Introduction For non-resectable squamous cell carcinoma of the head and neck (HNSCC), primary platinum-based chemoradiation (CRT) is still the therapy of choice. However, about 20 % of the patients do not respond to it and the residual tumor must be treated accordingly. With the immune checkpoint modulators there is a new option in this situation, but the immunological changes under CRT must first be understood.
Material and methods 67 paired biopsies before and after CRT were routinely collected and retrospectively analyzed by immunohistochemical staining. The samples were treated with antibodies against PD-1, PD-L1 and CD27. The expression on the tumor and the stromal cells was measured and evaluated by modified H-score. The changes and differences in expression were calculated using a T-test.
Results PD-1 expression did not change on tumor or on stromal cells during therapy. PD-L1 expression in the stroma of non-responder was significantly decreased (p = 0.008) before CRT, but without significant difference after CRT compared with patients with complete response. CD27 was measured on immune cells and there was a significant decrease in expression after CRT (p = 0.019). A survival analysis showed a significantly prolonged overall survival for patients with high CD27 expression (p = 0.039).
Conclusion Conventional chemoradiotherapy seems to have an effect on PD-L1 and CD27 expression on tumor and stromal cells. In particular, the observation that patients with high CD27 expression have improved survival but CD27 expression decreases after CRT may serve as a rationale for a combined CRT with a CD27 agonist.
Poster-PDF
A-1370.PDF
