Does Rituximab Influence the Prognostic Effect of Germinal Centre Phenotype in Diffuse Large B-Cell Lymphoma?.

PURPOSE: Germinal centre (GC) and non-GC phenotypes are predictors of outcome in diffuse large B-cell lymphoma (DLBCL), and can be used to stratify chemotherapy-treated patients into low- and high-risk groups. Our aim was to determine how combination of rituximab with chemotherapy influences GC-associated clinical outcome.

METHODS: 95 DLBCL patients treated with rituximab in combination with CHOP or CHOEP regimen (immunochemotherapy) were included in the study. The median follow-up time was 27 months. 107 patients previously treated with chemotherapy served as a historical control group. BCL-6, CD10, and MUM1 expression was analyzed immunohistochemically by means of identifying GC and non-GC phenotypes. In addition, BCL-2 expression was determined. Expression data was correlated with survival parameters.

RESULTS: Consistent with previous studies, chemotherapy-treated patients with GC phenotype displayed a significantly better overall survival (OS) than the non-GC group (70% vs 47% p=0.012). In contrast, GC-phenotype did not predict outcome in immunochemotherapy-treated patients. The OS for GC-group was 82% compared with 80% for those with non-GC phenotype (p=ns). Conversely, the relapse free survival (RFS) for patients with GC and non-GC phenotypes were 74% and 65% (p=ns), respectively. When the patients were grouped according to BCL-2 expression, survival rates among the group of BCL-2 negative patients tended to be better than in BCL-2 positive patients (OS, 94% vs 77%, p=0.097; RFS, 94% vs 66%, p=0.029).

CONCLUSIONS: Rituximab in combination with chemotherapy seems to interfere with the prognostic value of GC- and non-GC phenotypes in DLBCL. However, rituximab may have a positive impact on outcome among the patients with BCL-2 negativity.