Abstract 4784: CD8+ tumor-infiltrating lymphocytes predict favorable prognosis in malignant pleural mesothelioma

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Purpose: Defect in human leukocyte antigen (HLA) class I expression may provide tumor cell with a mechanism to escape immune recognition, while T-cell infiltration is associated with good prognosis in many cancers. However, little has been known about the role of HLA class I expression and tumor-infiltrating lymphocytes (TILs) in malignant pleural mesothelioma (MPM). In this study, we investigated the immune profile and conducted outcome analyses in MPM patients. Experimental Design: HLA class I expression and TILs (CD4+, CD8+, and NK cells) were detected by immunohistochemistry in a series of 44 MPM cases. To detect HLA class I expression, specimens were stained with the anti-pan HLA class I monoclonal antibody EMR8-5. Results: The expression of HLA class I was positive in 33 patients (75%) and heterogenous in 11 patients (25%). There was no case that showed negative HLA class I expression. The density of CD4+ and CD8+ TILs were strongly correlated (R = 0.76, p<0.001). High density of CD8+ TILs were significantly better prognostic factor for survival of patients with extrapleural pneumonectomy (p<0.05). Multivariate analysis revealed high density of CD8+ TILs to be an independent prognostic factor. Conclusion: The presence of intratumoral CD8+ T cells correlated with improved clinical outcome, raising the possibility that CD8+ T cells might play a pivotal role in anti-tumor immune response against MPMs. Thus stimulation of CD8+ lymphocytes might offer new opportunities for efficacious immunotherapy in MPM. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4784.