Proliferative double-negative T (DNT)-cell responses to PD-1 blockade therapy were positively correlated with good clinical outcomes in non-small cell lung cancer patients.

[OBJECTIVE] To explore the correlation between the frequency of circulating double-negative T cells (DNT) and clinical outcomes of tumor immunotherapy in non-small cell lung cancer (NSCLC) patients.

[METHODOLOGY] We conducted a retrospective, single-center study at Qingdao Central Hospital, China (from October 2020 to February 2023) involving a cohort of patients with advanced-stage NSCLC who received PD-1-targeted therapies. A basal and longitudinal analysis of peripheral DNT cells was performed on this cohort. The frequency and effector phenotypes of circulating DNT cells were examined using flow cytometry . The cytotoxicity of DNTs was assessed using DELFIA EuTDA cell cytotoxicity assay kits.

[RESULTS] Flow cytometry analyses showed a marked reduction in circulating DNTs in patients with late-stage (III/IV) NSCLC compared to those with early-stage (I/II) disease. Interestingly, we observed an increase in Ki-67+ DNT cells in approximately 57% (29/51) of late-stage NSCLC patients following the first cycle of anti-PD-1 treatment, and these proliferating DNT cells exhibited effector-like phenotypes and enhanced cytotoxicity towards the lung adenocarcinoma cell line A549. Notably, 70.27% (26/37) of patients who experienced clinical benefits showed a responsive DNT cell profile within four weeks of starting therapy, but not 82.35% (14/17) of patients who developed disease progression. Strikingly, patients with early proliferative DNT cell responses had a longer overall survival (OS) than non-responders. The frequency of DNTs was positively correlated with a good clinical prognosis in patients receiving anti-PD-1 therapy.

[CONCLUSION] Analysis of pre- and post-treatment DNT cells revealed that a higher DNT cell count was associated with better prognosis. Our findings suggest that peripheral DNT cells may serve as valuable biomarkers for monitoring clinical responses in NSCLC patients undergoing anti-PD-1 therapy.