Synergistic changes in bystander CD8 and conventional CD4 T cells during neoadjuvant chemoimmunotherapy for non-small cell lung cancer reveal treatment response

Objective We analyzed changes in intratumoral CD8 + and CD4 + T-cell subpopulations following neoadjuvant chemoimmunotherapy in non-small cell lung cancer. We then assessed whether these alterations favored better outcomes and explored their association with the tumor microenvironment. Methods Paired pre- and post-treatment samples from 32 patients with non-small cell lung cancer who underwent neoadjuvant chemoimmunotherapy at Shandong Cancer Hospital (January 2021–June 2023) were analyzed retrospectively. A quantitative analysis of tumor cells and their microenvironment was performed using a tissue microarray and a multiplex immunofluorescence technique. The analysis was based on the number of cells per thousand nucleated cells. Patients exhibiting a major pathologic response were classified as responders. The delta parameter (post-treatment minus pre-treatment) was utilized to assess changes in these indicators, and associations with treatment response were identified using the Wilcoxon Signed-Rank test and logistic regression analyses. Results Of the 32 patients, 59.38% were classified as responders. Across all patients, neoadjuvant chemoimmunotherapy significantly reduced the densities of dysfunctional CD8 + resident memory T cells and cytotoxic and dysfunctional CD8 + bystander T cells, while conventional CD4 + T cells increased significantly. Similar trends were observed in the response group. In the non-response group, only cytotoxic CD8 + bystander T cells were reduced in number. Logistic regression analysis revealed that a high delta conventional CD4 + T cells is more favorable for MPR (OR = 0.13, p = 0.038), exhibiting a similar trend to changes in HIF-1α (p = 0.049). Conclusion Alterations in specific CD8 + and CD4 + T-cell subpopulations during neoadjuvant chemoimmunotherapy may favor better outcomes and are potentially associated with tumor hypoxia. These findings provide a new perspective on developing strategies to improve treatment sensitivity in non-small cell lung cancer.