Impact of frequent whole-body CT scans during immune checkpoint inhibitor (ICI) therapy on antitumor immune efficacy

Abstract

Objective:The effect of frequent whole-body CT scanning during immune checkpoint inhibitor (ICI) therapy on the anti-tumor immune effect of ICI. Methods:We conducted a retrospective clinical study and a basic study in a mouse tumor model, respectively. Retrospective clinical study: We retrospectively analyzed the correlation between the frequency of CT scans during immune checkpoint inhibitor (ICI) treatment and the duration of remission (DOR) of ICI treatment in patients with stage IV non-small cell lung cancer (NSCLC). BASIC RESEARCH: We established a mouse lung adenocarcinoma tumor model and administered ICI to mice, which were irradiated with five whole-body CT scans during ICI treatment in order to observe the effect of frequent whole-body CT scans on the anti-tumor effect of ICI treatment in mice. The effects of frequent whole-body CT scans on the tumor microenvironment of mice were also analyzed by single-cell sequencing and multi-assay flow cytometry. Results:The more frequent CT scans during ICI treatment in NSCLC patients the longer the DOR of ICI treatment. In the mouse model we observed that the addition of whole-body CT scan radiation had a tendency to inhibit tumor growth in mice compared with the anti-PD-1 group alone.Frequent CT scan radiation during the application of the immune checkpoint inhibitor PD-1 increased the proportion of infiltrating CD8+ T cells in tumor tissues and significantly increased the proportion of IFNγ-secreting CD8+ T cells, and single-cell sequencing of the results also revealed that IFNγ and killing-related genes were significantly upregulated in tumor-infiltrating CD8T cells. Conclusions:To our knowledge this is the first study worldwide on the effect of multiple CT scan radiation on the anti-tumor immune effect of ICI. Our findings suggest that frequent CT scans during ICI treatment did not promote tumor progression; instead, a trend toward delayed tumor progression was observed.