The Effects Of Pegylated Recombinant Human Granulocyte Colony-stimulating Factor On Small Cell Lung Cancer Immune Status

Background:Small cell lung cancer(SCLC)is a highly invasive disease,with rapid proliferation and easy recurrence and metastasis,resulting poor prognosis.Etoposide combined with platinum-based systemic chemotherapy is the standard initial treatment of SCLC.In recent years,breakthroughs have been made in immunotherapy,however the benefit for SCLC patients is limited,immunodeficiency is one of the potential mechanisms,regulating the patient's immune status has potential benefits.Pegylated recombinant human granulocyte colony-stimulating factor(PEG-rhG-CSF)is widely used for prophylaxis of leukopenia,neutrophilia and febrile neutropenia(FN)during chemotherapy for tumors including SCLC.The main function of PEG-rhG-CSF is promoting the formation and release of neutrophils;besides,it may have an impact on immune cells however lack of research.This study is aim to explore the effect of PEG-rhG-CSF on the immune status of SCLC patients,especially on T cells,and to discuss the therapeutic optimization of SCLC in the era of immunotherapy.Methods:In this single center,prospective cohort study,treatment naive SCLC patients who were supposed to treat with conventional etoposide combined with platinum chemotherapy were enrolled.Patients were divided into the PEG-rhG-CSF group and the control group according to the risk of FN.Longitudinal sampling of peripheral blood was performed before(day 0),after(day 3)and 4-6 days after the first cycle of chemotherapy(day 8-10).Flow cytometry was used to assess lymphocyte subsets,including CD3+ T,CD4+T,CD8+T,NK,and B cells.The total T-cell receptor(TCR)repertoire was sequenced by next-generation sequencing(NGS),TCR diversity,clonality and types were analyzed.Based on the statistics of lymphocytes and TCR repertoire,plasma cytokines were detected by high-throughput liquid chip technique.The enrolled patients were followed up for hematologic toxicities and managements,metastasis and survival.Results:From February 2019 to December 2019,a total of 25 treatment naive SCLC patients were enrolled(16 patients in the PEG-rhG-CSF group and 9 patients in the control group).After chemotherapy compared to baseline,1)there were no significant changes of CD3+T,CD4+T,CD8+T,NK,and B cells proportions in both the PEG-rhG-CSF group and the control group;2)the TCR diversity decreased(p=0.028),while the TCR clonality increased(p=0.044)significantly;3)plasma cytokine showed no significance difference.After PEG-rhG-CSF injection,1)the proportions of CD3+T cells increased significantly(p=0.002)and especially in the CD4+T cells(p=0.020),whereas the CD8+T,NK,and B cells were not significantly increased.There were no significant changes in these cell proportions at the same time point in the control group;2)further,peripheral blood TCR diversity increased(P=0.013)and clonality decreased(P=0.007)significantly after PEG-rhG-CSF treatment,no significance changes were seen in the control group;V? and J?gene fragment types,which determine TCR,were amplified much more in the PEG-rhG-CSF group(29 vs.10 types);3)cytokine detection indicated that IL-22(P=0.014)and TGF-?(P=0.017)decreased significantly after PEG-rhG-CSF injection,no significant changes in the control group;4)the change in TCR diversity was significantly correlated with changes in the CD3+T or CD4+T cell proportions,but not correlated with the CD8+T cell proportion.Conclusion:PEG-rhG-CSF regulates immune status of SCLC patients,adjusting lymphocyte subsets,TCR diversity and clonality and CD4+T cell related cytokines in the peripheral blood;CD4+T cells may be the main effector cells involved in this process.These findings may optimize the treatment of SCLC.