Karasaki T, et al. - Whether high CC chemokine receptor 4 (CCR4) expression in the tumor microenvironment was related to a poor prognosis and would act as a biomarker in lung adenocarcinoma was investigated. Researchers used pooled data from public transcriptomic databases with online survival analysis software to explore the prognostic impact of CCR4 gene expression. Using immunohistochemistry, they evaluated the density of CCR4⁺ lymphocytes infiltrating the tumor and associated it with survival. To control confounding factors, multivariate analysis using the Cox proportional hazards model was performed. According to findings, high CCR4 expression in the tumor microenvironment could be a poor prognostic factor in lung adenocarcinoma. The results also suggested a poor prognosis in patients with high CCR4⁺ lymphocyte infiltration, and therefore, could be suitable candidates for clinical trials on anti-CCR4 antibody treatment.