Title : Peripheral blood T-cell subset kinetics in non-small cell lung cancer patients during immune checkpoint inhibitor
Abstract:
Introduction: Non-small cell lung cancer (NSCLC) represents the majority of lung cancer cases and remains a leading cause of global cancer mortality despite advances in therapies such as immune checkpoint inhibitors. PD-L1 immunohistochemistry, the most widely used biomarker, showed limited predictive power due to spatial heterogeneity and dynamic regulation. Emerging evidence indicates that the phenotypic and functional states of T cells, both in circulation and within the tumor microenvironment, play a decisive role in determining the therapeutic response and resistance.
Methods: Patients with stage II and IIIA NSCLC, who received anti-PD-1 therapy with chemotherapy in a neoadjuvant setting, were enrolled (n=13). Peripheral blood samples were collected before treatment, after the first treatment cycle, and at week 9 or at disease progression, if applicable. Peripheral blood mononuclear cells (PBMCs) were isolated using density-gradient centrifugation and analyzed by multiparametric flow cytometry with a standardized antibody panel to characterize dynamic T-cell subsets, including proliferative (Ki-67⁺), exhausted (PD-1⁺), and differentiation states (naïve, effector, and memory).
Results: Longitudinal immune profiling of patients treated with chemo-immunotherapy revealed dynamic changes in the peripheral T-cell subsets. The frequency of proliferative PD-1⁺Ki-67⁺CD8⁺ T cells increased markedly at week 3 compared to that at baseline. This early proliferative burst was observed in multiple patients and was particularly enriched in those who achieved a complete or major pathological response. A significant reduction in regulatory T cells was noted from pre-treatment to 9 weeks of therapy. In addition, the cytotoxic activity of T cells increased following treatment, although this increase was not statistically significant.
Conclusion: An early proliferative burst of PD-1+ki-67+CD8+ T cells after 3 weeks of treatment in peripheral blood can be a potential marker of chemo-immunotherapy response in NSCLC.
