Yuyan Xie Hao Sun Liying Shan ^* Xin Ma ^* Qingyu Sun ^* Fang Liu ^*

• Harbin Medical University Cancer Hospital, Harbin, China

Background: Unlike patients with lung adenocarcinoma, patients with lung squamous cell carcinoma (LUSC) do not derive significant benefits from targeted therapy. In recent years, immunotherapy has revolutionized the treatment approach for LUSC.However, not all patients with this type of cancer respond to immunotherapy, necessitating the identification of effective biomarkers to predict survival prognosis and evaluate the efficacy of PD-1 inhibitors.: We retrospectively collected case and hematologic data from 212 patients with advanced squamous lung cancer who received PD-1 combination therapy. Hematological indices mainly contained SCC, CEA, NSE, Hb, LDH, WBC and RBC at baseline, 6 and 12 weeks of treatment. All patients underwent imaging examinations and efficacy was evaluated according to RECIST1.1 criteria. Univariate tests were used to assess the relationship between changes in serum biomarkers, clinical characteristics and treatment outcome. The survival prognosis of patients was investigated by telephone follow-up. The optimal critical values of all hematological indicators were calculated by ROC curves, and then logistic regression and Cox regression were used to analyze multiple serum markers in relation to efficacy and survival prognosis, respectively. Finally, column line plots were constructed and validated to predict the probability of patient survival.Results：Post-treatment RBC12w<3.81 × 10 12 /L (p < 0.034) was associated with lower ORR, and WBC6w<9.34 × 10 9 /L (p=0.041) was associated with higher DCR.SCC12w≥2.25 ng/mL (p = 0.015) ， NSE6w ≥ 13.54 ng/mL(p = 0.044)and RBC0w≥4.2 × 10 9 /L (p = 0.003) were independent predictors of PFS. SCC12w≥2.25 ng/mL (p < 0.001) and NSE6w≥13.54ng/mL(p = 0.042) were independent predictor of