Abstract
The present study investigated how gilteritinib overcomes resistance to second‑generation tyrosine kinase inhibitors in anaplastic lymphoma kinase (ALK)‑rearranged non‑small‑cell lung cancer (NSCLC), providing new theoretical support for NSCLC treatment. The GSE191078 dataset was downloaded from Gene Expression Omnibus database. Cell clustering was performed using the FindClusters function, followed by uniform manifold approximation and projection dimensionality reduction and data filtering. Epithelial and T cells were extracted for single‑cell transcriptome sequencing and pseudotime analysis was conducted using the Monocle 2 algorithm. The inhibitory effects of gilteritinib on H2228/Al cells were evaluated using CCK8 and TUNEL assays. Western blotting, reverse transcription‑quantitative PCR and immunofluorescence were used to examine programmed death‑ligand 1 (PD‑L1) and cluster of differentiation 8 (CD8) expression. A PD‑L1/CD8 co‑culture system was established for rescue experiments and a nude mouse xenograft model was used to assess the anti‑tumor efficacy of gilteritinib. A total of 21,866 cells were obtained and grouped into 12 major cell types. In ALK‑rearranged NSCLC, epithelial cells were associated with regulation of the P53, glycolysis and hypoxia pathways, while pseudotemporal analysis linked T cells to endothelial cell‑related processes and ribosomal functions. In vitro, gilteritinib inhibited H2228/Al cell growth, induced apoptosis and reduced ALK protein levels. Co‑culture and rescue experiments suggested the mechanism involved inhibiting PD‑L1 and CD8 co‑expression, corroborated by animal experiments. Gilteritinib can overcome alectinib resistance and inhibit PD‑L1 and CD8 co‑expression in ALK‑rearranged NSCLC, providing a new therapeutic strategy.