[Effect of Pembrolizumab on T Lymphocyte Subsets in Patients with Advanced 
Non-small Cell Lung Cancer and Its Therapeutic Effect].

backgroundThe aim of this study is to investigate the changes of peripheral blood lymphocyte subsets before and after treatment with pembrolizumab for non-small cell lung cancer and its clinical significance.

methodsA total of 32 patients with non-small cell lung cancer who received pembrolizumab treatment in The Affiliated Hospital of Qingdao University and Weifang People's Hospital of Shandong Province from January 2015 to December 2020 were selected as the observation group, and 30 healthy people during the same period were selected as the control group. Before treatment and in cycles 1, 2 and 4 after treatment, fluid cytometry was used to detect changes in the levels of lymphocyte subsets in the peripheral blood of patients.

resultsThe CD3⁺, CD4⁺, CD4⁺/CD8⁺ indexes of patients with non-small cell lung cancer before the treatment were significantly lower than those in the control group (P<0.05), and the CD8⁺ level was significantly increased (P<0.05); After 1 cycle of pembrolizumab treatment, there was no significant difference in the changes of lymphocyte subsets compared with before immunotherapy; After 2 cycles of the treatment, the CD3⁺, CD4⁺, CD4⁺/CD8⁺ values were higher than before the treatment (P>0.05), and the CD8⁺ index was slightly lower than before the treatment (P<0.05); After the fourth cycle of treatment, the CD3⁺, CD4⁺, CD4⁺/CD8⁺ values were significantly improved compared to before the treatment (P<0.05), and the CD8⁺ index was significantly lower than before the treatment (P<0.05); In the treatment process of patients with stable disease (SD)/partial response (PR), the CD3⁺, CD4⁺, CD4⁺/CD8⁺ values of the fourth cycles were higher than before the treatment (P<0.05), and the CD8⁺ index was lower than before the treatment (P<0.05); During the treatment of progressive disease (PD) patients, the changes of lymphocyte subsets in the fourth cycles were not significantly different from those before the treatment (P>0.05). At the same time, this article shows through analysis that the expression of programmed cell death ligand 1 (PD-L1) and pathological types have no obvious influence on the effect of immunotherapy. Multi-factor analysis shows that it is more meaningful to observe the changes of CD3⁺, CD4⁺ and CD8⁺ at the same time to predict the effect of immunotherapy.

conclusionsPembrolizumab can regulate the changes of T lymphocyte subsets in patients with non-small cell lung cancer, improve the immune status of the patients, and there is no obvious adverse reaction. At the same time, monitoring the changes of lymphocyte subsets during treatment can predict the effect of immunotherapy.