Objective: In recent years, an association between serum soluble immune checkpoint molecules (sICMs) and malignant tumors has been reported, which may become important biomarkers in the future. Although several reports have suggested a correlation between sICMs and prognosis, their origin is unclear. In this study, changes in serum soluble PD-L1 (sPD-L1) during the perioperative period and its origin were analyzed in patients with lung cancer.Patients and Methods: Patients with lung tumors (n=39) were included. Samples for sPD-L1 measurements were collected at five time points before and after surgery, and their changes over time were analyzed. ELISA was used to measure sPD-L1 levels.Results: Thirty-nine patients with lung tumors (31, males; 8, females; age, 74 (years) ± 7.7 (range: 51–89) years; malignancy/benign, 33/6) were enrolled. Eight cases of driver gene mutation-positive tumors were included. Twenty-eight (72%) patients were smokers, and their performance status was 0-1 in all 39 patients. PD-L1 TPS was ≥50%/1–49%/<1% in 8/10/14 patients. Stage I/II/III/IV/postoperative recurrence of lung cancer was observed in 21/0/6/5/1 patients, respectively. There were no significant correlations between sPD-L1 levels and clinicopathological features and no correlation with PD-L1 TPS. Comparing localized lesions (stages I–III) with advanced lesions (stage IV and postoperative recurrence), the distribution of sPD-L1 was slightly higher in advanced lesions, although the difference was not significant. No obvious changes in sPD-L1 expression were observed before and after surgery.Conclusion: sPD-L1 levels tended to be high in stage III and above lung cancer. There was no change in sPD-L1 levels before and after surgery. sPD-L1 levels did not correlate with the PD-L1 TPS.

Objective: The extended outcomes of the KEYNOTE-024 study demonstrated a favorable 5-year overall survival (OS) rate of 31.9%. The present study investigated the outcomes of pembrolizumab monotherapy for advanced or recurrent non-small cell lung cancer (NSCLC) at our institution.Patient: The long-term outcomes of 102 patients with advanced or recurrent NSCLC treated with pembrolizumab monotherapy between March 2017 and December 2022 were retrospectively assessed.Results: This study included a total of 102 patients [mean age: 72 ± 9.6 years (range: 41–91 years), male/female=77/25; performance status (PS; 0, 1, 2, 3, 4)=49/38/15/0/0; smokers=91 (89%), non-squamous cell carcinoma/squamous cell carcinoma=66/36, PD-L1 tumor proportion score (TPS) ≥50%/1–49%=80/22, positive for EGFR mutation=5, advanced/postoperative recurrence=51/51, treatment line: first/second or later=81/21, treatment courses: median 8 (range: 1–39), objective response rate/disease control rate=44%/55%, immune-related adverse events (irAEs): 47, 5-year OS=34%]. On univariate analysis, PS, PD-L1 TPS, and irAEs were significant prognostic factors. On multivariate analysis, histology, PD-L1 TPS, and irAEs were significant prognostic factors.Conclusion: Pembrolizumab monotherapy demonstrated promising treatment outcomes for advanced or recurrent NSCLC, as evidenced by the significant association of PD-L1 TPS with irAEs and prognosis, suggesting its potential as a beneficial therapeutic option.