Circulating <scp>PD</scp>‐<scp>L</scp>1 in <scp>NSCLC</scp> patients and the correlation between the level of <scp>PD</scp>‐<scp>L</scp>1 expression and the clinical characteristics

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>The programmed cell death‐1/programmed cell death‐1 ligand (<jats:styled-content style="fixed-case">PD</jats:styled-content>‐1/<jats:styled-content style="fixed-case">PD</jats:styled-content>‐<jats:styled-content style="fixed-case">L</jats:styled-content>1) pathway plays a crucial role in tumor evasion. This study evaluated the association between circulating <jats:styled-content style="fixed-case">PD</jats:styled-content>‐L1 expression and clinical characteristics in patients with advanced non‐small cell lung cancer (<jats:styled-content style="fixed-case">NSCLC</jats:styled-content>).</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>A total of 109 advanced <jats:styled-content style="fixed-case">NSCLC</jats:styled-content> and 65 healthy patients from the <jats:styled-content style="fixed-case">B</jats:styled-content>eijng <jats:styled-content style="fixed-case">C</jats:styled-content>ancer <jats:styled-content style="fixed-case">H</jats:styled-content>ospital were enrolled in the study. Circulating <jats:styled-content style="fixed-case">PD</jats:styled-content>‐<jats:styled-content style="fixed-case">L</jats:styled-content>1 expression was tested by enzyme‐linked immunosorbent assay. The associations between the level of <jats:styled-content style="fixed-case">PD</jats:styled-content>‐<jats:styled-content style="fixed-case">L</jats:styled-content>1 expression and clinicopathologic features and prognosis were statistically analyzed.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The expression of <jats:styled-content style="fixed-case">PD</jats:styled-content>‐<jats:styled-content style="fixed-case">L</jats:styled-content>1 in advanced <jats:styled-content style="fixed-case">NSCLC</jats:styled-content> patients was significantly upregulated compared with the healthy control (<jats:italic>P</jats:italic> < 0.001). The expression of <jats:styled-content style="fixed-case">PD</jats:styled-content>‐L1 was significantly correlated with abdominal organ metastasis (<jats:italic>P</jats:italic> = 0.004). A high <jats:styled-content style="fixed-case">PD</jats:styled-content>‐<jats:styled-content style="fixed-case">L</jats:styled-content>1 expression had a worse prognosis than a low expression in patients (18.7 vs. 26.8 month, <jats:italic>P</jats:italic> < 0.001).</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p><jats:styled-content style="fixed-case">PD</jats:styled-content>‐<jats:styled-content style="fixed-case">L</jats:styled-content>1 was elevated in advanced <jats:styled-content style="fixed-case">NSCLC</jats:styled-content> patients and may play an important role in tumor immune evasion and patient prognosis.</jats:p></jats:sec>