The Change of Soluble Programmed Death Ligand 1 (sPD-L1) in Plasma of Small Cell Lung Cancer and Its Clinical Significance

Abstract

Background soluble programmed death-ligand 1 (sPD-L1) expression in lung squamous cell carcinoma and lung adenocarcinoma is associated with disease progression, and sPD-L1 expression in small cell lung cancer (SCLC) may have similar manifestations and become a potential marker for treatment. The purpose of this study was to observe the changes of plasma sPD-L1 expression in SCLC patients. Methods. 90 patients diagnosed with SCLC from January 2019 to November 2020 were selected as the test group, including 72 males and 18 women, $58.7\pm 6.6$ years; 30 healthy subjects were selected from the physical examination center, including 18 males, 12 females, and $60.3\pm 7.0$ years. There were no statistical difference in sex and age factors between the trial and control groups ( $p>0.05$ ). Selected SCLC used chemotherapy regimen: $\text{cisplatin}+\text{etoposide}$ (EP), $\text{carboplatin}+\text{etoposide}$ (CE), and SCLC group were divided into three subgroups of disease progression group, partial remission group, and disease stability group according to the treatment effect. Comparison of the differences in sPD-L1 expression content between the experimental and control populations. Plasma sPD-L1 levels were dynamically monitored pre- and posttreatment in 90 patients with small-cell lung cancer and were associated with efficacy among subgroups. Meanwhile, the risk factors for patient sPD-L1 expression content were analyzed by logistic regression. Results. Plasma sPD-L1 levels were higher in the SCLC group than in the healthy people group ( $t=7.40$ , $p<0.01$ ). In the disease progression group of the SCLC group, sPD-L1 levels were decreased in the SCLC group, sPD-L1 in some remission group was increased after treatment, and sPD-L1 levels in the disease-stable group ( $p>0.05$ ). Multivariate logistic regression analysis showed that factors promoting increased sPD-L1 expression in SCLC patients included increased smoking, brain metastasis, and ProGRP expression (both $p$ values < 0.05). Conclusion. (1) Higher peripheral sPD-L1 expression in SCLC patients than in healthy patients, and the expression levels were closely related to efficacy. (2) Dynamic changes in s PD-L1 were correlated with clinical efficacy. (3) The progression of sPD-L1 and ProGRP in SCLC patients showed the same extent during remission and stabilization, suggesting the effect of s PD-L1 in the evaluation of SCLC tumors and the reflection of the tumor marker ProGRP.