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

High efficacy of red light photodynamic therapy with 10 % aminolevulinic acid gel irrespective of the extent of keratinocyte atypia in actinic keratosis - exploratory post-hoc analysis of three pivotal phase III trials

BACKGROUND

Primary endpoints of clinical studies investigating treatments for actinic keratosis (AK) are mainly based on clinical evaluation, but a recent study showed that in AK, clinical classification according to Olsen and the extent of keratinocyte atypia do not necessarily correlate. The influence of the epidermal extent of atypia on treatment efficacy is usually not investigated and therefore remains largely unknown.

OBJECTIVE

To evaluate whether the extent of keratinocyte atypia influences efficacy of photodynamic therapy (PDT) when treating AK.

METHODS

We performed a post-hoc analysis of histological (keratinocyte intraepithelial neoplasia (KIN)), and clinical (Olsen) data of biopsied lesions of three pivotal studies evaluating PDT using 10 % aminolevulinic acid (ALA) gel or vehicle and narrow- or broad-spectrum red light lamps.

RESULTS

Overall, 514 biopsied lesions were considered. Clearance rates after red light PDT with 10 % ALA gel were comparable for KIN I-III (88.2 %, 92.0 % and 87.9 %) and Olsen I-II lesions for any given lamp type. Generally, clearance rates were higher using narrow- compared to broad-spectrum lamps. For both lamp types, the variation in clearance rates from KIN I-III was low. Clearance was lower with vehicle.

LIMITATIONS

Varying lesion numbers in the subgroups and a remaining risk of bias due to the biopsies are potential limitations.

CONCLUSION

Our results suggest that red light PDT with 10 % ALA gel is an effective treatment option for AK regardless of the extent of keratinocyte atypia.

Observational pilot study of multi-wavelength wearable light dosimetry for erythropoietic protoporphyria

BACKGROUND

Erythropoietic protoporphyria (EPP) causes painful light sensitivity, limiting quality of life. Our objective was to develop and validate a wearable light exposure device and correlate measurements with light sensitivity in EPP to predict and prevent symptoms.

METHODS

A wearable light dosimeter was developed to capture light doses of UVA, blue, and red wavelengths. A prospective observational pilot study was performed in which five EPP patients wore two light dosimeters for 3 weeks, one as a watch, and one as a shirt clip.

RESULTS

Standard deviation (SD) increases from the mean in the daily blue light dose increased the odds ratio (OR) for symptom risk more than the self-reported outdoor time (OR 2.76 vs. 2.38) or other wavelengths, and a one SD increase from the mean in the daily blue light wristband device dose increased the OR for symptom risk more than the daily blue light shirt clip (OR 2.45 vs. 1.62). The area under the receiver operator curve for the blue light wristband dose was 0.78, suggesting 78% predictive accuracy.

CONCLUSION

These data demonstrate that wearable blue light dosimetry worn as a wristband is a promising method for measuring light exposure and predicting and preventing symptoms in EPP.

Copper and Copper Complexes in Tumor Therapy

Copper (Cu), a crucial trace element in physiological processes, has garnered significant interest for its involvement in cancer progression and potential therapeutic applications. The regulation of cellular copper levels is essential for maintaining copper homeostasis, as imbalances can lead to toxicity and cell death. The development of drugs that target copper homeostasis has emerged as a promising strategy for anticancer treatment, with a particular focus on copper chelators, copper ionophores, and novel copper complexes. Recent research has also investigated the potential of copper complexes in cancer therapy.

Tumor fluorescence and oxygenation monitoring during photodynamic therapy with chlorin e6 photosensitizer

BACKGROUND

The study is aimed at developing a method for monitoring photodynamic therapy (PDT) of a tumor using chlorin-type photosensitizers (PSs). Lack of monitoring of chlorin e6 (Cе6) photobleaching, hemoglobin oxygenation and blood flow during light exposure can limit the PDT effectiveness.

MATERIALS AND METHODS

Phototheranostics includes spectral-fluorescence diagnostics of Ce6 distribution in the NIR range and PDT with simultaneous assessment of hemoglobin oxygenation and tumor blood flow. Fluorescence diagnostics and PDT were performed using the single laser λexc=660 ± 5 nm.

RESULTS

Combined spectroscopic PDT monitoring method allowed simultaneous estimation of Ce6 photobleaching, hemoglobin oxygenation and tumor vascular thrombosis during PDT without interrupting the therapeutic light exposure.

CONCLUSION

The developed method of tumor phototheranostics using chlorin-type PSs may make it possible to personalize the duration of therapeutic light exposure during PDT.

Nanoparticles drug delivery for 5-aminolevulinic acid (5-ALA) in photodynamic therapy (PDT) for multiple cancer treatment: a critical review on biosynthesis, detection, and therapeutic applications

Photodynamic therapy (PDT) is a promising cancer treatment that kills cancer cells selectively by stimulating reactive oxygen species generation with photosensitizers exposed to specific light wavelengths. 5-aminolevulinic acid (5-ALA) is a widely used photosensitizer. However, its limited tumour penetration and targeting reduce its therapeutic efficacy. Scholars have investigated nano-delivery techniques to improve 5-ALA administration and efficacy in PDT. This review summarises recent advances in biological host biosynthetic pathways and regulatory mechanisms for 5-ALA production. The review also highlights the potential therapeutic efficacy of various 5-ALA nano-delivery modalities, such as nanoparticles, liposomes, and gels, in treating various cancers. Although promising, 5-ALA nano-delivery methods face challenges that could impair targeting and efficacy. To determine their safety and biocompatibility, extensive preclinical and clinical studies are required. This study highlights the potential of 5-ALA-NDSs to improve PDT for cancer treatment, as well as the need for additional research to overcome barriers and improve medical outcomes.

Is a 4 J/cm2 PpIX-Weighted Simulated Daylight (SDL-PDT) Dose Still Efficient for Photodynamic Therapy of Actinic Keratosis?

Background: Several solutions are now proposed to provide indoor illumination with so-called artificial white light or simulated daylight (SDL-PDT), resulting in an effective treatment for actinic keratosis (AK). However, the optimal PpIX-weighted light dose is still debated. Integrating the effective irradiance over the irradiation time yields the effective light dose, which is also known as the protoporphyrin IX-weighted light dose and is a key parameter for the efficacy of the treatment. Objectives: The paper aims to report the clinical outcomes of SDL-PDT when using the PpIX-weighted light dose of 4 J/cm2, in patients treated for AK lesions of the scalp or the face at our medical dermatology center (ClinicalTrials.gov NCT052036). Methods: A total of 30 patients (16 males, 14 females), with a mean age of 71.0 ± 10.2, with phototype 1 (16 patients) and phototype 2 (14 patients) with grade I-II AK were treated with a drug light interval (DLI) of 10 min and a light exposure of 35 min (Dermaris, Surgiris, Croix, France), corresponding to a PpIX-weighted light dose of 4 J/cm2. The primary endpoint was the cure rate of patients at six months post-treatment. Secondary endpoints included scores of pain, erythema, crusts, and discomfort during or/and post the treatment. Results: In total, 762 AK were treated. Six months following treatment, the cure rate of the patients was 77%. The median pain score was less than 1 out of 10 for most of the patients. Erythema was observed in all patients and lasted 3 days (±1.5 day). Crusts were seen in 28 patients. Discomfort was reported as mild or less in more than 97% of patients. Conclusions: The shortening of the PpIX-weighted light dose to 4 J/cm2, corresponding to an illumination duration of 35 min with the Dermaris, does not modify the efficacy of the SDL-PDT. This observation is in agreement with recent published data demonstrating that the light dose can be reduced. Furthermore, this clinical study confirmed that SDL-PDT is an effective and nearly painless treatment with minimal side effects for patients with AK lesions of the scalp.

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.

Smartphone-based dual radiometric fluorescence and white-light imager for quantification of protoporphyrin IX in skin

Significance

The quantification of protoporphyrin IX (PpIX) in skin can be used to study photodynamic therapy (PDT) treatments, understand porphyrin mechanisms, and enhance preoperative mapping of non-melanoma skin cancers.

Aim

We aim to develop a smartphone-based imager for performing simultaneous radiometric fluorescence (FL) and white light (WL) imaging to study the baseline levels, accumulation, and photobleaching of PpIX in skin.

Approach

A smartphone-based dual FL and WL imager (sDUO) is introduced alongside new radiometric calibration methods for providing SI-units of measurements in both pre-clinical and clinical settings. These radiometric measurements and corresponding PpIX concentration estimations are applied to clinical measurements to understand mechanistic differences between PDT treatments, accumulation differences between normal tissue and actinic keratosis lesions, and the correlation of photosensitizer concentrations to treatment outcomes.

Results

The sDUO alongside the developed methods provided radiometric FL measurements (nW / cm 2 ) with a demonstrated sub nanomolar PpIX sensitivity in 1% intralipid phantoms. Patients undergoing PDT treatment of actinic keratosis (AK) lesions were imaged, capturing the increase and subsequent decrease in FL associated with the incubation and irradiation timepoints of lamp-based PDT. Furthermore, the clinical measurements showed mechanistic differences in new daylight-based treatment modalities alongside the selective accumulation of PpIX within AK lesions. The use of the radiometric calibration enabled the reporting of detected PpIX FL in units of nW / cm 2 with the use of liquid phantom measurements allowing for the estimation of in-vivo molar concentrations of skin PpIX.

Conclusions

The phantom, pre-clinical, and clinical measurements demonstrated the capability of the sDUO to provide quantitative measurements of PpIX FL. The results demonstrate the use of the sDUO for the quantification of PpIX accumulation and photobleaching in a clinical setting, with implications for improving the diagnosis and treatment of various skin conditions.