C-MYC and BCL2: Correlation between Protein Over-Expression and Gene Translocation and Impact on Outcome in Diffuse Large B Cell Lymphoma

Abstract

Background: Due to lack of availability of gene expression profiling (GEP) for most developing countries and clinicians; the immunohistochemistry (IHC) is mostly used in the clinical application. The aim of our study is to check the possibility of using IHC to detect MYC and BCL2 in our patients with diffuse large B-cell lymphoma (DLBCL) instead of GEP to stratify them into high and low-risk groups. This will help in a proper treatment choice of subsequent improvement in the survival outcome. Method: During the study period, 90 DLBCL patients were eligible. MYC and BCL2 evaluated by IHC and gene rearrangement by real-time PCR (RT-PCR) and correlated with clinical-pathological features and survival. Results: Through IHC, the expression of MYC, BCL2, and double expression was detected in 35.6%, 46.7% and 30% of patients, respectively. While by RT-PCR, it was 4.53±0.74 for MYC compared with 2.18±0.78 for BCL-2. Most patients with BCL2+/MYC+; double-expressor and double-hit lymphomas (DEL and DHL) had high stage (III, IV), more extra-nodal involvement, (P value <0.001) and intermediate to high International Prognostic Index (IPI) risk profile (P-value <0.001). The median overall survival was 14 months and 6 months for DEL and DHL, respectively. While all patients with DHL died during the follow-up period, the median PFS were only 2 months for DEL. There was a statistically significant correlation between mRNA of MYC and BCL2 with their protein expression (p<0.001). Conclusion: Our results confirmed the unique characters and poor outcome associated with DEL and DHL mandated the need for more intense therapy and not the standard protocol. Moreover, the significant correlation between protein overexpression and gene rearrangement may open the door for the possibility to use IHC instead of RT-PCR in developing countries.