This study investigates the role of purine metabolism (PM) in lung adenocarcinoma (LUAD) using single-cell analysis. The researchers developed a purine metabolism-associated signature (PAS) by analyzing gene expression data from TCGA and five GEO datasets. The PAS was constructed using PM-related genes and demonstrated strong prognostic predictive capability. Patients with low PAS scores exhibited better survival outcomes, increased immune cell infiltration, and lower PD-L1 expression, suggesting a potential link between PAS and tumour immunity. Additionally, the low-PAS group showed enhanced responses to immunotherapy. The PAS was validated across multiple datasets and showed high accuracy in predicting survival outcomes. The study also identified key PM genes and highlighted the importance of PM in cancer progression and immune evasion. The PAS was found to be a valuable tool for predicting patient outcomes and guiding immunotherapy decisions in LUAD. The study underscores the significance of PM in LUAD and provides insights into the molecular mechanisms underlying tumour immunity and immunotherapy response. The PAS has the potential to serve as a predictive biomarker for LUAD patients, offering a new approach for clinical stratification and treatment optimization.This study investigates the role of purine metabolism (PM) in lung adenocarcinoma (LUAD) using single-cell analysis. The researchers developed a purine metabolism-associated signature (PAS) by analyzing gene expression data from TCGA and five GEO datasets. The PAS was constructed using PM-related genes and demonstrated strong prognostic predictive capability. Patients with low PAS scores exhibited better survival outcomes, increased immune cell infiltration, and lower PD-L1 expression, suggesting a potential link between PAS and tumour immunity. Additionally, the low-PAS group showed enhanced responses to immunotherapy. The PAS was validated across multiple datasets and showed high accuracy in predicting survival outcomes. The study also identified key PM genes and highlighted the importance of PM in cancer progression and immune evasion. The PAS was found to be a valuable tool for predicting patient outcomes and guiding immunotherapy decisions in LUAD. The study underscores the significance of PM in LUAD and provides insights into the molecular mechanisms underlying tumour immunity and immunotherapy response. The PAS has the potential to serve as a predictive biomarker for LUAD patients, offering a new approach for clinical stratification and treatment optimization.