PD-L1 expression in patients with anaplastic thyroid carcinoma: prevalence and outcome

Abstract

Anaplastic thyroid carcinoma is a rare but aggressive cancer. Recurrently, there was lack of effective treatment options. Immune checkpoint inhibitors, like Anti-programmed cell death ligand 1 (PDL1) have recently proved to be effective in some cancer, like lung, melanoma, and lymphoma. The role of Anti-PD-L1 on ATC is still understudied. In this study, we examined the prevalence of PD-L1 expression in the tumor cell in patients with ATC. We also correlated with pathological status, prognosis and outcome with PD-L1 expression. Slides from 17 patients who diagnosed with ATC by biopsy or surgical resection were retrieved. By using immuo-histo-chemical stain and Tumor Proportion Score, the PD-L1 expression on tumor cell was assessed. Positive on PD-L1 expression was defined as TPS >1% and high PD-L1 expression defined as TPS >50%. Findings of PD-L1 expression were correlated with clinicopathological profile and overall survival. Slides from 17 patients with median age of 80 at diagnosis were included. Median overall survival was 11 weeks. Median TPS was 60% (0-100%). and PD-L1 was positive in 15 patients (88.2%). Patients with positive PD-L1 had a poor overall survival (7 vs 178 weeks, p = 0.014) and tended to present with extrathyroidal invasion, lymph node, and distant metastasis. Overall survival was also correlated to the degree of PD-L1 expression. (Negative vs. PD-L1 expression vs. high PDL1 expression: 178 vs. 15 vs. 7 weeks, p = 0.033). The PD-L1 expression is prevalent in ATC tumor cell. The degree of expression correlated with aggressiveness of tumor in patients with ATC. Patients with PD-L1 positive ATC should be treated aggressively and clinical role of anti-PD-L1 should be further evaluated.