In this paper, we applied ESTIMATE, ssGSEA, and TIMER computational methods to calculate the composition of immune cells infiltrated in the tumor microenvironment and the ratio of immune and stromal fractions of LUAD samples from The Cancer Genome Atlas (TCGA) database, and identified a predictive biomarker, Toll-like receptor 7 (TLR7), which can be used to guide the prognosis and prediction of the response to immunologic and pharmacologic therapy. The gene discussed is TLR7; the disease is neoplasm.