Novel antibody-drug conjugates (ADCs) are a hot spot in the research and development of new drugs for advanced solid tumors. ADCs have achieved significant efficacy in the treatment of advanced breast cancer, urothelial carcinoma, gastric cancer and other solid tumors, but their adverse reactions such as ocular toxicity, pulmonary toxicity, hematological toxicity, and liver toxicity cannot be ignored, and it is crucial to effectively deal with the adverse reactions of ADCs.

Purpose To investigate the expression of PD-1,PD-L1,CD3 and CD8 in the immune microenvironment of non-small cell lung cancer(NSCLC)and their clinical signifi-cance.Methods The clinical data of 39 patients with NSCLC brain metastasis(BM)were collected.The expression of PD-1,PD-L1,CD3 and CD8 in the tumor and stroma of BM was detec-ted using an immunofluorescence-based tissue microenvironment analysis panel.Targeted sequencing was carried out to catalog cancer-related genes.The clinical pathological features were an-alyzed with review of relevant literature.Results Thity-nine patients with NSCLC presented with tumor-infiltrating lympho-cytes(TIL)in different degree.CD3+TIL(P=0.000 7)and CD8+TIL(P=0.0006)were more prominent in the tumor stroma,and the positive PD-L1 expression was significantly higher in the interstitial tissues of tumor(P=0.025 8).Com-pared with the whole wild-type driver gene cohort,the expres-sion of PD-L1 in the stroma of BM was significantly increased in the EGFR mutation cohort(P=0.039).Patients with high in-filtration of stroma CD8+TIL had longer median overall survival than those with low infiltration(16 months vs 6 months,P=0.032);PD-L1-positive patients(36 months)were longer sur-vival time than PD-L1-negative patients(5.5 months,P=0.056).Compared with lung primary lesions,the variant allele frequencies(VAFs)in BM generally increased,and samples with higher VAFs corresponded to higher expression of PD-1,PD-L1,CD3 and CD8.Conclusion The TIL infiltration is most prominent in the stroma of NSCLC BM.The EGFR muta-tion of a tumor might affect the immune microenvironment of me-tastases;PD-L1 expression and TIL infiltration were correlated with overall survival.