Abstract:Objective To explore the synergistic effect of tislelizumab in the first-line treatment with paclitaxel and platinum for the advanced lung squamous cell carcinoma patients based on PD-1/PD-L1 expression, and to provide reference for clinical treatment.Methods Clinical data of 120 patients with advanced lung squamous cell carcinoma in our hospital from March 2020 to March 2023 were collected for retrospective analysis. 60 patients who met the inclusion and exclusion criteria receiving first-line treatment with tislelizumab and paclitaxel combined with platinum were set as the observation group, and 60 patients receiving first-line treatment with paclitaxel combined with platinum were chosen as the control group. The efficacy, toxicity, and the long-term survival rate were compared between the two groups, as well as the levels of tumor markers [squamous cell carcinoma antigen (SCCA), soluble fragment of cytokeratin 19 (CYFRA21-1) and carcinoembryonic antigen (CEA)], T lymphocyte subsets (CD4+, CD8+, and CD4+/CD8+), PD-1/PD-L1 signaling pathway-related indicators (PD-1, PD-L1).Results The objective remission rate (58.33%) and disease control rate (78.33%) in observation group were higher than those in control group (respectively 36.67% and 56.67%) (P<0.05). The incidence of gastrointestinal reaction (20.00%), alopecia (15.00%) and leukopenia (18.33%) in observation group was lower than that in control group (36.67%, 31.67%, 35.00%, respectively) (P<0.05). After 2 and 4 courses of treatment, the levels of CEA, CYFRA21-1 and SCCA in observation group were all lower than those in control group (P<0.05). The proportion of CD4+ and the CD4+/CD8+ in observation group were higher than those in control group, while the proportion of CD8+ was lower than that in control group (P<0.05). Moreover, the levels of PD-1 and PD-L1 in CD4+ T cells in the peripheral blood were lower in observation group than in control group (P<0.05). The 2-year survival rate of the observation group was significantly higher than that of the control group, and the overall survival (OS) and progression-free survival (PFS) were significantly longer than those of the control group (P<0.05).Conclusion Tislelizumab can play a synergistic role in combination with paclitaxel and platinum in the first-line treatment of middle and advanced lung squamous cell carcinoma, improve immunity, reduce toxic and side effects, and prolong the long-term survival rate of patiens. It may be related to the regulation of PD-1/PD-L1 pathway.