Influence of Photodynamic Therapy on the Expression of Cancer/Testis Antigens in Squamous Cell Carcinoma of the Head and Neck.

Background: Photodynamic therapy (PDT) represents a palliative treatment resulting in induction of inflammatory reactions with importance for the development of an antitumor immunity. Cancer/testis antigens (CTAs) have been associated with poor prognosis in different types of cancer, including head and neck squamous cell carcinoma (HNSCC).

Materials And Methods: Tumor tissue samples before and after PDT were evaluated for the expression of four different CTAs by immunohistochemistry. Expression intensity and subcellular expression pattern were assessed.

Results: Before PDT, expression of any CTA was detectable in 91%. Comparing the overall expression of CTAs, a decreased expression of all melanoma-associated antigens (MAGEs) post-treatment and a slightly increased expression of New York esophageal squamous cell carcinoma 1 (NY-ESO-1) was visible. The simultaneous cytoplasmic and nuclear expression of pan-MAGE or MAGE-A3/A4 correlated with reduced treatment-failure-free-survival (TFFS).

Conclusion: This study investigated the impact of PDT on CTA expression in HNSCC, detecting modified expression patterns after PDT. These changes may have been caused by immunological pressure or epigenetic regulation of CTA expression.