emphasis is placed on reducing the number of sitting required for completion of treatment and increasing the feasibility of cryospray process for larger lesions. Commercial SHN having a hole diameter of 0.8 mm is selected to compare results with the customised MHN having 5 holes of 0.8 mm diameter (4 holes are arranged in a circle of radius 2 mm around the central hole). Single freeze-thaw cycle is carried out to spray liquid nitrogen on tissue mimicking gel. Temperature profile accessed through infrared images advocates that lethal area formed through application of MHN is twice larger than the lethal area formed through the application of SHN on the surface of gel for same spraying distance (z). Thermocouples placed at various locations strengthen the fact that higher cooling rate (CR) corresponding to MHN ensures 15 mm spread of necrotic zone from the centre of spray (CS) and up to a depth of 2 mm from the gel surface while in case of SHN, it is limited to the vicinity of CS. On the basis of observations made through thermal images and digital images, it can be said that the ratio of lateral spread to penetration depth of ice ball remains almost same for SHN and MHN. However, the lateral spread of ice ball formed through the application of MHN is twice larger than SHN while the axial depth of ice ball does not record such increment. This reflects that MHN provides more destruction to superficial skin than SHN. Among the three spraying distances selected (i.e. z = 13 mm, 18 mm and 23 mm), the most optimised spraying distance (z) for MHN is also explored in this study. It has been found that cryoablation is not inversely proportional to the spraying distance. Spraying distance of z = 18 mm provided the most optimised result in terms of cryoablation.

5-aminolevulinic acid photodynamic therapy inhibits invasion and metastasis of SCL-1 cells probably via MTSS1 and p63 gene related pathways

OBJECTIVE

To investigate the effect of 5-aminolevulinic acid (ALA) mediated photodynamic therapy (PDT) on the invasion and metastasis in cutaneous squamous cell carcinoma (cSCC) cell line(SCL-1) and to study whether the effect was via the MTSS1 gene and p63 gene related pathways.

METHODS

SCL-1 cells were cultured and submitted to ALA-PDT treatment (ALA-PDT group), ALA treatment alone (ALA group), LED illumination alone (LED group) and remains untreated (control group). Scratch test, Transwell migration chamber assay and Matrigel cell invasion assay were used to detect the ability of migration and invasion of SCL-1 cells after treatment. The mRNA levels and protein expressions of tumor metastasis suppressor gene (MTSS1) and p63 gene were further detected by using quantitative real-time PCR and flow cytometry assay respectively after treatment.

RESULTS

The migration and invasion abilities of SCL-1 cells after treatment were significantly reduced in the ALA-PDT groups than that in ALA group, LED group and control group (P＜0.05). Both the mRNA and protein expression levels of MTSS1 gene were up-regulated, while the mRNA and protein expression levels of p63 gene were down-regulated after ALA-PDT treatment.

CONCLUSION

ALA-PDT suppressed the migration and invasion of human cSCC cell line, probably via the MTSS1 gene and p63 gene related pathways. This study put forward a possible mechanism of invasion in SCL-1 cell, also providing a potential target for the therapy of cSCC.

The evolving landscape for cellular nitric oxide and hydrogen sulfide delivery systems: A new era of customized medications

Nitric oxide (NO) and hydrogen sulfide (H2S) are industrial toxins or pollutants; however, both are produced endogenously and have important biological roles in most mammalian tissues. The recognition that these gasotransmitters have a role in physiological and pathophysiological processes has presented opportunities to harness their intracellular effects either through inhibition of their production; or more commonly, through inducing their levels and or delivering them by various modalities. In this review article, we have focused on an array of NO and H2S donors, their hybrids with other established classes of drugs, and the various engineered delivery platforms such a fibers, polymers, nanoparticles, hydrogels, and others. In each case, we have reviewed the rationale for their development.

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.

Anthraquinone encapsulation into polymeric nanocapsules as a new drug from biotechnological origin designed for photodynamic therapy

Photodynamic therapy has been applied for the treatment of many diseases, especially skin diseases. However, poor aqueous solubility and toxicity of some photosensitizer drugs are the main disadvantages for their direct clinical applications. Thus, biotechnology and nanotechnology are important tools in the development of new ways of obtaining photoactive compounds that are biocompatible. We investigated the potential of a new nanostructured photosensitizer, an anthraquinone derivative produced by biotechnological process; then we associated nanotechnology to obtain a nanostructured anthraquinone active molecule. For this, it was prepared a classical nanocapsule formulations containing poly(lactide-co-glycolide) (PLGA) coating for encapsulation of anthraquinone derivative. These formulations were characterized by their physicochemical, morphological, photophysical properties, and stability. We performed in vitro biocompatibility and photodynamic activity assays of free and nanostructured anthraquinone. Nanocapsule formulations containing anthraquinone derivative showed a nanometric profile with particle size around 250 nm, negative zeta potential around -30 mV, and partially monodisperse. Besides that, characteristic spherical morphology of nanocapsules and homogeneous particle surface were observed by AFM analyses. The in vitro biocompatibility assay showed absence of cytotoxicity for all tested RD/NC concentrations and also for unloaded/NC in NIH3T3 cells. In vitro photoactivation assay using NIH3T3 cells showed that nanocapsules promoted greater drug uptake by NIH3T3 cells, around of 87%, of cell death compared to free drug showed around 48% of cell death. The anthraquinone derivative showed potential for use in PDT. Besides the association with nanocapsules improved cell uptake of photosensitizer resulting in increased cell death compared to free anthraquinone.

Vitamin D and Other Differentiation-promoting Agents as Neoadjuvants for Photodynamic Therapy of Cancer

The efficacy of photodynamic therapy (PDT) using aminolevulinic acid (ALA), which is preferentially taken up by cancerous cells and converted to protoporphyrin IX (PpIX), can be substantially improved by pretreating the tumor cells with vitamin D (Vit D). Vit D is one of several "differentiation-promoting agents" that can promote the preferential accumulation of PpIX within the mitochondria of neoplastic cells, making them better targets for PDT. This article provides a historical overview of how the concept of using combination agents ("neoadjuvants") for PDT evolved, from initial discoveries about neoadjuvant effects of methotrexate and fluorouracil to later studies to determine how vitamin D and other agents actually work to augment PDT efficacy. While this review focuses mainly on skin cancer, it includes a discussion about how these concepts may be applied more broadly toward improving PDT outcomes in other types of cancer.

Successful treatment for multiple Bowen's disease using photodynamic therapy: A case report

Bowen's disease, also named squamous cell carcinoma in situ, is usually treated by surgical excision. However, surgery is not suitable to patients with large area of lesions, multiple lesions or in cosmetically important areas where a scar will be visible. Photodynamic therapy (PDT) has advantages of efficacy, safety, and does not generally induce scar or damage to joint function. It could also be used repeatedly. Therefore, PDT might be recommended to treat multiple Bowen's disease. This report shared a case of a patient having suffered from multiple Bowen's disease successfully treated by PDT. PDT not only avoided scars and joint dysfunction, but also raised quality of the patient's daily life.

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 5-aminolevulinic acid 5% gel for the treatment of mild-to-moderate inflammatory acne

BACKGROUND

Acne vulgaris is a chronic inflammatory disease that frequently occurs in adolescence. This common condition is often treated with topical or systemic therapies according to severity. Photodynamic therapy (PDT) with topical delta-aminolaevulinic acid is a novel drug-sparing, but time-consuming approach. Recently, sunlight exposure has been considered a quicker, safer, cheaper and more agreeable alternative light source for PDT, but efficacy has only been proven in the oncological field. This study aimed to evaluate the efficacy and tolerability of daylight PDT (DL-PDT) for the treatment of inflammatory acne vulgaris of face, chest and trunk lesions.

METHODS

Twenty patients with mild-to-moderate acne vulgaris were enrolled and treated with a topical gel based on 5% delta-aminolaevulinic acid, administered 4 times at 14-day intervals. Efficacy was assessed with mean lesion count, Physician Global Assessment (PGA), Investigator's Global Assessment (IGA) and patients' self-assessment (10-point scale).

RESULTS

Compared to T0, mean inflammatory lesions count decreased in all patients at FU1, from 16.7±4.4 to 5.2±3.3 (P). No adverse events were reported, and no patients were lost to follow-up. PGA results of "excellent" or "good" improvement were reported in 95% at T3 and 90% at FU1. Patients' self-assessments was 7.6±1.0 (T3). Discomfort was 0.5±0.2 (T3 and FU1).

CONCLUSIONS

DL-PDT seems to be an effective and tolerable therapy for the treatment of mild-to-severe inflammatory acne. This novel regimen seems to be a viable option in the panorama of acne therapies.

Methyl aminolevulinate-based photodynamic therapy of Bowen´s disease: Observational study of 21 lesions

BACKGROUND

Although surgical removal is the treatment of choice in Bowen's disease (BD), there are cases in which by age, comorbidities, use of anticoagulants, location, cosmetic result, or size, it is preferable to use other treatments such as cryotherapy, 5-fluorouracil cream, imiquimod 5% cream or photodynamic therapy (PDT). Efficacy of PDT in BD is supported by substantial research and clinical data.

OBJECTIVES

This study aimed to evaluate the long term effectiveness of methyl aminolevulinate-PDT (MAL/PDT) on a wide range of Bowen lesions in different locations and sizes.

METHODS

Patients diagnosed with BD were treated in 3 sessions with a 4-week interval in between with MAL/PDT between January 2016 and January 2017 in a private clinic. Clinical response and relevant patient and tumour characteristics were analyzed during the first year after start of the PDT sessions.

RESULTS

In total, 21 BD lesions in 18 patients were included in the study. Complete regression (CR) after 3rd PDT session was 87.5% and 100% at the 6-month follow-up. Treatment was well tolerated and local adverse reactions were very scarce. No recurrence was observed at 12-month follow-up. Cosmetic outcome at 12 months was good or excellent in 100% of patients.

CONCLUSIONS

MAL/PDT is an effective, non invasive and safe treatment modality for BD with excellent cosmesis.