Abstract Rationale Lung cancer remains one of the leading causes of cancer-related mortality globally, with immunotherapy emerging as a promising treatment strategy. Neutrophils, once considered passive bystanders, are now recognized as pivotal modulators of cancer progression and immune response. This study investigates how immunotherapy, specifically through PD-1/PD-L1 axis blockade, alters neutrophil function in human lung cancer patients. Methods Peripheral blood samples were collected from patients at three time points: before treatment, and after the first and second rounds of immunotherapy. Results Functional assays revealed a significant and sustained increase in neutrophil-mediated cytotoxicity toward tumor cells following treatment. Interestingly, this enhanced cytotoxic response occurred without a parallel increase in reactive oxygen species (ROS) production, suggesting a shift from the common ROS-dependent killing mechanism of neutrophils to alternative, ROS-independent pathways post-treatment. Phenotypic analysis further revealed dynamic changes in neutrophil subsets. There was a transient rise in CD10+ and CXCR4+ expression on normal-density neutrophils (NDNs) after the first treatment, indicating maturation and potential trafficking changes. Simultaneously, a marked decrease in low-density neutrophils (LDNs), which are typically immunosuppressive, was observed, particularly after the initial treatment round. These phenotypic shifts suggest a favorable reprogramming of neutrophil activity in response to immunotherapy. Conclusion Together, these findings highlight immunotherapy’s ability to enhance neutrophil cytotoxicity through non-ROS-dependent mechanisms and remodel neutrophil populations toward an anti-tumor phenotype. This neutrophil reprogramming may serve as a prognostic indicator and could uncover novel therapeutic targets. Further research will explore the underlying mechanisms driving ROS-independent cytotoxicity and their relationship to treatment outcomes. This abstract is funded by: None
Alsharif et al. (2026) studied this question.