Comparison of PD-L1 expression in squamous cell cancer of unknown primary and oropharyngeal squamous cell carcinoma

Abstract

Purpose The tumorigenesis of squamous cell cancer of unknown primary (SCCUP) in the head and neck area has not been decoded so far, while poor survival rates and limited therapeutic options pose a serious challenge. The aim of this project was to investigate immunological characteristics of SCCUPs and compare them to oropharyngeal squamous cell carcinoma (OPSCC). Methods PD-L1 expression (TC) was examined by immunohistochemistry in 50 lymph node metastases of SCCUP and 47 primaries of OPSCC. CD3 + and CD8 + lymphocytic infiltration was measured in 5 high power fields. Expression of p16 and HPV ISH were assessed. Results SCCUP demonstrated a significantly higher expression of PD-L1 than OPSCC. In p16-negative SCCUPs PD-L1 proved to be an independent prognostic factor to prioritize high-risk patients. Conclusions Immunologic differences between SCCUP and OPSCC were detected. A higher PD-L1 expression in SCCUP could potentially facilitate further evaluation of checkpoint inhibitor therapy.

Advances in Cancer Research: Current and Future Diagnostic and Therapeutic Strategies

“…CUP are highly aggressive and differ from other tumor types [1]. The effectiveness of immunotherapy largely depends on the tumor microenvironment (TME), but data on the immune microenvironment in CUP are scarce [68][69][70]. A study using the cBioPortal database compared the tumor cell genomes of CUP patients with those of patients with tumors suitable for ICI treatment (cervical, hepatocellular, gastric, etc.…”

“…In p16-negative patients, high PD-L1 expression was found to be an independent prognostic factor. One study found that 22% of 362 patients showed tumor PD-L1 expression, and 12% exhibited high tumor mutational burden (TMB-H), offering a new option for treating CUP patients with ICIs [70] (Figure 10B). For patients with poor-prognosis CUP, the effectiveness of immunotherapy and the selection of predictive biomarkers still require more evidence-based medical research.…”

“…(b) progression-free survival of p16-negative CUP patients in relation to PD-L1 expression. (c) comparison of Overall Survival of CUP patients stratifed by p16 and PD-L1 status[70].…”