Background
T cell infiltration in non-small cell lung cancer (NSCLC) is essential for the immunological response to malignant tissue, especially in the era of immune-checkpoint inhibition. To investigate the prognostic impact of CD4+ T helper cells (Th), CD8+ cytotoxic (Tc) and FOXP3+ regulatory T (Treg) cells in NSCLC, we performed this analysis.
Conclusions
High proportion of CD8+ Tc cells correlated with improved prognostic outcome in stage I-III NSCLC. Th cells and Treg cells have implications on outcome with respect to tumor histology and biology.
Methods
By counterstaining of CD4, CD8 and FOXP3 we used immunohistochemistry on tissue microarrays (TMA) to evaluate peritumoral Th cells, Treg cells and Tc cells in n=294 NSCLC patients with pTNM stage I-III disease.
Results
Strong CD4+ infiltration was associated with higher tumor stages and lymphonodal spread. However, strong CD4+ infiltration yielded improved overall survival (OS) (P=0.014) in adenocarcinoma (ADC) and large cell carcinoma (LCC) but not in squamous cell carcinoma (SCC). A CD4/CD8 ratio <1 was associated with high grade NSCLC tumors (P=0.020). High CD8+ T cell infiltration was an independent prognostic factor for OS (P=0.040) and progression-free survival (PFS) (P=0.012) in the entire study collective. The OS benefit of high CD8+ infiltration was especially prominent in PD-L1 negative NSCLC (P=0.001) but not in PD-L1 positive tissue (P=0.335). Moreover, positive FOXP3+ expression in tumor infiltrating lymphocytes was associated with increased OS (P=0.007) and PFS (P=0.014) in SCC but not in ADC and LCC (all P>0.05). Here, prognostic effects were prominent in PD-L1 positive SCC (P=0.023) but not in PD-L1 negative SCC (P=0.236). Conclusions: High proportion of CD8+ Tc cells correlated with improved prognostic outcome in stage I-III NSCLC. Th cells and Treg cells have implications on outcome with respect to tumor histology and biology.