The Role Of Radiotherapy In Patients Receiving Immunotherapy For Non-small Cell Lung Cancer And Safety Optimization Strategy Exploration

BackgroundLung cancer is one of the most common malignant tumors.Non-small cell lung cancer(NSCLC)accounts for approximately 85%of all lung cancer types.Its early diagnosis is low due to the lack of typical clinical symptoms.Many NSCLC patients beyond the optimal window for surgery at the time of initial diagnosis.In recent years,immunotherapy has become a hot research topic in NSCLC,which has shown durable efficacy in advanced and metastatic NSCLC patients and has become a cornerstone of systemic anti-tumor therapy.Radiotherapy(RT)is considered an important treatment for patients with non-surgical NSCLC.The aim of RT is evolving from direct tumor death to tumor immune microenvironment reconstitution and immune modulation.RT enhances the systemic antitumor response to immunotherapy.In theory,RT combined with immunotherapy has the potential to overcome mutual disadvantages and improve prognosis.In clinical practice,the role of RT in stage Ⅳ NSCLC patients treated with immunotherapy is still unclear.Both RT and the immune checkpoint inhibitors(ICIs)may result in immune system imbalance,which can induce a variety of adverse events.Pneumonia is one of the most common adverse effect after RT and immunotherapy in NSCLC patients,which often manifests as cough,sputum and dyspnea.Especially for patients with advanced NSCLC,serious complications such as pulmonary edema,hemoptysis and respiratory failure often occur,which threaten the survival of patients.An increasing number of clinical trials are exploring the efficacy of RT combined with ICIs in patients with NSCLC,however,many studies suggest that RT combined with ICIs increases the incidence of pneumonia.RT and immunotherapy associated pneumonia(RIAP)has become an important factor in limiting the benefit of NSCLC.Therefore,it is necessary to explore strategies to optimize the safety of RT combined with immunotherapy from the perspective of reducing the incidence of treatmentrelated pneumonia.The aim of our study is to evaluate the role of radiotherapy in patients with stage IV NSCLC receiving immunotherapy and to determine the population characteristics that would benefit from combination modality and the optimal combination model.Also,explore protective measures to reduce the occurrence of RIAP and optimize the safety of RT combined with immunotherapy.This is beneficial to further improve the therapeutic efficacy and improve the quality of patient survival.Methods1.The study retrospectively collected information on patients with stage Ⅳ NSCLC who received immunotherapy with Toripalimab or Tislelizumab between February 2019 and August 2021 at three oncology centers in Shandong Province.Radiotherapy includes both external beam radiation therapy(EBRT)and radioactive particle implantation(RPI).Overall survival(OS)is the primary study endpoint.Correlations between clinical baseline characteristics were assessed by Fisher’s exact probability method.Kaplan-Meier curve was generated to explore the prognosis of patients with stage Ⅳ NSCLC under different modalities of RT combined with immunotherapy.Cox risk proportional regression models was used to exploring prognostic factors in immunotherapy patients with stage Ⅳ NSCLC and prognostic trends of RT in different population subgroups.2.This study analyzed the Food and Drug Administration Adverse Event Reporting System(FAERS)database of NSCLC patients receiving immunotherapy with Durvalumab and Pembrolizumab reported from January 2015 to September 2022 through the AERSMine platform.We applied a relative risk test to rank the top 10 drugs that were protective against adverse events in patients with NSCLC receiving immunotherapy.3.The protective drugs screened by the database results were further validated by constructing a tumor-bearing mice models and related mechanisms were further explored.Male C57BL/6 mice of 6-8 weeks were treated with whole thorax RT and programmed cell death protein/ligand-1[PD-(L)1]immunotherapy at to construct a RT and immunotherapy associated pneumonia(RIAP)animal model.We examined the effect of metformin on RIAP and its relationship with related inflammatory cells and inflammatory factors in a mice model by a serious experimental approach,such as Hematoxylin-Eosin(HE)staining,immunohistochemistry(IHC),Enzyme-linked immunosorbent assay(ELISA),PCR and Western Blot.Results1.RT combined with immunotherapy did not improve the prognosis of patients with stage Ⅳ NSCLC.Concurrent RT with immunotherapy and first and second lines immunotherapy combined with RT had a tendency to improve the prognosis of stage ⅣNSCLC patients with longer survivalSurvival analysis in the whole population showed that median overall survival(mOS)was 10 months for EBRT combined immunotherapy,2 months for RPI combined immunotherapy,and 9 months for single-agent immunotherapy,with no statistically significant difference in three groups(P=0.148).To further clarify whether the intervention timing of RT combined with immunotherapy had an impact on the prognosis of patients with stage Ⅳ NSCLC,we analyzed the prognostic value of concurrent RT with immunotherapy.The Kaplan-Meier survival curves revealed an improved prognosis a trend for concurrent RT with immunotherapy over immunotherapy alone,with mOS of 17 months vs.9 months for the two groups,respectively.On the basis of studies showing that immunotherapy is more clinically effective when used in the first and second lines,we further analyzed whether first and second line immunotherapy combined with radiotherapy improved patient prognosis.The results found a trend towards improved prognosis for patients with first and second line immunotherapy combined with RT compared to first and second line immunotherapy alone,with 1-year survival rates of 45.5%vs.26.1%for the two groups respectively.This study has demonstrated a trend for RT to improve prognosis in specific populations receiving immunotherapy for stage Ⅳ NSCLC,and we further explored prognostic factors in the stageⅣ population.Cox multifactorial regression showed that ECOG score[ECOG≥2,Hazard ratio(HR)=2.701,95%confidence interval(CI):1.630-4.475,P<0.001]and number of lines of immunotherapy(≥3 lines of immunotherapy,HR=2.032.95%CI:1.189-3.471,P=0.009)were independent prognostic factors for patients receiving immunotherapy for stageⅣ NSCLC.Cox multivariate regression showed that ECOG score[ECOG≥2,Hazard ratio(HR)=2.701,95%confidence interval(CI):1.630-4.475,P<0.001]and number of lines of immunotherapy(≥3 lines of immunotherapy,HR=2.032.95%CI:1.189-3.471,P=0.009)were independent prognostic factors for patients receiving immunotherapy in stage ⅣNSCLC.2.Metformin treatment as a protective factor for RIAPThe top 10 drugs with protective effects against pneumonia were screened through the FAERS database,and metformin was in 8th place.Recent studies have shown that metformin has anti-inflammatory effects and we have explored the role of metformin in RIAP through animal experiments.HE staining results showed that interstitial edema and thickening of the lung,exudation of jelly material in the alveolar cavity,inflammatory infiltration and destruction of alveolar structures could be observed in lung tissue of the RT group and the RT+PD-(L)1 group,while there was a trend towards more severe lung injury in the RT+PD(L)1 group(Pneumonia score,4.17±0.17 vs.8.17±0.31,P>0.100).However,there was a trend towards reduction in the severity of pneumonia in the RT+metformin group compared to the RT group(Pneumonia score,1.00±0.26 vs.4.00±0.17,P=0.469),and the degree of lung injury was significantly alleviated in the RT+PD-(L)1+metformin group compared to the RT+PD-(L)1 group(Pneumonia score,2.33 ±0.33 vs.8.17± 0.31,P=0.044).3.Metformin reduces the occurrence of RIAP by affecting macrophages and related inflammatory cytokinesIHC results suggested a significant increase in macrophage infiltration in the lungs of mice treated with RT compared to the control group(0.43±0.04 vs.5.27±0.52,P=0.001),especially in the RT+PD-(L)1 group(0.43±0.04 vs.13.37±1.53,P=0.002).The infiltration of macrophages in the lungs was significantly diminished in the RT+metformin group compared to the RT group(5.27±0.52 vs.1.95±0.40,P=0.004),while the accumulation of macrophages in the lungs was significantly suppressed in mice receiving RT+PD-(L)1+metformin group compared to the RT+PD-(L)1 group(3.53±0.45 vs.13.37±1.53,P=0.005).PCR,Western Blot and ELISA results revealed that metformin alleviated RIAP by reducing the transcription,expression and release of IFN-γ,IL-6 and TNF-α,whereas there was no statistical difference in transcription,expression and release of IL-1β caused by metformin.Conclusions1.RT combined with immunotherapy may not improve the prognosis of patients with stage Ⅳ NSCLC.Concurrent RT with immunotherapy and first and second lines immunotherapy combined with RT had a tendency to improve the prognosis of stage ⅣNSCLC patients with longer survival.2.Metformin reduced the development of RIAP.Metformin alleviates the pathological changes of RIAP by inhibiting the infiltration of macrophages in lung tissue and reducing the transcription,expression and release of inflammatory factors such as IFN-y,IL-6 and TNF-α.Therefore,the use of metformin might be one of the optimal strategies for RT combined with immunotherapy regimens.