Abstract 2422: In vivo pilot study of the effect of EGCG in photodynamic therapy on non melanoma skin cancer

Abstract

Abstract Non-melanoma skin cancer (NSCLC) is the most frequent cancer in humans worldwide. Solar UV radiation is main risk factor to NSCLC developing in areas such as the face, neck, arms, etc. Basal cell carcinoma and precursor lesions of squamous cell carcinoma (SCC), such as actinic keratosis, Bowen’s disease, etc. can be treated with Photodynamic Therapy (PDT). PDT consists of applying a cream containing a photosensitizer on the skin lesion, to then being irradiated with light at a specific wavelength. The most used PS in skin cancer is methyl aminolevulinate (MAL). Light excites the photosensitizer, which interacts with intracellular O2, producing reactive oxygen species (ROS), triggering cancer cell death. One of the main advantages of PDT is that it offers satisfactory cosmetic results. However, its effectiveness is variable. Our previous results, using a PDT-resistant SCC cell model, showed that the addition of epigallocatechin gallate (EGCG) to PDT has a potentiated effect, killing 100% of these cells. Therefore, the aim of this work was to evaluate the effect of an EGCG-enhanced cream for PDT on squamous cell carcinoma lesions in an animal model.A two-step chemical carcinogenesis protocol (DMBA/TPA) was used in male and female mice of the Balb/c strain (21 animals). Once the animals developed the desired lesions, they were randomly separated into three groups. The first group received conventional cream (MAL 20%), the second group cream A (MAL 20% + EGCG 1%) and the third group B cream (MAL 20% + EGCG 3%). PDT was performed as follows: cream was applied for 4 hours on the lesion and then protected from the light with a patch. Subsequently, the excess cream was removed and the lesions were irradiated with 630 nm red light. The lesions were followed up for one month, measuring the size of the tumor and taking a final biopsy.We successfully develop an in vivo model of NSCLC using chemical inducers. Mice develops two kind of lesions: plane and/or papillar. All mice were treated with PDT using the three different formulations. Lesions reduced its size until a 50% more when treated with PDT plus EGCG. Formulation B (MAL 20% + EGCG 3%), was the most effective, given it had a greater on the relative reduction of the volume of the lesion. In conclusion, this in vivo pilot study evidences the enhancing effect of EGCG on PDT, encouraging the pursue to continue with the investigations on this matter, in order to improve the PDT and the quality of life of skin cancer patients. Citation Format: Carmen Gloria Ili, Daniela Leon, Maria Elena Reyes, Kurt Buchegger, Francisca Acevedo-Canala, Pablo Guzman, Claudia Nicklas, Cecicia Orlandi, Priscilla Brebi. In vivo pilot study of the effect of EGCG in photodynamic therapy on non melanoma skin cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2422.