FOXP3+/CD8+ tumor-infiltrating T-cell ratio as a marker for pathologic response to induction therapy of non-small cell lung cancer.

Abstract

e17517 Background: Survival benefits of induction therapy followed by surgery for advanced non-small cell lung cancer (NSCLC) have been shown. Anti-cancer agents are suggested to mediate cytotoxic effect not only directly on tumor cells but also through the immune system. We investigated the relationship between the status of T-cell differentiation in tumor stroma and pathologic responses to induction therapy in patients with advanced NSCLC. Methods: A total of 69 patients with c-stage IIA to IIIB NSCLC who underwent induction therapy followed by R0 surgery between January 2002 and July 2011 were enrolled. Tumor-infiltrating T cells expressing CD8 or FOXP3 were detected by immunohistochemical staining from biopsy and surgically removed specimens using anti-CD8 antibody and anti-FOXP3 antibody. Staining-positive T cells were counted in 10 fields at 200× magnification of digital images, and then FOXP3+/CD8+ T cell ratio was determined based on the average counts. Results: The mean values of FOXP3+/CD8+ T cell ratio in operative specimens were 1.11 for the patients with pathological no change (p-NC), 0.32 for those with pathological partial response (p-PR), and 0.21 for those with pathological complete response (p-CR) (p = 0.002). There was no association of FOXP3+/CD8+ T cell ratio with gender, histologic types of tumor, or clinical stages. Patients with p-CR showed better relapse-free survival, though statistically no-significant (p = 0.323). Pre-treatment TBLB specimens were available in 12 patients (3 p-NCs, 7 p-PRs, and 2 p-CRs). FOXP3+/CD8+ T cell ratios in operative specimens after induction therapies were elevated compared with that of biopsy specimens in p-NC patients (p = 0.105), whereas the ratios were decreased in p-PR and p-CR patients (p = 0.021). Conclusions: The status of tumor-infiltrating T cell differentiation indicated by FOXP3+/CD8+ T cell ratio was correlated with pathologic response in patients treated with induction therapy followed by surgery for NSCLC. FOXP3+/CD8+ T cell ratio can be a marker for effectiveness of induction treatment.