The Programmed Death Pathway in Ocular Adnexal Sebaceous Carcinoma

Area of Science:

• Oncology
• Immunology
• Dermatology

Background:

• Sebaceous carcinoma is a rare, aggressive skin cancer with limited treatment options.
• Immune checkpoint inhibitors have shown efficacy in various cancers, but their role in sebaceous carcinoma is unclear.
• Understanding the tumor microenvironment and immune response is crucial for developing novel therapies.

Purpose of the Study:

• To investigate the expression of programmed cell death protein 1 (PD-1) and its ligands (PD-L1, PD-L2) in sebaceous carcinoma.
• To evaluate the presence of these markers on both tumor cells and infiltrating immune cells.
• To explore the potential of immune checkpoint blockade as an adjuvant therapy for sebaceous carcinoma.

Main Methods:

• Retrospective analysis of 28 sebaceous carcinoma cases diagnosed between 1990 and 2017.
• Immunohistochemistry was used to assess the expression of PD-1, PD-L1, and PD-L2.
• Tumor and immune cells were considered positive for expression if ≥5% of cells exhibited membranous staining.

Main Results:

• PD-L1 and PD-1 were not significantly expressed on tumor cells.
• PD-L1 and PD-1 were expressed on infiltrating immune cells in 46% and 25% of cases, respectively.
• PD-L2 showed positive expression on tumor cells in 46% of cases and on infiltrating immune cells in 38% of cases.

Conclusions:

• PD-1, PD-L1, and PD-L2 expression on immune cells and PD-L2 on tumor cells may hinder anti-tumor T-cell responses.
• PD-1 or PD-L1 inhibitors could be potential therapeutic options for sebaceous carcinoma.
• PD-1 blockade, particularly given the prevalence of PD-L2 expression, may offer advantages and warrants further investigation as an adjuvant therapy.