Prognostic Significance of EBV Association in Diffuse Large B-Cell Lymphoma in the Rituximab Era

Introduction: Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous group of diseases in terms of morphology, immunohistochemistry and molecular features. The prognostic factors of DLBCL in the rituximab era are different from previously reported prognostic factors. Hans, et al. reported that patients with non-germinal center B-cell like (GCB)-type DLBCL had a significantly poorer prognosis than those with GCB-type DLBCL in the pre-rituximab era. In patients who received rituximab combination chemotherapy, there is a report that did not find a difference in survival ratio between those with GCB DLBCL or non-GCB DLBCL. On the other hand, there was a report that found a difference in survival ratio between patients with GCB DLBCL and those with non-GCB DLBCL. In addition, the previously reported that patients with Epstein-Barr virus (EBV)-positive DLBCL had a significantly poorer prognosis than those with EBV-negative DLBCL in the pre-rituximab era. In the present study, we considered the prognostic factors of DLBCL patients who received rituximab combined chemotherapy.

Patients and Methods: The subjects were 209 DLBCL patients in whom immunohistochemical markers (CD20, CD5, CD10, BCL-2, BCL-6, MUM-1) could be analyzed. In addition, 86 patients were examined EBV-encoded RNA (EBER) in situ hybridization. Pathologic evaluation of the materials from each patient was performed at several central review meetings by six hematopathologists in the ALTSG pathology review board. Patients were treated with cyclophosphamide, vincristine, bleomycin, etoposide, doxorubicin, and prednisolone (CyclOBEAP) regimen or CHOP regimen. Rituximab was administered to all patients. One hundred forty-six DLBCL patients who underwent CHOP-like therapy were assumed as historical controls. The median follow-up period was 69 months (range, 46-88months).

Results: In the R-chemotherapy and CHOP-like groups, patients with stage III or IV disease comprised 57% and 67%, respectively, patients with performance status≧2 comprised 32% and 23%, respectively, and patients with serum LDH >normal comprised 61% and 69%, respectively.  There were no significant differences in clinical characteristics between the R-chemotherapy group and CHOP-like group.  BCL2 was positive in 72 (55%) of the 131 patients who received the R-chemotherapy and in 71 (50%) of the 142 patients who received the CHOP-like regimen. When the 209 patients who received the R- chemotherapy group were divided into the GCB group and the non-GCB group, the GCB group consisted of 74 patients (35%) and the non-GCB group consisted of 135 patients. The relationships between immunohistological markers and outcome among the patients with DLBCL who received CHOP-like therapy were studied. CD5, CD10, and BCL6 had no prognostic impact on 5-year overall survival (OS) and progression-free survival (PFS) rates. When the patients were divided into the GCB DLBCL and non-GCB DLBCL groups, the 5-year PFS of the GCB group was 78% and that of the non-GCB group was 48% (p=0.0008). Next, the effect of rituximab with chemotherapy was examined. CD5, CD10, BCL2, BCL6, and MUM-1 had no prognostic impact on 5-year OS and PFS rates. When the patients were divided into the GCB DLBCL (n=74) and non-GCB DLBCL (n=135) groups, the 4-year PFS of the GCB group was 79% and that of the non-GCB group was 73%, showing no significant difference.

We also evaluated the significance of EBER expression among patients by incorporating the EBV-positive DLBCL (n=14) and EBV-negative DLBCL (n=72).There were no significant differences in immunophenotyping analysis between the EBV-positive DLBCL and EBV-negative DLBCL. As for EBER expression in DLBCL, the 4-year PFS of the EBER-positive group was 37% and that of the EBER-negative group was 75% (P=0.007), indicating that the EBER-positive group showed significantly poorer prognosis. The 4-year OS of the EBER-positive group was 50% and the EBER-negative group was 86% (P=0.0005).

Conclusions: The EBER may be an important prognostic factor in patients with DLBCL who underwent R-chemotherapy therapy.