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

Impact of frequent whole-body CT scans during immune checkpoint inhibitor (ICI) therapy on antitumor immune efficacy | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Impact of frequent whole-body CT scans during immune checkpoint inhibitor (ICI) therapy on antitumor immune efficacy Jigang Dong, Sha sha, Ying Qi, Chengrui Fu, Baosheng Li This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4431449/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 02 May, 2025 Read the published version in BMC Cancer → Version 1 posted 4 You are reading this latest preprint version 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. whole-body CT scanning radiation immune checkpoint inhibitor NSCLC Tumor immune microenvironment Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Immune checkpoint inhibitors (ICIs) have become an important treatment option for patients with non-small cell lung cancer (NSCLC). Periodic computed tomography (CT) scans are required during ICI therapy to monitor tumor efficacy and assess response to ICI antitumor therapy. Computed tomography (CT) is a medical imaging technique that uses X-rays to provide detailed cross-sectional images of internal structures in the body. During CT scanning, patients are exposed to a certain amount of ionizing radiation, this is because X-rays are themselves a form of ionizing radiation, and the low dose radiation (LDR) induced by CT scanning can have a damaging effect on immune cells, for example, it has been found that lymphocytes are highly sensitive to ionizing radiation, and that exposure to ionizing radiation can lead to DNA damage in lymphocytes in the bloodstream(Kaatsch, Becker et al. 2021, Fardid, Janipour et al. 2023, Schüle, Bunert et al. 2024, Wang, Li et al. 2024). This DNA damage phenomenon is more pronounced in cases undergoing multiple enhanced CT scans(Becker, Kaatsch et al. 2023) (Schüle, Bunert et al. 2024). Since CT scan radiation has a detrimental effect on immune cells, do frequent whole-body CT scans during immune checkpoint inhibitor (ICI) therapy have a detrimental effect on a patient's antitumor immunity? In the field of radiation protection and radiobiology, radiation dose is measured in milligrays (mGy), and the biological effects of radiation have a different dependence on its dose. Low Dose Radiation (LDR) is defined as a radiation dose of less than 100 mGy and is the commonly used radiation level for CT scans. Studies have shown that X-rays of 0.1 Gy or less can also kill some tumor cells, a phenomenon known as hypersensitivity to radiation therapy(Joiner, Marples et al. 2001, Le Reun, Granzotto et al. 2023)In some clinical studies, low-dose radiation in combination with chemotherapy, administered at doses to induce radiation hypersensitivity, has achieved striking rates of tumor control(Regine, Hanna et al. 2007, Balducci, Chiesa et al. 2012, Mantini, Valentini et al. 2012). Therefore, especially in the current era of immunotherapy, the combination of low-dose radiation and immunotherapy may be a new therapeutic approach for patients.Does CT scanning, as a low-dose radiation, also enhance the tumor killing effect if performed frequently with whole-body CT scanning during the application of immune checkpoint inhibitors? In recent years in the field of tumor immunology, it has been found that low-dose radiation can improve the immune microenvironment within tumor tissues and promote tumor clearance by the immune system(Gao and Zhang 2023 ). For example, low-dose radiation therapy has been shown to reduce the proportion of regulatory T cells (Tregs) in the tumor microenvironment by promoting M1-type macrophage polarization(Barsoumian, Ramapriyan et al. 2020), affecting the function and activation of NK and T cells(Khan, Blimkie et al. 2021), and reducing the proportion of regulatory T cells (Tregs) in the tumor microenvironment through multiple mechanisms(Herrera, Ronet et al. 2022) to enhance the immune system(Liao, Chen et al. 2023). Shows potential as an immune amplifier capable of reprogramming the tumor microenvironment, triggering an inflammatory response and sensitizing "cold" tumors to immune checkpoint blockade therapies(Liu, Liao et al. 2023 ) (Benoit, Vogin et al. 2023) (Patel, Hernandez et al. 2021). Studies on whether frequent whole-body CT scans during the application of immune checkpoint inhibitors may have an effect on patients' antitumor immunity have not been reported, and our study is the first of its kind in the world. We conducted a retrospective clinical study aimed at investigating the effect of the interval between CT scans during immune checkpoint inhibitor (ICI) therapy on the duration of remission (DOR) of non-small cell lung cancer (NSCLC) patients. We constructed a hormonal mouse model and administered immune checkpoint inhibitor (ICI) therapy to mice, and radiated five whole-body CT scans to mice during ICI therapy to observe whether frequent whole-body CT scans had an effect on the anti-tumor effect of immunotherapy in mice. Materials and Methods Cell lines The murine lung adenocarcinoma cell line LLC was purchased from Suzhou Haixing Biological Technology Co. (Suzhou, China; Item No: TCM-C742). The cells were cultured in DMEM (HyClone, Logan, UT, USA SH30243.01) supplemented with 10% FBS (Biological Industries, Israel Item No: 04-001-1ACS) and 1% penicillin/streptomycin biosharp BL505A and were incubated at 37°C in 5% CO2. Tumor models Six-week-old female C57BL/6 mice (18 ± 2 g) were purchased from Beijing HFK Bioscience Co., Ltd. (HFK Bioscience, Beijing, China). All mouse experiments were approved by the Animal Care and Use Committee of Shandong First Medical University(Ethical approval number: CUTCM/2021/9/113). Animal husbandry and experimental procedures were carried out after strict adherence to the guidelines of the Animal Care and Use Committee. C57BL/6 mice were injected subcutaneously with 1×10 6 LLC cells in the left hind limb. When the tumor size reached approximately 4 mm in diameter, the mice were randomly divided into 2 groups: anti-PD-1 group, whole body CT scan radiation (WBCTSs) + anti-PD-1 group Treatment When the tumor diameter was approximately 6 mm, mice in each group were treated as follows: anti-PD-1 alone group: anti-PD-1 was injected intraperitoneally with 200ug of anti-mouse PD-1 (CD279) (Bioxcell Catalog #BE0146) every other day for 3 times.wBCTSs + anti-PD-1 group: WBCTSs were performed using a spiral CT scanner (Ingenuity CT, Philips Medical Systems, Eindhoven, The Netherlands) with an operating voltage of 30–250 mA-s at 120 kV and a rotation time of 0.5–0.75 seconds. The mice were subjected to whole-body CT scanning at the parametric dose of abdominal CT scanning every other day for a total of 5 times, and anti-PD-1 was injected intraperitoneally with 200ug 1 day after whole-body CT scanning, every other day for a total of 3 times. The mice were executed by cervical dislocation when the tumors reached 15 mm in diameter. No chemicals were used in this procedure. Flow cytometry analysis(FCA) Tumors were taken from mice and then homogenized for 40 min at 37°C in DMEM medium with 0.2% type IV collagenase, 0.01% hyaluronidase, and 0.002% DNase I (all enzymes were obtained from Solarbio science, Beijing, China). The resulting single-cell suspensions were stained with fixable viability BV510, and then the harvested cells were labeled with the following antibodies: CD45 + FITC, CD3 + APC, CD8 + percpcy5.5, and IFN-γ + APC-Cy7. Antibodies were used according to the manufacturer's protocol (Biolegend, USA). After antibody labeling of the cell surface, cells were treated with the Fixation and Permeabilization Kit (Biolegend, USA) and stained with antibody IFN-γ. Stained samples were analyzed with a BD LSDFortessa flow cytometer. All flow cytometry data were analyzed using FlowJo software (version 10.0). Single-Cell RNA Sequene 10X genomics Single-Cell RNA Sequencing cell capture and cDNA synthesis Tissue collection resuspended witn PBS.cell suspensions were loaded on a Chromium Single Cell Controller (10x Genomics) to generate single-cell gel beads in emulsion (GEMs) by using Single Cell 3‘ Library and Gel Bead Kit V2 (10x Genomics, 120237) and Chromium Single Cell A Chip Kit (10x Genomics ,120236) according to the manufacturer’s protocol. sequencing was performed on an Illumina Novaseq6000 with pair end 150bp (PE150) mode. Statistical Analysis Single cell data preprocess Raw FASTQ files were mapped to the Reference genome (human, mouse et al) using Cell Ranger 6.0(10x Genomics). Mouse reference (mm10) − 2020-A t-SNE visualization and determination of the major cell types Gene expression analysis and cell type identification was analyzed using Seurat V3.0 pipeline ( http://satijalab.org/seurat/ ) after filtering and normalization, (Butler et al., 2018). As the data were already normalized, they were loaded into Seurat without normalization,scaling or centring. Along with the expression data, metadata for each cell was collected, including information such as clone identity, cell cycle phase, and time point. Next, highly variable genes were identified and used as input for dimensionality reduction via principal component analysis (PCA). The resulting PCs and the correlated genes were examined to determine the number of components to include in downstream analysis. t-SNE was then performed on the first 10 principal components to visualize cells in a two-dimensional space. To identify differentially expressed genes in each cluster, the Seurat function FindAllMarkers was used. For a gene to be differentially expressed in a cluster it must be expressed by at least 10% of cells, have a log-fold change greater than 0.25, and reach statistical significance of an adjusted p < 0.05 as determined by the Wilcox test. Finally, cell clusters were annotated to known biological cell types using canonical marker. Pseudotime Analysis Single cell trajectory was analyzed using matrix of cells and gene expressions by Monocle 3. Differentially expressed genes or significantly variable genes among cells were identified and used for dynamic trajectory analysis which ordered cells in pseudotime. First, the expression of transcripts of each gene was determined. Genes were then ranked using the coefficient of variation versus mean metric, selecting the top 3,000 genes as features. The resulting velocity estimates were projected onto the t-SNE embedding obtained in Seurat. Patient Our retrospective clinical study was conducted under the conditions of approval from the Clinical Research Ethics Committee of Qingdao People's Hospital Group (Jiaozhou) and written informed consent from all participants, and all methods were performed in accordance with the relevant guidelines and regulations of the Clinical Research Ethics Committee of Qingdao People's Hospital Group (Jiaozhou). Ethics No.: Jiaozhou Central Hospital Thesis Approval Document (2023) Thesis Review No. (003). Patient data Twenty patients with stage IV NSCLC treated with PD-1/PD-L1 from January 1, 2019 to December 31, 2021 at Shandong Cancer Hospital and 20 patients with stage IV NSCLC treated with PD-1/PD-L1 from January 1, 2019 to December 31, 2021 at Qingdao People's Hospital Group (Jiaozhou) were retrospectively collected. The patient inclusion criteria were as follows all histologically confirmed NSCLC patients were stage IV; they had received treatment with at least one PD-1/PD-L1 monoclonal antibody; and the case data were complete, including baseline data (age, gender, clinical stage, physical condition score, etc.) and treatment data (previous treatment, whether combined with chemotherapy, anti-angiogenic therapy or radiotherapy). Patients were treated in accordance with the guidelines of the Chinese Society of Clinical Oncology, with complete preclinical imaging and hematological indices and follow-up data. The exclusion criteria for patients were as follows small cell lung cancer; severe liver disease; gastrointestinal disease or other diseases that made it difficult to eat normally; cardiovascular accident within 1 month; chronic infection or acute attack of acute infection; use of steroids in the past 3 months; blood transfusion; and incomplete follow-up data. Observations were: duration of remission (DOR, Duration of Response) of ICI therapy: the time between the start of the first assessment of CR or PR and the first assessment of PD (Progressive Disease) or death from any cause in patients with stage IV NSCLC treated with ICI. Frequency of CT review during ICI maintenance therapy in patients with tumors: total number of CT scan reviews within the duration of remission (DOR) of ICI therapy/duration of remission (DOR) of ICI therapy. Statistical analysis According to Pearson correlation analysis, the frequency of CT review and the duration of remission (DOR) of ICI treatment in tumor patients were positively correlated (r = 0.3460, P = 0.0287). Statistical analysis All the statistical analyses were performed using GraphPad Prism 8.0 (GraphPad Software, La Jolla, CA, USA). The results are presented as the mean ± standard error of the mean (SEM). For comparing two groups, an unpaired 2-tailed Student t test was used; We indicated significance corresponding to the following: *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. Results 1. The more frequent CT scans during treatment of lung cancer patients ICI the longer the DOR of ICI treatment The aim of this study was to evaluate the relationship between the frequency of CT scan review during immunocheckpoint inhibitor (ICI) therapy and the effective maintenance time of immunocheckpoint inhibitor (ICI) therapy in patients with non-small cell lung cancer (NSCLC). We conducted a retrospective study of 20 patients with stage IV NSCLC treated with PD-1/PD-L1 at Shandong Cancer Hospital from January 1, 2019, to December 31, 2021, and 20 patients with stage IV NSCLC treated with PD-1/PD-L1 at Qingdao People's Hospital Group (Jiaozhou) from January 1, 2019, to December 31, 2021, in a retrospective Study. The baseline information of the patients is detailed in Table 1. Duration of remission (DOR, Duration of Response) of ICI treatment was defined as the time from the beginning of the first assessment of CR or PR to the first assessment of PD (Progressive Disease) or death from any cause in stage IV NSCLC patients treated with ICI. The frequency of CT review during ICI maintenance therapy in tumor patients was defined as the total number of CT scan reviews within the duration of remission (DOR) of ICI therapy/duration of remission (DOR) of ICI therapy. According to Pearson's correlation analysis, the frequency of CT review and the duration of remission (DOR) of ICI treatment in tumor patients were positively correlated (r = 0.3460, P = 0.0287) (Fig. 1 ). This result suggests that the more frequent the CT scan review during immune checkpoint inhibitor (ICI) therapy, the longer the duration of remission (DOR) of ICI therapy in non-small cell lung cancer (NSCLC) stage IV patients. 2. WBCTSs combined with ICI treatment inhibits tumor progression in mice To deeply analyze the effect of multiple whole-body CT scanning radiation on ICI anti-tumor immunity, we performed in vivo validation in a mouse tumor model. Mice were divided into two groups: anti-PD-1 group, WBCTSs + anti-PD-1 group (n = 7) (Fig. 2 A). anti-PD-1 group: anti-PD-1 alone intraperitoneal injection of 200ug, 1 time every other day for a total of 3 times. WBCTSs + anti-PD-1 group: (WBCTSs) whole-body CT scanning, 1 time every other day for a total of 5 times; anti - PD-1 intraperitoneal injection of 200ug, performed 1 day after whole-body CT scan, 1 time every other day, 3 times in total. We observed a more pronounced trend of tumor growth inhibition in mice in the WBCTSs + anti-PD-1 group compared to the anti-PD-1 group (n = 7), (Fig. 2 B). 3.WBCTSs increased CD8T cell infiltration in tumor tissues of mice We analyzed the tumor tissues of mice 24 hours after irradiation using multicolor flow cytometry. The results revealed that the average proportion of CD8 T cells to CD45 + T lymphocytes within the tumor tissues in the WBCTSs + anti-PD-1 group increased from 1.7–6.5% (n = 4) compared with that in the anti-PD-1 group alone (Fig. 3 A), and the proportion of IFN-γ-secreting CD8 T cells in the WBCTSs + anti-PD-1 group was significantly increased, with the The average proportion increased from 10.27–18.4% (n = 4) (Fig. 3 B). 4. WBCTSs upregulate IFNγ and killing-related genes in tumor-infiltrating CD8T cells In order to better understand the effect of radiation from frequent whole-body CT scans on CD8 + T cells in the whole body and tumor tissues, we performed WBCTSs on mice, 1 in the WBCTSs group and 1 in the NC group, and single-cell sequencing was performed on the tumor tissues and spleens of each mouse, respectively, for a total of 4 samples (Fig. 4 A\C), with a total of 4 samples (Fig. 4 A\C), with a total of 4 samples (Fig. 4 A\C), and the total number of cells measured Estimated Number of Cells 36,685; Fraction Reads in Cells 90.6%; Median Genes per Cell 2,352; Median UMI Counts per Cell 8,661. The CD8T cell population was identified by the characteristic gene of CD8T cells (CD3g CD3e CD3d Cd8a Cd28 Gzmk Ifng Klrg1) (Fig. 4 E), and the focus of our study was to detect the changes of CD8T cells before and after exposure to radiation from whole-body CT scans in tumor tissues and in the spleen. It was found that in the spleen, the percentage of CD3, CD4 and CD8 T cells to CD45 + cells in the spleen decreased after radiation, where the percentage of CD8 T cells to CD45 + cells in the spleen decreased from 6.53% before radiation exposure from whole-body CT scanning to 4.51% after radiation exposure (Fig. 4 D). Further gene expression analysis showed that low-dose irradiation downregulated the expression of IFNγ and killing-related genes (IFNg, KLRD1) in splenic CD8T cells (Fig. 4 F). In tumor tissues, the proportions of CD3T cells, CD4T cells and CD8T cells among CD45 + T lymphocytes were increased after multiple CT scanning radiation, in which the proportion of CD8T cells in tumor tissues as a percentage of CD45 + cells was increased from 4.49% before whole-body CT scanning radiation to 7.15% after radiation (Fig. 4 B); moreover, multiple CT scanning radiation up-regulated tumor expression of IFNγ and killing-related genes (IFNg, KLRD1, Gzmf, Tnfrsf9, Tnfrsf4) in infiltrating CD8T cells (Fig. 4 F),and the signal communication between CD8T cells and other cells was significantly enhanced after radiation (Fig. 4 H), specifically, the afferent signal intensity of CD8T cells was significantly enhanced (Fig. 4 H). We also noted that radiation enhanced functional signaling pathways related to t-cell receptors, cytokines, and antigen presentation in CD8T cells (Fig. 4 I), and also upregulated the PD-L1/PD-L2 signaling pathway (Fig. 4 I). In addition, radiation from multiple CT scans resulted in upregulation of CD8 T cell exhaustion-related genes (including Tox, LAG-3, CTLA-4, and PDCD1) in tumor tissues (Fig. 4 G). Discussion The emergence of immune checkpoint inhibitors (ICIs) has ushered in a new era of cancer treatment, marking the emergence of immunotherapy as a mainstream approach. In this study, we aimed to investigate whether frequent whole-body CT scans during immune checkpoint inhibitor (ICI) treatment had an effect on the antitumor therapeutic efficacy of ICI through a retrospective clinical study and a study in a mouse model, respectively. Our results showed that multiple CT scans during immune checkpoint inhibitor (ICI) treatment did not promote tumor progression; instead, a trend toward delayed tumor progression was observed. Previous studies have shown that low-dose radiation enhances immune activation, thereby increasing the sensitivity of tumor cells to ICI(Yin, Xue et al. 2020, Patel, Hernandez et al. 2021, Herrera, Ronet et al. 2022, Wang, Zhang et al. 2023). The results observed in our study are consistent with the results of these previous similar studies. Our further study in a mouse tumor model revealed that 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 number of IFN-γ-secreting CD8 + T cells. Thus, frequent whole-body CT scanning combined with immunotherapy inhibits tumor growth in mice. Consistent with our findings, Nowosielska et al. reported that whole-body low-dose radiation significantly inhibited LLC cell growth. In addition, the combination therapy of CTLA-4 + PD-1 + LDR showed significant effects both in vivo (lung and subcutaneous tumor growth) and in vitro (clonogenic potential of tumor cells) (Nowosielska, Cheda et al. 2021). Radiation from multiple whole-body CT scans had injurious effects on immune cells in both spleen and tumor tissue(Kaatsch, Becker et al. 2021, Fardid, Janipour et al. 2023, Schüle, Bunert et al. 2024, Wang, Li et al. 2024). We used single-cell sequencing to show that radiation from multiple whole-body CT scans resulted in a decrease in the proportion of CD8 + T cells in the spleen and down-regulation of IFN-γ-related gene expression in splenic CD8 + T cells. However, an increased proportion of CD8 + T cells in tumor tissues upregulated IFNγ and killing-related genes in tumor-infiltrating CD8T cells. These findings are consistent with other studies(Herrera, Ronet et al. 2022, Gao and Zhang 2023 , Wang, Huang et al. 2024). Consistent with this, low-dose radiation improves the immune microenvironment within the tumor tissue and promotes tumor clearance by the immune system. This paradox is explained by the fact that radiation from multiple whole-body CT scans has an injurious effect on immune cells in both spleen and tumor tissues, but tumor cells in tumor tissues are more sensitive to radiation and are able to activate immunity by initiating damage-associated molecular patterns (DAMPs)(De Martino, Daviaud et al. 2021). Radiation-induced DNA damage in tumor cells promotes IFN production and activates immunity(Chabanon, Rouanne et al. 2021) (Zhang, Gao et al. 2021) (Man and Jenkins 2022 ). As a result, immune activation is induced in the tumor tissue, counteracting the immunosuppressive effects of radiation damage on the immune cells However, radiation from multiple whole-body CT scans also upregulated genes associated with CD8 + T cell exhaustion (TOX LAG-3, CTLA-4, PDCD1) in tumor tissue. This highlights the importance of combining low-dose radiation with immune checkpoint inhibitors to restore functional viability of CD8 + T cells. We believe that this mechanism also represents another important aspect of radiation-ICI synergy. The commonly used radiation level for CT scanning is about 0.1 Gy or lower, and our findings suggest that CT scanning, as a low-dose radiation, is enhanced by frequent whole-body CT scanning during the application of immune checkpoint inhibitors to kill tumors. Several previous studies have shown that X-rays of 0.1 Gy or lower can also kill some tumor cells, a phenomenon known as radiotherapy hypersensitivity(Joiner, Marples et al. 2001, Le Reun, Granzotto et al. 2023). In some clinical studies, low-dose radiation in combination with chemotherapy, administered at doses to induce radiation hypersensitivity, has achieved striking rates of tumor control(Regine, Hanna et al. 2007, Balducci, Chiesa et al. 2012, Mantini, Valentini et al. 2012). Therefore, in the current era of immunotherapy, the combination of low-dose radiation and immunotherapy may be a new treatment for patients, which also requires further research at a later stage. Abbreviations LLC:Lewis Lung Carcinoma ICI：immunocheckpoint inhibitor NSCLCnon-small cell lung cancer . WBCTSs：whole body CT scan radiation DOR：duration of remission LDR：Low Dose Radiation FCA：Flow cytometry analysis Declarations Ethical Statement All mouse experiments in this study were approved by the Animal Care and Use Committee of Shandong First Medical University (Ethical Approval No. CUTCM/2021/9/113).All animal housing premises and conditions, animal care and monitoring details and experimental conditions were in accordance with ARRIVE guidelines. Consent for publication Not applicable. Availability of data and materials The data that support the findings of this study are available from the First authors or corresponding author, [Jigang Dong and Baosheng Li], upon reasonable request. Conflict of interest The authors declare no potential conflict of interest. Funding This study was supported by a special fund for the Key Laboratory of the Affiliated Tumor Hospital of the First Medical University of Shandong, China, and by a grant from the Qingdao Key Discipline Fund Contributions DJG (First Author):Conceptualization, Methodology, Software, Investigation, Formal Analysis, Writing - Original Draft;SS: Data Curation, Writing - Original Draft;QY: Visualization, Investigation;FCR:Software, ValidationLBS(Corresponding Author):Funding Acquisition, Resources, Supervision, Acknowledgments: We express our gratitude to the Key Laboratory of Radiation Oncology in Shandong Province for providing the research platform, which includes Molecular Biology Laboratory, Cell Biology Laboratory, Small Animal Radiation Research Platform, Flow Cytometry in the Animal Experiment Center. We also appreciate all the laboratory members for their valuable discussions and technical support. This work was funded by the Academic Enhancement Program of Shandong First Medical University (2019LJ004) and supported by the National Natural Science Foundation of China (U23A20461). Author information Jigang Dong 12 ,Sha sha 2 Ying qi 2 Chengrui Fu 13 , Baosheng Li 4 *, 1.Tianjin Medical University Cancer Institute & Hospital,National Clinical Research Center for Cancer, Tianjin’s Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy,Tianjin,300000 , China 2.Qingdao People's Hospital Group (Jiaozhou), Jiaozhou Central Hospital of Qingdao. China, [email protected] 3. Department of Radiotherapy.Shandong Cancer Hospital, Jinan,250000. China. 4*. Corresponding author: Baosheng Li, Department of Radiotherapy,Shandong Cancer Hospital, Jinan, China , [email protected] References Balducci M, et al. Low-dose fractionated radiotherapy and concomitant chemotherapy in glioblastoma multiforme with poor prognosis: a feasibility study. Neurooncology. 2012;14(1):79–86. Barsoumian HB et al. (2020). Low-dose radiation treatment enhances systemic antitumor immune responses by overcoming the inhibitory stroma. J Immunother Cancer 8(2). Becker BV, et al. Initial experience on abdominal photon-counting computed tomography in clinical routine: general image quality and dose exposure. Eur Radiol. 2023;33(4):2461–8. Benoit A, et al. Lighting up the fire in the microenvironment of cold tumors: A major challenge to improve cancer immunotherapy. Cells. 2023;12(13):1787. Chabanon RM, et al. Targeting the DNA damage response in immuno-oncology: developments and opportunities. Nat Rev Cancer. 2021;21(11):701–17. De Martino M, et al. Radiotherapy: An immune response modifier for immuno-oncology. Seminars in Immunology, Elsevier; 2021. Fardid R, et al. Evaluation of the relationship between γ-H2AX biomarker levels and dose received after radiation exposure in abdominal–pelvic and chest CT scans. Journal of Cancer Research and Therapeutics; 2023. Gao L, Zhang A. Low-dose radiotherapy effects the progression of anti-tumor response. Translational Oncol. 2023;35:101710. Herrera FG, et al. Low-dose radiotherapy reverses tumor immune desertification and resistance to immunotherapy. Cancer Discov. 2022;12(1):108–33. Joiner MC, et al. Low-dose hypersensitivity: current status and possible mechanisms. Int J Radiation Oncology* Biology* Phys. 2001;49(2):379–89. Kaatsch HL, et al. Gene expression changes and DNA damage after ex vivo exposure of peripheral blood cells to various CT photon spectra. Sci Rep. 2021;11(1):12060. Khan AUH, et al. Effects of chronic low-dose internal radiation on immune-stimulatory responses in mice. Int J Mol Sci. 2021;22(14):7303. Le Reun E, et al. Influence of the hypersensitivity to low dose phenomenon on the tumor response to hypofractionated stereotactic body radiation therapy. Cancers. 2023;15(15):3979. Liao Y, et al. Low-dose total body irradiation enhances systemic anti-tumor immunity induced by local cryotherapy. J Cancer Res Clin Oncol. 2023;149(12):10053–63. Liu S, et al. Effect of triple therapy with low-dose total body irradiation and hypo-fractionated radiation plus anti-programmed cell death protein 1 blockade on abscopal antitumor immune responses in breast cancer. Int Immunopharmacol. 2023;117:110026. Man SM, Jenkins BJ. Context-dependent functions of pattern recognition receptors in cancer. Nat Rev Cancer. 2022;22(7):397–413. Mantini G, et al. Low-dose radiotherapy as a chemo-potentiator of a chemotherapy regimen with pemetrexed for recurrent non-small-cell lung cancer: a prospective phase II study. Radiother Oncol. 2012;105(2):161–6. Nowosielska EM, et al. Effects of a unique combination of the whole-body low dose radiotherapy with inactivation of two immune checkpoints and/or a heat shock protein on the transplantable lung cancer in mice. Int J Mol Sci. 2021;22(12):6309. Patel RB, et al. Low-dose targeted radionuclide therapy renders immunologically cold tumors responsive to immune checkpoint blockade. Sci Transl Med. 2021;13(602):eabb3631. Regine WF, et al. Low-dose radiotherapy as a chemopotentiator of gemcitabine in tumors of the pancreas or small bowel: a phase I study exploring a new treatment paradigm. Int J Radiation Oncology* Biology* Phys. 2007;68(1):172–7. Tables (Table 1 ) characteristics of patients with stage IV NSCLC Characteristics Total(n = 40) Age (years) Range （54-79） ＞65 19 ≤65 21 Gender Male 34 Female 6 Histological Adenocarcinoma 23 Squamous 17 Clinical stage IV 40 ECOG PS 0-1 35 ≥2 5 Lines of ICIs First line 13 ≥Second line 27 With / Without chemotherapy Yes 10 No 30 With / Without radiotherapy Yes 0 No 40 With / Without AntiAngiogenesis therapy Yes 6 No 34 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 02 May, 2025 Read the published version in BMC Cancer → Version 1 posted Editorial decision: Revision requested 26 May, 2024 Editor assigned by journal 26 May, 2024 Submission checks completed at journal 22 May, 2024 First submitted to journal 16 May, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4431449","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":307024851,"identity":"ce7270bb-8137-4d96-b073-68c39b0d8d33","order_by":0,"name":"Jigang Dong","email":"","orcid":"","institution":"Tianjin Medical University Cancer Institute and Hospital","correspondingAuthor":false,"prefix":"","firstName":"Jigang","middleName":"","lastName":"Dong","suffix":""},{"id":307024852,"identity":"4b0c17d2-489e-4d3d-8f04-30a63c26b259","order_by":1,"name":"Sha sha","email":"","orcid":"","institution":"Qingdao People's Hospital Group (Jiaozhou), Jiaozhou Central Hospital of Qingdao","correspondingAuthor":false,"prefix":"","firstName":"Sha","middleName":"","lastName":"sha","suffix":""},{"id":307024853,"identity":"b7db6c01-66f2-4a81-91f8-c409f08646ab","order_by":2,"name":"Ying Qi","email":"","orcid":"","institution":"Shandong Tumor Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ying","middleName":"","lastName":"Qi","suffix":""},{"id":307024854,"identity":"9f6fbd1b-a295-4996-b019-25f5d1457b4c","order_by":3,"name":"Chengrui Fu","email":"","orcid":"","institution":"Shandong Tumor Hospital","correspondingAuthor":false,"prefix":"","firstName":"Chengrui","middleName":"","lastName":"Fu","suffix":""},{"id":307024855,"identity":"f79522b1-bbb7-44b1-b7cc-190fef7f9a7f","order_by":4,"name":"Baosheng Li","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3ElEQVRIiWNgGAWjYBACAyBmZiiQ4OFnbz74IKHChlgtBhIykj3Hkg0enEkjWguDjcENHzPJh22HCGsxZz98+HOBgQWPwQ0Gs4oEtgMM/O3dCXi1WPakpUnPMJDgkbzdkHYjgecOg8SZsxvwO+xAjhkzD1AL350Dx24kSDwD+iuXgJbzb4w/g7Qw3EhsK0gwOEyElhs5BtIgLQI3ktkYEhKI0GI541kaWAswkJklEg6k8RD0izl/8uHPPBV19vzs/R8//vxnI8ff3otfCwbgIU35KBgFo2AUjAKsAABEuUcrXosWAgAAAABJRU5ErkJggg==","orcid":"","institution":"Shandong Tumor Hospital","correspondingAuthor":true,"prefix":"","firstName":"Baosheng","middleName":"","lastName":"Li","suffix":""}],"badges":[],"createdAt":"2024-05-16 13:42:28","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4431449/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4431449/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12885-025-14119-7","type":"published","date":"2025-05-02T15:57:37+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":57941766,"identity":"0552345d-ed2f-4ae9-95e5-b089e096f3f0","added_by":"auto","created_at":"2024-06-07 18:58:59","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":20108,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe more frequent CT scans during treatment of lung cancer patients ICI the longer the DOR of ICI treatment\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe performed a Pearson correlation analysis between the frequency of CT review and the duration of remission (DOR) of ICI treatment in 40 tumor patients, and found that the frequency of CT review was positively correlated with the DOR (r=0.3460, P=0.0287).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4431449/v1/2f4e0ce59aaf04be4d3a5ed1.png"},{"id":57941765,"identity":"2f0f11da-9414-4390-85c4-4b26e0dc4a33","added_by":"auto","created_at":"2024-06-07 18:58:59","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":129215,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eWBCTSs combined with ICI treatment inhibits tumor progression in mice\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA: \u003c/strong\u003eIn order to deeply analyze the effect of multiple whole-body CT scan radiation on ICI anti-tumor immunity, we performed in vivo validation in model mice. LLC was implanted into the tumor mouse model, which was divided into two groups: anti-PD-1 group and whole-body CT scan radiation group (WBCTSs)+anti-PD-1 group (n=7). anti-PD-1 group: anti-PD-1 alone intraperitoneally injected with 200ug, once every other day, for a total of 3 times. WBCTSs+anti-PD-1 group: (WBCTSs) whole-body CT scan, once every other day , a total of 5 times; anti-PD-1 intraperitoneal injection of 200ug, performed 1 day after whole body CT scan, 1 time every other day, a total of 3 times.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB: \u003c/strong\u003eWe observed a more pronounced trend of tumor growth inhibition in mice in the WBCTSs+anti-PD-1 group compared to the anti-PD-1 group (n=7).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4431449/v1/c59f22489a67799f6aa70a83.png"},{"id":57941768,"identity":"a10651ff-507f-4d02-a654-ae95245f0b55","added_by":"auto","created_at":"2024-06-07 18:58:59","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1113668,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eWBCTSs increased CD8T cell infiltration in tumor tissues of mice\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA:\u003c/strong\u003e We analyzed the tumor tissues of mice 24 hours after irradiation using multicolor flow cytometry, and the average proportion of CD8 T cells to CD45+ T lymphocytes within the tumor tissues of the WBCTSs+anti-PD-1 group increased from 1.7% to 6.5% compared with that of the anti-PD-1 group alone (n=4).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB: \u003c/strong\u003eWe analyzed the tumor tissues of mice 24 hours after irradiation using multicolor flow cytometry, and the proportion of IFN-γ-secreting CD8 T cells was significantly increased in the WBCTSs+anti-PD-1 group compared with the anti-PD-1 group alone, with the average proportion rising from 10.27% to 18.4% (n=4).\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4431449/v1/c2022dd90db4ee31c49fa05b.png"},{"id":57941769,"identity":"7b55020f-a1fc-4f01-9fa1-b904ec3c4ef3","added_by":"auto","created_at":"2024-06-07 18:58:59","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":849843,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eWBCTSs upregulate IFNγ and killing-related genes in tumor-infiltrating CD8T cells.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA/C:\u003c/strong\u003eWe selected 1 mouse from each of the WBCTSs group and NC group, and took mouse tumor tissue and spleen for single-cell sequencing analysis, respectively. A total of 4 samples were collected from each mouse for sequencing of mouse tumor tissue and spleen, respectively. The total number of cells measured was estimated to be 36,685.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB:\u003c/strong\u003e CD3T cells, CD4T cells, and CD8T cells as a percentage of CD45+ T lymphocytes were increased in tumor tissues after WBCTS.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eD: \u003c/strong\u003eAfter WBCTSs, there was a significant decrease in the proportion of CD3, CD4 and CD8 T cells to CD45+ cells and a significant increase in the proportion of CD45+ T lymphocytes to CD45+ cells in the spleen.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eE:\u003c/strong\u003e CD8T cell population identified by CD8T cell signature gene (CD3g CD3e CD3d Cd8a Cd28 Gzmk Ifng Klrg1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eF: \u003c/strong\u003eIn tumor tissues, WBCTSs upregulated the expression of IFN-γand killing-related genes (IFNg, KLRD1, Gzmf, Tnfrsf9, Tnfrsf4) in tumor-infiltrating CD8T cells. While in spleen WBCTSs downregulated (IFNg, KLRD1) genes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eG: \u003c/strong\u003eRadiation from multiple CT scans resulted in up-regulation of CD8 T cell exhaustion-related genes (including Tox, LAG-3, CTLA-4 and PDCD1) in tumor tissues.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eH: \u003c/strong\u003eThe afferent signal intensity of CD8 T cells was significantly enhanced after WBCTS in tumor tissues.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eI:\u003c/strong\u003e WBCTS in tumor tissues enhanced functional signaling pathways related to t-cell receptors, cytokines and antigen presentation in CD8T cells, and also up-regulated the PD-L1/PD-L2 signaling pathway\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4431449/v1/11de280dc924339da0bc6499.png"},{"id":81987750,"identity":"937ff42b-c3b4-4d90-a265-f9b4c33887ca","added_by":"auto","created_at":"2025-05-05 16:05:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3124054,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4431449/v1/946d01f8-4017-4407-a725-88efd14945e6.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Impact of frequent whole-body CT scans during immune checkpoint inhibitor (ICI) therapy on antitumor immune efficacy","fulltext":[{"header":"Introduction","content":"\u003cp\u003eImmune checkpoint inhibitors (ICIs) have become an important treatment option for patients with non-small cell lung cancer (NSCLC). Periodic computed tomography (CT) scans are required during ICI therapy to monitor tumor efficacy and assess response to ICI antitumor therapy. Computed tomography (CT) is a medical imaging technique that uses X-rays to provide detailed cross-sectional images of internal structures in the body. During CT scanning, patients are exposed to a certain amount of ionizing radiation, this is because X-rays are themselves a form of ionizing radiation, and the low dose radiation (LDR) induced by CT scanning can have a damaging effect on immune cells, for example, it has been found that lymphocytes are highly sensitive to ionizing radiation, and that exposure to ionizing radiation can lead to DNA damage in lymphocytes in the bloodstream(Kaatsch, Becker et al. 2021, Fardid, Janipour et al. 2023, Sch\u0026uuml;le, Bunert et al. 2024, Wang, Li et al. 2024). This DNA damage phenomenon is more pronounced in cases undergoing multiple enhanced CT scans(Becker, Kaatsch et al. 2023) (Sch\u0026uuml;le, Bunert et al. 2024). Since CT scan radiation has a detrimental effect on immune cells, do frequent whole-body CT scans during immune checkpoint inhibitor (ICI) therapy have a detrimental effect on a patient's antitumor immunity?\u003c/p\u003e \u003cp\u003eIn the field of radiation protection and radiobiology, radiation dose is measured in milligrays (mGy), and the biological effects of radiation have a different dependence on its dose. Low Dose Radiation (LDR) is defined as a radiation dose of less than 100 mGy and is the commonly used radiation level for CT scans. Studies have shown that X-rays of 0.1 Gy or less can also kill some tumor cells, a phenomenon known as hypersensitivity to radiation therapy(Joiner, Marples et al. 2001, Le Reun, Granzotto et al. 2023)In some clinical studies, low-dose radiation in combination with chemotherapy, administered at doses to induce radiation hypersensitivity, has achieved striking rates of tumor control(Regine, Hanna et al. 2007, Balducci, Chiesa et al. 2012, Mantini, Valentini et al. 2012). Therefore, especially in the current era of immunotherapy, the combination of low-dose radiation and immunotherapy may be a new therapeutic approach for patients.Does CT scanning, as a low-dose radiation, also enhance the tumor killing effect if performed frequently with whole-body CT scanning during the application of immune checkpoint inhibitors?\u003c/p\u003e \u003cp\u003eIn recent years in the field of tumor immunology, it has been found that low-dose radiation can improve the immune microenvironment within tumor tissues and promote tumor clearance by the immune system(Gao and Zhang \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). For example, low-dose radiation therapy has been shown to reduce the proportion of regulatory T cells (Tregs) in the tumor microenvironment by promoting M1-type macrophage polarization(Barsoumian, Ramapriyan et al. 2020), affecting the function and activation of NK and T cells(Khan, Blimkie et al. 2021), and reducing the proportion of regulatory T cells (Tregs) in the tumor microenvironment through multiple mechanisms(Herrera, Ronet et al. 2022) to enhance the immune system(Liao, Chen et al. 2023). Shows potential as an immune amplifier capable of reprogramming the tumor microenvironment, triggering an inflammatory response and sensitizing \"cold\" tumors to immune checkpoint blockade therapies(Liu, Liao et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) (Benoit, Vogin et al. 2023) (Patel, Hernandez et al. 2021).\u003c/p\u003e \u003cp\u003eStudies on whether frequent whole-body CT scans during the application of immune checkpoint inhibitors may have an effect on patients' antitumor immunity have not been reported, and our study is the first of its kind in the world.\u003c/p\u003e \u003cp\u003eWe conducted a retrospective clinical study aimed at investigating the effect of the interval between CT scans during immune checkpoint inhibitor (ICI) therapy on the duration of remission (DOR) of non-small cell lung cancer (NSCLC) patients.\u003c/p\u003e \u003cp\u003eWe constructed a hormonal mouse model and administered immune checkpoint inhibitor (ICI) therapy to mice, and radiated five whole-body CT scans to mice during ICI therapy to observe whether frequent whole-body CT scans had an effect on the anti-tumor effect of immunotherapy in mice.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eCell lines\u003c/h2\u003e \u003cp\u003eThe murine lung adenocarcinoma cell line LLC was purchased from Suzhou Haixing Biological Technology Co. (Suzhou, China; Item No: TCM-C742). The cells were cultured in DMEM (HyClone, Logan, UT, USA SH30243.01) supplemented with 10% FBS (Biological Industries, Israel Item No: 04-001-1ACS) and 1% penicillin/streptomycin biosharp BL505A and were incubated at 37\u0026deg;C in 5% CO2.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eTumor models\u003c/h2\u003e \u003cp\u003eSix-week-old female C57BL/6 mice (18\u0026thinsp;\u0026plusmn;\u0026thinsp;2 g) were purchased from Beijing HFK Bioscience Co., Ltd. (HFK Bioscience, Beijing, China). All mouse experiments were approved by the Animal Care and Use Committee of Shandong First Medical University(Ethical approval number: CUTCM/2021/9/113). Animal husbandry and experimental procedures were carried out after strict adherence to the guidelines of the Animal Care and Use Committee.\u003c/p\u003e \u003cp\u003eC57BL/6 mice were injected subcutaneously with 1\u0026times;10\u003csup\u003e6\u003c/sup\u003e LLC cells in the left hind limb. When the tumor size reached approximately 4 mm in diameter, the mice were randomly divided into 2 groups: anti-PD-1 group, whole body CT scan radiation (WBCTSs)\u0026thinsp;+\u0026thinsp;anti-PD-1 group\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eTreatment\u003c/h2\u003e \u003cp\u003eWhen the tumor diameter was approximately 6 mm, mice in each group were treated as follows: anti-PD-1 alone group: anti-PD-1 was injected intraperitoneally with 200ug of anti-mouse PD-1 (CD279) (Bioxcell Catalog #BE0146) every other day for 3 times.wBCTSs\u0026thinsp;+\u0026thinsp;anti-PD-1 group: WBCTSs were performed using a spiral CT scanner (Ingenuity CT, Philips Medical Systems, Eindhoven, The Netherlands) with an operating voltage of 30\u0026ndash;250 mA-s at 120 kV and a rotation time of 0.5\u0026ndash;0.75 seconds. The mice were subjected to whole-body CT scanning at the parametric dose of abdominal CT scanning every other day for a total of 5 times, and anti-PD-1 was injected intraperitoneally with 200ug 1 day after whole-body CT scanning, every other day for a total of 3 times.\u003c/p\u003e \u003cp\u003eThe mice were executed by cervical dislocation when the tumors reached 15 mm in diameter. No chemicals were used in this procedure.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eFlow cytometry analysis(FCA)\u003c/h2\u003e \u003cp\u003eTumors were taken from mice and then homogenized for 40 min at 37\u0026deg;C in DMEM medium with 0.2% type IV collagenase, 0.01% hyaluronidase, and 0.002% DNase I (all enzymes were obtained from Solarbio science, Beijing, China). The resulting single-cell suspensions were stained with fixable viability BV510, and then the harvested cells were labeled with the following antibodies: CD45\u0026thinsp;+\u0026thinsp;FITC, CD3\u0026thinsp;+\u0026thinsp;APC, CD8\u0026thinsp;+\u0026thinsp;percpcy5.5, and IFN-γ\u0026thinsp;+\u0026thinsp;APC-Cy7. Antibodies were used according to the manufacturer's protocol (Biolegend, USA). After antibody labeling of the cell surface, cells were treated with the Fixation and Permeabilization Kit (Biolegend, USA) and stained with antibody IFN-γ. Stained samples were analyzed with a BD LSDFortessa flow cytometer. All flow cytometry data were analyzed using FlowJo software (version 10.0).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eSingle-Cell RNA Sequene\u003c/h2\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e10X genomics Single-Cell RNA Sequencing\u003c/h2\u003e \u003cdiv id=\"Sec9\" class=\"Section4\"\u003e \u003ch2\u003ecell capture and cDNA synthesis\u003c/h2\u003e \u003cp\u003e \u003cb\u003eTissue collection\u003c/b\u003e resuspended witn PBS.cell suspensions were loaded on a Chromium Single Cell Controller (10x Genomics) to generate single-cell gel beads in emulsion (GEMs) by using Single Cell 3\u0026lsquo; Library and Gel Bead Kit V2 (10x Genomics, 120237) and Chromium Single Cell A Chip Kit (10x Genomics ,120236) according to the manufacturer\u0026rsquo;s protocol. sequencing was performed on an Illumina Novaseq6000 with pair end 150bp (PE150) mode.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003eSingle cell data preprocess\u003c/h2\u003e \u003cp\u003eRaw FASTQ files were mapped to the Reference genome (human, mouse et al)\u003c/p\u003e \u003cp\u003eusing Cell Ranger 6.0(10x Genomics). Mouse reference (mm10) \u0026minus;\u0026thinsp;2020-A t-SNE visualization and determination of the major cell types Gene expression analysis and cell type identification was analyzed using Seurat V3.0 pipeline (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://satijalab.org/seurat/\u003c/span\u003e\u003cspan address=\"http://satijalab.org/seurat/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e) after filtering and normalization, (Butler et al., 2018). As the data were already normalized, they were loaded into Seurat without normalization,scaling or centring. Along with the expression data, metadata for each cell was collected, including information such as clone identity, cell cycle phase, and time point. Next, highly variable genes were identified and used as input for dimensionality reduction via principal component analysis (PCA). The resulting PCs and the correlated genes were examined to determine the number of components to include in downstream analysis. t-SNE was then performed on the first 10 principal components to visualize cells in a two-dimensional space. To identify differentially expressed genes in each cluster, the Seurat function FindAllMarkers was used. For a gene to be differentially expressed in a cluster it must be expressed by at least 10% of cells, have a log-fold change greater than 0.25, and reach statistical significance of an adjusted p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 as determined by the Wilcox test. Finally, cell clusters were annotated to known biological cell types using canonical marker.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003ePseudotime Analysis\u003c/h2\u003e \u003cp\u003eSingle cell trajectory was analyzed using matrix of cells and gene expressions by\u003c/p\u003e \u003cp\u003eMonocle 3. Differentially expressed genes or significantly variable genes among cells were identified and used for dynamic trajectory analysis which ordered cells in\u003c/p\u003e \u003cp\u003epseudotime. First, the expression of transcripts of each gene was determined. Genes\u003c/p\u003e \u003cp\u003ewere then ranked using the coefficient of variation versus mean metric, selecting the\u003c/p\u003e \u003cp\u003etop 3,000 genes as features. The resulting velocity estimates were projected onto the\u003c/p\u003e \u003cp\u003et-SNE embedding obtained in Seurat.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003ePatient\u003c/h2\u003e \u003cp\u003eOur retrospective clinical study was conducted under the conditions of approval from the Clinical Research Ethics Committee of Qingdao People's Hospital Group (Jiaozhou) and written informed consent from all participants, and all methods were performed in accordance with the relevant guidelines and regulations of the Clinical Research Ethics Committee of Qingdao People's Hospital Group (Jiaozhou). Ethics No.: Jiaozhou Central Hospital Thesis Approval Document (2023) Thesis Review No. (003).\u003c/p\u003e \u003cp\u003e \u003cstrong\u003ePatient data\u003c/strong\u003e \u003cp\u003eTwenty patients with stage IV NSCLC treated with PD-1/PD-L1 from January 1, 2019 to December 31, 2021 at Shandong Cancer Hospital and 20 patients with stage IV NSCLC treated with PD-1/PD-L1 from January 1, 2019 to December 31, 2021 at Qingdao People's Hospital Group (Jiaozhou) were retrospectively collected.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eThe patient inclusion criteria were as follows\u003c/strong\u003e \u003cp\u003eall histologically confirmed NSCLC patients were stage IV; they had received treatment with at least one PD-1/PD-L1 monoclonal antibody; and the case data were complete, including baseline data (age, gender, clinical stage, physical condition score, etc.) and treatment data (previous treatment, whether combined with chemotherapy, anti-angiogenic therapy or radiotherapy). Patients were treated in accordance with the guidelines of the Chinese Society of Clinical Oncology, with complete preclinical imaging and hematological indices and follow-up data.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eThe exclusion criteria for patients were as follows\u003c/strong\u003e \u003cp\u003esmall cell lung cancer; severe liver disease; gastrointestinal disease or other diseases that made it difficult to eat normally; cardiovascular accident within 1 month; chronic infection or acute attack of acute infection; use of steroids in the past 3 months; blood transfusion; and incomplete follow-up data.\u003c/p\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eObservations were:\u003c/h2\u003e \u003cp\u003eduration of remission (DOR, Duration of Response) of ICI therapy: the time between the start of the first assessment of CR or PR and the first assessment of PD (Progressive Disease) or death from any cause in patients with stage IV NSCLC treated with ICI.\u003c/p\u003e \u003cp\u003eFrequency of CT review during ICI maintenance therapy in patients with tumors: total number of CT scan reviews within the duration of remission (DOR) of ICI therapy/duration of remission (DOR) of ICI therapy.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eStatistical analysis\u003c/strong\u003e \u003cp\u003eAccording to Pearson correlation analysis, the frequency of CT review and the duration of remission (DOR) of ICI treatment in tumor patients were positively correlated (r\u0026thinsp;=\u0026thinsp;0.3460, P\u0026thinsp;=\u0026thinsp;0.0287).\u003c/p\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eAll the statistical analyses were performed using GraphPad Prism 8.0 (GraphPad Software, La Jolla, CA, USA). The results are presented as the mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard error of the mean (SEM). For comparing two groups, an unpaired 2-tailed Student t test was used; We indicated significance corresponding to the following: *P\u0026thinsp;\u0026lt;\u0026thinsp;0.05; **P\u0026thinsp;\u0026lt;\u0026thinsp;0.01; ***P\u0026thinsp;\u0026lt;\u0026thinsp;0.001; ****P\u0026thinsp;\u0026lt;\u0026thinsp;0.0001.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e \u003cb\u003e1. The more frequent CT scans during treatment of lung cancer patients ICI the longer the DOR of ICI treatment\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe aim of this study was to evaluate the relationship between the frequency of CT scan review during immunocheckpoint inhibitor (ICI) therapy and the effective maintenance time of immunocheckpoint inhibitor (ICI) therapy in patients with non-small cell lung cancer (NSCLC). We conducted a retrospective study of 20 patients with stage IV NSCLC treated with PD-1/PD-L1 at Shandong Cancer Hospital from January 1, 2019, to December 31, 2021, and 20 patients with stage IV NSCLC treated with PD-1/PD-L1 at Qingdao People's Hospital Group (Jiaozhou) from January 1, 2019, to December 31, 2021, in a retrospective Study. The baseline information of the patients is detailed in Table\u0026nbsp;1.\u003c/p\u003e \u003cp\u003eDuration of remission (DOR, Duration of Response) of ICI treatment was defined as the time from the beginning of the first assessment of CR or PR to the first assessment of PD (Progressive Disease) or death from any cause in stage IV NSCLC patients treated with ICI.\u003c/p\u003e \u003cp\u003eThe frequency of CT review during ICI maintenance therapy in tumor patients was defined as the total number of CT scan reviews within the duration of remission (DOR) of ICI therapy/duration of remission (DOR) of ICI therapy.\u003c/p\u003e \u003cp\u003eAccording to Pearson's correlation analysis, the frequency of CT review and the duration of remission (DOR) of ICI treatment in tumor patients were positively correlated (r\u0026thinsp;=\u0026thinsp;0.3460, P\u0026thinsp;=\u0026thinsp;0.0287) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). This result suggests that the more frequent the CT scan review during immune checkpoint inhibitor (ICI) therapy, the longer the duration of remission (DOR) of ICI therapy in non-small cell lung cancer (NSCLC) stage IV patients.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e2. WBCTSs combined with ICI treatment inhibits tumor progression in mice\u003c/h2\u003e \u003cp\u003eTo deeply analyze the effect of multiple whole-body CT scanning radiation on ICI anti-tumor immunity, we performed in vivo validation in a mouse tumor model. Mice were divided into two groups: anti-PD-1 group, WBCTSs\u0026thinsp;+\u0026thinsp;anti-PD-1 group (n\u0026thinsp;=\u0026thinsp;7) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e2\u003c/span\u003eA). anti-PD-1 group: anti-PD-1 alone intraperitoneal injection of 200ug, 1 time every other day for a total of 3 times. WBCTSs\u0026thinsp;+\u0026thinsp;anti-PD-1 group: (WBCTSs) whole-body CT scanning, 1 time every other day for a total of 5 times; anti - PD-1 intraperitoneal injection of 200ug, performed 1 day after whole-body CT scan, 1 time every other day, 3 times in total.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWe observed a more pronounced trend of tumor growth inhibition in mice in the WBCTSs\u0026thinsp;+\u0026thinsp;anti-PD-1 group compared to the anti-PD-1 group (n\u0026thinsp;=\u0026thinsp;7), (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e2\u003c/span\u003eB).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003e3.WBCTSs increased CD8T cell infiltration in tumor tissues of mice\u003c/h2\u003e \u003cp\u003eWe analyzed the tumor tissues of mice 24 hours after irradiation using multicolor flow cytometry. The results revealed that the average proportion of CD8 T cells to CD45\u0026thinsp;+\u0026thinsp;T lymphocytes within the tumor tissues in the WBCTSs\u0026thinsp;+\u0026thinsp;anti-PD-1 group increased from 1.7\u0026ndash;6.5% (n\u0026thinsp;=\u0026thinsp;4) compared with that in the anti-PD-1 group alone (Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e3\u003c/span\u003eA), and the proportion of IFN-γ-secreting CD8 T cells in the WBCTSs\u0026thinsp;+\u0026thinsp;anti-PD-1 group was significantly increased, with the The average proportion increased from 10.27\u0026ndash;18.4% (n\u0026thinsp;=\u0026thinsp;4) (Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e3\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003e4. WBCTSs upregulate IFNγ and killing-related genes in tumor-infiltrating CD8T cells\u003c/h2\u003e \u003cp\u003eIn order to better understand the effect of radiation from frequent whole-body CT scans on CD8\u0026thinsp;+\u0026thinsp;T cells in the whole body and tumor tissues, we performed WBCTSs on mice, 1 in the WBCTSs group and 1 in the NC group, and single-cell sequencing was performed on the tumor tissues and spleens of each mouse, respectively, for a total of 4 samples (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e4\u003c/span\u003eA\\C), with a total of 4 samples (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e4\u003c/span\u003eA\\C), with a total of 4 samples (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e4\u003c/span\u003eA\\C), and the total number of cells measured Estimated Number of Cells 36,685; Fraction Reads in Cells 90.6%; Median Genes per Cell 2,352; Median UMI Counts per Cell 8,661.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe CD8T cell population was identified by the characteristic gene of CD8T cells (CD3g CD3e CD3d Cd8a Cd28 Gzmk Ifng Klrg1) (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e4\u003c/span\u003eE), and the focus of our study was to detect the changes of CD8T cells before and after exposure to radiation from whole-body CT scans in tumor tissues and in the spleen.\u003c/p\u003e \u003cp\u003eIt was found that in the spleen, the percentage of CD3, CD4 and CD8 T cells to CD45\u0026thinsp;+\u0026thinsp;cells in the spleen decreased after radiation, where the percentage of CD8 T cells to CD45\u0026thinsp;+\u0026thinsp;cells in the spleen decreased from 6.53% before radiation exposure from whole-body CT scanning to 4.51% after radiation exposure (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e4\u003c/span\u003eD). Further gene expression analysis showed that low-dose irradiation downregulated the expression of IFNγ and killing-related genes (IFNg, KLRD1) in splenic CD8T cells (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e4\u003c/span\u003eF).\u003c/p\u003e \u003cp\u003eIn tumor tissues, the proportions of CD3T cells, CD4T cells and CD8T cells among CD45\u0026thinsp;+\u0026thinsp;T lymphocytes were increased after multiple CT scanning radiation, in which the proportion of CD8T cells in tumor tissues as a percentage of CD45\u0026thinsp;+\u0026thinsp;cells was increased from 4.49% before whole-body CT scanning radiation to 7.15% after radiation (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e4\u003c/span\u003eB); moreover, multiple CT scanning radiation up-regulated tumor expression of IFNγ and killing-related genes (IFNg, KLRD1, Gzmf, Tnfrsf9, Tnfrsf4) in infiltrating CD8T cells (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e4\u003c/span\u003eF),and the signal communication between CD8T cells and other cells was significantly enhanced after radiation (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e4\u003c/span\u003eH), specifically, the afferent signal intensity of CD8T cells was significantly enhanced (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e4\u003c/span\u003eH). We also noted that radiation enhanced functional signaling pathways related to t-cell receptors, cytokines, and antigen presentation in CD8T cells (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e4\u003c/span\u003eI), and also upregulated the PD-L1/PD-L2 signaling pathway (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e4\u003c/span\u003eI). In addition, radiation from multiple CT scans resulted in upregulation of CD8 T cell exhaustion-related genes (including Tox, LAG-3, CTLA-4, and PDCD1) in tumor tissues (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e4\u003c/span\u003eG).\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe emergence of immune checkpoint inhibitors (ICIs) has ushered in a new era of cancer treatment, marking the emergence of immunotherapy as a mainstream approach. In this study, we aimed to investigate whether frequent whole-body CT scans during immune checkpoint inhibitor (ICI) treatment had an effect on the antitumor therapeutic efficacy of ICI through a retrospective clinical study and a study in a mouse model, respectively. Our results showed that multiple CT scans during immune checkpoint inhibitor (ICI) treatment did not promote tumor progression; instead, a trend toward delayed tumor progression was observed. Previous studies have shown that low-dose radiation enhances immune activation, thereby increasing the sensitivity of tumor cells to ICI(Yin, Xue et al. 2020, Patel, Hernandez et al. 2021, Herrera, Ronet et al. 2022, Wang, Zhang et al. 2023). The results observed in our study are consistent with the results of these previous similar studies.\u003c/p\u003e \u003cp\u003eOur further study in a mouse tumor model revealed that frequent CT scan radiation during the application of the immune checkpoint inhibitor PD-1 increased the proportion of infiltrating CD8\u0026thinsp;+\u0026thinsp;T cells in tumor tissues and significantly increased the number of IFN-γ-secreting CD8\u0026thinsp;+\u0026thinsp;T cells. Thus, frequent whole-body CT scanning combined with immunotherapy inhibits tumor growth in mice. Consistent with our findings, Nowosielska et al. reported that whole-body low-dose radiation significantly inhibited LLC cell growth. In addition, the combination therapy of CTLA-4\u0026thinsp;+\u0026thinsp;PD-1\u0026thinsp;+\u0026thinsp;LDR showed significant effects both in vivo (lung and subcutaneous tumor growth) and in vitro (clonogenic potential of tumor cells) (Nowosielska, Cheda et al. 2021).\u003c/p\u003e \u003cp\u003eRadiation from multiple whole-body CT scans had injurious effects on immune cells in both spleen and tumor tissue(Kaatsch, Becker et al. 2021, Fardid, Janipour et al. 2023, Sch\u0026uuml;le, Bunert et al. 2024, Wang, Li et al. 2024). We used single-cell sequencing to show that radiation from multiple whole-body CT scans resulted in a decrease in the proportion of CD8\u0026thinsp;+\u0026thinsp;T cells in the spleen and down-regulation of IFN-γ-related gene expression in splenic CD8\u0026thinsp;+\u0026thinsp;T cells. However, an increased proportion of CD8\u0026thinsp;+\u0026thinsp;T cells in tumor tissues upregulated IFNγ and killing-related genes in tumor-infiltrating CD8T cells. These findings are consistent with other studies(Herrera, Ronet et al. 2022, Gao and Zhang \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e, Wang, Huang et al. 2024). Consistent with this, low-dose radiation improves the immune microenvironment within the tumor tissue and promotes tumor clearance by the immune system.\u003c/p\u003e \u003cp\u003eThis paradox is explained by the fact that radiation from multiple whole-body CT scans has an injurious effect on immune cells in both spleen and tumor tissues, but tumor cells in tumor tissues are more sensitive to radiation and are able to activate immunity by initiating damage-associated molecular patterns (DAMPs)(De Martino, Daviaud et al. 2021). Radiation-induced DNA damage in tumor cells promotes IFN production and activates immunity(Chabanon, Rouanne et al. 2021) (Zhang, Gao et al. 2021) (Man and Jenkins \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). As a result, immune activation is induced in the tumor tissue, counteracting the immunosuppressive effects of radiation damage on the immune cells\u003c/p\u003e \u003cp\u003eHowever, radiation from multiple whole-body CT scans also upregulated genes associated with CD8\u0026thinsp;+\u0026thinsp;T cell exhaustion (TOX LAG-3, CTLA-4, PDCD1) in tumor tissue. This highlights the importance of combining low-dose radiation with immune checkpoint inhibitors to restore functional viability of CD8\u0026thinsp;+\u0026thinsp;T cells. We believe that this mechanism also represents another important aspect of radiation-ICI synergy.\u003c/p\u003e \u003cp\u003eThe commonly used radiation level for CT scanning is about 0.1 Gy or lower, and our findings suggest that CT scanning, as a low-dose radiation, is enhanced by frequent whole-body CT scanning during the application of immune checkpoint inhibitors to kill tumors. Several previous studies have shown that X-rays of 0.1 Gy or lower can also kill some tumor cells, a phenomenon known as radiotherapy hypersensitivity(Joiner, Marples et al. 2001, Le Reun, Granzotto et al. 2023). In some clinical studies, low-dose radiation in combination with chemotherapy, administered at doses to induce radiation hypersensitivity, has achieved striking rates of tumor control(Regine, Hanna et al. 2007, Balducci, Chiesa et al. 2012, Mantini, Valentini et al. 2012). Therefore, in the current era of immunotherapy, the combination of low-dose radiation and immunotherapy may be a new treatment for patients, which also requires further research at a later stage.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eLLC:Lewis Lung Carcinoma\u003c/p\u003e\n\u003cp\u003eICI：immunocheckpoint inhibitor\u003c/p\u003e\n\u003cp\u003eNSCLCnon-small cell lung cancer .\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWBCTSs：whole body CT scan radiation\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDOR：duration of remission\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLDR：Low Dose Radiation\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFCA：Flow cytometry analysis\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eEthical Statement\u003c/h2\u003e\n\u003cp\u003eAll mouse experiments in this study were approved by the Animal Care and Use Committee of Shandong First Medical University (Ethical Approval No. CUTCM/2021/9/113).All animal housing premises and conditions, animal care and monitoring details and experimental conditions were in accordance with ARRIVE guidelines.\u003c/p\u003e\n\u003ch2\u003eConsent for publication\u003c/h2\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eAvailability of data and materials\u003c/h2\u003e\n\u003cp\u003eThe data that support the findings of this study are available from the First authors or corresponding author, [Jigang Dong and Baosheng Li], upon reasonable request.\u003c/p\u003e\n\u003ch2\u003eConflict of interest\u003c/h2\u003e\n\u003cp\u003eThe authors declare no potential conflict of interest.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp;This study was supported by a special fund for the Key Laboratory of the Affiliated Tumor Hospital of the First Medical University of Shandong, China, and by a grant from the Qingdao Key Discipline Fund\u003c/p\u003e\n\u003ch2\u003eContributions\u003c/h2\u003e\n\u003cp\u003eDJG (First Author):Conceptualization, Methodology, Software, Investigation, Formal Analysis, Writing - Original Draft;SS:\u0026nbsp;Data Curation, Writing - Original Draft;QY:\u0026nbsp;Visualization, Investigation;FCR:Software, ValidationLBS(Corresponding Author):Funding Acquisition, Resources, Supervision,\u003c/p\u003e\n\u003ch2\u003eAcknowledgments:\u003c/h2\u003e\n\u003cp\u003eWe express our gratitude to the Key Laboratory of Radiation Oncology in Shandong Province for providing the research platform, which includes Molecular Biology Laboratory, Cell Biology Laboratory, Small Animal Radiation Research Platform, Flow Cytometry in the Animal Experiment Center. We also appreciate all\u0026nbsp;the laboratory members for their valuable discussions and technical support. This work was funded by the Academic Enhancement Program of Shandong First Medical University (2019LJ004) and supported by the National Natural Science Foundation of China (U23A20461).\u003c/p\u003e\n\u003ch2\u003eAuthor information\u003c/h2\u003e\n\u003cp\u003eJigang Dong\u003csup\u003e12\u003c/sup\u003e,Sha sha\u003csup\u003e2\u003c/sup\u003e Ying qi\u003csup\u003e2\u003c/sup\u003e Chengrui Fu\u003csup\u003e13\u003c/sup\u003e, Baosheng Li\u003csup\u003e4\u003c/sup\u003e*,\u003c/p\u003e\n\u003cp\u003e1.Tianjin Medical University Cancer Institute \u0026amp; Hospital,National Clinical Research Center for Cancer, Tianjin\u0026rsquo;s Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy,Tianjin,300000\u003cins cite=\"mailto:Curie\" datetime=\"2024-01-30T14:39\"\u003e, China\u003c/ins\u003e\u003c/p\u003e\n\u003cp\u003e2.Qingdao People\u0026apos;s Hospital Group (Jiaozhou), Jiaozhou Central Hospital of Qingdao. China,[email protected]\u003c/p\u003e\n\u003cp\u003e3. Department of Radiotherapy.Shandong Cancer Hospital, Jinan,250000. China.\u003c/p\u003e\n\u003cp\u003e4*.\u003cstrong\u003eCorresponding\u0026nbsp;\u003c/strong\u003e\u003cins cite=\"mailto:Curie\" datetime=\"2024-01-30T14:39\"\u003eauthor: Baosheng\u003c/ins\u003e Li, Department of Radiotherapy,Shandong Cancer Hospital, Jinan, China\u003cins cite=\"mailto:Curie\" datetime=\"2024-01-30T14:39\"\u003e,\u0026nbsp;\u003c/ins\[email protected]\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBalducci M, et al. Low-dose fractionated radiotherapy and concomitant chemotherapy in glioblastoma multiforme with poor prognosis: a feasibility study. Neurooncology. 2012;14(1):79\u0026ndash;86.\u003c/li\u003e\n\u003cli\u003eBarsoumian HB et al. (2020). Low-dose radiation treatment enhances systemic antitumor immune responses by overcoming the inhibitory stroma. J Immunother Cancer 8(2).\u003c/li\u003e\n\u003cli\u003eBecker BV, et al. Initial experience on abdominal photon-counting computed tomography in clinical routine: general image quality and dose exposure. Eur Radiol. 2023;33(4):2461\u0026ndash;8.\u003c/li\u003e\n\u003cli\u003eBenoit A, et al. Lighting up the fire in the microenvironment of cold tumors: A major challenge to improve cancer immunotherapy. Cells. 2023;12(13):1787.\u003c/li\u003e\n\u003cli\u003eChabanon RM, et al. Targeting the DNA damage response in immuno-oncology: developments and opportunities. Nat Rev Cancer. 2021;21(11):701\u0026ndash;17.\u003c/li\u003e\n\u003cli\u003eDe Martino M, et al. Radiotherapy: An immune response modifier for immuno-oncology. Seminars in Immunology, Elsevier; 2021.\u003c/li\u003e\n\u003cli\u003eFardid R, et al. Evaluation of the relationship between \u0026gamma;-H2AX biomarker levels and dose received after radiation exposure in abdominal\u0026ndash;pelvic and chest CT scans. Journal of Cancer Research and Therapeutics; 2023.\u003c/li\u003e\n\u003cli\u003eGao L, Zhang A. Low-dose radiotherapy effects the progression of anti-tumor response. Translational Oncol. 2023;35:101710.\u003c/li\u003e\n\u003cli\u003eHerrera FG, et al. Low-dose radiotherapy reverses tumor immune desertification and resistance to immunotherapy. Cancer Discov. 2022;12(1):108\u0026ndash;33.\u003c/li\u003e\n\u003cli\u003eJoiner MC, et al. Low-dose hypersensitivity: current status and possible mechanisms. Int J Radiation Oncology* Biology* Phys. 2001;49(2):379\u0026ndash;89.\u003c/li\u003e\n\u003cli\u003eKaatsch HL, et al. Gene expression changes and DNA damage after ex vivo exposure of peripheral blood cells to various CT photon spectra. Sci Rep. 2021;11(1):12060.\u003c/li\u003e\n\u003cli\u003eKhan AUH, et al. Effects of chronic low-dose internal radiation on immune-stimulatory responses in mice. Int J Mol Sci. 2021;22(14):7303.\u003c/li\u003e\n\u003cli\u003eLe Reun E, et al. Influence of the hypersensitivity to low dose phenomenon on the tumor response to hypofractionated stereotactic body radiation therapy. Cancers. 2023;15(15):3979.\u003c/li\u003e\n\u003cli\u003eLiao Y, et al. Low-dose total body irradiation enhances systemic anti-tumor immunity induced by local cryotherapy. J Cancer Res Clin Oncol. 2023;149(12):10053\u0026ndash;63.\u003c/li\u003e\n\u003cli\u003eLiu S, et al. Effect of triple therapy with low-dose total body irradiation and hypo-fractionated radiation plus anti-programmed cell death protein 1 blockade on abscopal antitumor immune responses in breast cancer. Int Immunopharmacol. 2023;117:110026.\u003c/li\u003e\n\u003cli\u003eMan SM, Jenkins BJ. Context-dependent functions of pattern recognition receptors in cancer. Nat Rev Cancer. 2022;22(7):397\u0026ndash;413.\u003c/li\u003e\n\u003cli\u003eMantini G, et al. Low-dose radiotherapy as a chemo-potentiator of a chemotherapy regimen with pemetrexed for recurrent non-small-cell lung cancer: a prospective phase II study. Radiother Oncol. 2012;105(2):161\u0026ndash;6.\u003c/li\u003e\n\u003cli\u003eNowosielska EM, et al. Effects of a unique combination of the whole-body low dose radiotherapy with inactivation of two immune checkpoints and/or a heat shock protein on the transplantable lung cancer in mice. Int J Mol Sci. 2021;22(12):6309.\u003c/li\u003e\n\u003cli\u003ePatel RB, et al. Low-dose targeted radionuclide therapy renders immunologically cold tumors responsive to immune checkpoint blockade. Sci Transl Med. 2021;13(602):eabb3631.\u003c/li\u003e\n\u003cli\u003eRegine WF, et al. Low-dose radiotherapy as a chemopotentiator of gemcitabine in tumors of the pancreas or small bowel: a phase I study exploring a new treatment paradigm. Int J Radiation Oncology* Biology* Phys. 2007;68(1):172\u0026ndash;7.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003e\u003cstrong\u003e(Table 1 )\u0026nbsp;\u003c/strong\u003echaracteristics of patients with stage IV NSCLC\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"554\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCharacteristics \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Total(n = 40)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\" valign=\"top\"\u003e\n \u003cp\u003eAge (years)\u003c/p\u003e\n \u003cp\u003eRange \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;（54-79）\u003c/p\u003e\n \u003cp\u003e＞65 \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 19\u003c/p\u003e\n \u003cp\u003e\u0026le;65 \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;21 \u0026nbsp; \u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eGender\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eMale \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 34 \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eFemale \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 6\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eHistological\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eAdenocarcinoma \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 23\u003c/p\u003e\n \u003cp\u003eSquamous \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;17\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eClinical stage\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eIV \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 40\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eECOG PS\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e0-1 \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;35\u003c/p\u003e\n \u003cp\u003e\u0026ge;2 \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 5\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eLines of ICIs\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eFirst line \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 13\u003c/p\u003e\n \u003cp\u003e\u0026ge;Second line \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 27\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eWith / Without chemotherapy\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eYes \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;10\u003c/p\u003e\n \u003cp\u003eNo \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 30\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eWith / Without radiotherapy\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eYes \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 0\u003c/p\u003e\n \u003cp\u003eNo \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 40\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eWith / Without AntiAngiogenesis therapy\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eYes \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 6\u003c/p\u003e\n \u003cp\u003eNo \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bcan","sideBox":"Learn more about [BMC Cancer](http://bmccancer.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bcan/default.aspx","title":"BMC Cancer","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"whole-body CT scanning radiation, immune checkpoint inhibitor, NSCLC, Tumor immune microenvironment","lastPublishedDoi":"10.21203/rs.3.rs-4431449/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4431449/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjective:\u003c/strong\u003eThe effect of frequent whole-body CT scanning during immune checkpoint inhibitor (ICI) therapy on the anti-tumor immune effect of ICI.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003eWe 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.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003eThe 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.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003eTo 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.\u003c/p\u003e","manuscriptTitle":"Impact of frequent whole-body CT scans during immune checkpoint inhibitor (ICI) therapy on antitumor immune efficacy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-07 18:58:54","doi":"10.21203/rs.3.rs-4431449/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-05-27T03:17:38+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-05-27T02:57:17+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-05-22T12:53:56+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Cancer","date":"2024-05-16T13:41:10+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bcan","sideBox":"Learn more about [BMC Cancer](http://bmccancer.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bcan/default.aspx","title":"BMC Cancer","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d10f5ab4-b5d3-4925-bbb2-9ce7812cc971","owner":[],"postedDate":"June 7th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-05-05T16:01:18+00:00","versionOfRecord":{"articleIdentity":"rs-4431449","link":"https://doi.org/10.1186/s12885-025-14119-7","journal":{"identity":"bmc-cancer","isVorOnly":false,"title":"BMC Cancer"},"publishedOn":"2025-05-02 15:57:37","publishedOnDateReadable":"May 2nd, 2025"},"versionCreatedAt":"2024-06-07 18:58:54","video":"","vorDoi":"10.1186/s12885-025-14119-7","vorDoiUrl":"https://doi.org/10.1186/s12885-025-14119-7","workflowStages":[]},"version":"v1","identity":"rs-4431449","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4431449","identity":"rs-4431449","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}