Tumor immune microenvironment analysis of non-small cell lung cancer development through multiplex immunofluorescence

Emerging evidence has underscored the crucial role of infiltrating immune cells in the tumor immune microenvironment (TIME) of non-small cell lung cancer (NSCLC) development and progression. With the implementation of screening programs, the incidence of early-stage NSCLC is rising. However, the high risk of recurrence and poor survival rates associated with this disease necessitate a deeper understanding of the TIME and its relationship with driver alterations. The aim of this study was to provide an in-depth analysis of immune changes in early-stage NSCLC, highlighting the significant transitions in immune response during disease progression.

Tumor tissues were collected from 105 patients with precancerous lesions or stage I-III NSCLC. Next-generation sequencing (NGS) was used to detect cancer driver alterations. Multiplex immunofluorescence (mIF) was performed to evaluate immune cell density, percentage, and spatial proximity to cancer cells in the TIME. Next Among these patients, 64 had NGS results, including three with adenocarcinoma in situ (AIS), 10 with minimally invasive adenocarcinoma (MIA), and 51 with stage I invasive cancers. Additionally, three patients underwent neoadjuvant immuno-chemotherapy and tumor tissue specimens before and after treatment were obtained.

Patients with stage I invasive cancer had significantly higher density (P=0.01) and percentage (P=0.02) of CD8⁺ T cells and higher percentages of M1 macrophages (P=0.04) and immature natural killer (NK) cells (P=0.041) in the tumor parenchyma compared to those with AIS/MIA. Patients with mutated epidermal growth factor receptor (EGFR) gene exhibited decreased NK cell infiltration, increased M2 macrophage infiltration, and decreased aggregation of CD4⁺ T cells near tumor cells compared to EGFR wild-type patients. As NSCLC progressed from stage I to III, CD8⁺ T cell density and proportion increased, while PD-L1⁺ tumor cells were in closer proximity to PD-1⁺CD8⁺ T cells, potentially inhibiting CD8⁺ T cell function. Furthermore, M1 macrophages decreased in density and proportion, and the number of NK cells, macrophages, and B cells around tumor cells decreased. Additionally, patients with tertiary lymphoid structures (TLSs) had significantly higher proportion of M1 macrophages and lymphocytes near tumor cells, whereas those without TLS had PD-L1⁺ tumor cells more densely clustered around PD-1⁺CD8⁺ T cells. Notably, neoadjuvant immuno-chemotherapy induced the development of TLS.

This study offers an in-depth analysis of immune changes in NSCLC, demonstrating that the transition from AIS/MIA to invasive stage I NSCLC leads to immune activation, while the advancement from stage I to stage III cancer results in immune suppression. These findings contribute to our understanding of the molecular mechanisms underlying early-stage NSCLC progression and pave the way for the identification of potential treatment options.