Over the past decades, there has been a lack of significant breakthroughs in small cell lung cancer therapy, the current standard care is still concurrent chemoradiation. Recently, immune checkpoint inhibitors in anti-tumor clinical application has achieved remarkable results. There is evidence suggest that radiation and chemotherapy can alter the immune microenvironment, many clinical trials combing radiation or chemotherapy with checkpoint inhibitors are underway. But how chemotherapy or radiotherapy affects any existing anti-tumor immune response and how that response is changed following clinical treatment are still not elucidated fully. In this study, we investigated the changes of immune subsets in patients with LS-SCLC.
Blood samples were obtained from 48 patients before and after radiotherapy and 31 patients before and after induction chemotherapy. PBMCs were purified using standard Ficoll density gradient centrifugation. The percentage of circulating lymphocyte subsets were measured by flow cytometry. Patient data include clinical characteristics, disease prognostic information, survival information etc. The SPSS 22.0 software was used for the data analysis.
Among the 31 patients, most values of T-lymphocyte subsets showed no statistically significant difference before and after induction chemotherapy. Among the 48 patients, remarkable elevation of CD3+, CD8+ T cells were noticed, CD4+, CD56+, CD4+CD45RA+ cells and CD4+/CD8+ ratio were significantly decreased after radiotherapy. Then we further analyzed the changes of lymphocyte subsets in 17 patients before and after induction chemotherapy as well as radiotherapy, which further confirmed the changes of immune subsets caused by radiotherapy but not induction chemotherapy.
This study suggest that thoracic radiotherapy but not induction chemotherapy has an immunomodulatory effect on LS-SCLC patients, which provides new insights relevant for designing more optimal combination of immunotherapy in such cohort, especially for the appropriate time and sequence of immunotherapy, radiotherapy and chemotherapy.
Clinical trial identification
Legal entity responsible for the study
National Natural Science Foundation of China
All authors have declared no conflicts of interest.