Stem-like CD8 T cells in stage I lung adenocarcinoma as a prognostic biomarker: A preliminary study

Objectives: This study aimed to investigate the presence of stem-like CD8 T (CD8 T SL ) cells in lung adenocarcinoma (LUAD) and explore their relationships with the clinical outcomes. Methods: Multiplex immunofluorescence (mIF) was performed to identify CD8 T SL and antigen-presenting cells (APC) in 76 LUAD patients. Differences in the number of CD8 T SL cells based on tumor stage and the spatial relationships between CD8 T SL cells and APC niches were determined. The optimal cutoff value of CD8 T SL cells for predicting survival in patients with stage I LUAD was calculated. Results: CD8 T SL cells were present in all tumors, and their numbers were significantly higher in stage I patients than in stage III patients ( P = 0.010); CD8 T SL cells located in the APC niches accounted for 69.7% (53/76) of the hotspot fields. The optimal cutoff value for the number of CD8 T SL cells required to predict the overall survival (OS) in patients with stage I LUAD was 2.5 per 10000 μm 2 . The median OS and progression-free survival (PFS) in the high-level group (>2.5) were significantly ( P < 0.001) longer than those in the low-level group (≤2.5). The number of CD8 T SL cells was an independent prognostic factor for stage I LUAD. Patients with more CD8 T SL cells had a lower risk of death and disease progression than those with less CD8 T SL cells. Conclusion: CD8 T SL cells were observed in patients with stages I–III LUAD and might serve as prognostic biomarkers for stage I LUAD.