Impact of Treatment On CD4+CTLA-4+ T Cell Subset in Brazilian Patients with Classical Hodgkin Lymphoma

Abstract

4778 Cytotoxic T lymphocyte antigen-4 (CTLA-4) is one of the basic antigens involved in immune responses regulation associated with autoimmune diseases and cancer. Its key role in regulating the immune system has made CTLA-4 an attractive target for cancer. Augmentation of the immune response via blockade of CTLA-4 has shown an improvement in survival for patients with metastatic melanoma, which prompted the Food and Drug Administration (FDA) approval of the CTLA-4 function blocking antibody Ipilimumab for this disease. Objective: The aim of the study was to evaluate the surface expression of CTLA-4 on CD4+ T cells in peripheral blood mononuclear cells (PBMC) of patients with classical Hodgkin lymphoma (cHL) at diagnosis and post-treatment and correlate these findings with clinical and epidemiological aspects. Material and Methods: This is an open study and, so far, we included 35 patients from December 2009 to December 2011. Blood was drawn at diagnosis and post-treatment (1 to 4 months after completion of therapy). The T cell phenotype was evaluated by flow cytometry using CD3, CD4, CD8, CTLA-4 and correlated to phenotypic and clinical parameters in uni- and multivariate models pre and post-treatment. Eighteen healthy blood donors volunteers were recruited as controls. In this study, only cHL patients whose histology could be confirmed and Epstein-Barr (EBV) association established were studied. All patients were HIV negative and received ABVD chemotherapy protocol and radiotherapy if necessary. Three patients relapsed, and blood was also drawn at this time. Results: From the 35 cHL patients, 17 were EBV related and 18 EBV non-related. The percentage of CD4+ T cells with CTLA-4 surface expression was significantly increased in patients with cHL at diagnosis compared with healthy controls (median 7.36 vs 2.73; P<0.001). Additionally, CD4+CTLA-4+ T lymphocytes significantly decreased following treatment and complete response (7.36 vs 4.53; p=0.008), with values similar to healthy controls (4.53 vs 2.73; p=0.07). Interestingly, CD4+CTLA-4+ T lymphocytes on relapse were significantly different from post-treatment values and similar to pre treatment. There was no difference on CD4+CTLA-4+ T lymphocytes in the EBV related and non-related cHL patients. Regarding patient's baseline characteristics, CD4+CTLA-4+ T lymphocytes strongly correlated with erythrocyte sedimentation rate (ESR) values (r=0.67; p=0.002). Conclusions: We showed that CD4+CTLA-4+ T lymphocytes are increased in Brazilian cHL patients at diagnosis compared with post-treatment values and healthy controls. These results suggest a role of CTLA-4 on Hodgkin lymphomagenesis, possibly negatively regulating host anti-tumor immune response. The promising immunotherapy regimen targeting CTLA-4 might be beneficial in classical Hodgkin lymphoma. Disclosures: No relevant conflicts of interest to declare.