Prognostic Significance of Bcl-2 Expression in Non-germinal Center B-cell-Like Diffuse Large B-cell Lymphoma

Diffuse large B-cell lymphomas (DLBCLs) are a group of malignant neoplasms with extensive clinical and molecular heterogeneity. Several key genetic aberrations have been identified, such as those involving the MYC, BCL6, and BCL2 genes. Prior studies on the prognostic significance of Bcl-2 protein expression in DLBCL have been contradictory, with some suggesting it has an adverse effect, while others have shown no such association. Bcl-2 is known to be more highly expressed in the non-germinal center B-cell-like (non-GCB) subtype compared to germinal center B-cell-like (GCB) DLBCL. Non-GCB status is associated with a less favorable prognosis. This study aimed to investigate whether the expression of Bcl-2 protein in non-GCB DLBCL influences response to treatment, progression-free survival, or overall survival.

In this retrospective study, we investigated whether there was a difference in the clinical outcomes of non-GCB DLBCL cases (n = 97) that were confirmed by immunochemistry to demonstrate high levels of Bcl-2 protein expression (>50% neoplastic cells stained) when compared to those who were deemed negative based on this criterion. Response to rituximab-based induction immunochemotherapy, five-year progression-free survival, and five-year overall survival were assessed.

There was no statistically significant difference in response to treatment, five-year progression-free survival, or five-year overall survival between the patients who were positive for Bcl-2 (n = 70) compared to those who were considered Bcl-2 negative (n = 27).

High levels of Bcl-2 protein expression do not appear to be of prognostic significance in non-GCB DLBCL and therefore Bcl-2 may not be a key therapeutic target in the treatment and improvement of clinical outcome in such cases.