PD-L1 expression analyzes in Cutaneous Melanoma

Abstract

Immune-checkpoints are crucial to maintain self-tolerance (preventing autoimmunity) and to protect against tissue damage in case of infections by pathogens. The expression of proteins at the immune-checkpoints can be abnormal in Melanoma, which may become an important immune resistance mechanism. PD-L1 has a crucial role in suppressing immune response, mainly by binding to its receptor in T lymphocytes. To better understand the role of PD-L1 in Melanoma, we will do a double stain immunohistochemistry test for PD-L1 and Mitf in samples of Melanomas at different stages. Microphthalmia transcription factor (Mitf) is essential to the development and survival of melanocytes. That will allow the analyzes of the percentage of neoplastic cells that are positive to both in the tumor (PD-L1+Mitf+) and non-neoplastic cells that eventually also express PD-L1, but not Mitf (PD-L1+Mitf-). These cells are not well studied yet; they are usually myeloid cells and may carry some prognostic meaning for the patients. We'll study 150 Melanomas, 30 Melanomas in each group, as follow: in situ; thickness between 0,01 e 2,0 mm (T1 and T2); thickness >2,0mm (T3 and T4); in lymph nodes and in metastatic tissues. The main objective is to answer how PD-L1 is expressed in different stages of cutaneous Melanoma: localized disease X metastatic disease (regional or at distance) in both neoplastic and non-neoplastic cells. Secondary objective is to identify any association among those two kind of cells with clinical or histopathological aspects and specific disease survival. Samples and patient data will be collect at Cutaneous Oncology Dermatology in HC-FMUSP and ICESP. (AU)